[FFmpeg-devel] H.264 CABAC Decoder on IBM Cell

bajrang kumar bajrang.jnv
Thu May 7 15:24:07 CEST 2009

I want only mails as a monthely digest

On 5/7/09, Jason Garrett-Glaser <darkshikari at gmail.com> wrote:
> On Thu, May 7, 2009 at 4:39 AM, Erich Marth
> <destinationcloud at googlemail.com> wrote:
>> Dear ffmpeg Team,
>> my name is Erich Marth and I'm currently doing some research on porting
>> ffmpeg or to be more preciously the h.264 codec to the cell architecture.
>> Till now I do have a good code status, but i do suffer big problems in
>> doing an optimized version of the cabac entropy decoder.
>> F.e.: Playing Pirates III (1080p) with CAVLC, an I frame takes
>> about 18ms to decode, but trying to decode a single slices I frame from
>> a 720p cabac video takes about 100ms to decode.
> I'm going to blame the fact that the primary core of the Cell
> (stupidly) doesn't have a barrel shift unit, resulting in variable
> shifts, such as those in renormalization, being implemented in
> microcode (and correspondingly being extraordinarily slow).
> But that's just a guess.  It needs to be profiled.
> Dark Shikari
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