snd_sdl.c

   1 /*
   2 Copyright (C) 2004 Andreas Kirsch
   3
   4 This program is free software; you can redistribute it and/or
   5 modify it under the terms of the GNU General Public License
   6 as published by the Free Software Foundation; either version 2
   7 of the License, or (at your option) any later version.
   8
   9 This program is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  12
  13 See the GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with this program; if not, write to the Free Software
  17 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  18 */
  19 #include "quakedef.h"
  20
  21 #include <math.h>
  22 #include <SDL.h>
  23
  24 #include "snd_main.h"
  25
  26
  27 static unsigned int sdlaudiotime = 0;
  28
  29
  30 // Note: SDL calls SDL_LockAudio() right before this function, so no need to lock the audio data here
  31 static void Buffer_Callback (void *userdata, Uint8 *stream, int len)
  32 {
  33         unsigned int factor, RequestedFrames, MaxFrames, FrameCount;
  34         unsigned int StartOffset, EndOffset;
  35
  36         factor = snd_renderbuffer->format.channels * snd_renderbuffer->format.width;
  37         if ((unsigned int)len % factor != 0)
  38                 Sys_Error("SDL sound: invalid buffer length passed to Buffer_Callback (%d bytes)\n", len);
  39
  40         RequestedFrames = (unsigned int)len / factor;
  41
  42         if (snd_usethreadedmixing)
  43         {
  44                 S_MixToBuffer(stream, RequestedFrames);
  45                 if (snd_blocked)
  46                         memset(stream, snd_renderbuffer->format.width == 1 ? 0x80 : 0, len);
  47                 return;
  48         }
  49
  50         // Transfert up to a chunk of samples from snd_renderbuffer to stream
  51         MaxFrames = snd_renderbuffer->endframe - snd_renderbuffer->startframe;
  52         if (MaxFrames > RequestedFrames)
  53                 FrameCount = RequestedFrames;
  54         else
  55                 FrameCount = MaxFrames;
  56         StartOffset = snd_renderbuffer->startframe % snd_renderbuffer->maxframes;
  57         EndOffset = (snd_renderbuffer->startframe + FrameCount) % snd_renderbuffer->maxframes;
  58         if (StartOffset > EndOffset)  // if the buffer wraps
  59         {
  60                 unsigned int PartialLength1, PartialLength2;
  61
  62                 PartialLength1 = (snd_renderbuffer->maxframes - StartOffset) * factor;
  63                 memcpy(stream, &snd_renderbuffer->ring[StartOffset * factor], PartialLength1);
  64
  65                 PartialLength2 = FrameCount * factor - PartialLength1;
  66                 memcpy(&stream[PartialLength1], &snd_renderbuffer->ring[0], PartialLength2);
  67         }
  68         else
  69                 memcpy(stream, &snd_renderbuffer->ring[StartOffset * factor], FrameCount * factor);
  70
  71         snd_renderbuffer->startframe += FrameCount;
  72
  73         if (FrameCount < RequestedFrames && developer.integer >= 1000 && vid_activewindow)
  74                 Con_Printf("SDL sound: %u sample frames missing\n", RequestedFrames - FrameCount);
  75
  76         sdlaudiotime += RequestedFrames;
  77 }
  78
  79
  80 /*
  81 ====================
  82 SndSys_Init
  83
  84 Create "snd_renderbuffer" with the proper sound format if the call is successful
  85 May return a suggested format if the requested format isn't available
  86 ====================
  87 */
  88 qboolean SndSys_Init (const snd_format_t* requested, snd_format_t* suggested)
  89 {
  90         unsigned int buffersize;
  91         SDL_AudioSpec wantspec;
  92         SDL_AudioSpec obtainspec;
  93
  94         snd_threaded = false;
  95
  96         Con_DPrint ("SndSys_Init: using the SDL module\n");
  97
  98         // Init the SDL Audio subsystem
  99         if( SDL_InitSubSystem( SDL_INIT_AUDIO ) ) {
 100                 Con_Print( "Initializing the SDL Audio subsystem failed!\n" );
 101                 return false;
 102         }
 103
 104         buffersize = (unsigned int)ceil((double)requested->speed / 20.0);
 105
 106         // Init the SDL Audio subsystem
 107         wantspec.callback = Buffer_Callback;
 108         wantspec.userdata = NULL;
 109         wantspec.freq = requested->speed;
 110         wantspec.format = ((requested->width == 1) ? AUDIO_U8 : AUDIO_S16SYS);
 111         wantspec.channels = requested->channels;
 112         wantspec.samples = CeilPowerOf2(buffersize);  // needs to be a power of 2 on some platforms.
 113
 114         Con_Printf("Wanted audio Specification:\n"
 115                                 "\tChannels  : %i\n"
 116                                 "\tFormat    : 0x%X\n"
 117                                 "\tFrequency : %i\n"
 118                                 "\tSamples   : %i\n",
 119                                 wantspec.channels, wantspec.format, wantspec.freq, wantspec.samples);
 120
 121         if( SDL_OpenAudio( &wantspec, &obtainspec ) )
 122         {
 123                 Con_Printf( "Failed to open the audio device! (%s)\n", SDL_GetError() );
 124                 return false;
 125         }
 126
 127         Con_Printf("Obtained audio specification:\n"
 128                                 "\tChannels  : %i\n"
 129                                 "\tFormat    : 0x%X\n"
 130                                 "\tFrequency : %i\n"
 131                                 "\tSamples   : %i\n",
 132                                 obtainspec.channels, obtainspec.format, obtainspec.freq, obtainspec.samples);
 133
 134         // If we haven't obtained what we wanted
 135         if (wantspec.freq != obtainspec.freq ||
 136                 wantspec.format != obtainspec.format ||
 137                 wantspec.channels != obtainspec.channels)
 138         {
 139                 SDL_CloseAudio();
 140
 141                 // Pass the obtained format as a suggested format
 142                 if (suggested != NULL)
 143                 {
 144                         suggested->speed = obtainspec.freq;
 145                         // FIXME: check the format more carefully. There are plenty of unsupported cases
 146                         suggested->width = ((obtainspec.format == AUDIO_U8) ? 1 : 2);
 147                         suggested->channels = obtainspec.channels;
 148                 }
 149
 150                 return false;
 151         }
 152
 153         snd_threaded = true;
 154
 155         snd_renderbuffer = Snd_CreateRingBuffer(requested, 0, NULL);
 156         if (snd_channellayout.integer == SND_CHANNELLAYOUT_AUTO)
 157         {
 158                 int newlayout;
 159
 160 #ifdef __linux__
 161                 newlayout = SND_CHANNELLAYOUT_ALSA;
 162 #else
 163                 newlayout = SND_CHANNELLAYOUT_STANDARD;
 164 #endif
 165                 Cvar_SetValueQuick (&snd_channellayout, newlayout);
 166         }
 167
 168         sdlaudiotime = 0;
 169         SDL_PauseAudio( false );
 170
 171         return true;
 172 }
 173
 174
 175 /*
 176 ====================
 177 SndSys_Shutdown
 178
 179 Stop the sound card, delete "snd_renderbuffer" and free its other resources
 180 ====================
 181 */
 182 void SndSys_Shutdown(void)
 183 {
 184         SDL_CloseAudio();
 185
 186         if (snd_renderbuffer != NULL)
 187         {
 188                 Mem_Free(snd_renderbuffer->ring);
 189                 Mem_Free(snd_renderbuffer);
 190                 snd_renderbuffer = NULL;
 191         }
 192 }
 193
 194
 195 /*
 196 ====================
 197 SndSys_Submit
 198
 199 Submit the contents of "snd_renderbuffer" to the sound card
 200 ====================
 201 */
 202 void SndSys_Submit (void)
 203 {
 204         // Nothing to do here (this sound module is callback-based)
 205 }
 206
 207
 208 /*
 209 ====================
 210 SndSys_GetSoundTime
 211
 212 Returns the number of sample frames consumed since the sound started
 213 ====================
 214 */
 215 unsigned int SndSys_GetSoundTime (void)
 216 {
 217         return sdlaudiotime;
 218 }
 219
 220
 221 /*
 222 ====================
 223 SndSys_LockRenderBuffer
 224
 225 Get the exclusive lock on "snd_renderbuffer"
 226 ====================
 227 */
 228 qboolean SndSys_LockRenderBuffer (void)
 229 {
 230         SDL_LockAudio();
 231         return true;
 232 }
 233
 234
 235 /*
 236 ====================
 237 SndSys_UnlockRenderBuffer
 238
 239 Release the exclusive lock on "snd_renderbuffer"
 240 ====================
 241 */
 242 void SndSys_UnlockRenderBuffer (void)
 243 {
 244         SDL_UnlockAudio();
 245 }