Problem with: Broken Pipe

Problem with: Broken Pipe

[Holger Rostalski]

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moin.
i have a problem with development of a soundapplication for Linux 8.2 
with ALSA 0.9.0


if i take the "Minimal Interrupt Driven -Program" from the tutorial (in 
attachments) and changed a little bit the
play_callback-methode, i got at start a
"broken Pipe" error.

what means it?

my changes:
================
       int
	playback_callback (snd_pcm_sframes_t nframes)
	{
		int err;
	
		printf ("playback callback called with %u frames\n", nframes);
		unsigned char data[4*4096];
		for (int x=0; x<4096; x++)
		{
			buf[x]=10*x;
				data[4*x]=(unsigned char) buf[x];
				data[4*x+1]=buf[x] >> 8;
				data[4*x+2]=(unsigned char) buf[x];
				data[4*x+3]=buf[x] >> 8;
			cout << "test" << x;

			
		};
	
		if ((err = snd_pcm_writei (playback_handle, data, 4096)) < 0) {
			fprintf (stderr, "write failed (%s)\n", 	snd_strerror (err));
		}
	
		return err;
	}




-> if i delete the cout-command, the programm works fine...but with cout 
(or with fprint ) i got "broken pipe". ...

 >>>>>>>>>   this is only the simplest way to reproduce the error. my 
programm has much more code. <<<<<<<<<<<<<<<<<<<<<





greetz
Holger

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Re: Problem with: Broken Pipe

[Paul Davis]

>i have a problem with development of a soundapplication for Linux 8.2 
>with ALSA 0.9.0
>
>
>if i take the "Minimal Interrupt Driven -Program" from the tutorial (in 
>attachments) and changed a little bit the
>play_callback-methode, i got at start a
>"broken Pipe" error.

how many channels are you configuring? you are telling writei() that
you are supplying 4096 *frames* of data, yet from what i can tell, you
are actually trying to write data for, well, i don't know. could be 2
16 bit channels, or 1 32 bit channel, or 4 8 bit channels. i suspect
that is the source of the problem: you are not supplying enough data
to keep up with the card.

please remember that the arguments to almost every ALSA function that
measures "an amount of audio" are in units of *frames*, not bytes and
not samples.

--p


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