1 /*****************************************************************************
2 * oss.c : OSS /dev/dsp module for vlc
3 *****************************************************************************
4 * Copyright (C) 2000-2002 VideoLAN
5 * $Id: oss.c,v 1.21 2002/08/30 23:27:06 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 *****************************************************************************/
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;
108 /* Allocate structure */
109 p_aout->output.p_sys = p_sys = malloc( sizeof( aout_sys_t ) );
112 msg_Err( p_aout, "out of memory" );
116 /* Initialize some variables */
117 if( (psz_device = config_GetPsz( p_aout, "dspdev" )) == NULL )
119 msg_Err( p_aout, "no audio device given (maybe /dev/dsp ?)" );
124 /* Open the sound device */
125 if( (p_sys->i_fd = open( psz_device, O_WRONLY )) < 0 )
127 msg_Err( p_aout, "cannot open audio device (%s)", psz_device );
134 p_aout->output.pf_play = Play;
136 /* Reset the DSP device */
137 if( ioctl( p_sys->i_fd, SNDCTL_DSP_RESET, NULL ) < 0 )
139 msg_Err( p_aout, "cannot reset OSS audio device" );
143 /* Set the fragment size */
144 i_fragments = FRAME_COUNT << 16 | FRAME_SIZE;
145 if( ioctl( p_sys->i_fd, SNDCTL_DSP_SETFRAGMENT, &i_fragments ) < 0 )
147 msg_Err( p_aout, "cannot set fragment size (%.8x)", i_fragments );
151 /* Set the output format */
152 if ( p_aout->output.output.i_format == AOUT_FMT_SPDIF )
154 i_format = AOUT_FMT_SPDIF;
155 p_aout->output.i_nb_samples = A52_FRAME_NB;
156 p_aout->output.output.i_bytes_per_frame = AOUT_SPDIF_SIZE;
157 p_aout->output.output.i_frame_length = A52_FRAME_NB;
161 p_aout->output.output.i_format = i_format = AOUT_FMT_S16_NE;
162 p_aout->output.i_nb_samples = FRAME_SIZE;
165 if( ioctl( p_sys->i_fd, SNDCTL_DSP_SETFMT, &i_format ) < 0
166 || i_format != p_aout->output.output.i_format )
168 msg_Err( p_aout, "cannot set audio output format (%i)", i_format );
172 if ( p_aout->output.output.i_format != AOUT_FMT_SPDIF )
175 if ( p_aout->output.output.i_channels > 2 )
177 msg_Warn( p_aout, "only two channels are supported at the moment" );
178 /* Trigger downmixing */
179 p_aout->output.output.i_channels = 2;
182 /* Set the number of channels */
183 b_stereo = p_aout->output.output.i_channels - 1;
185 if( ioctl( p_sys->i_fd, SNDCTL_DSP_STEREO, &b_stereo ) < 0 )
187 msg_Err( p_aout, "cannot set number of audio channels (%i)",
188 p_aout->output.output.i_channels );
192 if ( b_stereo + 1 != p_aout->output.output.i_channels )
194 msg_Warn( p_aout, "driver forced up/downmixing %li->%li",
195 p_aout->output.output.i_channels,
197 p_aout->output.output.i_channels = b_stereo + 1;
200 /* Set the output rate */
201 i_rate = p_aout->output.output.i_rate;
202 if( ioctl( p_sys->i_fd, SNDCTL_DSP_SPEED, &i_rate ) < 0 )
204 msg_Err( p_aout, "cannot set audio output rate (%i)",
205 p_aout->output.output.i_rate );
209 if( i_rate != p_aout->output.output.i_rate )
211 msg_Warn( p_aout, "driver forced resampling %li->%li",
212 p_aout->output.output.i_rate, i_rate );
213 p_aout->output.output.i_rate = i_rate;
217 /* Create OSS thread and wait for its readiness. */
218 if( vlc_thread_create( p_aout, "aout", OSSThread,
219 VLC_THREAD_PRIORITY_OUTPUT, VLC_FALSE ) )
221 msg_Err( p_aout, "cannot create OSS thread (%s)", strerror(errno) );
222 close( p_sys->i_fd );
231 /*****************************************************************************
232 * Play: nothing to do
233 *****************************************************************************/
234 static void Play( aout_instance_t *p_aout )
238 /*****************************************************************************
239 * Close: close the dsp audio device
240 *****************************************************************************/
241 static void Close( vlc_object_t * p_this )
243 aout_instance_t *p_aout = (aout_instance_t *)p_this;
244 struct aout_sys_t * p_sys = p_aout->output.p_sys;
246 p_aout->b_die = VLC_TRUE;
247 vlc_thread_join( p_aout );
248 p_aout->b_die = VLC_FALSE;
250 ioctl( p_sys->i_fd, SNDCTL_DSP_RESET, NULL );
251 close( p_sys->i_fd );
257 /*****************************************************************************
258 * BufferDuration: buffer status query
259 *****************************************************************************
260 * This function returns the duration in microseconfs of the current buffer.
261 *****************************************************************************/
262 static mtime_t BufferDuration( aout_instance_t * p_aout )
264 struct aout_sys_t * p_sys = p_aout->output.p_sys;
265 audio_buf_info audio_buf;
268 /* Fill the audio_buf_info structure:
269 * - fragstotal: total number of fragments allocated
270 * - fragsize: size of a fragment in bytes
271 * - bytes: available space in bytes (includes partially used fragments)
272 * Note! 'bytes' could be more than fragments*fragsize */
273 ioctl( p_sys->i_fd, SNDCTL_DSP_GETOSPACE, &audio_buf );
275 /* calculate number of available fragments (not partially used ones) */
276 i_bytes = (audio_buf.fragstotal * audio_buf.fragsize) - audio_buf.bytes;
278 /* Return the fragment duration */
279 return (mtime_t)i_bytes * 1000000
280 / p_aout->output.output.i_bytes_per_frame
281 / p_aout->output.output.i_rate
282 * p_aout->output.output.i_frame_length;
285 /*****************************************************************************
286 * OSSThread: asynchronous thread used to DMA the data to the device
287 *****************************************************************************/
288 static int OSSThread( aout_instance_t * p_aout )
290 struct aout_sys_t * p_sys = p_aout->output.p_sys;
291 mtime_t next_date = 0;
293 while ( !p_aout->b_die )
295 aout_buffer_t * p_buffer;
299 if ( p_aout->output.output.i_format != AOUT_FMT_SPDIF )
301 mtime_t buffered = BufferDuration( p_aout );
303 /* Wait a bit - we don't want our buffer to be full */
304 while( buffered > AOUT_PTS_TOLERANCE * 2 )
306 msleep( buffered / 2 - 10000 );
307 buffered = BufferDuration( p_aout );
312 /* This is the _real_ presentation date */
313 next_date = mdate() + buffered;
317 /* Give a hint to the audio output about our drift, but
318 * not too much because we want to make it happy with our
319 * nicely calculated dates. */
320 next_date = ( (next_date * 7) + (mdate() + buffered) ) / 8;
323 /* Next buffer will be played at mdate()+buffered */
324 p_buffer = aout_OutputNextBuffer( p_aout, next_date, VLC_FALSE );
328 p_buffer = aout_OutputNextBuffer( p_aout, 0, VLC_TRUE );
331 if ( p_buffer != NULL )
333 p_bytes = p_buffer->p_buffer;
334 i_size = p_buffer->i_nb_bytes;
335 /* This is theoretical ... we'll see next iteration whether
337 next_date += p_buffer->end_date - p_buffer->start_date;
341 i_size = FRAME_SIZE / p_aout->output.output.i_frame_length
342 * p_aout->output.output.i_bytes_per_frame;
343 p_bytes = malloc( i_size );
344 memset( p_bytes, 0, i_size );
348 i_tmp = write( p_sys->i_fd, p_bytes, i_size );
352 msg_Err( p_aout, "write failed (%s)", strerror(errno) );
355 if ( p_buffer != NULL )
357 aout_BufferFree( p_buffer );