Video compression uses the sum of absolute differences (SAD) algorithm to reduce video file sizes by removing redundancy between consecutive video frames. The SAD algorithm calculates the pixel-by-pixel differences between two frames and discards pixels that have not changed. This results in data loss but high compression ratios needed for transmitting video over the internet. The document presents the SAD algorithm and its Verilog implementation to compress a video by calculating the absolute differences between corresponding pixels in two frames and summing those differences.

1. VIDEO COMPRESSION:
SUM OF ABSOLUTE DIFFRENCES
PRESENTED BY:
1. NIKUNJ HINSU
2. DHAVAL KANERIA

2. 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.

3. A Cinema Film Roll comprises of Pictures or
Frames only
Roll is projected onto screen at very high rate
Which 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

4. How Actually Video Compression Works ?
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

5. LOSSLESS COMPRESSION:
SUM OF ABSOLUTE DIFFRENCES
The pixels of House is steady, So
not included in transmitted
video

6. SUM OF ABSOLUTE DIFFRENCES
A,B are the memory elements which 1 byte long and
256 element deep.
SAD
A
256-byte array
32-bits
B
Sad_Out
256-byte array
Go
CLOCK
By using Matlab R2012, we generate hex file which can be used for reading
hexadecimal numbers to initialize memories i.e. A & B

8. 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;

9. VERILOG IMPLEMENTATION
Sum = 0
I=0
!Go
S0
Go
S1
S2
I < 256
I > 256
SAD_Reg = Sum
S4
S3
Sum=Sum+ABS(A[I]-B[I])
I=I+1

10. 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

11. 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;
begin
ABS = (IntVal>=0)?IntVal:-IntVal;
end
endfunction

12. Xilinx Waveform

13. Xilinx Waveform

14. Xilinx Waveform

15. 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