Subject: Re: [LAU] Playing a wav file from stdin in JACK?

From: Ken Restivo <ken@...> · Date: Saturday, November 17, 2007 - 7:19 am

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On Sat, Nov 17, 2007 at 02:02:28PM +1100, Erik de Castro Lopo wrote:

quoted text> Ken Restivo wrote:

>

> > I'm looking for a way to play a wav file from STDIN that'll work with JACK.

>

> In general, WAV files are not designed for reading from things like pipes.

> The problem is that they can contain metadata *after* the audio data.

>

> There are however file formats that are specifically design to be allowed

> to be read from pipes, like AU and CAF. Both of these formats have all

> metadata before the audio data and do not allow trailing metadata.

>

> Both AU and CAF formats support a wide range of audio data formats

> including 16, 24 and 32 bit integer PCM, 32 bit floats, 64 bit floats,

> Alaw, ulaw etc.

>

> > mplayer -ao jack (or just mplayer without JACK) won't handle WAV files on stdin, for some reason.

> >

> > 	Cannot seek backward in linear streams!

> > 	Seek failed

>

> Mplayer is probably being a little conservative.

>

> libsndfile does allow reading from pipes as long as the file is

> not too broken.

>

> > I need to do this because I'm playing wavpack'ed files: I need to do

> > "wvunpack -o - filename.wv | SOMETHING - ". I do *not* want to have to

> > unpack them to disk just to play them.

>

> Does wvunpack support output as AU of CAF?

>

> If wvunpack only does WAV output, you have two solutions:

>

>   - Write SOMETHING to use libsndfile which does read from a pipe.

>

>   - Hack wavpack support into libsndfile :-).

> 
Interestingly, wavpack can write *and read* wav files from a pipe.
I'll try inserting sndfile-convert into the pipeline and see if there's a way to make mplayer happy that way.
- -ken

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