VIDEO COMPRESSION: SUM OF ABSOLUTE DIFFRENCES

PRESENTED BY:

1. NIKUNJ HINSU2. DHAVAL KANERIA

What is VIDEO ? The technique in which images are recorded, manipulated and

displayed in a motion.

Persistence of Vision Plays an vital Role

An image shown to any human persists for 1/25th second on the retina, So if images are shown at a rate of 25 pictures per second then we wouldn’t be able to perceive the blank spaces.

A Cinema Film Roll comprises of Pictures or Frames only

Roll is projected onto screen at very high rateWhich gives feeling of Motion Picture

WHAT IS DIGITAL VIDEO?

Digital Video refers to the capturing, manipulation and storage of video in digital formats (MPEG, .avi, .mkv, etc.).

A digital video camcorder (Sony Handi-Cam ©), for example, is a video camera that captures and stores images on a digital medium

When Digital Video are transferred & modified over INTERNET the size of video really matters in terms of accessibility. So video compression is required to reduce the size upto reasonable extent

How Actually Video Compression Works ?

Compression

Lossless (Intra-Frame) Lossy (Inter-Frame)

No lose of information

Compression is comparatively low

Redundancy in consecutive frames is removed by SAD

Lose of information Occurs

Compression is comparatively high

Size compression occurs by discarding the data of frames in a video, it will ultimately reduce the quality of video.

It is used in internet telephony, video conference

LOSSLESS COMPRESSION: SUM OF ABSOLUTE DIFFRENCES

The pixels of House is steady, So not included in transmitted video

SUM OF ABSOLUTE DIFFRENCES

B

A

Go

SAD

Sad_Out

256-byte array

256-byte array

32-bits

CLOCK

A,B are the memory elements which 1 byte long and256 element deep.

By using Matlab R2012, we generate hex file which can be used for reading hexadecimal numbers to initialize memories i.e. A & B

VERILOG IMPLEMENTATION

module SADSAD(Go, outp, Clk, Rst);input Go;output reg [31:0] outp;input Clk, Rst;

reg [7:0]A [0:255];reg [7:0]B [0:255];reg [2:0]State;integer Sum, SAD_Reg;integer I;

S0 S1 S2

S4 S3

I = 0!Go

Go

VERILOG IMPLEMENTATION

I > 256

Sum=Sum+ABS(A[I]-B[I])I=I+1

I < 256

SAD_Reg = Sum

Sum = 0

VERILOG IMPLEMENTATION

initial $readmemh ("lenaorignal.txt", A);initial $readmemh ( "distorted.txt", B);

Program will start taking SAD when “GO” Pulse is being Provided

S3: begin

Sum <=Sum +ABS(A[I]-B[I]); I<= I+ 1; State <=S2;end

VERILOG IMPLEMENTATION

Function ABS depicts the Absolute Value for converting a negative difference of A & B into positive difference

function integer ABS;input integer IntVal;beginABS = (IntVal>=0)?IntVal:-IntVal;endendfunction

Xilinx Waveform

Xilinx Waveform

Xilinx Waveform

Conclusion:

Thus we successfully implemented VIDEO COMPRESSION ALGORITHM by using SUM of Absolute Differences

By using this algorithm we would be able to significantly reduce the size of VIDEO

Applications:1. Video Conferencing like Skype, Cisco WebEx

2. Video Streaming Websites like YouTube

3. Video-on-demand, Video surveillance

4. Digital storage media CD-ROM, DVD, BluRay