[FFmpeg-trac] #9484(undetermined:new): HLS muxer: inital fmp4 segment has non-zero duration even if `hls_init_time` is set to zero
FFmpeg
trac at avcodec.org
Fri Oct 29 03:33:38 EEST 2021
#9484: HLS muxer: inital fmp4 segment has non-zero duration even if
`hls_init_time` is set to zero
-------------------------------------+-------------------------------------
Reporter: kebl | Type: defect
Status: new | Priority: normal
Component: | Version:
undetermined | unspecified
Keywords: hls ffmpeg | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
-------------------------------------+-------------------------------------
The HLS muxer supports fragmented mp4, which by default produces an
initial segment called `init.mp4`. With ffmpeg from the Arch repo (version
`n4.4`) the command below produces an initial segment 6.08 seconds long,
but with static builds of ffmpeg `4.4.1` and `4.2.2` the initial segment
has no duration. `hls_init_time` is set to zero so the inital segment
should have no duration.
The effect the non-zero duration has is concatenating segments doesn't
work properly anymore. For example with a no-duration initial segment, `$
cat init.mp4 out2.m4s out3.m4s | ffplay -` will play the segments starting
from `out2.m4s` (12 seconds in from the input video). But with a non-zero
duration it'll play the first six seconds of the input video, freeze-frame
for six seconds, then play `out2.m4s`. (It looks like the initial segment
has the same video content as the 0th segment because `$ cat init.mp4 |
ffplay -` behaves identically to `$ cat init.mp4 out0.m4s | ffplay -`.
{{{
% ffmpeg -i in.webm -g 24 -sc_threshold 0 -f hls -hls_init_time 0
-hls_time 6 -hls_segment_type fmp4 out.m3u8
}}}
`in.webm` is
https://upload.wikimedia.org/wikipedia/commons/e/e7/Slow_motion_drop.webm.
----
Initial segment produced by Arch ffmpeg ('''{{{Duration:
00:00:06.08}}}'''):
{{{
% ffprobe init.mp4
ffprobe version n4.4 Copyright (c) 2007-2021 the FFmpeg developers
built with gcc 11.1.0 (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-
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-shared --enable-version3
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
libswscale 5. 9.100 / 5. 9.100
libswresample 3. 9.100 / 3. 9.100
libpostproc 55. 9.100 / 55. 9.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'init.mp4':
Metadata:
major_brand : iso5
minor_version : 512
compatible_brands: iso5iso6mp41
encoder : Lavf58.76.100
Duration: 00:00:06.08, start: 0.166341, bitrate: 381 kb/s
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p,
1280x720 [SAR 1:1 DAR 16:9], 378 kb/s, 24 fps, 24 tbr, 12288 tbn, 48 tbc
(default)
Metadata:
handler_name : VideoHandler
vendor_id : [0][0][0][0]
}}}
----
Initial segment produced by ffmpeg `4.4.1-static` ('''{{{Duration:
N/A}}}'''):
{{{
ffprobe version n4.4 Copyright (c) 2007-2021 the FFmpeg developers
built with gcc 11.1.0 (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-
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-shared --enable-version3
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
libswscale 5. 9.100 / 5. 9.100
libswresample 3. 9.100 / 3. 9.100
libpostproc 55. 9.100 / 55. 9.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x560481b4f240] Could not find codec parameters
for stream 0 (Video: h264 (avc1 / 0x31637661), none, 1280x720):
unspecified pixel format
Consider increasing the value for the 'analyzeduration' (0) and
'probesize' (5000000) options
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'init.mp4':
Metadata:
major_brand : iso5
minor_version : 512
compatible_brands: iso5iso6mp41
encoder : Lavf58.76.100
Duration: N/A, bitrate: N/A
Stream #0:0(und): Video: h264 (avc1 / 0x31637661), none, 1280x720, SAR
1:1 DAR 16:9, 12288 tbr, 12288 tbn, 24576 tbc (default)
Metadata:
handler_name : VideoHandler
vendor_id : [0][0][0][0]
}}}
--
Ticket URL: <https://trac.ffmpeg.org/ticket/9484>
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