[FFmpeg-trac] #7550(undetermined:new): Audible artifacts when converting from WAV to AAC
FFmpeg
trac at avcodec.org
Sat Nov 17 14:53:05 EET 2018
#7550: Audible artifacts when converting from WAV to AAC
-------------------------------------+-------------------------------------
Reporter: sleroux | Type: defect
Status: new | Priority: normal
Component: | Version: git-
undetermined | master
Keywords: | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
-------------------------------------+-------------------------------------
While converting a WAV file to AAC I noticed audible audio artifacts.
Especially, the artifacts seem to appear on only one channel even in dual-
mono.
The issue has improved in the latest build compared to ffmpeg
3.2.12-1~deb9u1 used on our Debian 9.4 production host but is still
clearly audible.
A particularly audible artifact is present between 00:05:30.930 and
00:05:30.940 is the attached example file. I copied the audio files in
extenso since the artifact seems to vanish when I trim the input file.
Attached:
* EP26-wav-to-aac-artifacts-orig.wav : the original uncompressed audio
file
* EP26-wav-to-aac-artifacts-ffmpeg-debian-stable.mp4 : the audio
transcoded as AAC by ffmpeg 3.2.12-1~deb9u1 on our Debian 9.4 production
host
* EP26-wav-to-aac-artifacts-ffmpeg-static-latest.mp4 : the audio
transcoded as AAC by the latest ffmpeg static build
* Audacity screen capture pinpointing an artifact (first stereo pair is
original WAV, second stereo pair is output produced by ffmpeg on Debian
9.4, third stereo pair in output produced by the lattest ffmpeg static
build)
How to reproduce:
{{{
$ /tmp/ffmpeg-git-20181115-amd64-static/ffmpeg -i EP26-wav-to-aac-
artifacts-orig.wav -c:a aac EP26-wav-to-aac-artifacts-ffmpeg-debian-
stable.mp4
ffmpeg version N-47455-g1096614c42-static
https://johnvansickle.com/ffmpeg/ Copyright (c) 2000-2018 the FFmpeg
developers
built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
configuration: --enable-gpl --enable-version3 --enable-static --disable-
debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio
--cc=gcc-6 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-
gray --enable-libaom --enable-libfribidi --enable-libass --enable-libvmaf
--enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb
--enable-libopencore-amrwb --enable-libopenjpeg --enable-librubberband
--enable-libsoxr --enable-libspeex --enable-libvorbis --enable-libopus
--enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-
libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2
--enable-libxvid --enable-libzimg
libavutil 56. 23.101 / 56. 23.101
libavcodec 58. 39.100 / 58. 39.100
libavformat 58. 22.100 / 58. 22.100
libavdevice 58. 6.100 / 58. 6.100
libavfilter 7. 43.100 / 7. 43.100
libswscale 5. 4.100 / 5. 4.100
libswresample 3. 4.100 / 3. 4.100
libpostproc 55. 4.100 / 55. 4.100
Guessed Channel Layout for Input Stream #0.0 : stereo
Input #0, wav, from 'EP26-wav-to-aac-artifacts-orig.wav':
Duration: 00:07:46.24, bitrate: 1536 kb/s
Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz,
stereo, s16, 1536 kb/s
Stream mapping:
Stream #0:0 -> #0:0 (pcm_s16le (native) -> aac (native))
Press [q] to stop, [?] for help
Output #0, mp4, to 'EP26-wav-to-aac-artifacts-ffmpeg-debian-stable-2.mp4':
Metadata:
encoder : Lavf58.22.100
Stream #0:0: Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo,
fltp, 128 kb/s
Metadata:
encoder : Lavc58.39.100 aac
size= 6513kB time=00:07:46.24 bitrate= 114.4kbits/s speed=36.3x
video:0kB audio:6427kB subtitle:0kB other streams:0kB global headers:0kB
muxing overhead: 1.342028%
[aac @ 0x55cedc0] Qavg: 15720.868
}}}
--
Ticket URL: <https://trac.ffmpeg.org/ticket/7550>
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