Fig. 1. The block diagram of the proposed system.
We present a hybrid and flexible error resilient system as shown in Fig. 1, which can transform the video signal into either standard or non-standard formats. To simplify the complexity of the system, the prototype is built for H.263 videos communicating in an error-prone environment without back channel. The system is divided into three stages, and some error-resilient techniques are independently or simultaneously adopted in each stage. In addition, we can make a different selection from the implemented techniques at different times to form a variety of error resilient systems.
Fig.
1. The block diagram of the proposed system.
The error resilient tools adopted by the proposed system can be classified into six major modules.
Fig.
2. Effects
of GOB Synchronization.
Fig.
3. Effects
of Intra Refreshing.
can
be decoded in both the forward and backward directions
can be used to eliminate error propagation and enhance error-resilience capabilities.
Four
modes of error concealments are provided:
–No
concealment.
–Zero
motion error concealment.
–Using
the motion vectors obtained from the neighbors of the lost macroblock to perform
concealment.
–Using the median motion vector obtained from the neighbors above, upper right, and left to the lost macroblock to perform concealment.
n
Chien-Wu Tsai,
“Investigation of reversible variable length codes and some techniques for
error resilience in video communications”, Doctoral Dissertation,
Department of CSIE, National Taiwan University, Jun 2001 (Advisor: Prof. Ja-Ling
Wu).
n
Chien-Wu Tsai, and Ja-Ling Wu,
“On Constructing the Huffman-Code Based Reversible Variable Length Codes,”
to be published in IEEE Trans. Commun.
n
Chien-Wu Tsai, To-Ju Huang, Kuo-Lin
Fang, and Ja-Ling Wu, “A Hybrid and Flexible H.263-based Error
Resilient and Testing System”, IEEE-TENCON’2001