2002 IEEE International Conference on Computer Design (ICCD'02)
Parallel Multiple-Symbol Variable-Length Decoding
Freiburg, Germany
September 16-September 18
ISBN: 0-7695-1700-5
In this paper, a parallel Variable-Length Decoding (VLD) scheme is introduced. The scheme is capable of decoding all the codewords in an N-bit buffer whose accumulated codelength is at most N. The proposed method partially breaks the recursive dependency related to the MPEG-2 VLD. All possible codewords in the buffer are detected in parallel and the sum of the codelengths is provided to the external shifter aligning the variable-length coded input stream for a new decoding cycle. Two length detection mechanisms are proposed: the first approach determines the length in a parallel/serial fashion and the second using a new device denoted as MultiplexedAdd. In order to prove feasibility and determine the limiting factors of our proposal, the parallel/serial codeword detector with 32-bit input has been described in behavioral non-optimized VHDL and mapped onto Altera?s ACEX EP1K100 FPGA. The implemented prototype exhibits a latency of 110 ns and uses 32% of the logic cells of the device. When applied to MPEG-2 standard benchmark scenes, on average 3.5 symbols are decoded per cycle.
Citation:
Jari Nikara, Stamatis Vassiliadis, Jarmo Takala, Mihai Sima, Petri Liuha, "Parallel Multiple-Symbol Variable-Length Decoding," iccd, pp.126, 2002 IEEE International Conference on Computer Design (ICCD'02), 2002