[FFmpeg-devel] [PATCH 3/4] VP8: token probs doesn't need padding

[Jason Garrett-Glaser]

2011/3/12 M?ns Rullg?rd <mans at mansr.com>:
> Jason Garrett-Glaser <darkshikari at gmail.com> writes:
>
>> 2011/3/11 M?ns Rullg?rd <mans at mansr.com>:
>>> Jason Garrett-Glaser <jason at x264.com> writes:
>>>
>>>> prob[0] is the only prob array ever accessed, so prob[1] can serve as padding
>>>> for prob[0].
>>>> ---
>>>> ?libavcodec/vp8.h | ? ?3 +--
>>>> ?1 files changed, 1 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/libavcodec/vp8.h b/libavcodec/vp8.h
>>>> index d3b8705..b94d453 100644
>>>> --- a/libavcodec/vp8.h
>>>> +++ b/libavcodec/vp8.h
>>>> @@ -233,8 +233,7 @@ typedef struct {
>>>> ? ? ? ? ?uint8_t golden;
>>>> ? ? ? ? ?uint8_t pred16x16[4];
>>>> ? ? ? ? ?uint8_t pred8x8c[3];
>>>> - ? ? ? ?/* Padded to allow overreads */
>>>> - ? ? ? ?uint8_t token[4][17][3][NUM_DCT_TOKENS-1];
>>>> + ? ? ? ?uint8_t token[4][16][3][NUM_DCT_TOKENS-1];
>>>> ? ? ? ? ?uint8_t mvc[2][19];
>>>> ? ? ?} prob[2];
>>>> ?} VP8Context;
>>>
>>> If only one is accessed, why are there two?
>>
>> The second is a backup. ?If update_probabilities = 0, the
>> probabilities used for the current frame are thrown away after
>> decoding it. ?So we copy the old probabilities to prob[1], use prob[0]
>> for the current frame, then restore them afterward.
>
> OK with me then.
>
> --
> M?ns Rullg?rd
> mans at mansr.com
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>

Applied.

Jason