#6 Image and Video Processing

8/12/2019 #6 Image and Video Processing

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4. Resolution this is the number of pixels present in the images of the video.This determines whether your video is standarddefinition or high definition. The higher theresolution the clearer the image the bigger thefile.

File size & Quality


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VIDEO ANDSOUND

FORMAT


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VIDEO FORMAT

Video formats involve two distinct, and verydifferent technology concepts: containers(sometimes called wrappers) & codecs(short for coder/decoder).


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AUDIO FORMAT

Codecs are used inside of a container and because of this video formats can beconfusing.


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Container

The container describes the structure ofthe file: where the various pieces are stored,how they are interleaved, and which codecsare used by which pieces. It may specify anaudio codec as well as video. It is used to

package the video & its components(audio/metadata) and is identified (usually)

by a file extension such as .AVI, .MP4 or

MOV.


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Codec

A codec (short for "coder/decoder") is awayof encoding audio or video into a stream of

bytes. It is the method used to encode thevideo and is the chief determiner of quality.


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AVI (Video for Windows)

AVI (Audio Video Interleave) is Microsoft's videoformat. Files are identified with AVI suffix.

Video for Windows drivers are included in theWindows 95 operating system, and AVI files can beviewed with Windows Media Player. In Windows3.11, Video for Windows has to be installedseparately.

AVI files can be used with PDF documents byinserting them into a PDF document in AdobeAcrobat Exchange program.


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MPEG (Moving Picture ExpertsGroup)

MPEG is a compression method for videoand audio. MPEG files are identifiedwith MPG suffix for videoand MP2 or MP3 for audio.

MPEG audio files (MP3) can be played withmany different programs.


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QuickTime

QuickTime is a video format developed by Apple.QuickTime files are identified with MOV or QT suffix.

QuickTime files can be viewed with the Movie Player program .

QuickTime files can be used with PDF documents byinserting them into a PDF document in Adobe AcrobatExchange program.


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WAV (Windows Wave Format)

WAV is a Windows sound format. Files areidentified with WAV suffix.

With most sound cards some kind ofsoftware is included for digitizing and editingWAV files. Software for editing WAV filescan also be found on the web as freeware orshareware programs.


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MIDI (Musical Instrument

Digital Interface)MIDI is like SGML of music. In comparison to digitizedaudio files such as WAV, MIDI files contain instructionsabout what is the instrument sound, its pitch and how long itwill be played etc. Usually these instructions are sent tosynthesizer but also soundcards can produce sound fromMIDI files.

MIDI files are usually identified with MID suffix.


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Bit rate

Bit rate is the number of bits that are conveyed or processed per unit of time.

The bitrate depends on several factors:a) The original material may be sampled at differentfrequencies

b) The samples may use different numbers of bitsc) The data may be encoded by different schemes


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Video Bit Rates

16 kbit/s videophone quality (minimum necessary for a consumer-acceptable"talking head" picture using various video compression schemes)128 384 kbit/s business-oriented videoconferencing quality using videocompression

1.5 Mbit/s max VCD quality (using MPEG1 compression) 3.5 Mbit/s typ Standard-definition television quality (with bit-rate reduction from MPEG-2compression)9.8 Mbit/s max DVD (using MPEG2 compression)8 to 15 Mbit/s typ HDTV quality (with bit-rate reduction from MPEG-4 AVCcompression)19 Mbit/s approximate HDV 720p (using MPEG2 compression)24 Mbit/s max AVCHD (using MPEG4 AVC compression)25 Mbit/s approximate HDV 1080i (using MPEG2 compression)29.4 Mbit/s max HD DVD40 Mbit/s max Blu-ray Disc (using MPEG2, AVC or VC-1 compression)


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Reference:

The Scientists and Engineers Guide to Digital Signal Processing 2 nd Edition by Steven W. Smith

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#6 Image and Video Processing