[FFmpeg-devel] [PATCH 5/5] avcodec/vc1: store zero MVs for all blocks in a MB

[Carl Eugen Hoyos]

2018-05-20 11:05 GMT+02:00, Jerome Borsboom <jerome.borsboom at carpalis.nl>:
>>> Direct prediction for interlace frame B pictures references the mv in the
>>> second block in an MB in the backward reference frame for the twomv case.
>>> When the backward reference frame is an I frame, this value may be unset.
>>>
>>> Signed-off-by: Jerome Borsboom <jerome.borsboom at carpalis.nl>
>>> ---
>>>  libavcodec/vc1_block.c | 6 ++++--
>>>  1 file changed, 4 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/libavcodec/vc1_block.c b/libavcodec/vc1_block.c
>>> index 74935ec9e9..9c170a1e3c 100644
>>> --- a/libavcodec/vc1_block.c
>>> +++ b/libavcodec/vc1_block.c
>>> @@ -2678,8 +2678,10 @@ static void vc1_decode_i_blocks_adv(VC1Context *v)
>>>              s->bdsp.clear_blocks(block[0]);
>>>              mb_pos = s->mb_x + s->mb_y * s->mb_stride;
>>>              s->current_picture.mb_type[mb_pos + v->mb_off]
>>>           = MB_TYPE_INTRA;
>>> -            s->current_picture.motion_val[1][s->block_index[0] +
>>> v->blocks_off][0] = 0;
>>> -            s->current_picture.motion_val[1][s->block_index[0] +
>>> v->blocks_off][1] = 0;
>>> +            for (int i = 0; i < 4; i++) {
>>> +                s->current_picture.motion_val[1][s->block_index[i] +
>>> v->blocks_off][0] = 0;
>>> +                s->current_picture.motion_val[1][s->block_index[i] +
>>> v->blocks_off][1] = 0;
>>> +            }
>>
>> see AV_ZERO*
>
> This style of setting motion_val to zero is used all over the VC-1
> decoder. vc1_decode_p_mb_intfr uses the exact same code. Changing to
> AV_ZERO may certainly a good point for improvement, however, for the
> sake of consistency the proposed code might be preferable.

Patch applied.

Thank you, Carl Eugen