Layered Coding Basic Overview

Outline Pyramidal Coding Scalability in the Standard Codecs Layered Coding with Wavelets Conclusion

Laplacian w/ Gaussian Pyramids

Laplacian w/ DCT Coefficient Pyramids

DCT Pyramid Example Figure 7.5

Reconstruction Data for Fig. 7.5

Scalability in the Standard Codecs Data Partitioning Signal-to-Noise Ratio (SNR) Spatial Temporal

Data Partitioning

SNR Scalable Coder

SNR Scalability – no drift

Spatial Scalability

Temporal Scalability

Scalability Applications Data Partitioning – Video of ATM networks SNR – Transmission of video at different qualities Video on demand, simultaneous TV and enhanced TV – Video over high packet loss networks (Internet) Spatial Scalability – Internetworking between two different standards – Simulcasting of drift-free video (TV & HDTV)

Scalability Applications Spatial Scalability (continued) – Reception of low spatial resolution pictures over mobile networks Temporal Scalability – Migration to HDTV from current interlaced – Internetworking between mobile and fixed networks

Layered Coding with Wavelets Growing interest due to new efficient coding techniques (Embedded Zero-tree Wavelets, or EZW) Accepted for coding of still images – MPEG-4 and JPEG 2000 Predicted to continues in growth

Discrete Wavelet Transform Split signal spectrum into several frequency bands analysis filters Figs. 7.27, 7.28, 7.29

Distortions

Filter Bank Solutions

Higher Order Systems Multiple wavelet transform coding by means of repeated two-band splits

Further Considerations Wavelet Example – Fig Zero-Tree Coding – Fig Quad-Tree Representation - Bands look like scaled versions of each other - Lower bands have 0.25 dimension of higher

Conclusion Layered coding facilitates – Error protection – Efficient use of resources – Multiple services – Customer satisfaction