[FFmpeg-devel] [PATCH] avcodec/cuvid: Use a dummy packet to flush cuvid.

[Hendrik Leppkes]

On Tue, May 16, 2017 at 3:41 PM, Philip Langdale <philipl at overt.org> wrote:
> On May 16, 2017, at 01:32, Timo Rothenpieler <timo at rothenpieler.org> wrote:
>>
>>> Am 16.05.2017 um 10:27 schrieb Wiki Wang:
>>> ---
>>> libavcodec/cuvid.c | 13 +++----------
>>> 1 file changed, 3 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/libavcodec/cuvid.c b/libavcodec/cuvid.c
>>> index 218be8495d..0b1710bd46 100644
>>> --- a/libavcodec/cuvid.c
>>> +++ b/libavcodec/cuvid.c
>>> @@ -1029,20 +1029,13 @@ static void cuvid_flush(AVCodecContext *avctx)
>>>         return;
>>>     }
>>>
>>> -    if (ctx->cudecoder) {
>>> -        ctx->cvdl->cuvidDestroyDecoder(ctx->cudecoder);
>>> -        ctx->cudecoder = NULL;
>>> -    }
>>> +    seq_pkt.flags = CUVID_PKT_ENDOFSTREAM;
>>>
>>> -    if (ctx->cuparser) {
>>> -        ctx->cvdl->cuvidDestroyVideoParser(ctx->cuparser);
>>> -        ctx->cuparser = NULL;
>>> -    }
>>> -
>>> -    ret = CHECK_CU(ctx->cvdl->cuvidCreateVideoParser(&ctx->cuparser, &ctx->cuparseinfo));
>>> +    ret = CHECK_CU(ctx->cvdl->cuvidParseVideoData(ctx->cuparser, &seq_pkt));
>>>     if (ret < 0)
>>>         goto error;
>>>
>>> +    seq_pkt.flags = 0;
>>>     seq_pkt.payload = ctx->cuparse_ext.raw_seqhdr_data;
>>>     seq_pkt.payload_size = ctx->cuparse_ext.format.seqhdr_data_length;
>>>
>>>
>>
>> I'm not exactly sure what was the issue for this to be done this way,
>> but I remember there being some issue with just flushing the decoder,
>> hence the re-creation.
>>
> The issue is that when flushing for a media player, you need to drop all
> frames in the pipeline too. Inserting EOS means you still have n frames
> that will come out after the flush which breaks interactive seeking.
>

Indeed, flush should be an actual flush - discard all data and start fresh.

It should use the dummy packet "flush" at EOF, we call that operation
"draining" here, the decoder gets called with an empty packet in that
case (if it sets the delay flag, anyway).

- Hendrik