[FFmpeg-devel] [PATCH] avcodec/decode: do not treat discarded frames as eof when draining

[Muhammad Faiz]

On Sun, Apr 30, 2017 at 8:31 PM, wm4 <nfxjfg at googlemail.com> wrote:
> On Sun, 30 Apr 2017 14:04:33 +0700
> Muhammad Faiz <mfcc64 at gmail.com> wrote:
>
>> Fix fate failures:
>>   make fate-mov THREADS=32
>>
>> Signed-off-by: Muhammad Faiz <mfcc64 at gmail.com>
>> ---
>>  libavcodec/decode.c | 12 ++++++------
>>  1 file changed, 6 insertions(+), 6 deletions(-)
>>
>> diff --git a/libavcodec/decode.c b/libavcodec/decode.c
>> index edfae55..6ec423b 100644
>> --- a/libavcodec/decode.c
>> +++ b/libavcodec/decode.c
>> @@ -557,9 +557,6 @@ FF_ENABLE_DEPRECATION_WARNINGS
>>          avci->showed_multi_packet_warning = 1;
>>      }
>>
>> -    if (!got_frame)
>> -        av_frame_unref(frame);
>> -
>>      if (ret >= 0 && avctx->codec->type == AVMEDIA_TYPE_VIDEO && !(avctx->flags & AV_CODEC_FLAG_TRUNCATED))
>>          ret = pkt->size;
>>
>> @@ -568,8 +565,9 @@ FF_ENABLE_DEPRECATION_WARNINGS
>>          avctx->time_base = av_inv_q(av_mul_q(avctx->framerate, (AVRational){avctx->ticks_per_frame, 1}));
>>  #endif
>>
>> -    /* do not stop draining when got_frame != 0 or ret < 0 */
>> -    if (avctx->internal->draining && !got_frame) {
>> +    /* do not stop draining when frame->buf[0] != NULL or ret < 0 */
>> +    /* at this point, got_frame == 0 when discarding frame */
>
> Does that means the internal API can return got_frame=0 but
> frame->buf[0] set or what? That seems like chaos. They're never

No. got_frame is unset in decode_simple_internal() when the frame has
AV_FRAME_FLAG_DISCARD.

> supposed to mismatch, and I think the av_frame_unref() you moved
> is supposed to keep this consistent to help decoders which allocated
> a frame, but did not successfully decode anything to it.

I moved av_frame_unref() to make frame->buf[0] available for eof testing.

>
>> +    if (avctx->internal->draining && !frame->buf[0]) {
>>          if (ret < 0) {
>>              /* prevent infinite loop if a decoder wrongly always return error on draining */
>>              /* reasonable nb_errors_max = maximum b frames + thread count */
>> @@ -603,7 +601,9 @@ FF_ENABLE_DEPRECATION_WARNINGS
>>          avci->last_pkt_props->dts = AV_NOPTS_VALUE;
>>      }
>>
>> -    if (got_frame)
>> +    if (!got_frame)
>> +        av_frame_unref(frame);
>> +    else
>>          av_assert0(frame->buf[0]);
>>
>>      return ret < 0 ? ret : 0;
>
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