NORTHWESTERN POLYTECHNICAL UNIVERSITY

SCHOOL OF ELECTRONICS AND INFORMATION

DEPARTMENT OF COMMUNICATION

MAJOR COMMUNICATION AND INFORMATION SYSTEMS

ASSIGNMENT OF SOURCE CODING THEORY AND APPLICATION

LECTURE Associated Prof WAN Shuai

DONE by Gaspard GASHEMA

Date21st March2013

ASSIGNMENT 1

We are asked to show that for a discrete source x the entropy is maximized when the output symbols are equally probable

ANSWER

To solve this problem let us consider tossing a coin with two cases

For one case its probabilities of coming up heads or tails are known but not necessarily fair

The second case its probabilities of coming up heads or tails are known and fair

For these two cases the entropy of the unknown result of the next toss of the coin is maximized if only the coin is fair (that is if heads and tails both have equal probability 12) otherwise the entropy will not be maximized Normally this is the situation of maximum uncertainty as it is most difficult to predict the outcome of the next toss the result of each toss of the coin delivers a full 1 bit of information as we are going to see them below

Consider a source that emits a sequence of statistically independent letters where each output letter is either 0 with probability q or 1 with probability 1-qThe entropy of this source isAs we will see on graph of Entropy against Probability of outcomes the maximum value of the entropy function occurs atq=05 where H(05)=1

H ( X ) equiv H (q) = minusq log q minus (1minus q)log (1minus q)

FigureGraph of Entropy against Probability of outcomes

As the above graph showsthe enthropy of the coin(fair case) will be maximum only when q=05Remember that the two probabilities are both equal ie q=12 and p=1-p=1-05=05Therefore also the graph shows the value of entropy for this system Its value is 1bi letter

However if we know the coin is not fair but comes up heads or tails with probabilities p and q where p ne q then there is less uncertainty Every time it is tossed one side is more likely to come up than the other The reduced uncertainty is quantified in a lower entropy on average each toss of the coin delivers less than a full 1 bit of information

For this case let us calculate the entropy when p=08As q=1-p we have q=1-08=02The entropy for this case will be

q=0 where H(05)=1H ( X ) equiv H (q) = minusq log q minus (1minus q)log (1minus q)

The extreme case is that of a double-headed coin that never comes up tails or a double-tailed coin that never results in a head Then there is no uncertainty The entropy is zero each toss of the coin delivers no information

Consider the case for a fair dice with of faces with probability p(1)=14p(2)=14p(3)=14 and p(4)=14 equally probable case

Entropy of e1hellipen is maximized when p1=p2=hellip=pn=1n 1048774 H(e1hellipen)=log2nNo symbol is ldquobetterrdquo than the other or contains more Information 2k symbols must be represented by k bits1048774 Entropy of e1hellipen is minimized when p1=1 p2=hellip=pn=0 H(e1hellipen)=0

Therefore entropy of will be calculated as follows

H(x)=-[14log2(14)+ 14log2(14)+ 14log2(14)+ 14log2(14)]= -44log(14)= - log2(14)=log24=2 bitssymbol

Let us see the the value of this entropy when the dice is unfair with probability p(1) = 12 p(2) =14 p(3) = p(4) = 18

The entropy for this case will be H(x)=-[ 12 log2(12)+14 log2(14)+18log2(18)+ 18log2(18)]=74 bitssymbol

As you see from those above two examples the entropy for fair case is always greater than that of unfair case

For generalization first consider a set of possible outcomes (events)

with

qual probability

The entropy of source for this outcomes will be

with the base of the logarithm is

Where p(xi)=1n the probability of each outcome as the output symbols are equally probable the above formula will become

Finally Thus the entropy becomes maximized

ASSIGNMENT 2

The problem consists of writing a program to implement Run length coding for 1100000000011000000101011111111

ANSWER

To solve this probremI have used matlab as programming language

Run length coding

Run length coding

Run Length Encoder EE113D Project function encoded = RLE_encode(input) my_size = size(input) length = my_size(2) run_length = 1 encoded = [] for i=2length if input(i) == input(i-1) run_length = run_length + 1 else encoded = [encoded input(i-1) run_length] run_length = 1 end end if length gt 1 Add last value and run length to output encoded = [encoded input(i) run_length] else Special case if input is of length 1

encoded = [input(1) 1] end

After Saving this matlab code with ldquoRLC_encoderdquo as file name you will run it using Window commend as follow

gtgt RLE_encode([1 1 0 0 0 0 0 0 0 0 0 1 0 1 0 1 1 1 1 1 1 1 1 ])

ans =

1 2 0 9 1 1 0 1 1 1 0 1 1 8 This means (1)2(0)9(1)1(0)1(1)1(0)1(1)8

ASSIGNMENT 3

The problem consists of finding or writing a JPEG and a JPEG 2000 algorithm to run both at same compression ratio my own photo

ANSWER

NB

The original photo is in JPEG format

Compression for both JPEG and JPEG2000 formats is 12 ie 50

Therefore to do this question two different softwares were used These softwares used are Adobe Photosho(PS) CS6 and JPEG 2000 Studio Adobe Photoshop CS6 was used to run(compress) original photo(Image) in JPEG format while JPEG2000 Studio used to run the same original Image in JPEG 2000 format

There were two steps to do this problem

The first step consists of taking this original photo compressing it then save it JPEG format using Adobe Photoshop CS6 (PS)

The size of image before compression is 231MB

When you run this image in Matlab when you type commend ldquoimread(lsquofile name of original Imagersquo) in matlab commend window then aigain you type commend ldquo whosrdquoin this matlab commend windowthe information of the size for this original image will look like

Name Size Bytes Class Attributes

ans 1944x2592x3 15116544 uint8

Information of Image after compression

1 Compression using Adobe Photoshop

After compressing this original Image and save it in JPEG format the size of it became 115 KBBy using Matlab commend in matlab window comment the information of this image after compression is

Name Size Bytes Class Attributes

ans 972x1296x3 3779136 uint8

NBAs I have mentioned on the beginning of the answer of this probmemthe compression ratio is 12(ie 50 ) and I chose medium quality to compress this image using this method

2 Compression using JPEG2000 format

When I used JPEG 2000 Studio software for Compressing this original Imageafter compression ist size became 295 KB

The information of Image in matlab commend window

NBTo compress these image using those two different softawes I have mentioned above I tried to do all possible in order to get at least images which was not degraded too much To do this my object is to compare the quality of the output image form those two different software

Discussions and Conclusion

From that information of Image in two cases above(for compressed cases) it is clear that the size of Image after compression using Adobe Photoshop is less than that obtained after compression using JPEG 2000 Studio When you compare these two quantities

using the rule of ratio ie 295115 which give 2565 cong 3 This means that when I take

original Image with 231MB as its size the result of this original Image after compressing and saving it using Adobe Photoshop CS6( in JPEG format) is approximately 3 times less than that obtained after compression using JPEG 2000 studio But at the other hand the quality of Image in JPEG 2000 is better than that of obtained after compression in JPEG format

ASSIGNMENT 4

We are required to find video stream with errors and try to explain how the errors propagate and they stop

To explain how errors propagate in video stream let make a quick look how video encoder work for decoding video

To see the diagram the below schematic block diagram of a typical encoder explains it in details Therefore let the schematic of a typical video encoder is shown in Figure below For video coding a frame is divided into MBs of 16x16 pixels For each MB motion estimation finds the best match from the reference frame(s) by minimizing the difference between the current MB and the candidate MBs (from the reference frame) These residual MBs form a residual frame that is essentially the difference between the current frame and the corresponding motion compensated predicted frame Simultaneously motion vectors (MVs) are used to encode the locations of MBs that have been used to each MB in the current frame The residual frame is then transformed through DCT or integer transform and quantized Usuallythe quantized coefficients and the MVs are coded by variable length codes (VLCs) The VLCs (egHuffman code arithmetic code) achieve a higher compression ratio compared to the fixed length codesand hence the VLC schemes have been extensively used in almost all coding standards to encode various syntax elements For every coded frame the encoder transmits the transformed coefficients motion vectors and some header information essential for decoding Some frames known as intra-frame in the video sequence are coded without using motion estimationcompensation

FigureThe block diagram of a typical video encoder

When the compressed video bitstream is transmitted over a communication channel it is subjected to channel errorsnoise Generally forward error correction (FEC) code is used for protecting data against channel errors The FEC is effective for random errors but inadequate in the case of long-duration bursterrors For this the study of the use of hierarchical quadratic amplitude modulation (QAM) for channel modulation is required This scheme provides unequal protection to the bits depending on theirpriority level The symbols with the same high priority bits are assigned to the same QAM constellation cluster and any two neighboring nodes in a cluster only differ in one bit This scheme provides asignificant PSNR improvement when the channel SNR is lowerTo handle the errors the following stages are required

Error detection and localizationResynchronizationError concealment

Error detection is done with the help of video syntax andor semantics When violation of video semanticssyntax is observed decoder reports an error and tries to resynchronize at the next start codewhich is typically a long codeword and different from any combination of other possible codes For some video coding standards (eg MPEG-4) which use reversible variable length codes (RVLCs) data is recovered from the corrupted packet by carrying out decoding in backward direction Therefore the corrupted packets are simply discarded and the lost region of video frame is concealed The error concealment schemes try to minimize the visual artifacts due to errors and can be grouped into two categories intra-frame interpolation and inter-frame interpolation In intra-frame interpolation the values of missing pixels are estimated from the surrounding pixels of the same frame without using the temporal information On the other hand the inter-frameinterpolation is done based on the corresponding region(s) of the reference frame(s) If a motion vector is missing it can be calculated based on the motion vectors of the surrounding regions

NBYou can watch this video to its errors on the following linkrdquo httpwwwyoutubecomwatchv=SSPv-xzMwOI

Apart from those have mentioned above the following are common streaming video problems

1 Website Issues

Many of the popular video streaming websites including YouTube use Adobe Flash Player Confirm that your computer is using the latest version of Adobe Flash Player To do this go to the Adobe website and download the appropriate uninstaller for your computer Once the current installation has been uninstalled go back to the Adobe website and install the most recent version of the plugin

2Firewall Issues

Firewalls may block streaming video ports If you are having problems watching streaming videos via a desktop application such as Windows Media Player and you normally have to use an proxy server to gain Web access you may have to enable your media player to also use the proxy server This option can be found in the Options or Preferences menu of your particular media player

3Internet Connection

The speed and stability of an Internet connection has a direct effect on the quality of streaming video A slow connection will result in choppy video and audio while an unstable Internet connection can result in video stopping suddenly Try to view streaming video using only a fast connection such as broadband cable or DSL If you are using a wireless broadband (Wi-Fi) connection make sure you have a strong signal

3Software Issues

Running out-of-date software can result in problems watching streaming video Other common issues include buffering problems or acceleration problems Consult your applications help file to learn how to update your media viewer to the latest version and to learn how to adjust the buffer or video acceleration

4Hardware Issues

The quality of your streaming video is dependent on the power of your graphics and sound cards Older computers may not have robust enough video or sound cards to handle modern streaming video If you have an older machine try updating the drivers for your video and sound cards to ensure the best quality

H ( X ) equiv H (q) = minusq log q minus (1minus q)log (1minus q)

FigureGraph of Entropy against Probability of outcomes

As the above graph showsthe enthropy of the coin(fair case) will be maximum only when q=05Remember that the two probabilities are both equal ie q=12 and p=1-p=1-05=05Therefore also the graph shows the value of entropy for this system Its value is 1bi letter

However if we know the coin is not fair but comes up heads or tails with probabilities p and q where p ne q then there is less uncertainty Every time it is tossed one side is more likely to come up than the other The reduced uncertainty is quantified in a lower entropy on average each toss of the coin delivers less than a full 1 bit of information

For this case let us calculate the entropy when p=08As q=1-p we have q=1-08=02The entropy for this case will be

q=0 where H(05)=1H ( X ) equiv H (q) = minusq log q minus (1minus q)log (1minus q)

The extreme case is that of a double-headed coin that never comes up tails or a double-tailed coin that never results in a head Then there is no uncertainty The entropy is zero each toss of the coin delivers no information

Consider the case for a fair dice with of faces with probability p(1)=14p(2)=14p(3)=14 and p(4)=14 equally probable case

Entropy of e1hellipen is maximized when p1=p2=hellip=pn=1n 1048774 H(e1hellipen)=log2nNo symbol is ldquobetterrdquo than the other or contains more Information 2k symbols must be represented by k bits1048774 Entropy of e1hellipen is minimized when p1=1 p2=hellip=pn=0 H(e1hellipen)=0

Therefore entropy of will be calculated as follows

H(x)=-[14log2(14)+ 14log2(14)+ 14log2(14)+ 14log2(14)]= -44log(14)= - log2(14)=log24=2 bitssymbol

Let us see the the value of this entropy when the dice is unfair with probability p(1) = 12 p(2) =14 p(3) = p(4) = 18

The entropy for this case will be H(x)=-[ 12 log2(12)+14 log2(14)+18log2(18)+ 18log2(18)]=74 bitssymbol

As you see from those above two examples the entropy for fair case is always greater than that of unfair case

For generalization first consider a set of possible outcomes (events)

with

qual probability

The entropy of source for this outcomes will be

with the base of the logarithm is

Where p(xi)=1n the probability of each outcome as the output symbols are equally probable the above formula will become

Finally Thus the entropy becomes maximized

ASSIGNMENT 2

The problem consists of writing a program to implement Run length coding for 1100000000011000000101011111111

ANSWER

To solve this probremI have used matlab as programming language

Run length coding

Run length coding

Run Length Encoder EE113D Project function encoded = RLE_encode(input) my_size = size(input) length = my_size(2) run_length = 1 encoded = [] for i=2length if input(i) == input(i-1) run_length = run_length + 1 else encoded = [encoded input(i-1) run_length] run_length = 1 end end if length gt 1 Add last value and run length to output encoded = [encoded input(i) run_length] else Special case if input is of length 1

encoded = [input(1) 1] end

After Saving this matlab code with ldquoRLC_encoderdquo as file name you will run it using Window commend as follow

gtgt RLE_encode([1 1 0 0 0 0 0 0 0 0 0 1 0 1 0 1 1 1 1 1 1 1 1 ])

ans =

1 2 0 9 1 1 0 1 1 1 0 1 1 8 This means (1)2(0)9(1)1(0)1(1)1(0)1(1)8

ASSIGNMENT 3

The problem consists of finding or writing a JPEG and a JPEG 2000 algorithm to run both at same compression ratio my own photo

ANSWER

NB

The original photo is in JPEG format

Compression for both JPEG and JPEG2000 formats is 12 ie 50

Therefore to do this question two different softwares were used These softwares used are Adobe Photosho(PS) CS6 and JPEG 2000 Studio Adobe Photoshop CS6 was used to run(compress) original photo(Image) in JPEG format while JPEG2000 Studio used to run the same original Image in JPEG 2000 format

There were two steps to do this problem

The first step consists of taking this original photo compressing it then save it JPEG format using Adobe Photoshop CS6 (PS)

The size of image before compression is 231MB

When you run this image in Matlab when you type commend ldquoimread(lsquofile name of original Imagersquo) in matlab commend window then aigain you type commend ldquo whosrdquoin this matlab commend windowthe information of the size for this original image will look like

Name Size Bytes Class Attributes

ans 1944x2592x3 15116544 uint8

Information of Image after compression

1 Compression using Adobe Photoshop

After compressing this original Image and save it in JPEG format the size of it became 115 KBBy using Matlab commend in matlab window comment the information of this image after compression is

Name Size Bytes Class Attributes

ans 972x1296x3 3779136 uint8

NBAs I have mentioned on the beginning of the answer of this probmemthe compression ratio is 12(ie 50 ) and I chose medium quality to compress this image using this method

2 Compression using JPEG2000 format

When I used JPEG 2000 Studio software for Compressing this original Imageafter compression ist size became 295 KB

The information of Image in matlab commend window

NBTo compress these image using those two different softawes I have mentioned above I tried to do all possible in order to get at least images which was not degraded too much To do this my object is to compare the quality of the output image form those two different software

Discussions and Conclusion

From that information of Image in two cases above(for compressed cases) it is clear that the size of Image after compression using Adobe Photoshop is less than that obtained after compression using JPEG 2000 Studio When you compare these two quantities

using the rule of ratio ie 295115 which give 2565 cong 3 This means that when I take

original Image with 231MB as its size the result of this original Image after compressing and saving it using Adobe Photoshop CS6( in JPEG format) is approximately 3 times less than that obtained after compression using JPEG 2000 studio But at the other hand the quality of Image in JPEG 2000 is better than that of obtained after compression in JPEG format

ASSIGNMENT 4

We are required to find video stream with errors and try to explain how the errors propagate and they stop

To explain how errors propagate in video stream let make a quick look how video encoder work for decoding video

To see the diagram the below schematic block diagram of a typical encoder explains it in details Therefore let the schematic of a typical video encoder is shown in Figure below For video coding a frame is divided into MBs of 16x16 pixels For each MB motion estimation finds the best match from the reference frame(s) by minimizing the difference between the current MB and the candidate MBs (from the reference frame) These residual MBs form a residual frame that is essentially the difference between the current frame and the corresponding motion compensated predicted frame Simultaneously motion vectors (MVs) are used to encode the locations of MBs that have been used to each MB in the current frame The residual frame is then transformed through DCT or integer transform and quantized Usuallythe quantized coefficients and the MVs are coded by variable length codes (VLCs) The VLCs (egHuffman code arithmetic code) achieve a higher compression ratio compared to the fixed length codesand hence the VLC schemes have been extensively used in almost all coding standards to encode various syntax elements For every coded frame the encoder transmits the transformed coefficients motion vectors and some header information essential for decoding Some frames known as intra-frame in the video sequence are coded without using motion estimationcompensation

FigureThe block diagram of a typical video encoder

When the compressed video bitstream is transmitted over a communication channel it is subjected to channel errorsnoise Generally forward error correction (FEC) code is used for protecting data against channel errors The FEC is effective for random errors but inadequate in the case of long-duration bursterrors For this the study of the use of hierarchical quadratic amplitude modulation (QAM) for channel modulation is required This scheme provides unequal protection to the bits depending on theirpriority level The symbols with the same high priority bits are assigned to the same QAM constellation cluster and any two neighboring nodes in a cluster only differ in one bit This scheme provides asignificant PSNR improvement when the channel SNR is lowerTo handle the errors the following stages are required

Error detection and localizationResynchronizationError concealment

Error detection is done with the help of video syntax andor semantics When violation of video semanticssyntax is observed decoder reports an error and tries to resynchronize at the next start codewhich is typically a long codeword and different from any combination of other possible codes For some video coding standards (eg MPEG-4) which use reversible variable length codes (RVLCs) data is recovered from the corrupted packet by carrying out decoding in backward direction Therefore the corrupted packets are simply discarded and the lost region of video frame is concealed The error concealment schemes try to minimize the visual artifacts due to errors and can be grouped into two categories intra-frame interpolation and inter-frame interpolation In intra-frame interpolation the values of missing pixels are estimated from the surrounding pixels of the same frame without using the temporal information On the other hand the inter-frameinterpolation is done based on the corresponding region(s) of the reference frame(s) If a motion vector is missing it can be calculated based on the motion vectors of the surrounding regions

NBYou can watch this video to its errors on the following linkrdquo httpwwwyoutubecomwatchv=SSPv-xzMwOI

Apart from those have mentioned above the following are common streaming video problems

1 Website Issues

Many of the popular video streaming websites including YouTube use Adobe Flash Player Confirm that your computer is using the latest version of Adobe Flash Player To do this go to the Adobe website and download the appropriate uninstaller for your computer Once the current installation has been uninstalled go back to the Adobe website and install the most recent version of the plugin

2Firewall Issues

Firewalls may block streaming video ports If you are having problems watching streaming videos via a desktop application such as Windows Media Player and you normally have to use an proxy server to gain Web access you may have to enable your media player to also use the proxy server This option can be found in the Options or Preferences menu of your particular media player

3Internet Connection

The speed and stability of an Internet connection has a direct effect on the quality of streaming video A slow connection will result in choppy video and audio while an unstable Internet connection can result in video stopping suddenly Try to view streaming video using only a fast connection such as broadband cable or DSL If you are using a wireless broadband (Wi-Fi) connection make sure you have a strong signal

3Software Issues

Running out-of-date software can result in problems watching streaming video Other common issues include buffering problems or acceleration problems Consult your applications help file to learn how to update your media viewer to the latest version and to learn how to adjust the buffer or video acceleration

4Hardware Issues

The quality of your streaming video is dependent on the power of your graphics and sound cards Older computers may not have robust enough video or sound cards to handle modern streaming video If you have an older machine try updating the drivers for your video and sound cards to ensure the best quality

The extreme case is that of a double-headed coin that never comes up tails or a double-tailed coin that never results in a head Then there is no uncertainty The entropy is zero each toss of the coin delivers no information

Consider the case for a fair dice with of faces with probability p(1)=14p(2)=14p(3)=14 and p(4)=14 equally probable case

Entropy of e1hellipen is maximized when p1=p2=hellip=pn=1n 1048774 H(e1hellipen)=log2nNo symbol is ldquobetterrdquo than the other or contains more Information 2k symbols must be represented by k bits1048774 Entropy of e1hellipen is minimized when p1=1 p2=hellip=pn=0 H(e1hellipen)=0

Therefore entropy of will be calculated as follows

H(x)=-[14log2(14)+ 14log2(14)+ 14log2(14)+ 14log2(14)]= -44log(14)= - log2(14)=log24=2 bitssymbol

Let us see the the value of this entropy when the dice is unfair with probability p(1) = 12 p(2) =14 p(3) = p(4) = 18

The entropy for this case will be H(x)=-[ 12 log2(12)+14 log2(14)+18log2(18)+ 18log2(18)]=74 bitssymbol

As you see from those above two examples the entropy for fair case is always greater than that of unfair case

For generalization first consider a set of possible outcomes (events)

with

qual probability

The entropy of source for this outcomes will be

with the base of the logarithm is

Where p(xi)=1n the probability of each outcome as the output symbols are equally probable the above formula will become

Finally Thus the entropy becomes maximized

ASSIGNMENT 2

The problem consists of writing a program to implement Run length coding for 1100000000011000000101011111111

ANSWER

To solve this probremI have used matlab as programming language

Run length coding

Run length coding

Run Length Encoder EE113D Project function encoded = RLE_encode(input) my_size = size(input) length = my_size(2) run_length = 1 encoded = [] for i=2length if input(i) == input(i-1) run_length = run_length + 1 else encoded = [encoded input(i-1) run_length] run_length = 1 end end if length gt 1 Add last value and run length to output encoded = [encoded input(i) run_length] else Special case if input is of length 1

encoded = [input(1) 1] end

After Saving this matlab code with ldquoRLC_encoderdquo as file name you will run it using Window commend as follow

gtgt RLE_encode([1 1 0 0 0 0 0 0 0 0 0 1 0 1 0 1 1 1 1 1 1 1 1 ])

ans =

1 2 0 9 1 1 0 1 1 1 0 1 1 8 This means (1)2(0)9(1)1(0)1(1)1(0)1(1)8

ASSIGNMENT 3

The problem consists of finding or writing a JPEG and a JPEG 2000 algorithm to run both at same compression ratio my own photo

ANSWER

NB

The original photo is in JPEG format

Compression for both JPEG and JPEG2000 formats is 12 ie 50

Therefore to do this question two different softwares were used These softwares used are Adobe Photosho(PS) CS6 and JPEG 2000 Studio Adobe Photoshop CS6 was used to run(compress) original photo(Image) in JPEG format while JPEG2000 Studio used to run the same original Image in JPEG 2000 format

There were two steps to do this problem

The first step consists of taking this original photo compressing it then save it JPEG format using Adobe Photoshop CS6 (PS)

The size of image before compression is 231MB

When you run this image in Matlab when you type commend ldquoimread(lsquofile name of original Imagersquo) in matlab commend window then aigain you type commend ldquo whosrdquoin this matlab commend windowthe information of the size for this original image will look like

Name Size Bytes Class Attributes

ans 1944x2592x3 15116544 uint8

Information of Image after compression

1 Compression using Adobe Photoshop

After compressing this original Image and save it in JPEG format the size of it became 115 KBBy using Matlab commend in matlab window comment the information of this image after compression is

Name Size Bytes Class Attributes

ans 972x1296x3 3779136 uint8

NBAs I have mentioned on the beginning of the answer of this probmemthe compression ratio is 12(ie 50 ) and I chose medium quality to compress this image using this method

2 Compression using JPEG2000 format

When I used JPEG 2000 Studio software for Compressing this original Imageafter compression ist size became 295 KB

The information of Image in matlab commend window

NBTo compress these image using those two different softawes I have mentioned above I tried to do all possible in order to get at least images which was not degraded too much To do this my object is to compare the quality of the output image form those two different software

Discussions and Conclusion

From that information of Image in two cases above(for compressed cases) it is clear that the size of Image after compression using Adobe Photoshop is less than that obtained after compression using JPEG 2000 Studio When you compare these two quantities

using the rule of ratio ie 295115 which give 2565 cong 3 This means that when I take

original Image with 231MB as its size the result of this original Image after compressing and saving it using Adobe Photoshop CS6( in JPEG format) is approximately 3 times less than that obtained after compression using JPEG 2000 studio But at the other hand the quality of Image in JPEG 2000 is better than that of obtained after compression in JPEG format

ASSIGNMENT 4

We are required to find video stream with errors and try to explain how the errors propagate and they stop

To explain how errors propagate in video stream let make a quick look how video encoder work for decoding video

To see the diagram the below schematic block diagram of a typical encoder explains it in details Therefore let the schematic of a typical video encoder is shown in Figure below For video coding a frame is divided into MBs of 16x16 pixels For each MB motion estimation finds the best match from the reference frame(s) by minimizing the difference between the current MB and the candidate MBs (from the reference frame) These residual MBs form a residual frame that is essentially the difference between the current frame and the corresponding motion compensated predicted frame Simultaneously motion vectors (MVs) are used to encode the locations of MBs that have been used to each MB in the current frame The residual frame is then transformed through DCT or integer transform and quantized Usuallythe quantized coefficients and the MVs are coded by variable length codes (VLCs) The VLCs (egHuffman code arithmetic code) achieve a higher compression ratio compared to the fixed length codesand hence the VLC schemes have been extensively used in almost all coding standards to encode various syntax elements For every coded frame the encoder transmits the transformed coefficients motion vectors and some header information essential for decoding Some frames known as intra-frame in the video sequence are coded without using motion estimationcompensation

FigureThe block diagram of a typical video encoder

When the compressed video bitstream is transmitted over a communication channel it is subjected to channel errorsnoise Generally forward error correction (FEC) code is used for protecting data against channel errors The FEC is effective for random errors but inadequate in the case of long-duration bursterrors For this the study of the use of hierarchical quadratic amplitude modulation (QAM) for channel modulation is required This scheme provides unequal protection to the bits depending on theirpriority level The symbols with the same high priority bits are assigned to the same QAM constellation cluster and any two neighboring nodes in a cluster only differ in one bit This scheme provides asignificant PSNR improvement when the channel SNR is lowerTo handle the errors the following stages are required

Error detection and localizationResynchronizationError concealment

Error detection is done with the help of video syntax andor semantics When violation of video semanticssyntax is observed decoder reports an error and tries to resynchronize at the next start codewhich is typically a long codeword and different from any combination of other possible codes For some video coding standards (eg MPEG-4) which use reversible variable length codes (RVLCs) data is recovered from the corrupted packet by carrying out decoding in backward direction Therefore the corrupted packets are simply discarded and the lost region of video frame is concealed The error concealment schemes try to minimize the visual artifacts due to errors and can be grouped into two categories intra-frame interpolation and inter-frame interpolation In intra-frame interpolation the values of missing pixels are estimated from the surrounding pixels of the same frame without using the temporal information On the other hand the inter-frameinterpolation is done based on the corresponding region(s) of the reference frame(s) If a motion vector is missing it can be calculated based on the motion vectors of the surrounding regions

NBYou can watch this video to its errors on the following linkrdquo httpwwwyoutubecomwatchv=SSPv-xzMwOI

Apart from those have mentioned above the following are common streaming video problems

1 Website Issues

Many of the popular video streaming websites including YouTube use Adobe Flash Player Confirm that your computer is using the latest version of Adobe Flash Player To do this go to the Adobe website and download the appropriate uninstaller for your computer Once the current installation has been uninstalled go back to the Adobe website and install the most recent version of the plugin

2Firewall Issues

Firewalls may block streaming video ports If you are having problems watching streaming videos via a desktop application such as Windows Media Player and you normally have to use an proxy server to gain Web access you may have to enable your media player to also use the proxy server This option can be found in the Options or Preferences menu of your particular media player

3Internet Connection

The speed and stability of an Internet connection has a direct effect on the quality of streaming video A slow connection will result in choppy video and audio while an unstable Internet connection can result in video stopping suddenly Try to view streaming video using only a fast connection such as broadband cable or DSL If you are using a wireless broadband (Wi-Fi) connection make sure you have a strong signal

3Software Issues

Running out-of-date software can result in problems watching streaming video Other common issues include buffering problems or acceleration problems Consult your applications help file to learn how to update your media viewer to the latest version and to learn how to adjust the buffer or video acceleration

4Hardware Issues

The quality of your streaming video is dependent on the power of your graphics and sound cards Older computers may not have robust enough video or sound cards to handle modern streaming video If you have an older machine try updating the drivers for your video and sound cards to ensure the best quality

Where p(xi)=1n the probability of each outcome as the output symbols are equally probable the above formula will become

Finally Thus the entropy becomes maximized

ASSIGNMENT 2

The problem consists of writing a program to implement Run length coding for 1100000000011000000101011111111

ANSWER

To solve this probremI have used matlab as programming language

Run length coding

Run length coding

Run Length Encoder EE113D Project function encoded = RLE_encode(input) my_size = size(input) length = my_size(2) run_length = 1 encoded = [] for i=2length if input(i) == input(i-1) run_length = run_length + 1 else encoded = [encoded input(i-1) run_length] run_length = 1 end end if length gt 1 Add last value and run length to output encoded = [encoded input(i) run_length] else Special case if input is of length 1

encoded = [input(1) 1] end

After Saving this matlab code with ldquoRLC_encoderdquo as file name you will run it using Window commend as follow

gtgt RLE_encode([1 1 0 0 0 0 0 0 0 0 0 1 0 1 0 1 1 1 1 1 1 1 1 ])

ans =

1 2 0 9 1 1 0 1 1 1 0 1 1 8 This means (1)2(0)9(1)1(0)1(1)1(0)1(1)8

ASSIGNMENT 3

The problem consists of finding or writing a JPEG and a JPEG 2000 algorithm to run both at same compression ratio my own photo

ANSWER

NB

The original photo is in JPEG format

Compression for both JPEG and JPEG2000 formats is 12 ie 50

Therefore to do this question two different softwares were used These softwares used are Adobe Photosho(PS) CS6 and JPEG 2000 Studio Adobe Photoshop CS6 was used to run(compress) original photo(Image) in JPEG format while JPEG2000 Studio used to run the same original Image in JPEG 2000 format

There were two steps to do this problem

The first step consists of taking this original photo compressing it then save it JPEG format using Adobe Photoshop CS6 (PS)

The size of image before compression is 231MB

When you run this image in Matlab when you type commend ldquoimread(lsquofile name of original Imagersquo) in matlab commend window then aigain you type commend ldquo whosrdquoin this matlab commend windowthe information of the size for this original image will look like

Name Size Bytes Class Attributes

ans 1944x2592x3 15116544 uint8

Information of Image after compression

1 Compression using Adobe Photoshop

After compressing this original Image and save it in JPEG format the size of it became 115 KBBy using Matlab commend in matlab window comment the information of this image after compression is

Name Size Bytes Class Attributes

ans 972x1296x3 3779136 uint8

NBAs I have mentioned on the beginning of the answer of this probmemthe compression ratio is 12(ie 50 ) and I chose medium quality to compress this image using this method

2 Compression using JPEG2000 format

When I used JPEG 2000 Studio software for Compressing this original Imageafter compression ist size became 295 KB

The information of Image in matlab commend window

NBTo compress these image using those two different softawes I have mentioned above I tried to do all possible in order to get at least images which was not degraded too much To do this my object is to compare the quality of the output image form those two different software

Discussions and Conclusion

From that information of Image in two cases above(for compressed cases) it is clear that the size of Image after compression using Adobe Photoshop is less than that obtained after compression using JPEG 2000 Studio When you compare these two quantities

using the rule of ratio ie 295115 which give 2565 cong 3 This means that when I take

original Image with 231MB as its size the result of this original Image after compressing and saving it using Adobe Photoshop CS6( in JPEG format) is approximately 3 times less than that obtained after compression using JPEG 2000 studio But at the other hand the quality of Image in JPEG 2000 is better than that of obtained after compression in JPEG format

ASSIGNMENT 4

We are required to find video stream with errors and try to explain how the errors propagate and they stop

To explain how errors propagate in video stream let make a quick look how video encoder work for decoding video

To see the diagram the below schematic block diagram of a typical encoder explains it in details Therefore let the schematic of a typical video encoder is shown in Figure below For video coding a frame is divided into MBs of 16x16 pixels For each MB motion estimation finds the best match from the reference frame(s) by minimizing the difference between the current MB and the candidate MBs (from the reference frame) These residual MBs form a residual frame that is essentially the difference between the current frame and the corresponding motion compensated predicted frame Simultaneously motion vectors (MVs) are used to encode the locations of MBs that have been used to each MB in the current frame The residual frame is then transformed through DCT or integer transform and quantized Usuallythe quantized coefficients and the MVs are coded by variable length codes (VLCs) The VLCs (egHuffman code arithmetic code) achieve a higher compression ratio compared to the fixed length codesand hence the VLC schemes have been extensively used in almost all coding standards to encode various syntax elements For every coded frame the encoder transmits the transformed coefficients motion vectors and some header information essential for decoding Some frames known as intra-frame in the video sequence are coded without using motion estimationcompensation

FigureThe block diagram of a typical video encoder

When the compressed video bitstream is transmitted over a communication channel it is subjected to channel errorsnoise Generally forward error correction (FEC) code is used for protecting data against channel errors The FEC is effective for random errors but inadequate in the case of long-duration bursterrors For this the study of the use of hierarchical quadratic amplitude modulation (QAM) for channel modulation is required This scheme provides unequal protection to the bits depending on theirpriority level The symbols with the same high priority bits are assigned to the same QAM constellation cluster and any two neighboring nodes in a cluster only differ in one bit This scheme provides asignificant PSNR improvement when the channel SNR is lowerTo handle the errors the following stages are required

Error detection and localizationResynchronizationError concealment

Error detection is done with the help of video syntax andor semantics When violation of video semanticssyntax is observed decoder reports an error and tries to resynchronize at the next start codewhich is typically a long codeword and different from any combination of other possible codes For some video coding standards (eg MPEG-4) which use reversible variable length codes (RVLCs) data is recovered from the corrupted packet by carrying out decoding in backward direction Therefore the corrupted packets are simply discarded and the lost region of video frame is concealed The error concealment schemes try to minimize the visual artifacts due to errors and can be grouped into two categories intra-frame interpolation and inter-frame interpolation In intra-frame interpolation the values of missing pixels are estimated from the surrounding pixels of the same frame without using the temporal information On the other hand the inter-frameinterpolation is done based on the corresponding region(s) of the reference frame(s) If a motion vector is missing it can be calculated based on the motion vectors of the surrounding regions

NBYou can watch this video to its errors on the following linkrdquo httpwwwyoutubecomwatchv=SSPv-xzMwOI

Apart from those have mentioned above the following are common streaming video problems

1 Website Issues

Many of the popular video streaming websites including YouTube use Adobe Flash Player Confirm that your computer is using the latest version of Adobe Flash Player To do this go to the Adobe website and download the appropriate uninstaller for your computer Once the current installation has been uninstalled go back to the Adobe website and install the most recent version of the plugin

2Firewall Issues

Firewalls may block streaming video ports If you are having problems watching streaming videos via a desktop application such as Windows Media Player and you normally have to use an proxy server to gain Web access you may have to enable your media player to also use the proxy server This option can be found in the Options or Preferences menu of your particular media player

3Internet Connection

The speed and stability of an Internet connection has a direct effect on the quality of streaming video A slow connection will result in choppy video and audio while an unstable Internet connection can result in video stopping suddenly Try to view streaming video using only a fast connection such as broadband cable or DSL If you are using a wireless broadband (Wi-Fi) connection make sure you have a strong signal

3Software Issues

Running out-of-date software can result in problems watching streaming video Other common issues include buffering problems or acceleration problems Consult your applications help file to learn how to update your media viewer to the latest version and to learn how to adjust the buffer or video acceleration

4Hardware Issues

The quality of your streaming video is dependent on the power of your graphics and sound cards Older computers may not have robust enough video or sound cards to handle modern streaming video If you have an older machine try updating the drivers for your video and sound cards to ensure the best quality

encoded = [input(1) 1] end

After Saving this matlab code with ldquoRLC_encoderdquo as file name you will run it using Window commend as follow

gtgt RLE_encode([1 1 0 0 0 0 0 0 0 0 0 1 0 1 0 1 1 1 1 1 1 1 1 ])

ans =

1 2 0 9 1 1 0 1 1 1 0 1 1 8 This means (1)2(0)9(1)1(0)1(1)1(0)1(1)8

ASSIGNMENT 3

The problem consists of finding or writing a JPEG and a JPEG 2000 algorithm to run both at same compression ratio my own photo

ANSWER

NB

The original photo is in JPEG format

Compression for both JPEG and JPEG2000 formats is 12 ie 50

Therefore to do this question two different softwares were used These softwares used are Adobe Photosho(PS) CS6 and JPEG 2000 Studio Adobe Photoshop CS6 was used to run(compress) original photo(Image) in JPEG format while JPEG2000 Studio used to run the same original Image in JPEG 2000 format

There were two steps to do this problem

The first step consists of taking this original photo compressing it then save it JPEG format using Adobe Photoshop CS6 (PS)

The size of image before compression is 231MB

When you run this image in Matlab when you type commend ldquoimread(lsquofile name of original Imagersquo) in matlab commend window then aigain you type commend ldquo whosrdquoin this matlab commend windowthe information of the size for this original image will look like

Name Size Bytes Class Attributes

ans 1944x2592x3 15116544 uint8

Information of Image after compression

1 Compression using Adobe Photoshop

After compressing this original Image and save it in JPEG format the size of it became 115 KBBy using Matlab commend in matlab window comment the information of this image after compression is

Name Size Bytes Class Attributes

ans 972x1296x3 3779136 uint8

NBAs I have mentioned on the beginning of the answer of this probmemthe compression ratio is 12(ie 50 ) and I chose medium quality to compress this image using this method

2 Compression using JPEG2000 format

When I used JPEG 2000 Studio software for Compressing this original Imageafter compression ist size became 295 KB

The information of Image in matlab commend window

NBTo compress these image using those two different softawes I have mentioned above I tried to do all possible in order to get at least images which was not degraded too much To do this my object is to compare the quality of the output image form those two different software

Discussions and Conclusion

From that information of Image in two cases above(for compressed cases) it is clear that the size of Image after compression using Adobe Photoshop is less than that obtained after compression using JPEG 2000 Studio When you compare these two quantities

using the rule of ratio ie 295115 which give 2565 cong 3 This means that when I take

original Image with 231MB as its size the result of this original Image after compressing and saving it using Adobe Photoshop CS6( in JPEG format) is approximately 3 times less than that obtained after compression using JPEG 2000 studio But at the other hand the quality of Image in JPEG 2000 is better than that of obtained after compression in JPEG format

ASSIGNMENT 4

We are required to find video stream with errors and try to explain how the errors propagate and they stop

To explain how errors propagate in video stream let make a quick look how video encoder work for decoding video

To see the diagram the below schematic block diagram of a typical encoder explains it in details Therefore let the schematic of a typical video encoder is shown in Figure below For video coding a frame is divided into MBs of 16x16 pixels For each MB motion estimation finds the best match from the reference frame(s) by minimizing the difference between the current MB and the candidate MBs (from the reference frame) These residual MBs form a residual frame that is essentially the difference between the current frame and the corresponding motion compensated predicted frame Simultaneously motion vectors (MVs) are used to encode the locations of MBs that have been used to each MB in the current frame The residual frame is then transformed through DCT or integer transform and quantized Usuallythe quantized coefficients and the MVs are coded by variable length codes (VLCs) The VLCs (egHuffman code arithmetic code) achieve a higher compression ratio compared to the fixed length codesand hence the VLC schemes have been extensively used in almost all coding standards to encode various syntax elements For every coded frame the encoder transmits the transformed coefficients motion vectors and some header information essential for decoding Some frames known as intra-frame in the video sequence are coded without using motion estimationcompensation

FigureThe block diagram of a typical video encoder

When the compressed video bitstream is transmitted over a communication channel it is subjected to channel errorsnoise Generally forward error correction (FEC) code is used for protecting data against channel errors The FEC is effective for random errors but inadequate in the case of long-duration bursterrors For this the study of the use of hierarchical quadratic amplitude modulation (QAM) for channel modulation is required This scheme provides unequal protection to the bits depending on theirpriority level The symbols with the same high priority bits are assigned to the same QAM constellation cluster and any two neighboring nodes in a cluster only differ in one bit This scheme provides asignificant PSNR improvement when the channel SNR is lowerTo handle the errors the following stages are required

Error detection and localizationResynchronizationError concealment

Error detection is done with the help of video syntax andor semantics When violation of video semanticssyntax is observed decoder reports an error and tries to resynchronize at the next start codewhich is typically a long codeword and different from any combination of other possible codes For some video coding standards (eg MPEG-4) which use reversible variable length codes (RVLCs) data is recovered from the corrupted packet by carrying out decoding in backward direction Therefore the corrupted packets are simply discarded and the lost region of video frame is concealed The error concealment schemes try to minimize the visual artifacts due to errors and can be grouped into two categories intra-frame interpolation and inter-frame interpolation In intra-frame interpolation the values of missing pixels are estimated from the surrounding pixels of the same frame without using the temporal information On the other hand the inter-frameinterpolation is done based on the corresponding region(s) of the reference frame(s) If a motion vector is missing it can be calculated based on the motion vectors of the surrounding regions

NBYou can watch this video to its errors on the following linkrdquo httpwwwyoutubecomwatchv=SSPv-xzMwOI

Apart from those have mentioned above the following are common streaming video problems

1 Website Issues

Many of the popular video streaming websites including YouTube use Adobe Flash Player Confirm that your computer is using the latest version of Adobe Flash Player To do this go to the Adobe website and download the appropriate uninstaller for your computer Once the current installation has been uninstalled go back to the Adobe website and install the most recent version of the plugin

2Firewall Issues

Firewalls may block streaming video ports If you are having problems watching streaming videos via a desktop application such as Windows Media Player and you normally have to use an proxy server to gain Web access you may have to enable your media player to also use the proxy server This option can be found in the Options or Preferences menu of your particular media player

3Internet Connection

The speed and stability of an Internet connection has a direct effect on the quality of streaming video A slow connection will result in choppy video and audio while an unstable Internet connection can result in video stopping suddenly Try to view streaming video using only a fast connection such as broadband cable or DSL If you are using a wireless broadband (Wi-Fi) connection make sure you have a strong signal

3Software Issues

Running out-of-date software can result in problems watching streaming video Other common issues include buffering problems or acceleration problems Consult your applications help file to learn how to update your media viewer to the latest version and to learn how to adjust the buffer or video acceleration

4Hardware Issues

The quality of your streaming video is dependent on the power of your graphics and sound cards Older computers may not have robust enough video or sound cards to handle modern streaming video If you have an older machine try updating the drivers for your video and sound cards to ensure the best quality

ans 1944x2592x3 15116544 uint8

Information of Image after compression

1 Compression using Adobe Photoshop

After compressing this original Image and save it in JPEG format the size of it became 115 KBBy using Matlab commend in matlab window comment the information of this image after compression is

Name Size Bytes Class Attributes

ans 972x1296x3 3779136 uint8

NBAs I have mentioned on the beginning of the answer of this probmemthe compression ratio is 12(ie 50 ) and I chose medium quality to compress this image using this method

2 Compression using JPEG2000 format

When I used JPEG 2000 Studio software for Compressing this original Imageafter compression ist size became 295 KB

The information of Image in matlab commend window

NBTo compress these image using those two different softawes I have mentioned above I tried to do all possible in order to get at least images which was not degraded too much To do this my object is to compare the quality of the output image form those two different software

Discussions and Conclusion

From that information of Image in two cases above(for compressed cases) it is clear that the size of Image after compression using Adobe Photoshop is less than that obtained after compression using JPEG 2000 Studio When you compare these two quantities

using the rule of ratio ie 295115 which give 2565 cong 3 This means that when I take

original Image with 231MB as its size the result of this original Image after compressing and saving it using Adobe Photoshop CS6( in JPEG format) is approximately 3 times less than that obtained after compression using JPEG 2000 studio But at the other hand the quality of Image in JPEG 2000 is better than that of obtained after compression in JPEG format

ASSIGNMENT 4

We are required to find video stream with errors and try to explain how the errors propagate and they stop

To explain how errors propagate in video stream let make a quick look how video encoder work for decoding video

To see the diagram the below schematic block diagram of a typical encoder explains it in details Therefore let the schematic of a typical video encoder is shown in Figure below For video coding a frame is divided into MBs of 16x16 pixels For each MB motion estimation finds the best match from the reference frame(s) by minimizing the difference between the current MB and the candidate MBs (from the reference frame) These residual MBs form a residual frame that is essentially the difference between the current frame and the corresponding motion compensated predicted frame Simultaneously motion vectors (MVs) are used to encode the locations of MBs that have been used to each MB in the current frame The residual frame is then transformed through DCT or integer transform and quantized Usuallythe quantized coefficients and the MVs are coded by variable length codes (VLCs) The VLCs (egHuffman code arithmetic code) achieve a higher compression ratio compared to the fixed length codesand hence the VLC schemes have been extensively used in almost all coding standards to encode various syntax elements For every coded frame the encoder transmits the transformed coefficients motion vectors and some header information essential for decoding Some frames known as intra-frame in the video sequence are coded without using motion estimationcompensation

FigureThe block diagram of a typical video encoder

When the compressed video bitstream is transmitted over a communication channel it is subjected to channel errorsnoise Generally forward error correction (FEC) code is used for protecting data against channel errors The FEC is effective for random errors but inadequate in the case of long-duration bursterrors For this the study of the use of hierarchical quadratic amplitude modulation (QAM) for channel modulation is required This scheme provides unequal protection to the bits depending on theirpriority level The symbols with the same high priority bits are assigned to the same QAM constellation cluster and any two neighboring nodes in a cluster only differ in one bit This scheme provides asignificant PSNR improvement when the channel SNR is lowerTo handle the errors the following stages are required

Error detection and localizationResynchronizationError concealment

Error detection is done with the help of video syntax andor semantics When violation of video semanticssyntax is observed decoder reports an error and tries to resynchronize at the next start codewhich is typically a long codeword and different from any combination of other possible codes For some video coding standards (eg MPEG-4) which use reversible variable length codes (RVLCs) data is recovered from the corrupted packet by carrying out decoding in backward direction Therefore the corrupted packets are simply discarded and the lost region of video frame is concealed The error concealment schemes try to minimize the visual artifacts due to errors and can be grouped into two categories intra-frame interpolation and inter-frame interpolation In intra-frame interpolation the values of missing pixels are estimated from the surrounding pixels of the same frame without using the temporal information On the other hand the inter-frameinterpolation is done based on the corresponding region(s) of the reference frame(s) If a motion vector is missing it can be calculated based on the motion vectors of the surrounding regions

NBYou can watch this video to its errors on the following linkrdquo httpwwwyoutubecomwatchv=SSPv-xzMwOI

Apart from those have mentioned above the following are common streaming video problems

1 Website Issues

Many of the popular video streaming websites including YouTube use Adobe Flash Player Confirm that your computer is using the latest version of Adobe Flash Player To do this go to the Adobe website and download the appropriate uninstaller for your computer Once the current installation has been uninstalled go back to the Adobe website and install the most recent version of the plugin

2Firewall Issues

Firewalls may block streaming video ports If you are having problems watching streaming videos via a desktop application such as Windows Media Player and you normally have to use an proxy server to gain Web access you may have to enable your media player to also use the proxy server This option can be found in the Options or Preferences menu of your particular media player

3Internet Connection

The speed and stability of an Internet connection has a direct effect on the quality of streaming video A slow connection will result in choppy video and audio while an unstable Internet connection can result in video stopping suddenly Try to view streaming video using only a fast connection such as broadband cable or DSL If you are using a wireless broadband (Wi-Fi) connection make sure you have a strong signal

3Software Issues

Running out-of-date software can result in problems watching streaming video Other common issues include buffering problems or acceleration problems Consult your applications help file to learn how to update your media viewer to the latest version and to learn how to adjust the buffer or video acceleration

4Hardware Issues

The quality of your streaming video is dependent on the power of your graphics and sound cards Older computers may not have robust enough video or sound cards to handle modern streaming video If you have an older machine try updating the drivers for your video and sound cards to ensure the best quality

using the rule of ratio ie 295115 which give 2565 cong 3 This means that when I take

original Image with 231MB as its size the result of this original Image after compressing and saving it using Adobe Photoshop CS6( in JPEG format) is approximately 3 times less than that obtained after compression using JPEG 2000 studio But at the other hand the quality of Image in JPEG 2000 is better than that of obtained after compression in JPEG format

ASSIGNMENT 4

We are required to find video stream with errors and try to explain how the errors propagate and they stop

To explain how errors propagate in video stream let make a quick look how video encoder work for decoding video

To see the diagram the below schematic block diagram of a typical encoder explains it in details Therefore let the schematic of a typical video encoder is shown in Figure below For video coding a frame is divided into MBs of 16x16 pixels For each MB motion estimation finds the best match from the reference frame(s) by minimizing the difference between the current MB and the candidate MBs (from the reference frame) These residual MBs form a residual frame that is essentially the difference between the current frame and the corresponding motion compensated predicted frame Simultaneously motion vectors (MVs) are used to encode the locations of MBs that have been used to each MB in the current frame The residual frame is then transformed through DCT or integer transform and quantized Usuallythe quantized coefficients and the MVs are coded by variable length codes (VLCs) The VLCs (egHuffman code arithmetic code) achieve a higher compression ratio compared to the fixed length codesand hence the VLC schemes have been extensively used in almost all coding standards to encode various syntax elements For every coded frame the encoder transmits the transformed coefficients motion vectors and some header information essential for decoding Some frames known as intra-frame in the video sequence are coded without using motion estimationcompensation

FigureThe block diagram of a typical video encoder

When the compressed video bitstream is transmitted over a communication channel it is subjected to channel errorsnoise Generally forward error correction (FEC) code is used for protecting data against channel errors The FEC is effective for random errors but inadequate in the case of long-duration bursterrors For this the study of the use of hierarchical quadratic amplitude modulation (QAM) for channel modulation is required This scheme provides unequal protection to the bits depending on theirpriority level The symbols with the same high priority bits are assigned to the same QAM constellation cluster and any two neighboring nodes in a cluster only differ in one bit This scheme provides asignificant PSNR improvement when the channel SNR is lowerTo handle the errors the following stages are required

Error detection and localizationResynchronizationError concealment

Error detection is done with the help of video syntax andor semantics When violation of video semanticssyntax is observed decoder reports an error and tries to resynchronize at the next start codewhich is typically a long codeword and different from any combination of other possible codes For some video coding standards (eg MPEG-4) which use reversible variable length codes (RVLCs) data is recovered from the corrupted packet by carrying out decoding in backward direction Therefore the corrupted packets are simply discarded and the lost region of video frame is concealed The error concealment schemes try to minimize the visual artifacts due to errors and can be grouped into two categories intra-frame interpolation and inter-frame interpolation In intra-frame interpolation the values of missing pixels are estimated from the surrounding pixels of the same frame without using the temporal information On the other hand the inter-frameinterpolation is done based on the corresponding region(s) of the reference frame(s) If a motion vector is missing it can be calculated based on the motion vectors of the surrounding regions

NBYou can watch this video to its errors on the following linkrdquo httpwwwyoutubecomwatchv=SSPv-xzMwOI

Apart from those have mentioned above the following are common streaming video problems

1 Website Issues

Many of the popular video streaming websites including YouTube use Adobe Flash Player Confirm that your computer is using the latest version of Adobe Flash Player To do this go to the Adobe website and download the appropriate uninstaller for your computer Once the current installation has been uninstalled go back to the Adobe website and install the most recent version of the plugin

2Firewall Issues

Firewalls may block streaming video ports If you are having problems watching streaming videos via a desktop application such as Windows Media Player and you normally have to use an proxy server to gain Web access you may have to enable your media player to also use the proxy server This option can be found in the Options or Preferences menu of your particular media player

3Internet Connection

The speed and stability of an Internet connection has a direct effect on the quality of streaming video A slow connection will result in choppy video and audio while an unstable Internet connection can result in video stopping suddenly Try to view streaming video using only a fast connection such as broadband cable or DSL If you are using a wireless broadband (Wi-Fi) connection make sure you have a strong signal

3Software Issues

Running out-of-date software can result in problems watching streaming video Other common issues include buffering problems or acceleration problems Consult your applications help file to learn how to update your media viewer to the latest version and to learn how to adjust the buffer or video acceleration

4Hardware Issues

The quality of your streaming video is dependent on the power of your graphics and sound cards Older computers may not have robust enough video or sound cards to handle modern streaming video If you have an older machine try updating the drivers for your video and sound cards to ensure the best quality

FigureThe block diagram of a typical video encoder

When the compressed video bitstream is transmitted over a communication channel it is subjected to channel errorsnoise Generally forward error correction (FEC) code is used for protecting data against channel errors The FEC is effective for random errors but inadequate in the case of long-duration bursterrors For this the study of the use of hierarchical quadratic amplitude modulation (QAM) for channel modulation is required This scheme provides unequal protection to the bits depending on theirpriority level The symbols with the same high priority bits are assigned to the same QAM constellation cluster and any two neighboring nodes in a cluster only differ in one bit This scheme provides asignificant PSNR improvement when the channel SNR is lowerTo handle the errors the following stages are required

Error detection and localizationResynchronizationError concealment

Error detection is done with the help of video syntax andor semantics When violation of video semanticssyntax is observed decoder reports an error and tries to resynchronize at the next start codewhich is typically a long codeword and different from any combination of other possible codes For some video coding standards (eg MPEG-4) which use reversible variable length codes (RVLCs) data is recovered from the corrupted packet by carrying out decoding in backward direction Therefore the corrupted packets are simply discarded and the lost region of video frame is concealed The error concealment schemes try to minimize the visual artifacts due to errors and can be grouped into two categories intra-frame interpolation and inter-frame interpolation In intra-frame interpolation the values of missing pixels are estimated from the surrounding pixels of the same frame without using the temporal information On the other hand the inter-frameinterpolation is done based on the corresponding region(s) of the reference frame(s) If a motion vector is missing it can be calculated based on the motion vectors of the surrounding regions

NBYou can watch this video to its errors on the following linkrdquo httpwwwyoutubecomwatchv=SSPv-xzMwOI

Apart from those have mentioned above the following are common streaming video problems

1 Website Issues

Many of the popular video streaming websites including YouTube use Adobe Flash Player Confirm that your computer is using the latest version of Adobe Flash Player To do this go to the Adobe website and download the appropriate uninstaller for your computer Once the current installation has been uninstalled go back to the Adobe website and install the most recent version of the plugin

2Firewall Issues

Firewalls may block streaming video ports If you are having problems watching streaming videos via a desktop application such as Windows Media Player and you normally have to use an proxy server to gain Web access you may have to enable your media player to also use the proxy server This option can be found in the Options or Preferences menu of your particular media player

3Internet Connection

The speed and stability of an Internet connection has a direct effect on the quality of streaming video A slow connection will result in choppy video and audio while an unstable Internet connection can result in video stopping suddenly Try to view streaming video using only a fast connection such as broadband cable or DSL If you are using a wireless broadband (Wi-Fi) connection make sure you have a strong signal

3Software Issues

Running out-of-date software can result in problems watching streaming video Other common issues include buffering problems or acceleration problems Consult your applications help file to learn how to update your media viewer to the latest version and to learn how to adjust the buffer or video acceleration

4Hardware Issues

The quality of your streaming video is dependent on the power of your graphics and sound cards Older computers may not have robust enough video or sound cards to handle modern streaming video If you have an older machine try updating the drivers for your video and sound cards to ensure the best quality

NBYou can watch this video to its errors on the following linkrdquo httpwwwyoutubecomwatchv=SSPv-xzMwOI

Apart from those have mentioned above the following are common streaming video problems

1 Website Issues

Many of the popular video streaming websites including YouTube use Adobe Flash Player Confirm that your computer is using the latest version of Adobe Flash Player To do this go to the Adobe website and download the appropriate uninstaller for your computer Once the current installation has been uninstalled go back to the Adobe website and install the most recent version of the plugin

2Firewall Issues

Firewalls may block streaming video ports If you are having problems watching streaming videos via a desktop application such as Windows Media Player and you normally have to use an proxy server to gain Web access you may have to enable your media player to also use the proxy server This option can be found in the Options or Preferences menu of your particular media player

3Internet Connection

The speed and stability of an Internet connection has a direct effect on the quality of streaming video A slow connection will result in choppy video and audio while an unstable Internet connection can result in video stopping suddenly Try to view streaming video using only a fast connection such as broadband cable or DSL If you are using a wireless broadband (Wi-Fi) connection make sure you have a strong signal

3Software Issues

Running out-of-date software can result in problems watching streaming video Other common issues include buffering problems or acceleration problems Consult your applications help file to learn how to update your media viewer to the latest version and to learn how to adjust the buffer or video acceleration

4Hardware Issues

The quality of your streaming video is dependent on the power of your graphics and sound cards Older computers may not have robust enough video or sound cards to handle modern streaming video If you have an older machine try updating the drivers for your video and sound cards to ensure the best quality