layered coding basic overview. outline pyramidal coding scalability in the standard codecs layered...
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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. 7.32
• Zero-Tree Coding – Fig. 7.34
• 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