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 <math.h>
  20 #include <SDL.h>
  21
  22 #include "quakedef.h"
  23
  24 #include "snd_main.h"
  25
  26
  27 static unsigned int sdlaudiotime = 0;
  28 static int audio_device = 0;
  29
  30
  31 // Note: SDL calls SDL_LockAudio() right before this function, so no need to lock the audio data here
  32 static void Buffer_Callback (void *userdata, Uint8 *stream, int len)
  33 {
  34         unsigned int factor, RequestedFrames, MaxFrames, FrameCount;
  35         unsigned int StartOffset, EndOffset;
  36
  37         factor = snd_renderbuffer->format.channels * snd_renderbuffer->format.width;
  38         if ((unsigned int)len % factor != 0)
  39                 Sys_Error("SDL sound: invalid buffer length passed to Buffer_Callback (%d bytes)\n", len);
  40
  41         RequestedFrames = (unsigned int)len / factor;
  42
  43         if (SndSys_LockRenderBuffer())
  44         {
  45                 if (snd_usethreadedmixing)
  46                 {
  47                         S_MixToBuffer(stream, RequestedFrames);
  48                         if (snd_blocked)
  49                                 memset(stream, snd_renderbuffer->format.width == 1 ? 0x80 : 0, len);
  50                         SndSys_UnlockRenderBuffer();
  51                         return;
  52                 }
  53
  54                 // Transfert up to a chunk of samples from snd_renderbuffer to stream
  55                 MaxFrames = snd_renderbuffer->endframe - snd_renderbuffer->startframe;
  56                 if (MaxFrames > RequestedFrames)
  57                         FrameCount = RequestedFrames;
  58                 else
  59                         FrameCount = MaxFrames;
  60                 StartOffset = snd_renderbuffer->startframe % snd_renderbuffer->maxframes;
  61                 EndOffset = (snd_renderbuffer->startframe + FrameCount) % snd_renderbuffer->maxframes;
  62                 if (StartOffset > EndOffset)  // if the buffer wraps
  63                 {
  64                         unsigned int PartialLength1, PartialLength2;
  65
  66                         PartialLength1 = (snd_renderbuffer->maxframes - StartOffset) * factor;
  67                         memcpy(stream, &snd_renderbuffer->ring[StartOffset * factor], PartialLength1);
  68
  69                         PartialLength2 = FrameCount * factor - PartialLength1;
  70                         memcpy(&stream[PartialLength1], &snd_renderbuffer->ring[0], PartialLength2);
  71
  72                         // As of SDL 2.0 buffer needs to be fully initialized, so fill leftover part with silence
  73                         // FIXME this is another place that assumes 8bit is always unsigned and others always signed
  74                         memset(&stream[PartialLength1 + PartialLength2], snd_renderbuffer->format.width == 1 ? 0x80 : 0, len - (PartialLength1 + PartialLength2));
  75                 }
  76                 else
  77                 {
  78                         memcpy(stream, &snd_renderbuffer->ring[StartOffset * factor], FrameCount * factor);
  79
  80                         // As of SDL 2.0 buffer needs to be fully initialized, so fill leftover part with silence
  81                         // FIXME this is another place that assumes 8bit is always unsigned and others always signed
  82                         memset(&stream[FrameCount * factor], snd_renderbuffer->format.width == 1 ? 0x80 : 0, len - (FrameCount * factor));
  83                 }
  84
  85                 snd_renderbuffer->startframe += FrameCount;
  86
  87                 if (FrameCount < RequestedFrames && developer_insane.integer && vid_activewindow)
  88                         Con_DPrintf("SDL sound: %u sample frames missing\n", RequestedFrames - FrameCount);
  89
  90                 sdlaudiotime += RequestedFrames;
  91
  92                 SndSys_UnlockRenderBuffer();
  93         }
  94 }
  95
  96
  97 /*
  98 ====================
  99 SndSys_Init
 100
 101 Create "snd_renderbuffer" with the proper sound format if the call is successful
 102 May return a suggested format if the requested format isn't available
 103 ====================
 104 */
 105 qboolean SndSys_Init (snd_format_t* fmt)
 106 {
 107         unsigned int buffersize;
 108         SDL_AudioSpec wantspec;
 109         SDL_AudioSpec obtainspec;
 110
 111         snd_threaded = false;
 112
 113         Con_DPrint ("SndSys_Init: using the SDL module\n");
 114
 115         // Init the SDL Audio subsystem
 116         if( SDL_InitSubSystem( SDL_INIT_AUDIO ) ) {
 117                 Con_Print( "Initializing the SDL Audio subsystem failed!\n" );
 118                 return false;
 119         }
 120
 121         buffersize = (unsigned int)ceil((double)fmt->speed / 25.0); // 2048 bytes on 24kHz to 48kHz
 122
 123         // Init the SDL Audio subsystem
 124         memset(&wantspec, 0, sizeof(wantspec));
 125         wantspec.callback = Buffer_Callback;
 126         wantspec.userdata = NULL;
 127         wantspec.freq = fmt->speed;
 128         wantspec.format = fmt->width == 1 ? AUDIO_U8 : (fmt->width == 2 ? AUDIO_S16SYS : AUDIO_F32);
 129         wantspec.channels = fmt->channels;
 130         wantspec.samples = CeilPowerOf2(buffersize);  // needs to be a power of 2 on some platforms.
 131
 132         Con_Printf("Wanted audio Specification:\n"
 133                                 "    Channels  : %i\n"
 134                                 "    Format    : 0x%X\n"
 135                                 "    Frequency : %i\n"
 136                                 "    Samples   : %i\n",
 137                                 wantspec.channels, wantspec.format, wantspec.freq, wantspec.samples);
 138
 139         if ((audio_device = SDL_OpenAudioDevice(NULL, 0, &wantspec, &obtainspec, SDL_AUDIO_ALLOW_FREQUENCY_CHANGE | SDL_AUDIO_ALLOW_CHANNELS_CHANGE)) == 0)
 140         {
 141                 Con_Printf(CON_ERROR "Failed to open the audio device! (%s)\n", SDL_GetError() );
 142                 return false;
 143         }
 144
 145         Con_Printf("Obtained audio specification:\n"
 146                                 "    Channels  : %i\n"
 147                                 "    Format    : 0x%X\n"
 148                                 "    Frequency : %i\n"
 149                                 "    Samples   : %i\n",
 150                                 obtainspec.channels, obtainspec.format, obtainspec.freq, obtainspec.samples);
 151
 152         fmt->speed = obtainspec.freq;
 153         fmt->channels = obtainspec.channels;
 154
 155         snd_threaded = true;
 156
 157         snd_renderbuffer = Snd_CreateRingBuffer(fmt, 0, NULL);
 158         if (snd_channellayout.integer == SND_CHANNELLAYOUT_AUTO)
 159                 Cvar_SetValueQuick (&snd_channellayout, SND_CHANNELLAYOUT_STANDARD);
 160
 161         sdlaudiotime = 0;
 162         SDL_PauseAudioDevice(audio_device, 0);
 163
 164         return true;
 165 }
 166
 167
 168 /*
 169 ====================
 170 SndSys_Shutdown
 171
 172 Stop the sound card, delete "snd_renderbuffer" and free its other resources
 173 ====================
 174 */
 175 void SndSys_Shutdown(void)
 176 {
 177         if (audio_device > 0) {
 178                 SDL_CloseAudioDevice(audio_device);
 179                 audio_device = 0;
 180         }
 181         if (snd_renderbuffer != NULL)
 182         {
 183                 Mem_Free(snd_renderbuffer->ring);
 184                 Mem_Free(snd_renderbuffer);
 185                 snd_renderbuffer = NULL;
 186         }
 187 }
 188
 189
 190 /*
 191 ====================
 192 SndSys_Submit
 193
 194 Submit the contents of "snd_renderbuffer" to the sound card
 195 ====================
 196 */
 197 void SndSys_Submit (void)
 198 {
 199         // Nothing to do here (this sound module is callback-based)
 200 }
 201
 202
 203 /*
 204 ====================
 205 SndSys_GetSoundTime
 206
 207 Returns the number of sample frames consumed since the sound started
 208 ====================
 209 */
 210 unsigned int SndSys_GetSoundTime (void)
 211 {
 212         return sdlaudiotime;
 213 }
 214
 215
 216 /*
 217 ====================
 218 SndSys_LockRenderBuffer
 219
 220 Get the exclusive lock on "snd_renderbuffer"
 221 ====================
 222 */
 223 qboolean SndSys_LockRenderBuffer (void)
 224 {
 225         SDL_LockAudioDevice(audio_device);
 226         return true;
 227 }
 228
 229
 230 /*
 231 ====================
 232 SndSys_UnlockRenderBuffer
 233
 234 Release the exclusive lock on "snd_renderbuffer"
 235 ====================
 236 */
 237 void SndSys_UnlockRenderBuffer (void)
 238 {
 239         SDL_UnlockAudioDevice(audio_device);
 240 }
 241
 242 /*
 243 ====================
 244 SndSys_SendKeyEvents
 245
 246 Send keyboard events originating from the sound system (e.g. MIDI)
 247 ====================
 248 */
 249 void SndSys_SendKeyEvents(void)
 250 {
 251         // not supported
 252 }