[MPlayer-users] Audio encoding speed?

[Josef Wolf]

On Mon, Jan 24, 2005 at 12:16:08PM -0500, Piszcz, Justin Michael wrote:

> mplayer -vo null -vc dummy -ao pcm file.mpg
> the output will be called audiodump.wav

Ah, OK.  This gives me a file of 1.2GB length.  Strange, the original
video+audio is only 2.6GB (The movie is about 1:45 length).

So here are the results:

  mencoder -ni -cache 4096 in.vdr -o out.avi \
    -ovc lavc -lavcopts vcodec=mpeg4:vqmin=2:mbd=0:vpass=1 \
    -oac mp3lame -lameopts q=0:vbr=0:aq=0             # about 5 hours

Sum: 5:00 hours
---------------

  mencoder -ni -cache 4096 in.vdr -o out.avi \
    -ovc lavc -lavcopts vcodec=mpeg4:vqmin=2:mbd=0:vpass=1 \
    -oac copy                                         # 1 hour
  mplayer -vo null -vc dummy -ao pcm file.mpg         # 4 minutes
  lame -h audiodump.wav foo.mp3                       # 18 minutes

Sum: 1:22 hours
---------------

  mencoder -ni -cache 4096 in.vdr -o out.avi \
    -ovc lavc -lavcopts vcodec=mpeg4:vqmin=2:mbd=0:vpass=1 \
    -oac copy                                        # 1 hour
  mplayer -vo null -vc dummy -ao pcm file.mpg        # 4 minutes
  lame -V 0 audiodump.wav foo.mp3                    # 30 minutes

Sum: 1:34 hours
---------------

  mencoder -ni -cache 4096 in.vdr -o out.avi \
    -ovc lavc -lavcopts vcodec=mpeg4:vqmin=2:mbd=0:vpass=1 \
    -oac copy                                        # 1 hour
  mplayer -dumpaudio in.vdr                          # 3 minutes
  lame -V 0 --mp2input stream.dump foo.mp3           # 34 minutes

Sum: 1:37 hours
---------------

So obviously, about 3.5 hours are lost somewhere.  Any ideas what I can
do next to find the cause why the 3.5 hours are lost?

PS: I can not find an equivalent to the aq=0 option in lame's options.
    What does this aq=0 mean?

BTW: I noticed that the dumped mp2 file is even shorter than the
     resulting mp3 file (154MB vs. 166MB).  So I wondered whether it is
     really worth to reencode the audio.  But at least mpg123 complains
     (and gives artefacts) when playing the dumped mp2 stream:

       Playing MPEG stream from stream.dump ...
       MPEG 1.0 layer II, 192 kbit/s, 48000 Hz stereo
       Illegal Audio-MPEG-Header 0x37bd24f9 at offset 0x38cb3.
       Skipped 2035 bytes in input.

     It does not complain or giving any artefacts when playing the
     re-encoded mp3 file.

-- 
No software patents!
-- Josef Wolf -- jw at raven.inka.de --