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

[Giacomo Comes]

On Mon, Oct 03, 2005 at 11:01:29PM -0400, Rich Felker wrote:
> 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

I don't see a problem here. I know that k has this value with the 
rawaudio demuxer. Why I cannot use it?

> demuxer. Making a script rely on it not changing from one version to
> another is IMO a very very bad idea.

You are suggesting then to NOT write scripts that uses mplayer.
Because with EVERY new relase of mplayer there are some changes
that will ALWAYS break a (non trivial) script.
For example -ao pcm, and -vo png syntax has changed in the last
two relases (just to tell the first two that I remember).
The fact that the changes were documented didn't prevent the
breakage, it simply made easier the implementation of the fix.

Giacomo