[dash muxer] Unplayable (empty) HLS, audio-only, master playlist

[pszemus]

When using ​DASH muxer to create DASH and HLS streams from an audio-only (e.g. mp3) file, consuming only one encoding process, the HLS stream is unplayable (DASH stream works OK).

While writing HLS master playlist, ​DASH muxer treats all audio streams as an alternative HLS audio tracks for video tracks, and when there's no video tracks the master HLS playlist becomes empty:

#EXTM3U
#EXT-X-VERSION:7
#EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID="group_A1",NAME="audio_0",DEFAULT=YES,URI="media_0.m3u8"

(no chunklists)

How to reproduce:

$ffmpeg -i https://filesamples.com/samples/audio/mp3/sample3.mp3 -c:a aac -use_timeline 1 -use_template 1 -adaptation_sets "id=0,streams=a" -hls_playlist 1 -f dash /tmp/dash/manifest.mpd
ffmpeg version 4.4 Copyright (c) 2000-2021 the FFmpeg developers
  built with gcc 11 (GCC)
  configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --docdir=/usr/share/doc/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -flto=auto -ffat-lto-objects -fexceptions -g -grecord-gcc-switches -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection' --extra-ldflags='-Wl,-z,relro -Wl,--as-needed -Wl,-z,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld ' --extra-cflags=' -I/usr/include/rav1e' --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libvo-amrwbenc --enable-version3 --enable-bzlib --disable-crystalhd --enable-fontconfig --enable-frei0r --enable-gcrypt --enable-gnutls --enable-ladspa --enable-libaom --enable-libdav1d --enable-libass --enable-libbluray --enable-libcdio --enable-libdrm --enable-libjack --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-nvenc --enable-openal --enable-opencl --enable-opengl --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librav1e --enable-libsmbclient --enable-version3 --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvidstab --enable-libvmaf --enable-version3 --enable-vapoursynth --enable-libvpx --enable-vulkan --enable-libglslang --enable-libx264 --enable-libx265 --enable-libxvid --enable-libxml2 --enable-libzimg --enable-libzvbi --enable-lv2 --enable-avfilter --enable-avresample --enable-libmodplug --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-lto --enable-libmfx --enable-runtime-cpudetect
  libavutil      56. 70.100 / 56. 70.100
  libavcodec     58.134.100 / 58.134.100
  libavformat    58. 76.100 / 58. 76.100
  libavdevice    58. 13.100 / 58. 13.100
  libavfilter     7.110.100 /  7.110.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  9.100 /  5.  9.100
  libswresample   3.  9.100 /  3.  9.100
  libpostproc    55.  9.100 / 55.  9.100
[mp3 @ 0x55599eb0acc0] invalid concatenated file detected - using bitrate for duration
Input #0, mp3, from 'https://filesamples.com/samples/audio/mp3/sample3.mp3':
  Metadata:
    encoder         : Lavf57.83.100
  Duration: N/A, start: 0.025057, bitrate: 128 kb/s
  Stream #0:0: Audio: mp3, 44100 Hz, stereo, fltp, 128 kb/s
    Metadata:
      encoder         : Lavc57.10
Stream mapping:
  Stream #0:0 -> #0:0 (mp3 (mp3float) -> aac (native))
Press [q] to stop, [?] for help
[dash @ 0x55599f110500] Opening '/tmp/dash/init-stream0.m4s' for writing
Output #0, dash, to '/tmp/dash/manifest.mpd':
  Metadata:
    encoder         : Lavf58.76.100
  Stream #0:0: Audio: aac (LC), 44100 Hz, stereo, fltp, 128 kb/s
    Metadata:
      encoder         : Lavc58.134.100 aac
[dash @ 0x55599f110500] Opening '/tmp/dash/chunk-stream0-00001.m4s.tmp' for writing
[dash @ 0x55599f110500] Opening '/tmp/dash/manifest.mpd.tmp' for writing
[dash @ 0x55599f110500] Opening '/tmp/dash/media_0.m3u8.tmp' for writing
[dash @ 0x55599f110500] Opening '/tmp/dash/master.m3u8.tmp' for writing
[...]
[dash @ 0x55599f110500] Opening '/tmp/dash/chunk-stream0-00022.m4s.tmp' for writing
[dash @ 0x55599f110500] Opening '/tmp/dash/manifest.mpd.tmp' for writing
[dash @ 0x55599f110500] Opening '/tmp/dash/media_0.m3u8.tmp' for writing
size=N/A time=00:01:45.79 bitrate=N/A speed= 114x    
video:0kB audio:1667kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
[aac @ 0x55599ebce0c0] Qavg: 207.240


$ cat /tmp/dash/master.m3u8 
#EXTM3U
#EXT-X-VERSION:7
#EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID="group_A1",NAME="audio_0",DEFAULT=YES,URI="media_0.m3u8"


$ mpv /tmp/dash/master.m3u8 
Empty playlist!

Exiting... (End of file)

[Carl Eugen Hoyos]

Please confirm that the issue is reproducible with current FFmpeg git head to make this a valid ticket.

[pszemus]

Yes it is. I've even proposed a patch to fix this: ​https://patchwork.ffmpeg.org/project/ffmpeg/patch/b6c1b15b-1297-b59a-9a1b-c6d3fb24e070@gmail.com/

[Balling]

Replying to pszemus:

Yes it is. I've even proposed a patch to fix this: ​https://patchwork.ffmpeg.org/project/ffmpeg/patch/b6c1b15b-1297-b59a-9a1b-c6d3fb24e070@gmail.com/

Yet it did not even apply. You can use this one thingy to send patches with git send-email, except it will send gmail through oath2, that is what I do. ​https://github.com/google/gmail-oauth2-tools/tree/master/go/sendgmail

The instruction is outdated though, you will have to publish an app in Google Cloud console.

[Carl Eugen Hoyos]

Please remove the re-indentation from your patch to make reviews easier.

[pszemus]

Replying to Carl Eugen Hoyos:

Please remove the re-indentation from your patch to make reviews easier.

I've prepared a patch that ignores indentation changes and sent it with git send-email.
I hope now you'll be able to review it.

[Balling]

Fixed in 575e52272d42f4278c6620f1a999c41425db2094.