The compression schemes applied for the storage and transmission of digital video data leave content sensitive to transmission errors, information loss and quality degradation. Recent developments in error resilience techniques allow improved quality of service of video communication over a range of network platforms. Digital video communications, supported by the Internet, ATM networks and Broadband ISDN, have undergone significant development over the past few years. Emerging applications include videoconferencing, tele-medicine and distance learning. This leading edge text addresses the problems associated with the delivery and design of video communication services. It presents a comprehensive overview of the principles and techniques employed in the improvement of the performance of video codecs in error prone environments. It provides a performance evaluation and comparison of video coding standards, MPEG-4, H.261 and H.2 63. It outlines methods of video communication over mobile networks. It provides guidance on quality enhancement and the meeting Quality of Service (QoS) requirements for digital video communications.Accompanying CD-ROM containing video clips illustrate the coding and error resilience technology described within the text. This is a valuable resource for researchers and postgraduate students working with video communication technology, as well as practising electronic and communications engineers designing and implementing video communication systems and consultants working in the video, television, computing and communications industries.
Table of Contents
Video quality assessment and performance
2. Overview of digital video compression
Why video compression?
User requirements from video.
Contemporary video coding schemes.
Object-based video coding.
3. Flow control in compressed video
Bit rate variability of video coders.
Fixed rate coding.
Adusting encoding parameters for rate control.
Variable quantisation step size rate control.
Improved quality rate control using ROI
Rate control using prioritised information
Rate control using the internal feedback loop.
Reduced resolution rate control.
Rate control using multi-layer coding.
Fine granular scaleability.
4. Error resilience in compressed video
Effects of bit errors on perceptual video
Error concealment techniques.
Forward error correction (FEC) in video
Duplicate MV information.
Modified H.263 for mobile channel services
Two-way decoding and reversible VLC.
Error-resilient entropy coding (EREC)
Combined error resilience schemes.
Error resilience based on reference picture
5. Video communications over mobile IP
Evolution of 3G mobile networks.
Video communications from a network
Description of future mobile networks.
QoS issues for packet video over mobile
Real-time video transmissions over mobile IP
Quality optimisation for video transmissions
over mobile networks.
Prioritised transport for robust video
transmissions over mobile networks.
Video transmissions over GPRS/UMTS networks.
6. Video transcoding.
Video transcoding for inter-network
What is transcoding?
Homogeneous video transcoding.
Bit rate reduction.
Cascaded fully decoded/re-encoding scheme.
Transcoding with re-quantisation scheme.
Transcoding with motion re-use scheme.
Transcoding with motion data re-estimation
Performance evaluation of rate reduction
Frame rate reduction.
Heterogeneous video transcoding.
Video Transcoding for error-resilience
Video transcoding for multimedia traffic