The VideoLAN Forums

Hello.

I use RTMPDump to grab sports videos, but VLC doesn't play the sound correctly (sound volume is messy). Other software play it OK but I prefer to use VLC. Here is a sample of a video with that problem:

http://www60.zippyshare.com/v/33051220/file.html

Any Ideas?

That's an interesting sample, 3-channel AAC is quite unsual.

However I'm getting the same volume pumping up and down problem with every player I've tried.
What player is playing it fine ?

Hi Lotesdelere, thanks for your reply.

The third channel might be the game commentary which sometimes is optional. I suspect that the third channel might be the issue origin.
Both MPC-HC and SMPlayer can handle the audio fine.

Hi
Maybe it's because VLC uses faad, and faad doesn't seem to decode 3 channel aac well.

MPlayer uses:-
'Selected audio codec: [ffaac] afm: ffmpeg (FFmpeg AAC (MPEG-2/MPEG-4 Audio))'
VLC uses:-
'main decoder debug: using decoder module "faad"'
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Note.
My installed MPlayer is configured with faad support.
'Checking for FAAD2 support ... yes'
It chooses to use FFmpeg's native aac decoder instead of faad with the sample file provided, but maybe it still needs to use faad for 'difficult' aac that FFmpeg can't decode (yet).
*******************************

This is what I did...
Extract the 3 channel aac audio track from testfile.flv:-
Result, testfile.m4a plays OK with MPlayer, but sounds bad with VLC.

Convert the m4a file to wav using FFmpeg and faad:-
Result, outfile1.wav plays OK with both MPlayer and VLC but outfile2.wav sounds bad with both MPlayer and VLC.
*******************************
Programs used:-
VLC media player 2.0.9 Twoflower (revision 2.0.8+git20131210+r49167+4+5~ubuntu12.04.1)
MPlayer SVN-r36766-4.6
ffmpeg version git-2014-02-04-c93e691
faad Ahead Software MPEG-4 AAC Decoder V2.7 Build: Nov 7 2013
*******************************
Results are here ---> http://www.mediafire.com/download/m2l54 ... les.tar.xz

u're a genius, I tried to delete libfaad_plugin.dll from vlc codec folder and it works like a charm. perfect, thanks a lot for your help!

... delete libfaad_plugin.dll from vlc codec folder...

Good thinking.
It's a workaround for Windows users.
Probably it would be OK to re-name the file XXXlibfaad_plugin.dll in case you need it again some time.

You can also force it with --codec avcodec

You can also force it with --codec avcodec

And with the GUI...
Tools > Preferences > All > Input/Codecs > Preferred decoders list