[FFmpeg-devel] [PATCH] lavc/hevc_ps: fix crop info

[Zhao Zhili]

On 2018年08月16日 11:46, James Almer wrote:
> On 8/16/2018 12:29 AM, Zhao Zhili wrote:
>> ---
>>   libavcodec/hevc_ps.c | 26 ++++++++++++++++++++++----
>>   1 file changed, 22 insertions(+), 4 deletions(-)
>>
>> diff --git a/libavcodec/hevc_ps.c b/libavcodec/hevc_ps.c
>> index fbd9fbf..4161ab6 100644
>> --- a/libavcodec/hevc_ps.c
>> +++ b/libavcodec/hevc_ps.c
>> @@ -628,8 +628,17 @@ static void decode_vui(GetBitContext *gb, AVCodecContext *avctx,
>>           vui->default_display_window_flag = get_bits1(gb);
>>   
>>       if (vui->default_display_window_flag) {
>> -        int vert_mult  = 1 + (sps->chroma_format_idc < 2);
>> -        int horiz_mult = 1 + (sps->chroma_format_idc < 3);
>> +        unsigned horiz_mult, vert_mult;
>> +        if (sps->chroma_format_idc == 1) {
>> +            horiz_mult = 2;
>> +            vert_mult = 2;
>> +        } else if (sps->chroma_format_idc == 2) {
>> +            horiz_mult = 2;
>> +            vert_mult = 1;
>> +        } else {
>> +            horiz_mult = 1;
>> +            vert_mult = 1;
> Can you explain what this patch is meant to do? For chroma_format_idc ==
> 1, 2 and 3 nothing changes with this, only chroma_format_idc == 0, where
> both horiz_mult and vert_mult become 1 instead of 2. Is that
> correct/intended?

Yes, this is intended. See ISO/IEC 23008-2 Table 6-1.

./ffprobe ~/Videos/hevc-monochrome.ts
     Stream #0:0[0x100]: Video: hevc (Rext) ([36][0][0][0] / 0x0024), 
gray(tv), 384x224, 15 fps, 15 tbr, 90k tbn, 15 tbc

The correct size is 384x240.

>> +        }
>>           vui->def_disp_win.left_offset   = get_ue_golomb_long(gb) * horiz_mult;
>>           vui->def_disp_win.right_offset  = get_ue_golomb_long(gb) * horiz_mult;
>>           vui->def_disp_win.top_offset    = get_ue_golomb_long(gb) *  vert_mult;
>> @@ -923,8 +932,17 @@ int ff_hevc_parse_sps(HEVCSPS *sps, GetBitContext *gb, unsigned int *sps_id,
>>           return ret;
>>   
>>       if (get_bits1(gb)) { // pic_conformance_flag
>> -        int vert_mult  = 1 + (sps->chroma_format_idc < 2);
>> -        int horiz_mult = 1 + (sps->chroma_format_idc < 3);
>> +        unsigned horiz_mult, vert_mult;
>> +        if (sps->chroma_format_idc == 1) {
>> +            horiz_mult = 2;
>> +            vert_mult = 2;
>> +        } else if (sps->chroma_format_idc == 2) {
>> +            horiz_mult = 2;
>> +            vert_mult = 1;
>> +        } else {
>> +            horiz_mult = 1;
>> +            vert_mult = 1;
>> +        }
>>           sps->pic_conf_win.left_offset   = get_ue_golomb_long(gb) * horiz_mult;
>>           sps->pic_conf_win.right_offset  = get_ue_golomb_long(gb) * horiz_mult;
>>           sps->pic_conf_win.top_offset    = get_ue_golomb_long(gb) *  vert_mult;
>>
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