/*****************************************************************************
* alsa.c : alsa plugin for vlc
*****************************************************************************
* Copyright (C) 2000-2001 VideoLAN
* $Id: alsa.c,v 1.21 2002/07/31 20:56:50 sam Exp $
*
* Authors: Henri Fallon <henri@videolan.org> - Original Author
* Jeffrey Baker <jwbaker@acm.org> - Port to ALSA 1.0 API
* John Paul Lorenti <jpl31@columbia.edu> - Device selection
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
*****************************************************************************/
/*****************************************************************************
* Preamble
*****************************************************************************/
#include <errno.h> /* ENOMEM */
#include <string.h> /* strerror() */
#include <stdlib.h> /* calloc(), malloc(), free() */
#include <vlc/vlc.h>
#include <vlc/aout.h>
#include <alsa/asoundlib.h>
/*****************************************************************************
* Local prototypes
*****************************************************************************/
static int Open ( vlc_object_t * );
static void Close ( vlc_object_t * );
static int SetFormat ( aout_thread_t * );
static int GetBufInfo ( aout_thread_t *, int );
static void Play ( aout_thread_t *, byte_t *, int );
static void HandleXrun ( aout_thread_t *);
/*****************************************************************************
* Module descriptor
*****************************************************************************/
vlc_module_begin();
add_category_hint( N_("Device"), NULL );
add_string( "alsa-device", NULL, NULL, N_("Name"), NULL );
set_description( _("ALSA audio module") );
set_capability( "audio output", 50 );
set_callbacks( Open, Close );
vlc_module_end();
/*****************************************************************************
* Preamble
*****************************************************************************/
typedef struct alsa_device_t
{
int i_num;
} alsa_device_t;
typedef struct alsa_card_t
{
int i_num;
} alsa_card_t;
/* here we store plugin dependant informations */
struct aout_sys_t
{
snd_pcm_t * p_alsa_handle;
unsigned long buffer_time;
unsigned long period_time;
unsigned long chunk_size;
unsigned long buffer_size;
unsigned long rate;
unsigned int bytes_per_sample;
unsigned int samples_per_frame;
unsigned int bytes_per_frame;
};
/*****************************************************************************
* Open: create a handle and open an alsa device
*****************************************************************************
* This function opens an alsa device, through the alsa API
*****************************************************************************/
static int Open( vlc_object_t *p_this )
{
aout_thread_t *p_aout = (aout_thread_t *)p_this;
/* Allows user to choose which ALSA device to use */
char psz_alsadev[128];
char *psz_device, *psz_userdev;
int i_ret;
/* Allocate structures */
p_aout->p_sys = malloc( sizeof( aout_sys_t ) );
if( p_aout->p_sys == NULL )
{
msg_Err( p_aout, "out of memory" );
return -1;
}
p_aout->pf_setformat = SetFormat;
p_aout->pf_getbufinfo = GetBufInfo;
p_aout->pf_play = Play;
/* Read in ALSA device preferences from configuration */
psz_userdev = config_GetPsz( p_aout, "alsa-device" );
if( psz_userdev )
{
psz_device = psz_userdev;
}
else
{
/* Use the internal logic to decide on the device name */
if( p_aout->i_format != AOUT_FMT_AC3 )
{
psz_device = "default";
}
else
{
unsigned char s[4];
s[0] = IEC958_AES0_CON_EMPHASIS_NONE | IEC958_AES0_NONAUDIO;
s[1] = IEC958_AES1_CON_ORIGINAL | IEC958_AES1_CON_PCM_CODER;
s[2] = 0;
s[3] = IEC958_AES3_CON_FS_48000;
sprintf( psz_alsadev,
"iec958:AES0=0x%x,AES1=0x%x,AES2=0x%x,AES3=0x%x",
s[0], s[1], s[2], s[3] );
psz_device = psz_alsadev;
}
}
/* Open device */
i_ret = snd_pcm_open( &(p_aout->p_sys->p_alsa_handle),
psz_device, SND_PCM_STREAM_PLAYBACK, 0);
if( i_ret != 0 )
{
msg_Err( p_aout, "cannot open ALSA device `%s' (%s)",
psz_device, snd_strerror(i_ret) );
if( psz_userdev )
{
free( psz_userdev );
}
return -1;
}
if( psz_userdev )
{
free( psz_userdev );
}
return 0;
}
/*****************************************************************************
* SetFormat : sets the alsa output format
*****************************************************************************
* This function prepares the device, sets the rate, format, the mode
* ( "play as soon as you have data" ), and buffer information.
*****************************************************************************/
static int SetFormat( aout_thread_t *p_aout )
{
int i_rv;
int i_format;
snd_pcm_hw_params_t *p_hw;
snd_pcm_sw_params_t *p_sw;
snd_pcm_hw_params_alloca(&p_hw);
snd_pcm_sw_params_alloca(&p_sw);
/* default value for snd_pcm_hw_params_set_buffer_time_near() */
p_aout->p_sys->buffer_time = AOUT_BUFFER_DURATION;
switch (p_aout->i_format)
{
case AOUT_FMT_S16_LE:
i_format = SND_PCM_FORMAT_S16_LE;
p_aout->p_sys->bytes_per_sample = 2;
break;
case AOUT_FMT_AC3:
i_format = SND_PCM_FORMAT_S16_LE;
p_aout->p_sys->bytes_per_sample = 2;
/* buffer_time must be 500000 to avoid a system crash */
p_aout->p_sys->buffer_time = 500000;
break;
default:
i_format = SND_PCM_FORMAT_S16_BE;
p_aout->p_sys->bytes_per_sample = 2;
break;
}
p_aout->p_sys->samples_per_frame = p_aout->i_channels;
p_aout->p_sys->bytes_per_frame = p_aout->p_sys->samples_per_frame *
p_aout->p_sys->bytes_per_sample;
i_rv = snd_pcm_hw_params_any( p_aout->p_sys->p_alsa_handle, p_hw );
if( i_rv < 0 )
{
msg_Err( p_aout, "unable to retrieve initial parameters" );
return -1;
}
i_rv = snd_pcm_hw_params_set_access( p_aout->p_sys->p_alsa_handle, p_hw,
SND_PCM_ACCESS_RW_INTERLEAVED );
if( i_rv < 0 )
{
msg_Err( p_aout, "unable to set interleaved stream format" );
return -1;
}
i_rv = snd_pcm_hw_params_set_format( p_aout->p_sys->p_alsa_handle,
p_hw, i_format );
if( i_rv < 0 )
{
msg_Err( p_aout, "unable to set stream sample size and word order" );
return -1;
}
i_rv = snd_pcm_hw_params_set_channels( p_aout->p_sys->p_alsa_handle, p_hw,
p_aout->i_channels );
if( i_rv < 0 )
{
msg_Err( p_aout, "unable to set number of output channels" );
return -1;
}
i_rv = snd_pcm_hw_params_set_rate_near( p_aout->p_sys->p_alsa_handle, p_hw,
p_aout->i_rate, 0 );
if( i_rv < 0 )
{
msg_Err( p_aout, "unable to set sample rate" );
return -1;
}
p_aout->p_sys->rate = i_rv;
i_rv = snd_pcm_hw_params_set_buffer_time_near( p_aout->p_sys->p_alsa_handle,
p_hw,
p_aout->p_sys->buffer_time,
0 );
if( i_rv < 0 )
{
msg_Err( p_aout, "unable to set buffer time" );
return -1;
}
p_aout->p_sys->buffer_time = i_rv;
i_rv = snd_pcm_hw_params_set_period_time_near( p_aout->p_sys->p_alsa_handle,
p_hw, p_aout->p_sys->buffer_time / p_aout->p_sys->bytes_per_frame, 0 );
if( i_rv < 0 )
{
msg_Err( p_aout, "unable to set period time" );
return -1;
}
p_aout->p_sys->period_time = i_rv;
i_rv = snd_pcm_hw_params(p_aout->p_sys->p_alsa_handle, p_hw);
if (i_rv < 0)
{
msg_Err( p_aout, "unable to set hardware configuration" );
return -1;
}
p_aout->p_sys->chunk_size = snd_pcm_hw_params_get_period_size( p_hw, 0 );
p_aout->p_sys->buffer_size = snd_pcm_hw_params_get_buffer_size( p_hw );
snd_pcm_sw_params_current( p_aout->p_sys->p_alsa_handle, p_sw );
i_rv = snd_pcm_sw_params_set_sleep_min( p_aout->p_sys->p_alsa_handle, p_sw,
0 );
i_rv = snd_pcm_sw_params_set_avail_min( p_aout->p_sys->p_alsa_handle, p_sw,
p_aout->p_sys->chunk_size );
/* Worked with the CVS version but not with 0.9beta3
i_rv = snd_pcm_sw_params_set_start_threshold( p_aout->p_sys->p_alsa_handle,
p_sw, p_aout->p_sys->buffer_size );
i_rv = snd_pcm_sw_params_set_stop_threshold( p_aout->p_sys->p_alsa_handle,
p_sw, p_aout->p_sys->buffer_size);
*/
i_rv = snd_pcm_sw_params( p_aout->p_sys->p_alsa_handle, p_sw );
if( i_rv < 0 )
{
msg_Err( p_aout, "unable to set software configuration" );
return -1;
}
return 0;
}
/*****************************************************************************
* HandleXrun : reprepare the output
*****************************************************************************
* When buffer gets empty, the driver goes in "Xrun" state, where it needs
* to be reprepared before playing again
*****************************************************************************/
static void HandleXrun(aout_thread_t *p_aout)
{
int i_rv;
msg_Err( p_aout, "resetting output after buffer underrun" );
// i_rv = snd_pcm_reset( p_aout->p_sys->p_alsa_handle );
i_rv = snd_pcm_prepare( p_aout->p_sys->p_alsa_handle );
if( i_rv < 0 )
{
msg_Err( p_aout, "unable to recover from buffer underrun (%s)",
snd_strerror( i_rv ) );
}
}
/*****************************************************************************
* BufInfo: buffer status query
*****************************************************************************
* This function returns the number of used byte in the queue.
* It also deals with errors : indeed if the device comes to run out
* of data to play, it switches to the "underrun" status. It has to
* be flushed and re-prepared
*****************************************************************************/
static int GetBufInfo( aout_thread_t *p_aout, int i_buffer_limit )
{
snd_pcm_status_t *p_status;
int i_alsa_get_status_returns;
snd_pcm_status_alloca( &p_status );
i_alsa_get_status_returns = snd_pcm_status( p_aout->p_sys->p_alsa_handle,
p_status );
if( i_alsa_get_status_returns )
{
msg_Err( p_aout, "failed getting alsa buffer info (%s)",
snd_strerror ( i_alsa_get_status_returns ) );
return ( -1 );
}
switch( snd_pcm_status_get_state( p_status ) )
{
case SND_PCM_STATE_XRUN :
HandleXrun( p_aout );
break;
case SND_PCM_STATE_OPEN:
case SND_PCM_STATE_PREPARED:
case SND_PCM_STATE_RUNNING:
break;
default:
msg_Err( p_aout, "unhandled condition %i",
snd_pcm_status_get_state( p_status ) );
break;
}
return snd_pcm_status_get_avail(p_status) * p_aout->p_sys->bytes_per_frame;
}
/*****************************************************************************
* Play : plays a sample
*****************************************************************************
* Plays a sample using the snd_pcm_writei function from the alsa API
*****************************************************************************/
static void Play( aout_thread_t *p_aout, byte_t *buffer, int i_size )
{
snd_pcm_uframes_t tot_frames;
snd_pcm_uframes_t frames_left;
snd_pcm_uframes_t rv;
tot_frames = i_size / p_aout->p_sys->bytes_per_frame;
frames_left = tot_frames;
while( frames_left > 0 )
{
rv = snd_pcm_writei( p_aout->p_sys->p_alsa_handle, buffer +
(tot_frames - frames_left) *
p_aout->p_sys->bytes_per_frame, frames_left );
if( (signed int) rv < 0 )
{
msg_Err( p_aout, "failed writing to output (%s)",
snd_strerror( rv ) );
return;
}
frames_left -= rv;
}
}
/*****************************************************************************
* Close: close the Alsa device
*****************************************************************************/
static void Close( vlc_object_t *p_this )
{
aout_thread_t *p_aout = (aout_thread_t *)p_this;
int i_close_returns;
i_close_returns = snd_pcm_close( p_aout->p_sys->p_alsa_handle );
if( i_close_returns )
{
msg_Err( p_aout, "failed closing ALSA device (%s)",
snd_strerror( i_close_returns ) );
}
free( p_aout->p_sys );
}