<title>Error-resilient compression and transmission of scalable video</title>

Abstract

Compressed video bitstreams require protection from channel errors in a wireless channel and protection from packet loss in a wired ATM channel. The three-dimensional (3-D) SPIHT coder has proved its efficiency and its real-time capability in compression of video. A forward-error-correcting(FEC) channel (RCPC) code 1 combined with a single ARQ (automatic-repeat-request) proved to be an effective means for protecting the bitstream. There were two problems with this scheme: the noiseless reverse channel ARQ may not be feasible in practice; and, in the absence of channel coding and ARQ, the decoded sequence was hopelessly corrupted even for relatively clean channels. In this paper, we first show how to make the 3-D SPIHT bitstream more robust to channel errors by breaking the wavelet transform into a number of spatio-temporal tree blocks which can be encoded and decoded independently. This procedure brings the added benefit of parallelization of the compression and decompression algorithms. Then we demonstrate the packetization of the bit stream and the reorganization of these packets to achieve scalability in bit rate and/or resolution in addition to robustness. Then we encode each packet with a channel code. Not only does this protect the integrity of the packets in most cases, but it also allows detection of packet decoding failures, so that only the cleanly recovered packets are reconstructed. This procedure obviates ARQ, because the performance is only about 1 dB worse than normal 3-D SPIHT with FEC and ARQ. Furthermore, the parallelization makes possible real-time implementation in hardware and software.

<title>Unequal error protection of embedded video bitstreams</title>

“…We used the same set of parameters for the CRC parity checker and RCPC channel coder 10,7,8 : N = 200, c = 16, and m = 6. We focused on bit error rates (BER) of = 0.01 and 0.001, because the BER's of most wireless communication channels are = 0.01 -0.001.…”

Error-resilient image and video transmission over the internet using unequal error protection

“…The main ideas underlying these methods are 1) protecting the bitstream generated by the source coder by using strong concatenated channel codes (RCPC/CRC) [2]; 2) providing robustness by producing independently decodable packets [3]; 3) combining packetized zerotree wavelet encoding with channel codes [4]; 4) dividing wavelet coefficients into several groups and compressing each group independently [5], [6]; 5) dividing the bitstream into several substreams and protecting each substream with different channel codes [7], [8];…”

“…The algorithm allows more uncorrupted information to reach the decoder because a bit error in one group does not affect the others. The authors in [6] extended Creusere's work to a 3-D SPIHT coder and also applied the channel coding method proposed by [2] to each packet. The authors in [7] modified the SPIHT algorithm to contain a large portion of fixed rate symbols.…”

“…Now, let us define (4) as the accumulated number of source data bytes up to and including bit-plane and as the peak signal to noise ratio (PSNR) at the receiver relative to the original video sequence when the receiver decodes source data bytes, given the redundancy assignment vector . Then, the total number of source data bytes for a vector when bitplanes are transmitted is given by (5) Next, we define (6) as the amount of PSNR increment when the receiver decodes the additional bit-plane , given that all bit-planes prior to have already been decoded. We can now calculate the expected PSNR at the receiver as (7) where is the probability that packets are lost when a total of packets are transmitted, , and .…”

Combined Error Concealment and Error Correction in Rate-Distortion Analysis for Multiple Substream Transmissions

“…In recent years, some wavelet-based coders [4,5] have used FEC methods and multiple correlated bitstreams to transmit and decode each bitstream independently, which provides additional error-resilience at high loss rates [6,7,8,9,10]. The decoder, furthermore, applies a post-processing concealment procedure to the received bitstreams to conceal packets tion about the formulation and realization of our framework.…”