#11540: Audio artifacts in hls/dash segments
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Reporter: Mike | Owner: (none)
Type: defect | Status: new
Priority: normal | Component: ffmpeg
Version: 7.1 | Resolution:
Keywords: | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Description changed by Mike:
Old description:
> When generating a segmented audio live stream (hls/dash), ffmpeg
> introduces inaudible artifacts in segments, at the beginning and at the
> end of each segment. This results in audio peaking over 0dB.
>
> It's happening with both hls and dash outputs, regardless of the audio
> input type (file, pipe, device) or audio codec input/output (tested with
> AAC, libopus, libmp3lame). Also, the output codec container doesn't seem
> to make a difference: I've tested with mpeg-ts and webm.
>
> Also, this is not operating system specific, it happens on MacOS and a
> few linux distros as well, on both arm64 and x86-64. Tested with ffmpeg
> version 5.1.6 up to 7.1.
>
> How to reproduce:
> {{{
> % ffmpeg \
> -y \
> -fflags +nobuffer \
> -analyzeduration 1000000 \
> -probesize 32768 \
> -i "input_file_here" \
> -map 0:a -c:a:0 aac -b:a:0 64k \
> -map 0:a -c:a:1 aac -b:a:1 128k \
> -map 0:a -c:a:2 aac -b:a:2 192k \
> -var_stream_map "a:0,name:64k a:1,name:128k a:2,name:192k" \
> -master_pl_name stream.m3u8 \
> -hls_segment_type mpegts \
> -hls_segment_filename "destination_folder/stream_%v_%03d.ts" \
> -lhls 1 \
> -hls_init_time 2 \
> -hls_time 3 \
> -movflags +faststart \
> -tune zerolatency \
> -remove_at_exit 1 \
> -f hls \
> "destination_folder/stream_%v.m3u8"
> }}}
> ...and then check the audio spectogram of a few segments.
>
> [[Image(https://i.postimg.cc/mk1kVNWy/beginning-of-the-segment.png)]]
> [[Image(https://i.postimg.cc/LshJnMQW/end-of-segment.png)]]
New description:
When generating a segmented audio live stream (hls/dash), ffmpeg
introduces inaudible artifacts in segments, at the beginning and at the
end of each segment. This results in audio peaking over 0dB.
It's happening with both hls and dash outputs, regardless of the audio
input type (file, pipe, device) or audio codec input/output (tested with
AAC, libopus, libmp3lame). Also, the output codec container doesn't seem
to make a difference: I've tested with mpeg-ts and webm.
Also, this is not operating system specific, it happens on MacOS and a few
linux distros as well, on both arm64 and x86-64. Tested with ffmpeg
version 5.1.6 up to 7.1.
How to reproduce:
{{{
% ffmpeg \
-y \
-fflags +nobuffer \
-analyzeduration 1000000 \
-probesize 32768 \
-i "input_file_here" \
-map 0:a -c:a:0 aac -b:a:0 64k \
-map 0:a -c:a:1 aac -b:a:1 128k \
-map 0:a -c:a:2 aac -b:a:2 192k \
-var_stream_map "a:0,name:64k a:1,name:128k a:2,name:192k" \
-master_pl_name stream.m3u8 \
-hls_segment_type mpegts \
-hls_segment_filename "destination_folder/stream_%v_%03d.ts" \
-lhls 1 \
-hls_init_time 2 \
-hls_time 3 \
-movflags +faststart \
-tune zerolatency \
-remove_at_exit 1 \
-f hls \
"destination_folder/stream_%v.m3u8"
}}}
...and then check the audio spectogram of a few segments.
--
--
Ticket URL: <https://trac.ffmpeg.org/ticket/11540#comment:1>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker
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