[FFmpeg-trac] #4546(ffmpeg:new): -acodec copy doesn't work with AAC VBR
FFmpeg
trac at avcodec.org
Sun May 10 17:17:35 CEST 2015
#4546: -acodec copy doesn't work with AAC VBR
-------------------------------------+-------------------------------------
Reporter: ericzutter | Type: defect
Status: new | Priority: important
Component: ffmpeg | Version:
Keywords: AAC VBR | unspecified
copy | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
-------------------------------------+-------------------------------------
Summary of the bug:
When using "-acodec copy" to extract AAC VBR codec from video, the
extracted codec becomes AAC CBR. I use MediaInfo CLI to check if AAC codec
is CBR or VBR.
How to reproduce:
1. test.mp4 contains an AAC VBR audio codec
2. MediaInfo.exe test.mp4 => says "Audio Bitrate mode=variable"
3. ffmpeg.exe -i test.mp4 -vn -acodec copy test.m4a
4. MediaInfo.exe test.m4a => says "Audio Bitrate mode=constant"
Expected result:
Normally when using '-acodec copy', the "Bitrate mode" on the output
should be the same as the input.
My configuration :
I am using ffmpeg.exe 64 bits with Windows 7-64 bits
ffmpeg version N-71899-g6ef3426 Copyright (c) 2000-2015 the FFmpeg
developers
built with gcc 4.9.2 (GCC)
configuration: --enable-gpl --enable-version3 --disable-w32threads
--enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r
--enable-gnutls --enable-iconv --enable-libass --enable-libbluray
--enable-libbs2b --enable-libcaca --enable-libdcadec --enable-libfreetype
--enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug
--enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb
--enable-libopenjpeg --enable-libopus --enable-librtmp --enable-
libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora
--enable-libtwolame --enable-libvidstab --enable-libvo-aacenc --enable-
libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack
--enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs
--enable-libxvid --enable-lzma --enable-decklink --enable-zlib
libavutil 54. 23.101 / 54. 23.101
libavcodec 56. 37.100 / 56. 37.100
libavformat 56. 31.102 / 56. 31.102
libavdevice 56. 4.100 / 56. 4.100
libavfilter 5. 16.101 / 5. 16.101
libswscale 3. 1.101 / 3. 1.101
libswresample 1. 1.100 / 1. 1.100
libpostproc 53. 3.100 / 53. 3.100
--
Ticket URL: <https://trac.ffmpeg.org/ticket/4546>
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