[MPlayer-users] How to create a wav file with silence with MPlayer

[Rich Felker]

On Mon, Oct 03, 2005 at 05:54:51PM -0400, Giacomo Comes wrote:
> On Mon, Oct 03, 2005 at 05:32:02PM -0400, Rich Felker wrote:
> > On Mon, Oct 03, 2005 at 10:54:53AM -0400, Giacomo Comes wrote:
> > > Hi,
> > > Up to MPlayer 1.0pre7 I was able to create a wav file with silence with the
> > > following command line:
> > > 
> > > mplayer -rawaudio on:format=0x1:rate=48000 /dev/zero -nocache -frames 4 -ao pcm:waveheader:file=silence.wav
> > > 
> > > The advantage of this method is that I can easily select the frame rate and
> > > the duration (-frames) of the wav file.
> > > 
> > > With CVS the syntax has changed. The corresponding command line is:
> > > 
> > > mplayer -demuxer 20 -rawaudio format=0x1:rate=48000 /dev/zero -nocache -frames 4 -ao pcm:waveheader:file=silence.wav
> > > 
> > > The problem now is that MPlayer never stops. It ignores completly the option -frames. Is there a way to restore the old beahviour?
> > 
> > What in the world do you mean by 4 frames of pcm audio??
> 
> That's a feature of mplayer! 
> With the previous command line I would create a silent wav file
> with duration of n+1 * k seconds where n is the argument of -frames 
> and k=341.3ms

This k is very arbitrary and depends on the implementation of the
demuxer. Making a script rely on it not changing from one version to
another is IMO a very very bad idea.

> May be it is meanless to use -frames with pure audio, but it
> worked like that.

Yes it is meaningless..

> > Anyway using mplayer for this is rather overkill. It can be done
> > trivially with a shell script, almost as short as your mplayer command
> > line...
> 
> I'm sure there are plent of possibilities, mplayer is not
> the only tool that can do it, I'm just saying that it does
> not work anymore in CVS and it worked before.

It's probably a good thing that it doesn't work, instead of exhibiting
random behavior that you won't be able to rely on in the future.

Rich