[FFmpeg-devel] Pipeline: H.264 speed improvements

Jason Garrett-Glaser darkshikari
Tue Dec 23 13:21:31 CET 2008

On Tue, Dec 23, 2008 at 7:19 AM, Jason Garrett-Glaser
<darkshikari at gmail.com> wrote:
>> i suggest:
>> coeff= get_vlc2();
>> if(coeff<0)
>>    do escape with prefix= -coeff
> But coeff can be negative or positive: the only reserved value that it
> cannot be is zero (the idea is to make this a coeff lookup table, NOT
> a levelcode lookup table, if possible).  So we should have:
> coeff= get_vlc2();
> if(!coeff)
>    do escape with prefix= -coeff
> Also, what about the fact that we will need to "roll back" X bits in
> the case of an escape?

Oh, I see what you're trying to do here; you want to re-use coeff in
the escape process.  I don't think this will work with my proposal
given the fact that "coeff" will be "the actual coefficient value
based on the X bits read, assuming there wasn't an escape", as I don't
think its simple to re-derive the original bits from these X bits and
probably easier to just show_bits/skip_bits as necessary...

Dark Shikari

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