Implementation of Video Layering in Multicast Transmission L. Suniga, I Tabios, J. Ibabao Computer Networks Laboratory University of the Philippines

APAN –Fukuoka 2003University of the Philippines Problem How to deliver scalable multicast video over networks with varying bandwidth constraints without compromising quality? 100 Mbps 10 Mbps

APAN –Fukuoka 2003University of the Philippines Problem Congestion on the slow links Limit data to fit slowest link  everybody suffers Encode and send different files depending on connection speed  processor intensive  user must know link speed

APAN –Fukuoka 2003University of the Philippines Solution Split video information over a number of layers and have clients receive only the layers they need 100 Mbps 10 Mbps 100 Mbps 10 Mbps

APAN –Fukuoka 2003University of the Philippines How do you layer video? Use wavelet coding scheme –Multi-resolution analysis: time scale representation of a signal using digital filtering techniques –Discrete Wavelet Transform (DWT) Decompose the signal to its course approximation and its detailed approximation Half-band filters Upsampling / Downsampling

APAN –Fukuoka 2003University of the Philippines Discrete Wavelet Transform High-pass filter Low-pass filter

APAN –Fukuoka 2003University of the Philippines Software Design Video Compression Module Transport Module Video Decompression Module Rate Control Module Client Interface Module Multicast Network Multicast Network Server-side moduleClient-side module C/C++ VB6, OpenGL

APAN –Fukuoka 2003University of the Philippines Server Compression Module Raw AVI DIB File Format Convert RGB frame to 4:2:2 YCrCb Frame Get each frame ONE FRAME Y Coeff Cr Coeff Cb Coeff For each coeff 5-level FDWT, quantization thresholding Put result to DWT file Y base layer Y layer 1 Y layer 2 Y layer 3 Y layer 4 Cr base layer Cr layer 1 Cr layer 2 Cr layer 3 Cr layer 4 Cb base layer Cb layer 1 Cb layer 2 Cb layer 3 Cb layer 4 DWT FILE Code Table Y base layer Y layer 1 Y layer 2 Y layer 3 Y layer 4 Cr base layer Cr layer 1 Cr layer 2 Cr layer 3 Cr layer 4 Cb base layer Cb layer 1 Cb layer 2 Cb layer 3 Cb layer 4 HUFFMAN FILE Build Huffman tree & code table Perform Huffman compression Source Encoder (DWT) Quantizer Huffman Encoder Daubechies-6 Raw video file (Per layer) Transport

APAN –Fukuoka 2003University of the Philippines Server Transport Code Table Compressed Y base layer Compressed Y layer 1 Compressed Y layer 2 Compressed Y layer 3 Compressed Y layer 4 Compressed Cr base layer Compressed Cr layer 1 Compressed Cr layer 2 Compressed Cr layer 3 Compressed Cr layer 4 Compressed Cb base layer Compressed Cb layer 1 Compressed Cb layer 2 Compressed Cb layer 3 Compressed Cb layer 4 HUFFMAN FILE Join base multicast group Any client? None At least one Send code table Send base layer L1 request? Open layer 1 multicast address & send layer 1 coefficients L2 request? L3 request? Open layer 2 multicast address & send layer 2 coefficients Open layer 3 multicast address & send layer 3 coefficients L4 request? Open layer 4multicast address & send layer 4coefficients

APAN –Fukuoka 2003University of the Philippines Client Side Join base multicast group & connect to server Code Table Compressed Y base layer Compressed Y layer 1 Compressed Y layer 2 Compressed Y layer 3 Compressed Y layer 4 Compressed Cr base layer Compressed Cr layer 1 Compressed Cr layer 2 Compressed Cr layer 3 Compressed Cr layer 4 Compressed Cb base layer Compressed Cb layer 1 Compressed Cb layer 2 Compressed Cb layer 3 Compressed Cb layer 4 HUFFMAN FILE Receive code table Receive base layer Add new layer Rebuild Huffman tree IDWT YUV-to- RGB Congestion ? Drop new layer None, probe succesful Yes, probe failed

APAN –Fukuoka 2003University of the Philippines Testing 10 Mbps 100 Mbps Client1 Client2

APAN –Fukuoka 2003University of the Philippines Results Time (sec) Base Layer 1 Layer 2 Layer 3 Layer 4 Client1 (10 Mbps) Client2 (100 Mbps)

APAN –Fukuoka 2003University of the Philippines Problems Encountered Asymmetrical system –Off-line compression, real-time decompression –Slow display  graphics card &processor specific “Live” testing with more clients Not that easy to implement multi-threading

APAN –Fukuoka 2003University of the Philippines Recommendations Develop a faster codec to enable smoother playback Perform inter-frame techniques to achieve better compression Experiment on the optimum “probe window” length (dynamic or fixed?)

APAN –Fukuoka 2003University of the Philippines Thank you! Robe Polikar’s Wavelet Tutorial Based on the paper “Highly-Scalable Wavelet-Base Video Codec for Low Bit Rate Environment” Tham, Ranganath, Kassim. IEEE Journal on Selected Areas in Communications, January 1998.