[FFmpeg-devel] VP8 decoder optimization status

[Stefan Gehrer]

On 06/30/2010 10:15 PM, Stefan Gehrer wrote:
> On 06/30/2010 08:54 PM, Jason Garrett-Glaser wrote:
>> On Wed, Jun 30, 2010 at 8:55 AM, Stefan Gehrer<stefan.gehrer at gmx.de>
>> wrote:
>>> On 06/29/2010 04:09 AM, Jason Garrett-Glaser wrote:
>>>>
>>>> Here's a rough guide to what's done and what needs to be done before
>>>> ffmpeg's VP8 decoder is as fast as a politician running away from an
>>>> ethics committee.
>>>
>>> [...]
>>>
>>>> C:
>>>>
>>>> Fully convert vp5/6/7/8 arithmetic coder to bytestream: eliminate the
>>>> looped renormalization.
>>>
>>> Like attached?
>>
>> We should try to reuse the h264 table if possible, IMO.
>
> If we are talking about the same table (ff_h264_norm_shift*),
> it can not be used as is,
> I think these are the options:
>
> 1. shift = 7 - av_log2_16bit(c->high);
>
> 2. shift = 7 - ff_log2_tab[c->high];
>
> 3. shift = ff_h264_norm_shift_old[c->high] + !!c->high;

3. shift = ff_h264_norm_shift_old[c->high] + 1;

as c->high should never become zero.

Stefan