alsa.c

VLC Player Source Code

/*****************************************************************************
 * alsa.c : alsa plugin for vlc
 *****************************************************************************
 * Copyright (C) 2000-2001 the VideoLAN team
 * $Id: 6c020d86dd59aa3953308c98275bcb98c6277760 $
 *
 * Authors: Henri Fallon <[e-mail]> - Original Author
 *          Jeffrey Baker <[e-mail]> - Port to ALSA 1.0 API
 *          John Paul Lorenti <[e-mail]> - Device selection
 *          Arnaud de Bossoreille de Ribou <[e-mail]> - S/PDIF and aout3
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
 *****************************************************************************/

/*****************************************************************************
 * Preamble
 *****************************************************************************/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <vlc_common.h>
#include <vlc_plugin.h>

#include <errno.h>                                                 /* ENOMEM */
#include <vlc_interface.h>

#include <vlc_aout.h>

/* ALSA part
   Note: we use the new API which is available since 0.9.0beta10a. */
#define ALSA_PCM_NEW_HW_PARAMS_API
#define ALSA_PCM_NEW_SW_PARAMS_API
#include <alsa/asoundlib.h>

/*#define ALSA_DEBUG*/

/*****************************************************************************
 * aout_sys_t: ALSA audio output method descriptor
 *****************************************************************************
 * This structure is part of the audio output thread descriptor.
 * It describes the ALSA specific properties of an audio device.
 *****************************************************************************/
struct aout_sys_t
{
    snd_pcm_t         * p_snd_pcm;
    unsigned int                 i_period_time;

#ifdef ALSA_DEBUG
    snd_output_t      * p_snd_stderr;
#endif

    int b_playing;                                         /* playing status */
    mtime_t start_date;

    vlc_mutex_t lock;
    vlc_cond_t  wait ;

    snd_pcm_status_t *p_status;
};

#define A52_FRAME_NB 1536

/* These values are in frames.
   To convert them to a number of bytes you have to multiply them by the
   number of channel(s) (eg. 2 for stereo) and the size of a sample (eg.
   2 for int16_t). */
#define ALSA_DEFAULT_PERIOD_SIZE        1024
#define ALSA_DEFAULT_BUFFER_SIZE        ( ALSA_DEFAULT_PERIOD_SIZE << 8 )
#define ALSA_SPDIF_PERIOD_SIZE          A52_FRAME_NB
#define ALSA_SPDIF_BUFFER_SIZE          ( ALSA_SPDIF_PERIOD_SIZE << 4 )
/* Why << 4 ? --Meuuh */
/* Why not ? --Bozo */
/* Right. --Meuuh */

#define DEFAULT_ALSA_DEVICE N_("default")

/*****************************************************************************
 * Local prototypes
 *****************************************************************************/
static int   Open         ( vlc_object_t * );
static void  Close        ( vlc_object_t * );
static void  Play         ( aout_instance_t * );
static void* ALSAThread   ( vlc_object_t * );
static void  ALSAFill     ( aout_instance_t * );
static int FindDevicesCallback( vlc_object_t *p_this, char const *psz_name,
                                vlc_value_t newval, vlc_value_t oldval, void *p_unused );

/*****************************************************************************
 * Module descriptor
 *****************************************************************************/
static const char *const ppsz_devices[] = { "default" };
static const char *const ppsz_devices_text[] = { N_("Default") };
vlc_module_begin();
    set_shortname( "ALSA" );
    set_description( N_("ALSA audio output") );
    set_category( CAT_AUDIO );
    set_subcategory( SUBCAT_AUDIO_AOUT );
    add_string( "alsadev", DEFAULT_ALSA_DEVICE, aout_FindAndRestart,
                N_("ALSA Device Name"), NULL, false );
        change_string_list( ppsz_devices, ppsz_devices_text, FindDevicesCallback );
        change_action_add( FindDevicesCallback, N_("Refresh list") );

    set_capability( "audio output", 150 );
    set_callbacks( Open, Close );
vlc_module_end();

/*****************************************************************************
 * Probe: probe the audio device for available formats and channels
 *****************************************************************************/
static void Probe( aout_instance_t * p_aout,
                   const char * psz_device, const char * psz_iec_device,
                   int *pi_snd_pcm_format )
{
    struct aout_sys_t * p_sys = p_aout->output.p_sys;
    vlc_value_t val, text;
    int i_ret;

    var_Create ( p_aout, "audio-device", VLC_VAR_INTEGER | VLC_VAR_HASCHOICE );
    text.psz_string = _("Audio Device");
    var_Change( p_aout, "audio-device", VLC_VAR_SETTEXT, &text, NULL );

    /* We'll open the audio device in non blocking mode so we can just exit
     * when it is already in use, but for the real stuff we'll still use
     * the blocking mode */

    /* Now test linear PCM capabilities */
    if ( !(i_ret = snd_pcm_open( &p_sys->p_snd_pcm, psz_device,
                                 SND_PCM_STREAM_PLAYBACK,
                                 SND_PCM_NONBLOCK ) ) )
    {
        int i_channels;
        snd_pcm_hw_params_t * p_hw;
        snd_pcm_hw_params_alloca (&p_hw);

        if ( snd_pcm_hw_params_any( p_sys->p_snd_pcm, p_hw ) < 0 )
        {
            msg_Warn( p_aout, "unable to retrieve initial hardware parameters"
                              ", disabling linear PCM audio" );
            snd_pcm_close( p_sys->p_snd_pcm );
            var_Destroy( p_aout, "audio-device" );
            return;
        }

        if ( snd_pcm_hw_params_set_format( p_sys->p_snd_pcm, p_hw,
                                           *pi_snd_pcm_format ) < 0 )
        {
            int i_snd_rc = -1;

            if( *pi_snd_pcm_format != SND_PCM_FORMAT_S16 )
            {
                *pi_snd_pcm_format = SND_PCM_FORMAT_S16;
                i_snd_rc = snd_pcm_hw_params_set_format( p_sys->p_snd_pcm,
                                                    p_hw, *pi_snd_pcm_format );
            }
            if ( i_snd_rc < 0 )
            {
                msg_Warn( p_aout, "unable to set stream sample size and "
                          "word order, disabling linear PCM audio" );
                snd_pcm_close( p_sys->p_snd_pcm );
                var_Destroy( p_aout, "audio-device" );
                return;
            }
        }

        i_channels = aout_FormatNbChannels( &p_aout->output.output );

        while ( i_channels > 0 )
        {
            if ( !snd_pcm_hw_params_test_channels( p_sys->p_snd_pcm, p_hw,
                                                   i_channels ) )
            {
                switch ( i_channels )
                {
                case 1:
                    val.i_int = AOUT_VAR_MONO;
                    text.psz_string = (char*)N_("Mono");
                    var_Change( p_aout, "audio-device",
                                VLC_VAR_ADDCHOICE, &val, &text );
                    break;
                case 2:
                    val.i_int = AOUT_VAR_STEREO;
                    text.psz_string = (char*)N_("Stereo");
                    var_Change( p_aout, "audio-device",
                                VLC_VAR_ADDCHOICE, &val, &text );
                    var_Set( p_aout, "audio-device", val );
                    break;
                case 4:
                    val.i_int = AOUT_VAR_2F2R;
                    text.psz_string = (char*)N_("2 Front 2 Rear");
                    var_Change( p_aout, "audio-device",
                                VLC_VAR_ADDCHOICE, &val, &text );
                    break;
                case 6:
                    val.i_int = AOUT_VAR_5_1;
                    text.psz_string = (char*)"5.1";
                    var_Change( p_aout, "audio-device",
                                VLC_VAR_ADDCHOICE, &val, &text );
                    break;
                }
            }

            --i_channels;
        }

        /* Special case for mono on stereo only boards */
        i_channels = aout_FormatNbChannels( &p_aout->output.output );
        var_Change( p_aout, "audio-device", VLC_VAR_CHOICESCOUNT, &val, NULL );
        if( val.i_int <= 0 && i_channels == 1 )
        {
            if ( !snd_pcm_hw_params_test_channels( p_sys->p_snd_pcm, p_hw, 2 ))
            {
                val.i_int = AOUT_VAR_STEREO;
                text.psz_string = (char*)N_("Stereo");
                var_Change( p_aout, "audio-device",
                            VLC_VAR_ADDCHOICE, &val, &text );
                var_Set( p_aout, "audio-device", val );
            }
        }

        /* Close the previously opened device */
        snd_pcm_close( p_sys->p_snd_pcm );
    }
    else if ( i_ret == -EBUSY )
    {
        msg_Warn( p_aout, "audio device: %s is already in use", psz_device );
    }

    /* Test for S/PDIF device if needed */
    if ( psz_iec_device )
    {
        /* Opening the device should be enough */
        if ( !(i_ret = snd_pcm_open( &p_sys->p_snd_pcm, psz_iec_device,
                                     SND_PCM_STREAM_PLAYBACK,
                                     SND_PCM_NONBLOCK ) ) )
        {
            val.i_int = AOUT_VAR_SPDIF;
            text.psz_string = (char*)N_("A/52 over S/PDIF");
            var_Change( p_aout, "audio-device",
                        VLC_VAR_ADDCHOICE, &val, &text );
            if( config_GetInt( p_aout, "spdif" ) )
                var_Set( p_aout, "audio-device", val );

            snd_pcm_close( p_sys->p_snd_pcm );
        }
        else if ( i_ret == -EBUSY )
        {
            msg_Warn( p_aout, "audio device: %s is already in use",
                      psz_iec_device );
        }
    }

    var_Change( p_aout, "audio-device", VLC_VAR_CHOICESCOUNT, &val, NULL );
    if( val.i_int <= 0 )
    {
        /* Probe() has failed. */
        msg_Dbg( p_aout, "failed to find a useable alsa configuration" );
        var_Destroy( p_aout, "audio-device" );
        return;
    }

    /* Add final settings to the variable */
    var_AddCallback( p_aout, "audio-device", aout_ChannelsRestart, NULL );
    val.b_bool = true;
    var_Set( p_aout, "intf-change", val );
}

/*****************************************************************************
 * Open: create a handle and open an alsa device
 *****************************************************************************
 * This function opens an alsa device, through the alsa API.
 *
 * Note: the only heap-allocated string is psz_device. All the other pointers
 * are references to psz_device or to stack-allocated data.
 *****************************************************************************/
static int Open( vlc_object_t *p_this )
{
    aout_instance_t * p_aout = (aout_instance_t *)p_this;
    struct aout_sys_t * p_sys;
    vlc_value_t val;

    char psz_default_iec_device[128]; /* Buffer used to store the default
                                         S/PDIF device */
    char * psz_device, * psz_iec_device; /* device names for PCM and S/PDIF
                                            output */

    int i_vlc_pcm_format; /* Audio format for VLC's data */
    int i_snd_pcm_format; /* Audio format for ALSA's data */

    snd_pcm_uframes_t i_buffer_size = 0;
    snd_pcm_uframes_t i_period_size = 0;
    int i_channels = 0;

    snd_pcm_hw_params_t *p_hw;
    snd_pcm_sw_params_t *p_sw;

    int i_snd_rc = -1;
    unsigned int i_old_rate;
    bool b_retry = true;

    /* Allocate structures */
    p_aout->output.p_sys = p_sys = malloc( sizeof( aout_sys_t ) );
    if( p_sys == NULL )
        return VLC_ENOMEM;
    p_sys->b_playing = false;
    p_sys->start_date = 0;
    vlc_cond_init( p_aout, &p_sys->wait );
    vlc_mutex_init( &p_sys->lock );

    /* Get device name */
    if( (psz_device = config_GetPsz( p_aout, "alsadev" )) == NULL )
    {
        msg_Err( p_aout, "no audio device given (maybe \"default\" ?)" );
        intf_UserFatal( p_aout, false, _("No Audio Device"),
                        _("No audio device name was given. You might want to " \
                          "enter \"default\".") );
        free( p_sys );
        return VLC_EGENERIC;
    }

    /* Choose the IEC device for S/PDIF output:
       if the device is overriden by the user then it will be the one
       otherwise we compute the default device based on the output format. */
    if( AOUT_FMT_NON_LINEAR( &p_aout->output.output )
        && !strcmp( psz_device, DEFAULT_ALSA_DEVICE ) )
    {
        snprintf( psz_default_iec_device, sizeof(psz_default_iec_device),
                  "iec958:AES0=0x%x,AES1=0x%x,AES2=0x%x,AES3=0x%x",
                  IEC958_AES0_CON_EMPHASIS_NONE | IEC958_AES0_NONAUDIO,
                  IEC958_AES1_CON_ORIGINAL | IEC958_AES1_CON_PCM_CODER,
                  0,
                  ( p_aout->output.output.i_rate == 48000 ?
                    IEC958_AES3_CON_FS_48000 :
                    ( p_aout->output.output.i_rate == 44100 ?
                      IEC958_AES3_CON_FS_44100 : IEC958_AES3_CON_FS_32000 ) ) );