[FFmpeg-trac] #11560(avformat:new): HLS audio streams do not use var_stream_map name in master playlist

[FFmpeg]

#11560: HLS audio streams do not use var_stream_map name in master playlist
----------------------------------------+----------------------------------
             Reporter:  Christian Koop  |                     Type:  defect
               Status:  new             |                 Priority:  normal
            Component:  avformat        |                  Version:  7.1
             Keywords:  HLS             |               Blocked By:
             Blocking:                  |  Reproduced by developer:  0
Analyzed by developer:  0               |
----------------------------------------+----------------------------------
 **Summary of the bug:**
 Setting `name` in `-var_stream_map` for audio streams, allows overriding
 `%v` in all the related paths.
 HLS also writes a name for audio streams into the master playlist,
 but it does not use that name. Instead it will continue to use the 'old'
 auto-generated name (e.g. `audio_1`).


 **How to reproduce:**
 {{{
 ffmpeg -f lavfi \
        -i testsrc=duration=10:size=1280x720:rate=30 \
        -f lavfi \
        -i sine=frequency=1000:duration=10:sample_rate=44100 \
        -c:v libx264 \
        -c:a aac \
        -shortest \
        -f hls \
        -hls_time 2 \
        -master_pl_name master.m3u8 \
        -hls_segment_filename stream_%v/chunk_%d.ts \
        -hls_list_size 0 \
        -var_stream_map 'v:0,agroup:audio,name:custom_video_name
 a:0,agroup:audio,name:custom_audio_name,language:und,default:yes' \
        stream_%v/manifest.m3u8
 }}}

 Please, pay attention to the created `stream_custom_audio_name/` directory
 and the contents of the `master.m3u8` file.
 It will contain the audio stream with the auto-generated name.
 {{{
 #EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID="group_audio",NAME="audio_1" [...]
 }}}

 **Why is this an issue?**
 This name can be used by video players to signal to the user what kind of
 audio track this is.
 There may be multiple ones for a given language (e.g. English and
 Commentary (in English)), so only using the language to generate a name
 instead is not always an option.

 I do not know of any other option that I could supply to ffmpeg, to add
 additional metadata to the streams that I could parse for the video
 player.
 Right now, I have to supply a mapping next to the master playlist and use
 it for the UI.

 **What did I already find?**
 * Looks like the `name` parameter was added in
 https://github.com/FFmpeg/FFmpeg/commit/86f04b918c0d00a286180906279b7ed0f1cd0bed
   * It only touches `%v` but I think this is unexpected behavior and there
 should be some way to influence the stream's name
 * The audio stream line for the master playlist seems to written in
 `libavformat/hlsplaylist.c#L48`
   *
 https://github.com/FFmpeg/FFmpeg/blob/d11d4277f9339b4c31a4619af8f273a5910840e8/libavformat/hlsplaylist.c#L48
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/11560>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker