1 /*****************************************************************************
2 * sdl.c : SDL audio output plugin for vlc
3 *****************************************************************************
4 * Copyright (C) 2000-2002 VideoLAN
5 * $Id: sdl.c,v 1.6 2002/08/25 09:40:00 sam Exp $
7 * Authors: Michel Kaempf <maxx@via.ecp.fr>
8 * Samuel Hocevar <sam@zoy.org>
9 * Pierre Baillet <oct@zoy.org>
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 <string.h> /* strerror() */
32 #include <unistd.h> /* write(), close() */
33 #include <stdlib.h> /* calloc(), malloc(), free() */
37 #include "aout_internal.h"
39 #include SDL_INCLUDE_FILE
41 #define FRAME_SIZE 2048
43 /*****************************************************************************
44 * aout_sys_t: SDL audio output method descriptor
45 *****************************************************************************
46 * This structure is part of the audio output thread descriptor.
47 * It describes the specific properties of an audio device.
48 *****************************************************************************/
55 /*****************************************************************************
57 *****************************************************************************/
58 static int Open ( vlc_object_t * );
59 static void Close ( vlc_object_t * );
61 static int SetFormat ( aout_instance_t * );
62 static void Play ( aout_instance_t * );
64 static void SDLCallback ( void *, Uint8 *, int );
66 /*****************************************************************************
68 *****************************************************************************/
70 set_description( _("Simple DirectMedia Layer audio module") );
71 set_capability( "audio output", 40 );
72 set_callbacks( Open, Close );
75 /*****************************************************************************
76 * Open: open the audio device
77 *****************************************************************************/
78 static int Open ( vlc_object_t *p_this )
80 aout_instance_t *p_aout = (aout_instance_t *)p_this;
83 Uint32 i_flags = SDL_INIT_AUDIO;
85 if( SDL_WasInit( i_flags ) )
90 /* Allocate structure */
91 p_aout->output.p_sys = p_sys = malloc( sizeof( aout_sys_t ) );
94 msg_Err( p_aout, "out of memory" );
98 p_aout->output.pf_setformat = SetFormat;
99 p_aout->output.pf_play = Play;
102 /* Win32 SDL implementation doesn't support SDL_INIT_EVENTTHREAD yet*/
103 i_flags |= SDL_INIT_EVENTTHREAD;
106 /* In debug mode you may want vlc to dump a core instead of staying
108 i_flags |= SDL_INIT_NOPARACHUTE;
111 /* Initialize library */
112 if( SDL_Init( i_flags ) < 0 )
114 msg_Err( p_aout, "cannot initialize SDL (%s)", SDL_GetError() );
122 /*****************************************************************************
123 * SetFormat: reset the audio device and sets its format
124 *****************************************************************************/
125 static int SetFormat( aout_instance_t *p_aout )
127 aout_sys_t * p_sys = p_aout->output.p_sys;
129 /* TODO: finish and clean this */
130 SDL_AudioSpec desired;
132 desired.freq = p_aout->output.output.i_rate;
133 desired.format = AUDIO_S16SYS;
134 desired.channels = p_aout->output.output.i_channels;
135 desired.callback = SDLCallback;
136 desired.userdata = p_aout;
137 desired.samples = FRAME_SIZE;
139 /* Open the sound device - FIXME : get the "natural" parameters */
140 if( SDL_OpenAudio( &desired, NULL ) < 0 )
145 p_aout->output.output.i_format = AOUT_FMT_S16_NE;
146 p_aout->output.i_nb_samples = FRAME_SIZE;
148 p_sys->call_time = 0;
149 p_sys->buffer_time = (mtime_t)FRAME_SIZE * 1000000
150 / p_aout->output.output.i_rate;
157 /*****************************************************************************
158 * Play: play a sound samples buffer
159 *****************************************************************************/
160 static void Play( aout_instance_t * p_aout )
164 /*****************************************************************************
165 * Close: close the audio device
166 *****************************************************************************/
167 static void Close ( vlc_object_t *p_this )
169 aout_instance_t *p_aout = (aout_instance_t *)p_this;
170 aout_sys_t * p_sys = p_aout->output.p_sys;
174 SDL_QuitSubSystem( SDL_INIT_AUDIO );
179 /*****************************************************************************
180 * SDLCallback: what to do once SDL has played sound samples
181 *****************************************************************************/
182 static void SDLCallback( void * _p_aout, byte_t * p_stream, int i_len )
184 aout_instance_t * p_aout = (aout_instance_t *)_p_aout;
185 aout_sys_t * p_sys = p_aout->output.p_sys;
187 aout_buffer_t * p_buffer;
189 /* We try to stay around call_time + buffer_time/2. This is kludgy but
190 * unavoidable because SDL is completely unable to 1. tell us about its
191 * latency, and 2. call SDLCallback at regular intervals. */
192 if( mdate() < p_sys->call_time + p_sys->buffer_time / 2 )
194 /* We can't wait too much, because SDL will be lost, and we can't
195 * wait too little, because we are not sure that there will be
196 * samples in the queue. */
197 mwait( p_sys->call_time + p_sys->buffer_time / 4 );
198 p_sys->call_time += p_sys->buffer_time;
202 p_sys->call_time = mdate() + p_sys->buffer_time / 4;
205 /* Tell the output we're playing samples at call_time + 2*buffer_time */
206 p_buffer = aout_OutputNextBuffer( p_aout, p_sys->call_time
207 + 2 * p_sys->buffer_time, VLC_TRUE );
209 if ( i_len != FRAME_SIZE * sizeof(s16)
210 * p_aout->output.output.i_channels )
212 msg_Err( p_aout, "SDL doesn't know its buffer size (%d)", i_len );
215 if ( p_buffer != NULL )
217 p_aout->p_vlc->pf_memcpy( p_stream, p_buffer->p_buffer, i_len );
218 aout_BufferFree( p_buffer );
222 p_aout->p_vlc->pf_memset( p_stream, 0, i_len );