[FFmpeg-devel] [PATCH v2] fftools/ffmpeg_mux: fix reporting muxer EOF as error

[Marton Balint]

On Sun, 23 Apr 2023, Anton Khirnov wrote:

> Quoting Marton Balint (2023-04-23 11:12:38)
>>
>>
>> On Sat, 22 Apr 2023, Anton Khirnov wrote:
>>
>>> Quoting Zhao Zhili (2023-04-22 14:56:34)
>>>> From: Zhao Zhili <zhilizhao at tencent.com>
>>>>
>>>> Fix #10327.
>>>>
>>>> Signed-off-by: Zhao Zhili <zhilizhao at tencent.com>
>>>> ---
>>>>  fftools/ffmpeg_mux.c | 12 +++++++++---
>>>>  1 file changed, 9 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/fftools/ffmpeg_mux.c b/fftools/ffmpeg_mux.c
>>>> index a2e8873ad2..0e1a5d7dc5 100644
>>>> --- a/fftools/ffmpeg_mux.c
>>>> +++ b/fftools/ffmpeg_mux.c
>>>> @@ -214,9 +214,15 @@ static void *muxer_thread(void *arg)
>>>>          ost = of->streams[stream_idx];
>>>>          ret = sync_queue_process(mux, ost, ret < 0 ? NULL : pkt, &stream_eof);
>>>>          av_packet_unref(pkt);
>>>> -        if (ret == AVERROR_EOF && stream_eof)
>>>> -            tq_receive_finish(mux->tq, stream_idx);
>>>> -        else if (ret < 0) {
>>>> +        if (ret == AVERROR_EOF) {
>>>> +            if (stream_eof) {
>>>> +                tq_receive_finish(mux->tq, stream_idx);
>>>> +            } else {
>>>> +                av_log(mux, AV_LOG_VERBOSE, "Muxer %s\n", av_err2str(ret));
>>>
>>> That seems unnecesarily convoluted, given that we _know_ the error to be
>>> EOF here. Also, please make it "Muxer returned EOF" to make it clear
>>> what exactly is the source of EOF.
>>>
>>> Otherwise ok, feel free to push with this change.
>>
>> This seems like yet another clash of AVERROR_EOF error codes coming from
>> different places with different semantics. For
>> av_interleaved_write_frame(), AVERROR_EOF is an error condition, so
>> file encoding should fail,
>
> Why should it fail? I'd think a muxer returning EOF is the way to signal
> non-error muxer-side termination.

That would be an API change. AVERROR_EOF is not special in any way from 
other error codes for av_interleaved_write_frame. A muxer cannot signal 
non-error muxer side termination with existing API.

Regards,
Marton