[FFmpeg-trac] #1693(avcodec:new): AAC Scalable Sample Rate (SSR)
FFmpeg
trac at avcodec.org
Tue Feb 13 20:28:54 EET 2018
#1693: AAC Scalable Sample Rate (SSR)
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Reporter: cehoyos | Owner:
Type: defect | Status: new
Priority: normal | Component: avcodec
Version: git-master | Resolution:
Keywords: aac | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Comment (by dalecurtis):
There's more samples and discussion here too,
https://bugs.chromium.org/p/chromium/issues/detail?id=808064
This became in issue in Chrome because we stopped silently dropping these
packets and instead emit an error now. Not decoding the SSR packet seems
to lead to an accumulation of ~1 seconds of audio loss every 10 seconds.
Given the volume of complaints quite a few folks have been silently losing
their audio over the years. The workaround for now is to re-encode with
libfdk_aac which can parse the SSR packets:
./ffmpeg -acodec libfdk_aac -i <file> -acodec libfdk_aac -vcodec copy <out
file>
Here's a recent log from a sample I have:
$ ffmpeg -i ssr_chrome.aac out.wav
ffmpeg version N-89956-gcaa4bd7a9f Copyright (c) 2000-2018 the FFmpeg
developers
built with clang version 6.0.0 (trunk 321529)
configuration: --enable-shared --enable-nonfree --enable-gpl --cc=clang
--ld=clang --enable-libfdk-aac
libavutil 56. 7.100 / 56. 7.100
libavcodec 58. 9.100 / 58. 9.100
libavformat 58. 7.100 / 58. 7.100
libavdevice 58. 0.101 / 58. 0.101
libavfilter 7. 11.101 / 7. 11.101
libswscale 5. 0.101 / 5. 0.101
libswresample 3. 0.101 / 3. 0.101
libpostproc 55. 0.100 / 55. 0.100
[aac @ 0x24ad480] Estimating duration from bitrate, this may be inaccurate
Input #0, aac, from 'ssr_chrome.aac':
Duration: 00:00:19.50, bitrate: 134 kb/s
Stream #0:0: Audio: aac (LC), 48000 Hz, stereo, fltp, 134 kb/s
File 'out.wav' already exists. Overwrite ? [y/N] y
Stream mapping:
Stream #0:0 -> #0:0 (aac (native) -> pcm_s16le (native))
Press [q] to stop, [?] for help
Output #0, wav, to 'out.wav':
Metadata:
ISFT : Lavf58.7.100
Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz,
stereo, s16, 1536 kb/s
Metadata:
encoder : Lavc58.9.100 pcm_s16le
[aac @ 0x24d0b00] SSR is not implemented. Update your FFmpeg version to
the newest one from Git. If the problem still occurs, it means that your
file has a feature which has not been implemented.
[aac @ 0x24d0b00] If you want to help, upload a sample of this file to
ftp://upload.ffmpeg.org/incoming/ and contact the ffmpeg-devel mailing
list. (ffmpeg-devel at ffmpeg.org)
Error while decoding stream #0:0: Not yet implemented in FFmpeg, patches
welcome
[aac @ 0x24d0b00] SSR is not implemented. Update your FFmpeg version to
the newest one from Git. If the problem still occurs, it means that your
file has a feature which has not been implemented.
[aac @ 0x24d0b00] If you want to help, upload a sample of this file to
ftp://upload.ffmpeg.org/incoming/ and contact the ffmpeg-devel mailing
list. (ffmpeg-devel at ffmpeg.org)
--
Ticket URL: <https://trac.ffmpeg.org/ticket/1693#comment:9>
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