[FFmpeg-devel] [PATCH]lavf/matroskaenc: Do not write 0 duration for subtitles

Carl Eugen Hoyos ceffmpeg at gmail.com
Wed Nov 15 00:18:17 EET 2017

2017-11-14 19:02 GMT+01:00 Jerome Martinez <jerome at mediaarea.net>:
> On 12/11/2017 03:12, Carl Eugen Hoyos wrote:
>> -            put_ebml_uint(pb, MATROSKA_ID_BLOCKDURATION, duration);
>> +            if (duration > 0)
>> +                put_ebml_uint(pb, MATROSKA_ID_BLOCKDURATION, duration);
> In that case, the duration of the block is DefaultDuration (if it exists),
> completely different.
> Is it intended to say that a duration of 0 at this place means that the
> block has the default block duration if it exists?
> What is the use case for a duration of 0?

Iirc, pgs subtitles send an empty "frame" to reset / remove the

> (Note: the meaning of the a block duration of 0 is unclear to me, I'll ask
> on CELLAR mailing list to clarify that)

So maybe the issue is with mkvalidate?

Carl Eugen

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