FFMPEG 5.1 Sound Misplaced

AlanJames1987 · 5th April 2011, 09:58

When converting video on Linux from an 5.1 source to an AAC 5.1 source my channels get mapped incorrectly. The most noticeable problem is the sound from the center speaker comes out of the front right speaker. I am using the latest Git version on Ubuntu 10.04. Can anyone help me figure out why this is happening?

Here is an example of a video I converted.
http://www.alanjames1987.com/develop...hannelTest.zip

5th April 2011, 14:23

ffmpeg revision and command line options? Also, ffprobe output of the source material.

poisondeathray · 5th April 2011, 14:55

channel mapping convention is different for AC3 and AAC

see remark 1:
http://avisynth.org/mediawiki/GetChannel

AlanJames1987 · 5th April 2011, 16:26

FFMPEG Command

Code:

ffmpeg -i $originalsVideosDir/$1.* \
  -vcodec libx264 -vf 'scale=1920:-1' -b 1920k \
  -acodec aac -strict experimental $outputAudioChannels -ab 192k \
  -vpre $renderSpeed -threads 0 -map_metadata -1 -y $tempDir/$1_hd.mp4
qt-faststart $tempDir/$1_hd.mp4 $finalsVideosDir/$1.mp4

FFPROBE

Code:

FFprobe version git-N-28456-g1c31b26, Copyright (c) 2007-2011 the FFmpeg developers
  built on Mar 17 2011 12:49:56 with gcc 4.4.3
  configuration: --enable-gpl --enable-version3 --enable-nonfree --enable-postproc --enable-libfaac --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid --enable-x11grab
  libavutil    50. 39. 0 / 50. 39. 0
  libavcodec   52.114. 0 / 52.114. 0
  libavformat  52.103. 0 / 52.103. 0
  libavdevice  52.  3. 0 / 52.  3. 0
  libavfilter   1. 76. 0 /  1. 76. 0
  libswscale    0. 12. 0 /  0. 12. 0
  libpostproc  51.  2. 0 / 51.  2. 0
[matroska,webm @ 0x20770d0] Estimating duration from bitrate, this may be inaccurate
Input #0, matroska,webm, from '11.mkv':
  Duration: 00:01:04.39, start: 0.000000, bitrate: 1536 kb/s
    Stream #0.0(eng): Video: h264 (High), yuv420p, 1920x816 [PAR 1:1 DAR 40:17], 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc
    Metadata:
      title           : Tron.Legacy.2010.BluRay.1080p.x264.DTS-MySiLU
    Stream #0.1(eng): Audio: dca (DTS), 48000 Hz, 5.1, s16, 1536 kb/s (default)

I am using the aac codec within FFMPEG because it is creating a better sounding file. However, using libfaac produces the same incorrectly mapped channels.

poisondeathray that link seems to be not working right now.

poisondeathray · 5th April 2011, 16:35

Quote:

Originally Posted by AlanJames1987

poisondeathray that link seems to be not working right now.

you can use googlecache to view it

AlanJames1987 · 5th April 2011, 18:02

Quote:

you can use googlecache to view it

Thanks. I viewed it that way and understand the different formats now. My next question is, how can I use that knowledge to correct the problem?

poisondeathray · 5th April 2011, 18:07

you can remap the channels

not sure how you would do that in linux

you could remap in avisynth, or use eac3to , wavewizard, or any audio editor on pc

AlanJames1987 · 6th April 2011, 21:47

I found a Linux program called SOX that might be able to fix my problem. Has anyone ever used SOX?

kypec · 7th April 2011, 08:15

You better start new thread specific to SOX in Audio encoding section, there are lots of helpful members over there, moderator tebasuna is awesome

5th April 2011, 09:58	#1 \| Link
AlanJames1987 Registered User Join Date: Mar 2011 Location: Orlando, Fl Posts: 11	FFMPEG 5.1 Sound Misplaced When converting video on Linux from an 5.1 source to an AAC 5.1 source my channels get mapped incorrectly. The most noticeable problem is the sound from the center speaker comes out of the front right speaker. I am using the latest Git version on Ubuntu 10.04. Can anyone help me figure out why this is happening? Here is an example of a video I converted. http://www.alanjames1987.com/develop...hannelTest.zip __________________ Alan James Editor, Director, Producer Orlando Video Production, Orlando Film Production Company, 9IronProductions.com Last edited by AlanJames1987; 5th April 2011 at 10:09. Reason: Added Example

6th April 2011, 21:47	#8 \| Link
AlanJames1987 Registered User Join Date: Mar 2011 Location: Orlando, Fl Posts: 11	I found a Linux program called SOX that might be able to fix my problem. Has anyone ever used SOX? __________________ Alan James Editor, Director, Producer Orlando Video Production, Orlando Film Production Company, 9IronProductions.com

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5th April 2011, 14:23	#2 \| Link
MickJT Guest Posts: n/a	ffmpeg revision and command line options? Also, ffprobe output of the source material.

5th April 2011, 14:55	#3 \| Link
poisondeathray Registered User Join Date: Sep 2007 Posts: 5,374	channel mapping convention is different for AC3 and AAC see remark 1: http://avisynth.org/mediawiki/GetChannel

5th April 2011, 18:07	#7 \| Link
poisondeathray Registered User Join Date: Sep 2007 Posts: 5,374	you can remap the channels not sure how you would do that in linux you could remap in avisynth, or use eac3to , wavewizard, or any audio editor on pc

7th April 2011, 08:15	#9 \| Link
kypec User of free A/V tools Join Date: Jul 2006 Location: SK Posts: 826	You better start new thread specific to SOX in Audio encoding section, there are lots of helpful members over there, moderator tebasuna is awesome