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Subject: Re: Anyone up for ALSA?

Re: Anyone up for ALSA?

From: Dave Hooper <>
Date: Wed, 13 Jul 2005 23:27:07 +0100

One idea - rather than using snd_pcm_open would it be possible to just open
/dev/dsp? (e.g. the same way the irivermidi code works when running on
C - pasted below hopefully)
Just a thought .. all of that snd_pcm_xxx looks more complex than I
suspect it needs to be

void initSound()


//OSS Stuff, set the sampling rate, etc: 48000, Mono, 16bit

fd=open("/dev/dsp", O_WRONLY); // | O_NONBLOCK);

int arg, status;

int bit, samp, ch;

arg = 16; // sample size

status = ioctl(fd, SOUND_PCM_WRITE_BITS, &arg);

status = ioctl(fd, SOUND_PCM_READ_BITS, &arg);


arg = 1; //Number of channels, 1=mono

status = ioctl(fd, SOUND_PCM_WRITE_CHANNELS, &arg);

status = ioctl(fd, SOUND_PCM_READ_CHANNELS, &arg);


arg = SAMPLE_RATE; //Yeah. sampling rate

status = ioctl(fd, SOUND_PCM_WRITE_RATE, &arg);

status = ioctl(fd, SOUND_PCM_READ_RATE, &arg);


//Print out what we *actually* got.. not that the program

//pays attention to these values anyway

printf("\nDSP Says:\n%dHz %dCh %dbit", samp, ch, bit);


----- Original Message -----
From: "Daniel Stenberg" <>
To: "Rockbox" <>
Sent: Wednesday, July 13, 2005 10:56 PM
Subject: Anyone up for ALSA?

> Howdy
> I just wrote up a first stab at providing sound in the X11 (on Linux)
> simulator. It doesn't work. :-/
> Even though the code is still very basic and crappy, I fell over some
> annoying ALSA initialization issues which aren't really my standard
> neighbourhood issues so I thought I'd cry for help at once...
> The problem is this:
> I wrote a tiny little stand-alone app first that uses ALSA fine and that
> plays PCM data (and I can hear the glitch in my speakers when it plays
> some random stack data). But when I convert that very same code into a
> function for Rockbox (there's a new PCM playback thread started that will
> deal with all the ALSA/PCM playback stuff) the initial call to
> snd_pcm_open() fails and it prints this informative blurb on stderr:
> ALSA lib conf.c:2715:(snd_config_hooks) id of field i is not and integer
> ALSA lib conf.c:3052:(snd_config_update_r) hooks failed, removing
> configuration
> cannot open audio device default (Invalid argument)
> Here's this first patch:
> 1. Beware, it is not even close to fit for commit yet
> 2. You need to edit your main Makefile and add "-lasound" along the libs
> to
> link with.
> Anyone?
> --
> Daniel Stenberg -- --
> _______________________________________________

Received on 2005-07-14

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