Baslinux mailing list

[sindi keesan <keesan AT sdf.lonestar.org>]

On Sat, 7 May 2005, David Moberg wrote:

> ----- Original Message -----
> From: "sindi keesan" <keesan AT sdf.lonestar.org>
>
> > > Try:
> > >
> > > mkfifo audiodump.wav
> > > mplayer -ao pcm http://(URL of streaming mp3) & play audiodump.wav & fg; fg
> >
> >
> > I tried various combinations (using the latest compiled mplayer,
> > which now installs properly) and if I mkfifo audiodump.wav, mplayer
> > does not seem to write anything to audiodump.wav (I have a 0 file)
> > though it says something about filling a cache.
>
> An explanation of FIFOs is in order. Basically, a FIFO is a file
> which behaves like a pipe. If you tell something like MPlayer to
> write to a file, it will write to it, _and stop_ when the FIFO
> is full. Nothing will happen until you tell something to read
> from the FIFO (e.g. play from sox). So you need to:
>
> 1) Make a FIFO (mkfifo)
> 2) Tell MPlayer to start sending data to the FIFO
> 3) Tell play to play the FIFO
> 4) If any of the above programs have gone into the background,
> you must awaken them with fg (at least, I have to with bash)
>
> It may be best to do everything manually:
>
> 1) In VT1, mkfifo audiodump.wav
> 2) Still in VT1, mplayer -ao pcm http://(URL of streaming mp3)
> 3) Switch to VT2 and play audiodump.wav
>
> You can automate this once you verify that it works.

This is what I am doing, except I had to leave out the mkfifo line because 
otherwise nothing writes to the .wav file, it stays at 0 size.

I do not have an 'fg' on this computer either.


> > If I just type in the part before the & and then play audiodump.wav
> > (which I did now) it plays just fine but my file keeps getting
> > larger.  I will try this on realaudio some time.  We are going to
> > work on the 600 and 750MHz models now instead.
>
> The FIFO is what is supposed to keep the size in check. Once a byte
> is read from a FIFO, whatever is writing into a FIFO is allowed to
> send another byte in. The original byte is lost, so the FIFO does
> not grow.

The FIFO .wav file did not get larger than 0 bytes.  Do I need to set it 
up differently, specifying the maximum size somehow?

> > I started the play only about 30 sec after I started mplayer, and
> > it is still playing a few minutes later, so as long as I have lots
> > of free hard drive space I will be okay, but wav files are large.
> > I am already at 18MB in 5 minutes.  60 minutes would be 200MB.  I
> > suppose I could delete and restart at the end of each piece.
>
> Or have a kludgey shell script do this for you by waiting a set period,
> deleting the file, and restarting everything. I would prefer the FIFO
> method, as this method will result in gaps in the audio.

I can time the gaps to be during the parts where they talk.

> > I see at the end of the screen:
> >
> > Starting playback...
> > mpg123:  Can't rewind stream by 62 bits!
> > A:  5:40.2 (the time?) 93.5% 0%
> >
> >
> > But ps says I am using sox, not mpg123.
>
> Perhaps MPlayer uses mpg123 if it exists?
Maybe, but it appeared to be using sox/play.

> > I will try this on a realaudio file next (same URL harvesting
> > technique as for mp3 files).
It worked, also on a WMP file.
> David
> --

Are you also sitting inside all afternoon on the nicest day in May?