[FFmpeg-trac] #8416(avformat:new): disposition option ignored when muxing hls from a web url and srt subtitle file together in an mkv container

[FFmpeg]

#8416: disposition option ignored when muxing hls from a web url and srt subtitle
file together in an mkv container
-------------------------------------+-------------------------------------
             Reporter:  bgx90        |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:  avformat
              Version:  4.2          |               Resolution:
             Keywords:  disposition  |               Blocked By:
  mkv                                |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Comment (by bgx90):

 Yes, the Matroska muxer will set all tracks of a type to default when no
 track has the default flag explicitly set to 0 or 1 via the disposition
 option. However, The option used in #8173(ticket) is
 {{{-disposition[:stream_specifier] 0}}} which does not do the same thing
 as the option {{{-disposition:s -default}}} which is what I am using.
 {{{-disposition:s -default}}} explicitly sets the default flag to 0
 (false); {{{-disposition[:stream_specifier] 0}}} removes the dispositions
 entirely.

 If I have an mkv file (input.mkv) with a single subtitle stream and that
 subtitle stream is marked as default, I can create a new mkv with the
 subtitle stream not marked as default with this command:
 {{{% ffmpeg -i input.mkv -codec copy -disposition:s -default
 no_default_subtitles.mkv}}}

 However, when I mux a local mkv and a local subtitle file together, I can
 successfully create a new mkv with no default subtitle whether or not I
 include {{{-disposition:s -default}}}. I would have expected that
 {{{-disposition:s -default}}} would be required in this case to prevent
 the subtitle stream from being flagged as default. This behavior seems
 strange, but is not a problem for me.

 The problem I am having is that when I try to mux streams coming from a
 web url in TS segments with the local subtitle file the subtitle track
 gets flagged as default even though I include the option {{{-disposition:s
 -default}}}.

 In short, the question is why do both of these commands result in mkv
 files that do not mark the subtitle stream as default
 {{{% ffmpeg -i some_local_video_file.mkv -i some_local_subtitles.srt
 -vcodec copy -acodec copy -scodec srt -metadata:s:s:0 language=eng
 no_default_subtitles.mkv}}}

 {{{% ffmpeg -i some_local_video_file.mkv -i some_local_subtitles.srt
 -vcodec copy -acodec copy -scodec srt -disposition:s -default
 -metadata:s:s:0 language=eng no_default_subtitles.mkv}}}

 while this command results in an mkv file that marks the subtitle stream
 as default even thought the default flag is explicitly set to 0 (false) by
 the disposition option and the only difference is that the audio and video
 streams are being downloaded from a web url in TS packets instead of
 coming from a local mkv file like in the two commands above
 {{{% ffmpeg -i 'http://some_video_site/somevideo.m3u8' -i
 local_subtitles_file.srt  -vcodec copy -acodec copy -scodec srt
 -disposition:s -default -metadata:s:s:0 language=eng output.mkv}}}

--
Ticket URL: <https://trac.ffmpeg.org/ticket/8416#comment:2>
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