[FFmpeg-trac] #10015(ffmpeg:new): [feature request] Set disposition(s) based on language, not the stream specifier

[FFmpeg]

#10015: [feature request] Set disposition(s) based on language, not the stream
specifier
-------------------------------------+-------------------------------------
             Reporter:  chm          |                     Type:
                                     |  enhancement
               Status:  new          |                 Priority:  wish
            Component:  ffmpeg       |                  Version:  git-
             Keywords:  disposition  |  master
  language metadata                  |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 As far as I know, setting a disposition for a stream is only based on
 stream specifier.

 {{{
      -disposition:s:0 default
 }}}

 For videos with streams of multiple languages, it would be great if we can
 also set a disposition based on the language, regardless of its stream
 specifier number.

 {{{
      -disposition:s:m:language:eng default
 }}}

 If there are multiple subtitles for the same language, and only want to
 set one as default, forced, or any other output, an additional option will
 be helpful too.

 In this example, there are 3 Spanish subtitles, and want to set the 3rd
 Spanish subtitle as the default, maybe something like?

 {{{
      -disposition:s:m:language:eng:2 default
 }}}

 (with 2 referring to Stream #0:4 (the 3rd Spanish subtitle stream))

 {{{
 Stream #0:0[0x1](und): Video: h264 (Constrained Baseline) (avc1 /
 0x31637661), yuv420p(progressive), 626x360, 1231 kb/s, 26.20 fps, 26.17
 tbr, 10k tbn (default)
     Metadata:
       handler_name    : VideoHandler
       vendor_id       : [0][0][0][0]
   Stream #0:1[0x3](und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz,
 mono, fltp, 128 kb/s (default)
     Metadata:
       handler_name    : SoundHandler
       vendor_id       : [0][0][0][0]
   Stream #0:2[0x4](spa): Subtitle: mov_text (tx3g / 0x67337874), 0 kb/s
 (default)
     Metadata:
       handler_name    : SubtitleHandler
   Stream #0:3[0x5](spa): Subtitle: mov_text (tx3g / 0x67337874), 0 kb/s
     Metadata:
       handler_name    : SubtitleHandler
   Stream #0:4[0x6](spa): Subtitle: mov_text (tx3g / 0x67337874), 0 kb/s
     Metadata:
       handler_name    : SubtitleHandler
   Stream #0:5[0x7](eng): Subtitle: mov_text (tx3g / 0x67337874), 0 kb/s
     Metadata:
       handler_name    : SubtitleHandler
   Stream #0:6[0x8](fra): Subtitle: mov_text (tx3g / 0x67337874), 0 kb/s
     Metadata:
       handler_name    : SubtitleHandler
 }}}


 ----

 Reason for request: I have hundreds of videos with multiple subtitles in
 different languages, however a lot of them are default/forced in another
 language and I want to set all of them to default in English WITHOUT
 removing the other languages.

 Thank you!
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/10015>
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