modules/audio_output/sdl.c

   1 /*****************************************************************************
   2  * sdl.c : SDL audio output plugin for vlc
   3  *****************************************************************************
   4  * Copyright (C) 2000-2002 the VideoLAN team
   5  * $Id$
   6  *
   7  * Authors: Michel Kaempf <maxx@via.ecp.fr>
   8  *          Sam Hocevar <sam@zoy.org>
   9  *          Pierre Baillet <oct@zoy.org>
  10  *          Christophe Massiot <massiot@via.ecp.fr>
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with this program; if not, write to the Free Software
  24  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  25  *****************************************************************************/
  26
  27 /*****************************************************************************
  28  * Preamble
  29  *****************************************************************************/
  30 #include <unistd.h>                                      /* write(), close() */
  31
  32 #ifdef HAVE_CONFIG_H
  33 # include "config.h"
  34 #endif
  35
  36 #include <vlc_common.h>
  37 #include <vlc_plugin.h>
  38 #include <vlc_aout.h>
  39
  40 #include <SDL.h>
  41
  42 #define FRAME_SIZE 2048
  43
  44 /*****************************************************************************
  45  * aout_sys_t: SDL audio output method descriptor
  46  *****************************************************************************
  47  * This structure is part of the audio output thread descriptor.
  48  * It describes the specific properties of an audio device.
  49  *****************************************************************************/
  50 struct aout_sys_t
  51 {
  52     mtime_t next_date;
  53     mtime_t buffer_time;
  54 };
  55
  56 /*****************************************************************************
  57  * Local prototypes
  58  *****************************************************************************/
  59 static int  Open        ( vlc_object_t * );
  60 static void Close       ( vlc_object_t * );
  61 static void Play        ( aout_instance_t * );
  62 static void SDLCallback ( void *, uint8_t *, int );
  63
  64 /*****************************************************************************
  65  * Module descriptor
  66  *****************************************************************************/
  67 vlc_module_begin ()
  68     set_shortname( "SDL" )
  69     set_description( N_("Simple DirectMedia Layer audio output") )
  70     set_capability( "audio output", 40 )
  71     set_category( CAT_AUDIO )
  72     set_subcategory( SUBCAT_AUDIO_AOUT )
  73     add_shortcut( "sdl" )
  74     set_callbacks( Open, Close )
  75 vlc_module_end ()
  76
  77 /*****************************************************************************
  78  * Open: open the audio device
  79  *****************************************************************************/
  80 static int Open ( vlc_object_t *p_this )
  81 {
  82     aout_instance_t *p_aout = (aout_instance_t *)p_this;
  83     SDL_AudioSpec desired, obtained;
  84     int i_nb_channels;
  85     vlc_value_t val, text;
  86
  87     /* Check that no one uses the DSP. */
  88     uint32_t i_flags = SDL_INIT_AUDIO;
  89     if( SDL_WasInit( i_flags ) )
  90     {
  91         return VLC_EGENERIC;
  92     }
  93
  94     i_flags |= SDL_INIT_EVENTTHREAD;
  95 #ifndef NDEBUG
  96     /* In debug mode you may want vlc to dump a core instead of staying
  97      * stuck */
  98     i_flags |= SDL_INIT_NOPARACHUTE;
  99 #endif
 100
 101     /* Initialize library */
 102     if( SDL_Init( i_flags ) < 0 )
 103     {
 104         msg_Err( p_aout, "cannot initialize SDL (%s)", SDL_GetError() );
 105         return VLC_EGENERIC;
 106     }
 107
 108     if( var_Get( p_aout, "audio-device", &val ) != VLC_ENOVAR )
 109     {
 110         /* The user has selected an audio device. */
 111         if ( val.i_int == AOUT_VAR_STEREO )
 112         {
 113             p_aout->output.output.i_physical_channels
 114                 = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
 115         }
 116         else if ( val.i_int == AOUT_VAR_MONO )
 117         {
 118             p_aout->output.output.i_physical_channels = AOUT_CHAN_CENTER;
 119         }
 120     }
 121
 122     i_nb_channels = aout_FormatNbChannels( &p_aout->output.output );
 123     if ( i_nb_channels > 2 )
 124     {
 125         /* SDL doesn't support more than two channels. */
 126         i_nb_channels = 2;
 127         p_aout->output.output.i_physical_channels
 128             = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
 129     }
 130     desired.freq       = p_aout->output.output.i_rate;
 131     desired.format     = AUDIO_S16SYS;
 132     desired.channels   = i_nb_channels;
 133     desired.callback   = SDLCallback;
 134     desired.userdata   = p_aout;
 135     desired.samples    = FRAME_SIZE;
 136
 137     /* Open the sound device. */
 138     if( SDL_OpenAudio( &desired, &obtained ) < 0 )
 139     {
 140         return VLC_EGENERIC;
 141     }
 142
 143     SDL_PauseAudio( 0 );
 144
 145     /* Now have a look at what we got. */
 146     switch ( obtained.format )
 147     {
 148     case AUDIO_S16LSB:
 149         p_aout->output.output.i_format = VLC_CODEC_S16L; break;
 150     case AUDIO_S16MSB:
 151         p_aout->output.output.i_format = VLC_CODEC_S16B; break;
 152     case AUDIO_U16LSB:
 153         p_aout->output.output.i_format = VLC_CODEC_U16L; break;
 154     case AUDIO_U16MSB:
 155         p_aout->output.output.i_format = VLC_CODEC_U16B; break;
 156     case AUDIO_S8:
 157         p_aout->output.output.i_format = VLC_CODEC_S8; break;
 158     case AUDIO_U8:
 159         p_aout->output.output.i_format = VLC_CODEC_U8; break;
 160     }
 161     /* Volume is entirely done in software. */
 162     aout_VolumeSoftInit( p_aout );
 163
 164     if ( obtained.channels != i_nb_channels )
 165     {
 166         p_aout->output.output.i_physical_channels = (obtained.channels == 2 ?
 167                                             AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT :
 168                                             AOUT_CHAN_CENTER);
 169
 170         if ( var_Type( p_aout, "audio-device" ) == 0 )
 171         {
 172             var_Create( p_aout, "audio-device",
 173                         VLC_VAR_INTEGER | VLC_VAR_HASCHOICE );
 174             text.psz_string = _("Audio Device");
 175             var_Change( p_aout, "audio-device", VLC_VAR_SETTEXT, &text, NULL );
 176
 177             val.i_int = (obtained.channels == 2) ? AOUT_VAR_STEREO :
 178                         AOUT_VAR_MONO;
 179             text.psz_string = (obtained.channels == 2) ? _("Stereo") :
 180                               _("Mono");
 181             var_Change( p_aout, "audio-device",
 182                         VLC_VAR_ADDCHOICE, &val, &text );
 183             var_AddCallback( p_aout, "audio-device", aout_ChannelsRestart,
 184                              NULL );
 185         }
 186     }
 187     else if ( var_Type( p_aout, "audio-device" ) == 0 )
 188     {
 189         /* First launch. */
 190         var_Create( p_aout, "audio-device",
 191                     VLC_VAR_INTEGER | VLC_VAR_HASCHOICE );
 192         text.psz_string = _("Audio Device");
 193         var_Change( p_aout, "audio-device", VLC_VAR_SETTEXT, &text, NULL );
 194
 195         val.i_int = AOUT_VAR_STEREO;
 196         text.psz_string = _("Stereo");
 197         var_Change( p_aout, "audio-device", VLC_VAR_ADDCHOICE, &val, &text );
 198         val.i_int = AOUT_VAR_MONO;
 199         text.psz_string = _("Mono");
 200         var_Change( p_aout, "audio-device", VLC_VAR_ADDCHOICE, &val, &text );
 201         if ( i_nb_channels == 2 )
 202         {
 203             val.i_int = AOUT_VAR_STEREO;
 204         }
 205         else
 206         {
 207             val.i_int = AOUT_VAR_MONO;
 208         }
 209         var_Change( p_aout, "audio-device", VLC_VAR_SETDEFAULT, &val, NULL );
 210         var_AddCallback( p_aout, "audio-device", aout_ChannelsRestart, NULL );
 211     }
 212
 213     var_SetBool( p_aout, "intf-change", true );
 214
 215     p_aout->output.output.i_rate = obtained.freq;
 216     p_aout->output.i_nb_samples = obtained.samples;
 217     p_aout->output.pf_play = Play;
 218
 219     return VLC_SUCCESS;
 220 }
 221
 222 /*****************************************************************************
 223  * Play: play a sound samples buffer
 224  *****************************************************************************/
 225 static void Play( aout_instance_t * p_aout )
 226 {
 227     VLC_UNUSED(p_aout);
 228 }
 229
 230 /*****************************************************************************
 231  * Close: close the audio device
 232  *****************************************************************************/
 233 static void Close ( vlc_object_t *p_this )
 234 {
 235     VLC_UNUSED(p_this);
 236     SDL_PauseAudio( 1 );
 237     SDL_CloseAudio();
 238     SDL_QuitSubSystem( SDL_INIT_AUDIO );
 239 }
 240
 241 /*****************************************************************************
 242  * SDLCallback: what to do once SDL has played sound samples
 243  *****************************************************************************/
 244 static void SDLCallback( void * _p_aout, uint8_t * p_stream, int i_len )
 245 {
 246     aout_instance_t * p_aout = (aout_instance_t *)_p_aout;
 247     aout_buffer_t *   p_buffer;
 248
 249     /* SDL is unable to call us at regular times, or tell us its current
 250      * hardware latency, or the buffer state. So we just pop data and throw
 251      * it at SDL's face. Nah. */
 252
 253     vlc_mutex_lock( &p_aout->output_fifo_lock );
 254     p_buffer = aout_FifoPop( p_aout, &p_aout->output.fifo );
 255     vlc_mutex_unlock( &p_aout->output_fifo_lock );
 256
 257     if ( p_buffer != NULL )
 258     {
 259         vlc_memcpy( p_stream, p_buffer->p_buffer, i_len );
 260         aout_BufferFree( p_buffer );
 261     }
 262     else
 263     {
 264         vlc_memset( p_stream, 0, i_len );
 265     }
 266 }
 267