[FFmpeg-devel] [PATCH] lavc: report frame field order in avctx

[Rodger Combs]

> On Nov 15, 2016, at 03:43, Michael Niedermayer <michael at niedermayer.cc> wrote:
> 
> On Mon, Nov 14, 2016 at 05:19:25PM -0600, Rodger Combs wrote:
>> ---
>> libavcodec/utils.c                   | 13 +++++++++++++
>> tests/api/api-codec-param-test.c     |  3 +++
>> tests/fate/matroska.mak              |  2 +-
>> tests/ref/fate/api-mjpeg-codec-param |  2 +-
>> tests/ref/fate/api-png-codec-param   |  2 +-
>> tests/ref/fate/mov-zombie            |  2 +-
>> 6 files changed, 20 insertions(+), 4 deletions(-)
>> 
>> diff --git a/libavcodec/utils.c b/libavcodec/utils.c
>> index d6dca18..b9af880 100644
>> --- a/libavcodec/utils.c
>> +++ b/libavcodec/utils.c
>> @@ -2296,6 +2296,12 @@ fail:
>>                                                guess_correct_pts(avctx,
>>                                                                  picture->pts,
>>                                                                  picture->pkt_dts));
>> +
>> +            if (avctx->field_order == AV_FIELD_UNKNOWN) {
>> +                avctx->field_order = picture->interlaced_frame
>> +                                   ? (picture->top_field_first ? AV_FIELD_TT : AV_FIELD_BB)
>> +                                   : AV_FIELD_PROGRESSIVE;
>> +            }
>>         } else
>>             av_frame_unref(picture);
>>     } else
>> @@ -2895,6 +2901,13 @@ int attribute_align_arg avcodec_receive_frame(AVCodecContext *avctx, AVFrame *fr
>>                 av_frame_set_best_effort_timestamp(frame,
>>                     guess_correct_pts(avctx, frame->pts, frame->pkt_dts));
>>             }
>> +
>> +            if (avctx->field_order == AV_FIELD_UNKNOWN &&
>> +                avctx->codec_type == AVMEDIA_TYPE_VIDEO) {
>> +                avctx->field_order = frame->interlaced_frame
>> +                                   ? (frame->top_field_first ? AV_FIELD_TT : AV_FIELD_BB)
>> +                                   : AV_FIELD_PROGRESSIVE;
>> +            }
>>         }
>>         return ret;
>>     }
> 
> This doesnt leave any "unknown" option left.
> What should a decoder do that knows the field order is unknown

Is this a real case?

What I really need here is a stream-level "is interlaced" indicator; I've considered adding an AV_FIELD_INTERLACED_UNKNOWN value to indicate "This is interlaced, but I don't know the field order".
Thoughts?

> 
> [...]
> -- 
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
> 
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