[FFmpeg-trac] #10463(undetermined:new): HLS with fragmented mp4 muxing: audio-only stream not signaling encoder delay

[FFmpeg]

#10463: HLS with fragmented mp4 muxing: audio-only stream not signaling encoder
delay
-------------------------------------+-------------------------------------
             Reporter:  John Regan   |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 When producing an audio-only HLS stream with fragmented mp4, the
 initialization segment has an Edit List box, but the media_time is set to
 0. So stream consumers are unaware of any priming samples that need to be
 discarded.

 How to reproduce:

 Generate an audio-only hls stream
 {{{
 % ffmpeg -f lavfi -i anullsrc=r=48000:d=10 -c:a aac -f hls
 -hls_segment_type fmp4 -hls_time 1 hls/stream.m3u8
 }}}

 Then inspect the generated init.mp4 file. Using boxdumper from l-smash,
 here's the edit list box:

 {{{
 [edts: Edit Box]
     position = 244
     size = 36
     [elst: Edit List Box]
         position = 252
         size = 28
         version = 0
         flags = 0x000000
         entry_count = 1
         entry[0]
             segment_duration = 0
             media_time = 0
             media_rate = 1.000000
 }}}

 In this case, the media_time should be 1024, since that's how many priming
 samples the native aac encoder adds.

 ffmpeg version:

 {{{
 % ffmpeg -version
 ffmpeg version n6.0 Copyright (c) 2000-2023 the FFmpeg developers
 built with gcc 13.1.1 (GCC) 20230429
 configuration: --prefix=/usr --disable-debug --disable-static --disable-
 stripping --enable-amf --enable-avisynth --enable-cuda-llvm --enable-lto
 --enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl --enable-
 ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b
 --enable-libdav1d --enable-libdrm --enable-libfreetype --enable-libfribidi
 --enable-libgsm --enable-libiec61883 --enable-libjack --enable-libjxl
 --enable-libmfx --enable-libmodplug --enable-libmp3lame --enable-
 libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg
 --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librav1e
 --enable-librsvg --enable-libsoxr --enable-libspeex --enable-libsrt
 --enable-libssh --enable-libsvtav1 --enable-libtheora --enable-libv4l2
 --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx
 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb
 --enable-libxml2 --enable-libxvid --enable-libzimg --enable-nvdec
 --enable-nvenc --enable-opencl --enable-opengl --enable-shared --enable-
 version3 --enable-vulkan
 libavutil      58.  2.100 / 58.  2.100
 libavcodec     60.  3.100 / 60.  3.100
 libavformat    60.  3.100 / 60.  3.100
 libavdevice    60.  1.100 / 60.  1.100
 libavfilter     9.  3.100 /  9.  3.100
 libswscale      7.  1.100 /  7.  1.100
 libswresample   4. 10.100 /  4. 10.100
 libpostproc    57.  1.100 / 57.  1.100
 }}}
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/10463>
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