1 /*****************************************************************************
2 * oss.c : OSS /dev/dsp module for vlc
3 *****************************************************************************
4 * Copyright (C) 2000-2002 VideoLAN
5 * $Id: oss.c,v 1.22 2002/08/31 22:10:25 stef 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 *****************************************************************************/
67 #define FRAME_SIZE 1024
69 #define A52_FRAME_NB 1536
71 /*****************************************************************************
73 *****************************************************************************/
74 static int Open ( vlc_object_t * );
75 static void Close ( vlc_object_t * );
77 static void Play ( aout_instance_t * );
78 static int OSSThread ( aout_instance_t * );
80 /*****************************************************************************
82 *****************************************************************************/
84 add_category_hint( N_("OSS"), NULL );
85 add_file( "dspdev", "/dev/dsp", NULL, N_("OSS dsp device"), NULL );
86 set_description( _("Linux OSS /dev/dsp module") );
87 set_capability( "audio output", 100 );
88 add_shortcut( "dsp" );
89 set_callbacks( Open, Close );
92 /*****************************************************************************
93 * Open: open the audio device (the digital sound processor)
94 *****************************************************************************
95 * This function opens the dsp as a usual non-blocking write-only file, and
96 * modifies the p_aout->p_sys->i_fd with the file's descriptor.
97 *****************************************************************************/
98 static int Open( vlc_object_t *p_this )
100 aout_instance_t * p_aout = (aout_instance_t *)p_this;
101 struct aout_sys_t * p_sys;
109 /* Allocate structure */
110 p_aout->output.p_sys = p_sys = malloc( sizeof( aout_sys_t ) );
113 msg_Err( p_aout, "out of memory" );
117 /* Initialize some variables */
118 if( (psz_device = config_GetPsz( p_aout, "dspdev" )) == NULL )
120 msg_Err( p_aout, "no audio device given (maybe /dev/dsp ?)" );
125 /* Open the sound device */
126 if( (p_sys->i_fd = open( psz_device, O_WRONLY )) < 0 )
128 msg_Err( p_aout, "cannot open audio device (%s)", psz_device );
135 p_aout->output.pf_play = Play;
137 /* Reset the DSP device */
138 if( ioctl( p_sys->i_fd, SNDCTL_DSP_RESET, NULL ) < 0 )
140 msg_Err( p_aout, "cannot reset OSS audio device" );
144 /* Set the fragment size
145 * i_fragment = xxxxyyyy where: xxxx is fragtotal
146 * 1 << yyyy is fragsize */
148 i_frame_size = FRAME_SIZE;
149 while( i_frame_size >>= 1 )
153 i_fragments |= FRAME_COUNT << 16;
154 if( ioctl( p_sys->i_fd, SNDCTL_DSP_SETFRAGMENT, &i_fragments ) < 0 )
156 msg_Err( p_aout, "cannot set fragment size (%.8x)", i_fragments );
160 /* Set the output format */
161 if ( p_aout->output.output.i_format == AOUT_FMT_SPDIF )
163 i_format = AOUT_FMT_SPDIF;
164 p_aout->output.i_nb_samples = A52_FRAME_NB;
165 p_aout->output.output.i_bytes_per_frame = AOUT_SPDIF_SIZE;
166 p_aout->output.output.i_frame_length = A52_FRAME_NB;
170 p_aout->output.output.i_format = i_format = AOUT_FMT_S16_NE;
171 p_aout->output.i_nb_samples = FRAME_SIZE;
174 if( ioctl( p_sys->i_fd, SNDCTL_DSP_SETFMT, &i_format ) < 0
175 || i_format != p_aout->output.output.i_format )
177 msg_Err( p_aout, "cannot set audio output format (%i)", i_format );
181 if ( p_aout->output.output.i_format != AOUT_FMT_SPDIF )
184 if ( p_aout->output.output.i_channels > 2 )
186 msg_Warn( p_aout, "only two channels are supported at the moment" );
187 /* Trigger downmixing */
188 p_aout->output.output.i_channels = 2;
191 /* Set the number of channels */
192 b_stereo = p_aout->output.output.i_channels - 1;
194 if( ioctl( p_sys->i_fd, SNDCTL_DSP_STEREO, &b_stereo ) < 0 )
196 msg_Err( p_aout, "cannot set number of audio channels (%i)",
197 p_aout->output.output.i_channels );
201 if ( b_stereo + 1 != p_aout->output.output.i_channels )
203 msg_Warn( p_aout, "driver forced up/downmixing %li->%li",
204 p_aout->output.output.i_channels,
206 p_aout->output.output.i_channels = b_stereo + 1;
209 /* Set the output rate */
210 i_rate = p_aout->output.output.i_rate;
211 if( ioctl( p_sys->i_fd, SNDCTL_DSP_SPEED, &i_rate ) < 0 )
213 msg_Err( p_aout, "cannot set audio output rate (%i)",
214 p_aout->output.output.i_rate );
218 if( i_rate != p_aout->output.output.i_rate )
220 msg_Warn( p_aout, "driver forced resampling %li->%li",
221 p_aout->output.output.i_rate, i_rate );
222 p_aout->output.output.i_rate = i_rate;
226 /* Create OSS thread and wait for its readiness. */
227 if( vlc_thread_create( p_aout, "aout", OSSThread,
228 VLC_THREAD_PRIORITY_OUTPUT, VLC_FALSE ) )
230 msg_Err( p_aout, "cannot create OSS thread (%s)", strerror(errno) );
231 close( p_sys->i_fd );
240 /*****************************************************************************
241 * Play: nothing to do
242 *****************************************************************************/
243 static void Play( aout_instance_t *p_aout )
247 /*****************************************************************************
248 * Close: close the dsp audio device
249 *****************************************************************************/
250 static void Close( vlc_object_t * p_this )
252 aout_instance_t *p_aout = (aout_instance_t *)p_this;
253 struct aout_sys_t * p_sys = p_aout->output.p_sys;
255 p_aout->b_die = VLC_TRUE;
256 vlc_thread_join( p_aout );
257 p_aout->b_die = VLC_FALSE;
259 ioctl( p_sys->i_fd, SNDCTL_DSP_RESET, NULL );
260 close( p_sys->i_fd );
266 /*****************************************************************************
267 * BufferDuration: buffer status query
268 *****************************************************************************
269 * This function returns the duration in microseconds of the current buffer.
270 *****************************************************************************/
271 static mtime_t BufferDuration( aout_instance_t * p_aout )
273 struct aout_sys_t * p_sys = p_aout->output.p_sys;
274 audio_buf_info audio_buf;
277 /* Fill the audio_buf_info structure:
278 * - fragstotal: total number of fragments allocated
279 * - fragsize: size of a fragment in bytes
280 * - bytes: available space in bytes (includes partially used fragments)
281 * Note! 'bytes' could be more than fragments*fragsize */
282 ioctl( p_sys->i_fd, SNDCTL_DSP_GETOSPACE, &audio_buf );
284 /* calculate number of available fragments (not partially used ones) */
285 i_bytes = (audio_buf.fragstotal * audio_buf.fragsize) - audio_buf.bytes;
287 /* Return the fragment duration */
288 return (mtime_t)i_bytes * 1000000
289 / p_aout->output.output.i_bytes_per_frame
290 / p_aout->output.output.i_rate
291 * p_aout->output.output.i_frame_length;
294 /*****************************************************************************
295 * OSSThread: asynchronous thread used to DMA the data to the device
296 *****************************************************************************/
297 static int OSSThread( aout_instance_t * p_aout )
299 struct aout_sys_t * p_sys = p_aout->output.p_sys;
300 mtime_t next_date = 0;
302 while ( !p_aout->b_die )
304 aout_buffer_t * p_buffer;
308 if ( p_aout->output.output.i_format != AOUT_FMT_SPDIF )
310 mtime_t buffered = BufferDuration( p_aout );
312 /* Wait a bit - we don't want our buffer to be full */
313 while( buffered > AOUT_PTS_TOLERANCE * 2 )
315 msleep( buffered / 2 - 10000 );
316 buffered = BufferDuration( p_aout );
321 /* This is the _real_ presentation date */
322 next_date = mdate() + buffered;
326 /* Give a hint to the audio output about our drift, but
327 * not too much because we want to make it happy with our
328 * nicely calculated dates. */
329 next_date = ( (next_date * 7) + (mdate() + buffered) ) / 8;
332 /* Next buffer will be played at mdate()+buffered */
333 p_buffer = aout_OutputNextBuffer( p_aout, next_date, VLC_FALSE );
337 p_buffer = aout_OutputNextBuffer( p_aout, 0, VLC_TRUE );
340 if ( p_buffer != NULL )
342 p_bytes = p_buffer->p_buffer;
343 i_size = p_buffer->i_nb_bytes;
344 /* This is theoretical ... we'll see next iteration whether
346 next_date += p_buffer->end_date - p_buffer->start_date;
350 i_size = FRAME_SIZE / p_aout->output.output.i_frame_length
351 * p_aout->output.output.i_bytes_per_frame;
352 p_bytes = malloc( i_size );
353 memset( p_bytes, 0, i_size );
357 i_tmp = write( p_sys->i_fd, p_bytes, i_size );
361 msg_Err( p_aout, "write failed (%s)", strerror(errno) );
364 if ( p_buffer != NULL )
366 aout_BufferFree( p_buffer );