[FFmpeg-trac] #10112(avformat:new): HLS Demuxer - Live Playlists needlessly re-download initialization segment

[FFmpeg]

#10112: HLS Demuxer - Live Playlists needlessly re-download initialization segment
-------------------------------------+-------------------------------------
             Reporter:  John Regan   |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:  avformat     |                  Version:
                                     |  unspecified
             Keywords:  HLS hls      |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug:

 Hi there - I noticed when playing HLS playlists, ffplay (and apps using
 libavformat) will re-download the initialization segment for each new
 media segment added to the list. This causes some warnings to appear, and
 essentially doubles the number of HTTP requests made during a live
 playlist.

 The warning messages are for duplicated MOOV atoms:

 {{{
 [http @ 0x7fc4e8008a40] Opening 'http://127.0.0.1:8080/init.mp4' for
 reading
 [hls @ 0x7fc4e8000c80] Opening 'http://127.0.0.1:8080/stream4.m4s' for
 reading
 [mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fc4e80076c0] Found duplicated MOOV Atom.
 Skipped it
 [http @ 0x7fc4e8101f40] Opening 'http://127.0.0.1:8080/stream.m3u8' for
 reading
 [hls @ 0x7fc4e8000c80] Skip ('#EXT-X-VERSION:7')
 [http @ 0x7fc4e8008a40] Opening 'http://127.0.0.1:8080/init.mp4' for
 reading
 [hls @ 0x7fc4e8000c80] Opening 'http://127.0.0.1:8080/stream5.m4s' for
 reading
 [http @ 0x7fc4e8025480] Opening 'http://127.0.0.1:8080/stream6.m4s' for
 reading
 [mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fc4e80076c0] Found duplicated MOOV Atom.
 Skipped it

 }}}

 How to reproduce:

 {{{
 % ffmpeg -i http://something-live.example -c:a aac -vn -f hls
 -hls_segment_type fmp4 /path/to/folder/stream.m3u8
 # in another terminal serve /path/to/folder
 % python -m http.server --directory /path/to/folder 8080
 # play the stream
 % ffplay http://127.0.0.1:8080/stream.m3u8
 }}}

 ffmpeg info from my machine:

 {{{
 ffmpeg version n5.1.2 Copyright (c) 2000-2022 the FFmpeg developers
 built with gcc 12.2.0 (GCC)
 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-libmfx
 --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb
 --enable-libopencore_amrwb --enable-libopenjpeg --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      57. 28.100 / 57. 28.100
 libavcodec     59. 37.100 / 59. 37.100
 libavformat    59. 27.100 / 59. 27.100
 libavdevice    59.  7.100 / 59.  7.100
 libavfilter     8. 44.100 /  8. 44.100
 libswscale      6.  7.100 /  6.  7.100
 libswresample   4.  7.100 /  4.  7.100
 libpostproc    56.  6.100 / 56.  6.100
 }}}
 Patches should be submitted to the ffmpeg-devel mailing list and not this
 bug tracker.
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/10112>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker