Error Resilience and Concealment Techniques for Packet Video Transmission

The Hong Kong University of Science and Technology
Department of Computer Science and Engineering


PhD Thesis Defence


Title: "Error Resilience and Concealment Techniques for Packet Video 
Transmission"

By

Miss Mengyao Ma


Abstract

Since the quality of compressed video is vulnerable to errors, video 
transmission over unreliable Internet is very challenging today. In this 
thesis, two important issues about robust packet video transmission are 
investigated.

The first issue is error resilient (ER) video compression. Motivated by 
two-hypothesis motion-compensated prediction (THMCP), we first propose an 
error resilient video coding technique, where two-hypothesis and 
one-hypothesis predictions are alternately used to encode the video 
stream. We use some schemes to determine which kind of prediction should 
be used, so that in some cases of frame losses, the propagated error can 
be first decreased to some extent before it spreads to the subsequent 
frames. Then we extend the previous work for THMCP to a more generalized 
one, i.e. the reference frames can be some distance from the current 
frame, instead of only the immediately preceding ones. Three types of 
prediction patterns are proposed and implemented by the generalized B 
pictures in H.264/AVC. In the case of a single frame loss during the 
transmission, the induced error propagation is analyzed and the 
closed-form expression for error energy is derived.

The second issue is error concealment (EC) for packet losses in video 
transmission. We first propose an error concealment algorithm to 
reconstruct a lost INTER-frame in the odd/even temporal sub-sampling MDC. 
The neighboring frames in the error-free stream are used to temporally 
interpolate the lost frame, based the preserved motion vector in this 
correct stream. To further improve the reconstructed video quality after 
the lost one, we also propose a multi-hypothesis error concealment (MHC) 
algorithm. In addition to error-concealing the lost frame, MHC also 
applies temporal interpolation to some additional frames after the frame 
loss so as to reduce propagated error quickly. After discussing the EC 
algorithms for INTER-frame losses, we propose two algorithms to 
error-conceal a lost INTRA-frame. The novelty is that not only the 
INTRA-frame but also the subsequent INTER-frames are error concealed based 
on the strong correlation between adjacent pixel values. In addition, 
motion compensation is used to reconstruct the INTER-pixel which has an 
INTRA-pixel in its motion trajectory. Finally, we propose an edge-directed 
error concealment algorithm to recover lost slices in FMO-encoded video. 
The strong edges in a corrupted frame are estimated first, which are then 
used to direct the recovery of the structure regions and the remaining 
erroneous regions.


Date:			Thursday, 22 January 2009

Time:			2:00p.m.-4:00p.m.

Venue:			Room 3501
 			Lifts 25-26

Chairman:		Prof. Vladimir Chigrinov (ECE)

Committee Members:	Prof. Gary Chan (Supervisor)
 			Prof. Oscar Au (Supervisor, ECE)
 			Prof. Albert Chung
 			Prof. David Rossiter
 			Prof. Bertram Shi (ECE)
 			Prof. Nam Ling (Comp. Engg., Santa Clara Univ.)


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