The robustness of the recently ratified video compression standard H.264/MPEG-4 AVC against channel errors is evaluated with the focus on rate distortion matters. After a brief introduction of the standard and an explanation of its error-resistant features, it is investigated how the error resilience tools of H.264 can be deployed best for packet-wise transmission as in ATM, H.323, and IP-based services. Further, the performances of two error concealment strategies for use in an H.264-conform decoder are compared to each other.
Various techniques for SNR scalability in hybrid block-based
video coding exist in the literature and in different standards.
A new approach based on transform coefficient refinement is proposed
in this article. The coefficient difference is computed after quantization, subsequently entropy-encoded, and transmitted for reconstruction of a high-quality layer at the decoder. The approach achieves in most cases only a moderate increase in bit rate as compared to other schemes. The bit rate of our two-layer framework converges towards the rate of a single-layer system as the quality gap between both layers increases. The gains come at the cost of increased computational complexity and memory requirements.
Proc. SPIE. 4671, Visual Communications and Image Processing 2002
KEYWORDS: Automatic repeat request, Visualization, Forward error correction, Binary data, Global system for mobile communications, Multimedia, Receivers, Error analysis, Video, Information visualization
The transmission of large data streams over error-prone channels as e.g. in multimedia applications is inherently linked to long transmission delays if automatic repeat request schemes are used. As this article will show, the delay can be reasonably traded against residual bit errors if a short transmission time has highest priority. The dependency of the delay on two important factors, packet length and channel bit error rate, is determined to be non-linear and strictly monotonously growing. Furthermore, transmission behavior and properties of a plain binary symmetric channel and one with additional repeat request technique are simulated and compared to previous research. The simulations finally lead to a redefinition of the formula for the estimation of the residual bit error rate of a non-transparent channel.