[MPlayer-users] Bug: Poor quality decoding of ac3 audio

Rashkae rashkae at tigershaunt.com
Wed Mar 2 04:56:42 CET 2011

I'm uploading some samples to the upload.mplayerhq.hu as 

I'm sorry for the very large file size. I did not want to cut the audio 
samples to avoid introducing  audio errors that way (since the error I'm 
reporting does sound a little like a 'cut' to my untrained ear)

Audio 'click' noise when mplayer decodes dvd audio.

In the above samples, when 3.ac3 is played with mplayer, an audio 
'click' can be heard at 157s.

3.ac3 was was created with mplayer -dumpaudio -dumpfile 3.ac3 3.vob

I've observed the same audio noise on several television dvd's when 
playing with svn mplayer for various releases the past year.  When the 
audio is decoded with a52dec, the output is perfect, without the extra 

mplayer.ogg was created by:
mplayer 3.ac3 -ao pcm:file=3.wav
normalize-audio --peak 3.wav
oggenc -q 6 3.wav

a52dec.ogg was created by:
a52dec -o wav 3.ac3 > 3.wav
normalize-audio --peak 3.wav
oggenc -q 6 3.wav

You can clearly hear the difference if you play these two files with:
mplayer -ss 157 mplayer.ogg
mplayer -ss 157 a52dec.ogg

The same noise can be heard when playing from the produced wav files, 
though I didn't upload those.

If anyone works on this and finds the cause, I would greatly appreciate 
a heads up message to rashkae at tigershaunt.com.  It can be a difficult 
and tedious thing to test since I have no "scientific" way of measuring 
the glitch other than listening by ear.

Thank you.

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