1 /*****************************************************************************
2 * oss.c : OSS /dev/dsp module for vlc
3 *****************************************************************************
4 * Copyright (C) 2000-2002 VideoLAN
5 * $Id: oss.c,v 1.20 2002/08/29 23:53:22 massiot Exp $
7 * Authors: Michel Kaempf <maxx@via.ecp.fr>
8 * Samuel Hocevar <sam@zoy.org>
9 * Christophe Massiot <massiot@via.ecp.fr>
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 2 of the License, or
14 * (at your option) any later version.
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
24 *****************************************************************************/
26 /*****************************************************************************
28 *****************************************************************************/
29 #include <errno.h> /* ENOMEM */
30 #include <fcntl.h> /* open(), O_WRONLY */
31 #include <sys/ioctl.h> /* ioctl() */
32 #include <string.h> /* strerror() */
33 #include <unistd.h> /* write(), close() */
34 #include <stdlib.h> /* calloc(), malloc(), free() */
44 #include "aout_internal.h"
46 /* SNDCTL_DSP_RESET, SNDCTL_DSP_SETFMT, SNDCTL_DSP_STEREO, SNDCTL_DSP_SPEED,
47 * SNDCTL_DSP_GETOSPACE */
48 #ifdef HAVE_SOUNDCARD_H
49 # include <soundcard.h>
50 #elif defined( HAVE_SYS_SOUNDCARD_H )
51 # include <sys/soundcard.h>
52 #elif defined( HAVE_MACHINE_SOUNDCARD_H )
53 # include <machine/soundcard.h>
56 /*****************************************************************************
57 * aout_sys_t: OSS audio output method descriptor
58 *****************************************************************************
59 * This structure is part of the audio output thread descriptor.
60 * It describes the dsp specific properties of an audio device.
61 *****************************************************************************/
65 volatile vlc_bool_t b_initialized;
68 #define FRAME_SIZE 1024
70 #define A52_FRAME_NB 1536
72 /*****************************************************************************
74 *****************************************************************************/
75 static int Open ( vlc_object_t * );
76 static void Close ( vlc_object_t * );
78 static int SetFormat ( aout_instance_t * );
79 static void Play ( aout_instance_t * );
80 static int OSSThread ( aout_instance_t * );
82 /*****************************************************************************
84 *****************************************************************************/
86 add_category_hint( N_("OSS"), NULL );
87 add_file( "dspdev", "/dev/dsp", NULL, N_("OSS dsp device"), NULL );
88 set_description( _("Linux OSS /dev/dsp module") );
89 set_capability( "audio output", 100 );
90 add_shortcut( "dsp" );
91 set_callbacks( Open, Close );
94 /*****************************************************************************
95 * Open: open the audio device (the digital sound processor)
96 *****************************************************************************
97 * This function opens the dsp as a usual non-blocking write-only file, and
98 * modifies the p_aout->p_sys->i_fd with the file's descriptor.
99 *****************************************************************************/
100 static int Open( vlc_object_t *p_this )
102 aout_instance_t * p_aout = (aout_instance_t *)p_this;
103 struct aout_sys_t * p_sys;
106 /* Allocate structure */
107 p_aout->output.p_sys = p_sys = malloc( sizeof( aout_sys_t ) );
110 msg_Err( p_aout, "out of memory" );
114 /* Initialize some variables */
115 if( (psz_device = config_GetPsz( p_aout, "dspdev" )) == NULL )
117 msg_Err( p_aout, "no audio device given (maybe /dev/dsp ?)" );
122 /* Open the sound device */
123 if( (p_sys->i_fd = open( psz_device, O_WRONLY )) < 0 )
125 msg_Err( p_aout, "cannot open audio device (%s)", psz_device );
132 /* Create OSS thread and wait for its readiness. */
133 p_sys->b_initialized = VLC_FALSE;
134 if( vlc_thread_create( p_aout, "aout", OSSThread,
135 VLC_THREAD_PRIORITY_OUTPUT, VLC_FALSE ) )
137 msg_Err( p_aout, "cannot create OSS thread (%s)", strerror(errno) );
138 close( p_sys->i_fd );
144 p_aout->output.pf_setformat = SetFormat;
145 p_aout->output.pf_play = Play;
150 /*****************************************************************************
151 * SetFormat: reset the dsp and set its format
152 *****************************************************************************
153 * This functions resets the DSP device, tries to initialize the output
154 * format with the value contained in the dsp structure, and if this value
155 * could not be set, the default value returned by ioctl is set. It then
156 * does the same for the stereo mode, and for the output rate.
157 *****************************************************************************/
158 static int SetFormat( aout_instance_t *p_aout )
160 struct aout_sys_t * p_sys = p_aout->output.p_sys;
166 p_sys->b_initialized = VLC_FALSE;
168 /* Reset the DSP device */
169 if( ioctl( p_sys->i_fd, SNDCTL_DSP_RESET, NULL ) < 0 )
171 msg_Err( p_aout, "cannot reset OSS audio device" );
175 /* Set the fragment size */
176 i_fragments = FRAME_COUNT << 16 | FRAME_SIZE;
177 if( ioctl( p_sys->i_fd, SNDCTL_DSP_SETFRAGMENT, &i_fragments ) < 0 )
179 msg_Err( p_aout, "cannot set fragment size (%.8x)", i_fragments );
183 /* Set the output format */
184 if ( p_aout->output.output.i_format == AOUT_FMT_SPDIF )
186 i_format = AOUT_FMT_SPDIF;
187 p_aout->output.i_nb_samples = A52_FRAME_NB;
188 p_aout->output.output.i_bytes_per_frame = AOUT_SPDIF_SIZE;
189 p_aout->output.output.i_frame_length = A52_FRAME_NB;
193 p_aout->output.output.i_format = i_format = AOUT_FMT_S16_NE;
194 p_aout->output.i_nb_samples = FRAME_SIZE;
197 if( ioctl( p_sys->i_fd, SNDCTL_DSP_SETFMT, &i_format ) < 0
198 || i_format != p_aout->output.output.i_format )
200 msg_Err( p_aout, "cannot set audio output format (%i)", i_format );
204 if ( p_aout->output.output.i_format != AOUT_FMT_SPDIF )
207 if ( p_aout->output.output.i_channels > 2 )
209 msg_Warn( p_aout, "only two channels are supported at the moment" );
210 /* Trigger downmixing */
211 p_aout->output.output.i_channels = 2;
214 /* Set the number of channels */
215 b_stereo = p_aout->output.output.i_channels - 1;
217 if( ioctl( p_sys->i_fd, SNDCTL_DSP_STEREO, &b_stereo ) < 0 )
219 msg_Err( p_aout, "cannot set number of audio channels (%i)",
220 p_aout->output.output.i_channels );
224 if ( b_stereo + 1 != p_aout->output.output.i_channels )
226 msg_Warn( p_aout, "driver forced up/downmixing %li->%li",
227 p_aout->output.output.i_channels,
229 p_aout->output.output.i_channels = b_stereo + 1;
232 /* Set the output rate */
233 i_rate = p_aout->output.output.i_rate;
234 if( ioctl( p_sys->i_fd, SNDCTL_DSP_SPEED, &i_rate ) < 0 )
236 msg_Err( p_aout, "cannot set audio output rate (%i)",
237 p_aout->output.output.i_rate );
241 if( i_rate != p_aout->output.output.i_rate )
243 msg_Warn( p_aout, "driver forced resampling %li->%li",
244 p_aout->output.output.i_rate, i_rate );
245 p_aout->output.output.i_rate = i_rate;
249 p_sys->b_initialized = VLC_TRUE;
254 /*****************************************************************************
255 * Play: queue a buffer for playing by OSSThread
256 *****************************************************************************/
257 static void Play( aout_instance_t *p_aout )
261 /*****************************************************************************
262 * Close: close the dsp audio device
263 *****************************************************************************/
264 static void Close( vlc_object_t * p_this )
266 aout_instance_t *p_aout = (aout_instance_t *)p_this;
267 struct aout_sys_t * p_sys = p_aout->output.p_sys;
269 p_aout->b_die = VLC_TRUE;
270 vlc_thread_join( p_aout );
271 p_aout->b_die = VLC_FALSE;
273 ioctl( p_sys->i_fd, SNDCTL_DSP_RESET, NULL );
274 close( p_sys->i_fd );
280 /*****************************************************************************
281 * BufferDuration: buffer status query
282 *****************************************************************************
283 * This function returns the duration in microseconfs of the current buffer.
284 *****************************************************************************/
285 static mtime_t BufferDuration( aout_instance_t * p_aout )
287 struct aout_sys_t * p_sys = p_aout->output.p_sys;
288 audio_buf_info audio_buf;
291 /* Fill the audio_buf_info structure:
292 * - fragstotal: total number of fragments allocated
293 * - fragsize: size of a fragment in bytes
294 * - bytes: available space in bytes (includes partially used fragments)
295 * Note! 'bytes' could be more than fragments*fragsize */
296 ioctl( p_sys->i_fd, SNDCTL_DSP_GETOSPACE, &audio_buf );
298 /* calculate number of available fragments (not partially used ones) */
299 i_bytes = (audio_buf.fragstotal * audio_buf.fragsize) - audio_buf.bytes;
301 /* Return the fragment duration */
302 return (mtime_t)i_bytes * 1000000
303 / p_aout->output.output.i_bytes_per_frame
304 / p_aout->output.output.i_rate
305 * p_aout->output.output.i_frame_length;
308 /*****************************************************************************
309 * OSSThread: asynchronous thread used to DMA the data to the device
310 *****************************************************************************/
311 static int OSSThread( aout_instance_t * p_aout )
313 struct aout_sys_t * p_sys = p_aout->output.p_sys;
314 mtime_t next_date = 0;
316 while ( !p_aout->b_die )
318 aout_buffer_t * p_buffer;
322 if( !p_sys->b_initialized )
324 msleep( THREAD_SLEEP );
328 if ( p_aout->output.output.i_format != AOUT_FMT_SPDIF )
330 mtime_t buffered = BufferDuration( p_aout );
332 /* Wait a bit - we don't want our buffer to be full */
333 while( buffered > AOUT_PTS_TOLERANCE * 2 )
335 msleep( buffered / 2 - 10000 );
336 buffered = BufferDuration( p_aout );
341 /* This is the _real_ presentation date */
342 next_date = mdate() + buffered;
346 /* Give a hint to the audio output about our drift, but
347 * not too much because we want to make it happy with our
348 * nicely calculated dates. */
349 next_date = ( (next_date * 7) + (mdate() + buffered) ) / 8;
352 /* Next buffer will be played at mdate()+buffered */
353 p_buffer = aout_OutputNextBuffer( p_aout, next_date, VLC_FALSE );
357 p_buffer = aout_OutputNextBuffer( p_aout, 0, VLC_TRUE );
360 if ( p_buffer != NULL )
362 p_bytes = p_buffer->p_buffer;
363 i_size = p_buffer->i_nb_bytes;
364 /* This is theoretical ... we'll see next iteration whether
366 next_date += p_buffer->end_date - p_buffer->start_date;
370 i_size = FRAME_SIZE / p_aout->output.output.i_frame_length
371 * p_aout->output.output.i_bytes_per_frame;
372 p_bytes = malloc( i_size );
373 memset( p_bytes, 0, i_size );
377 i_tmp = write( p_sys->i_fd, p_bytes, i_size );
381 msg_Err( p_aout, "write failed (%s)", strerror(errno) );
384 if ( p_buffer != NULL )
386 aout_BufferFree( p_buffer );