I had initially posted this to the alsa-devel list but haven't
received a response and thought that maybe that was the wrong list. If
this is the incorrect place for this please let me know.
I am attempting to upgrade from Ubuntu version 10.04 to version 12.04. Version
10.04 has ALSA version 1.0.22 and version 12.04 has ALSA 1.0.25. I have a
simple test application that captures microphone input and then plays the
audio through the speaker. When run with ALSA 1.0.22 the program works as
expected. When I run the program with ALSA 1.0.25, I get a bad pipe error
indicating buffer underrun when calling writes. Both systems have the same
hardware (Dell Latitude E6400 laptop).
I tried looking through the change logs to determine if there were any obvious
changes that stood out to me, but couldn't find anything. I have attached
my code. Any suggestions?
Program is compiled using "g++ audio_test.cpp -o audio_test -lasound"
Audio sample rate: 8000
Buffer size: 1800
Format: Signed 16bit LE, interleaved
#include <alsa/asoundlib.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#define BUFFER_SIZE 1800
int main( int argc, char* argv[] )
{
//Speaker
snd_pcm_t* pcm_handle;
snd_pcm_t* cap_handle;
snd_pcm_stream_t stream = SND_PCM_STREAM_PLAYBACK;
snd_pcm_stream_t receive = SND_PCM_STREAM_CAPTURE;
snd_pcm_hw_params_t *hwparams;
char *pcm_name;
pcm_name = strdup( "default" );
snd_pcm_hw_params_alloca( &hwparams );
if( snd_pcm_open( &pcm_handle, pcm_name, stream, 0 ) < 0 )
{
fprintf( stderr, "Error opening PCM device %s\n", pcm_name );
return -1;
}
if( snd_pcm_open( &cap_handle, pcm_name, receive, 0 ) < 0 )
{
fprintf( stderr, "Error opening PCM device %s\n", pcm_name );
return -1;
}
if( snd_pcm_hw_params_malloc( &hwparams ) < 0 )
{
fprintf( stderr, "cannot allocate hardware parameter structure\n" );
return -1;
}
if( snd_pcm_hw_params_any( pcm_handle, hwparams ) < 0 )
{
fprintf( stderr, "cannot initialize hardware parameter structure\n" );
return -1;
}
if( snd_pcm_hw_params_any( cap_handle, hwparams ) < 0 )
{
fprintf( stderr, "cannot initialize hardware parameter structure\n" );
return -1;
}
int rate = 8000;
unsigned int exact_rate;
unsigned int periods = 2;
int chan = 1;
int err;
if( err = ( snd_pcm_hw_params_set_access( pcm_handle, hwparams,
SND_PCM_ACCESS_RW_INTERLEAVED ) < 0 ) )
{
fprintf( stderr, "Error setting access (%s).\n", snd_strerror( err ) );
return -1;
}
if( err = ( snd_pcm_hw_params_set_access( cap_handle, hwparams,
SND_PCM_ACCESS_RW_INTERLEAVED ) < 0 ) )
{
fprintf( stderr, "Error setting access (%s).\n", snd_strerror( err ) );
return -1;
}
if( snd_pcm_hw_params_set_format( pcm_handle, hwparams,
SND_PCM_FORMAT_S16_LE ) < 0 )
{
fprintf( stderr, "Error setting rate.\n" );
return -1;
}
if( snd_pcm_hw_params_set_format( cap_handle, hwparams,
SND_PCM_FORMAT_S16_LE ) < 0 )
{
fprintf( stderr, "Error setting rate.\n" );
return -1;
}
exact_rate = rate;
if( snd_pcm_hw_params_set_rate_near( pcm_handle, hwparams, &exact_rate,
0 ) < 0 )
{
fprintf( stderr, "Error setting rate.\n" );
return -1;
}
if( rate != exact_rate )
{
fprintf( stderr, "The rate %d Hz is not supported by your hardware.\n "
" ==> Using %d Hz instead.\n", rate, exact_rate );
}
exact_rate = rate;
if( snd_pcm_hw_params_set_rate_near( cap_handle, hwparams, &exact_rate,
0 ) < 0 )
{
fprintf( stderr, "Error setting rate.\n" );
return -1;
}
if( rate != exact_rate )
{
fprintf( stderr, "The rate %d Hz is not supported by your hardware.\n "
" ==> Using %d Hz instead.\n", rate, exact_rate );
}
if( snd_pcm_hw_params_set_channels( pcm_handle, hwparams, chan ) < 0 )
{
fprintf( stderr, "Error setting channels.\n" );
return -1;
}
if( snd_pcm_hw_params_set_channels( cap_handle, hwparams, chan ) < 0 )
{
fprintf( stderr, "Error setting channels.\n" );
return -1;
}
if( snd_pcm_hw_params_set_periods_near( pcm_handle, hwparams, &periods, 0 )
< 0 )
{
fprintf( stderr, "Error setting periods.\n" );
return -1;
}
if( snd_pcm_hw_params_set_periods_near( cap_handle, hwparams, &periods, 0 )
< 0 )
{
fprintf( stderr, "Error setting periods.\n" );
return -1;
}
int frameSize = chan * 2;
snd_pcm_uframes_t frme = BUFFER_SIZE / frameSize * periods;
if( snd_pcm_hw_params_set_buffer_size_near( pcm_handle, hwparams, &frme )
< 0 )
{
fprintf( stderr, "Error setting buffersize.\n" );
return -1;
}
if( BUFFER_SIZE != ( int )( frme * frameSize / periods ) )
{
printf( "asked for %d, got %d\n", BUFFER_SIZE,
( int )( frme * frameSize / periods ) );
}
frme = BUFFER_SIZE / frameSize * periods;
if( snd_pcm_hw_params_set_buffer_size_near( cap_handle, hwparams, &frme )
< 0 )
{
fprintf( stderr, "Error setting buffersize.\n" );
return -1;
}
if( BUFFER_SIZE != ( int )( frme * frameSize / periods ) )
{
printf( "asked for %d, got %d\n", BUFFER_SIZE,
( int )( frme * frameSize / periods ) );
}
if( snd_pcm_hw_params( pcm_handle, hwparams ) < 0 )
{
fprintf( stderr, "Error setting HW params.\n" );
return -1;
}
if( snd_pcm_hw_params( cap_handle, hwparams ) < 0 )
{
fprintf( stderr, "Error setting HW params.\n" );
return -1;
}
unsigned char *data;
int frames;
data = ( unsigned char* )malloc( BUFFER_SIZE );
frames = BUFFER_SIZE/frameSize;
while( true )
{
if( ( pcmreturn = snd_pcm_readi( cap_handle, data, frames ) ) < 0 )
{
snd_pcm_prepare( cap_handle );
printf( "read error: %d\n", pcmreturn );
}
else
{
if( ( pcmreturn = snd_pcm_writei( pcm_handle, data, frames ) )
< 0 )
{
printf( "write error: %d\n", pcmreturn );
}
}
}
snd_pcm_drop( pcm_handle );
snd_pcm_drain( pcm_handle );
return 0;
}
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