[FFmpeg-devel] Question about parallelizing h264 decoding

Loren Merritt lorenm
Fri May 11 06:04:39 CEST 2007

On Fri, 11 May 2007, mark cox wrote:

> I found this article while doing a google for 'cabac', "Parallel
> Decoding of Context-Based Adaptive Binary Arithmetic Codes Based on
> Most Probable Symbol Prediction"  by Chung-Hyo KIM1 and  In-Cheol
> PARK. From the abstract.
> "a prediction scheme is proposed that enhances overall decoding
> performance by decoding two binary symbols at a time. A CABAC decoder
> based on the proposed prediction scheme improves the decoding
> performance by 24% compared to conventional decoders."

Interesting, but they used an ASIC, so they can do lots of computations 
in parallel and their main problem is latency. A single CABAC 
decision is far too small to consider multithreading it, so we could 
only use instruction-level parallelism. And I doubt our CABAC 
implementation is so latency-bound that you could interleave a whole 
second copy at less than 24% cost.

--Loren Merritt

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