[FFmpeg-devel] [PATCH] ffmpeg: always use single threaded decoding for attached pictures

[Marton Balint]

On Fri, 6 Oct 2017, Hendrik Leppkes wrote:

> On Fri, Oct 6, 2017 at 10:14 PM, Marton Balint <cus at passwd.hu> wrote:
>> Since af1761f7b5b1b72197dc40934953b775c2d951cc ffmpeg waits for a frame in each
>> stream before writing the output header. If we are using threaded decoding for
>> attached pictures, we have to read till EOF to be able to finally flush the
>> decoder and output the decoded frame. This essentially makes ffmpeg buffer all
>> non-attached picture packets, which will cause a "Too many packets buffered for
>> output stream" eventually.
>>
>> By forcing single threaded decoding, we get a frame from a single packet as
>> well and we can avoid the error.
>>
>> Fixes part of ticket #6375:
>> ffmpeg -i 46564100.mp3 -acodec libmp3lame -ab 128k -ac 2 out.mp3
>>
>> Signed-off-by: Marton Balint <cus at passwd.hu>
>> ---
>>  fftools/ffmpeg.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
>> index 5be8788ea8..6eb7bf9d84 100644
>> --- a/fftools/ffmpeg.c
>> +++ b/fftools/ffmpeg.c
>> @@ -2909,6 +2909,9 @@ static int init_input_stream(int ist_index, char *error, int error_len)
>>
>>          if (!av_dict_get(ist->decoder_opts, "threads", NULL, 0))
>>              av_dict_set(&ist->decoder_opts, "threads", "auto", 0);
>> +        /* Attached pics are sparse, therefore we would not want to delay their decoding till EOF. */
>> +        if (ist->st->disposition & AV_DISPOSITION_ATTACHED_PIC)
>> +            av_dict_set(&ist->decoder_opts, "threads", "1", 0);
>>
>
> LGTM.

Thanks, applied.

Regards,
Marton