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                 else
  73                         memcpy(stream, &snd_renderbuffer->ring[StartOffset * factor], FrameCount * factor);
  74
  75                 snd_renderbuffer->startframe += FrameCount;
  76
  77                 if (FrameCount < RequestedFrames && developer_insane.integer && vid_activewindow)
  78                         Con_DPrintf("SDL sound: %u sample frames missing\n", RequestedFrames - FrameCount);
  79
  80                 sdlaudiotime += RequestedFrames;
  81
  82                 SndSys_UnlockRenderBuffer();
  83         }
  84 }
  85
  86
  87 /*
  88 ====================
  89 SndSys_Init
  90
  91 Create "snd_renderbuffer" with the proper sound format if the call is successful
  92 May return a suggested format if the requested format isn't available
  93 ====================
  94 */
  95 qboolean SndSys_Init (snd_format_t* fmt)
  96 {
  97         unsigned int buffersize;
  98         SDL_AudioSpec wantspec;
  99         SDL_AudioSpec obtainspec;
 100
 101         snd_threaded = false;
 102
 103         Con_DPrint ("SndSys_Init: using the SDL module\n");
 104
 105         // Init the SDL Audio subsystem
 106         if( SDL_InitSubSystem( SDL_INIT_AUDIO ) ) {
 107                 Con_Print( "Initializing the SDL Audio subsystem failed!\n" );
 108                 return false;
 109         }
 110
 111         buffersize = (unsigned int)ceil((double)fmt->speed / 25.0); // 2048 bytes on 24kHz to 48kHz
 112
 113         // Init the SDL Audio subsystem
 114         memset(&wantspec, 0, sizeof(wantspec));
 115         wantspec.callback = Buffer_Callback;
 116         wantspec.userdata = NULL;
 117         wantspec.freq = fmt->speed;
 118         wantspec.format = fmt->width == 1 ? AUDIO_U8 : (fmt->width == 2 ? AUDIO_S16SYS : AUDIO_F32);
 119         wantspec.channels = fmt->channels;
 120         wantspec.samples = CeilPowerOf2(buffersize);  // needs to be a power of 2 on some platforms.
 121
 122         Con_Printf("Wanted audio Specification:\n"
 123                                 "\tChannels  : %i\n"
 124                                 "\tFormat    : 0x%X\n"
 125                                 "\tFrequency : %i\n"
 126                                 "\tSamples   : %i\n",
 127                                 wantspec.channels, wantspec.format, wantspec.freq, wantspec.samples);
 128
 129         if ((audio_device = SDL_OpenAudioDevice(NULL, 0, &wantspec, &obtainspec, SDL_AUDIO_ALLOW_FREQUENCY_CHANGE | SDL_AUDIO_ALLOW_CHANNELS_CHANGE)) == 0)
 130         {
 131                 Con_Printf( "Failed to open the audio device! (%s)\n", SDL_GetError() );
 132                 return false;
 133         }
 134
 135         Con_Printf("Obtained audio specification:\n"
 136                                 "\tChannels  : %i\n"
 137                                 "\tFormat    : 0x%X\n"
 138                                 "\tFrequency : %i\n"
 139                                 "\tSamples   : %i\n",
 140                                 obtainspec.channels, obtainspec.format, obtainspec.freq, obtainspec.samples);
 141
 142         fmt->speed = obtainspec.freq;
 143         fmt->channels = obtainspec.channels;
 144
 145         snd_threaded = true;
 146
 147         snd_renderbuffer = Snd_CreateRingBuffer(fmt, 0, NULL);
 148         if (snd_channellayout.integer == SND_CHANNELLAYOUT_AUTO)
 149                 Cvar_SetValueQuick (&snd_channellayout, SND_CHANNELLAYOUT_STANDARD);
 150
 151         sdlaudiotime = 0;
 152         SDL_PauseAudioDevice(audio_device, 0);
 153
 154         return true;
 155 }
 156
 157
 158 /*
 159 ====================
 160 SndSys_Shutdown
 161
 162 Stop the sound card, delete "snd_renderbuffer" and free its other resources
 163 ====================
 164 */
 165 void SndSys_Shutdown(void)
 166 {
 167         if (audio_device > 0) {
 168                 SDL_CloseAudioDevice(audio_device);
 169                 audio_device = 0;
 170         }
 171         if (snd_renderbuffer != NULL)
 172         {
 173                 Mem_Free(snd_renderbuffer->ring);
 174                 Mem_Free(snd_renderbuffer);
 175                 snd_renderbuffer = NULL;
 176         }
 177 }
 178
 179
 180 /*
 181 ====================
 182 SndSys_Submit
 183
 184 Submit the contents of "snd_renderbuffer" to the sound card
 185 ====================
 186 */
 187 void SndSys_Submit (void)
 188 {
 189         // Nothing to do here (this sound module is callback-based)
 190 }
 191
 192
 193 /*
 194 ====================
 195 SndSys_GetSoundTime
 196
 197 Returns the number of sample frames consumed since the sound started
 198 ====================
 199 */
 200 unsigned int SndSys_GetSoundTime (void)
 201 {
 202         return sdlaudiotime;
 203 }
 204
 205
 206 /*
 207 ====================
 208 SndSys_LockRenderBuffer
 209
 210 Get the exclusive lock on "snd_renderbuffer"
 211 ====================
 212 */
 213 qboolean SndSys_LockRenderBuffer (void)
 214 {
 215         SDL_LockAudioDevice(audio_device);
 216         return true;
 217 }
 218
 219
 220 /*
 221 ====================
 222 SndSys_UnlockRenderBuffer
 223
 224 Release the exclusive lock on "snd_renderbuffer"
 225 ====================
 226 */
 227 void SndSys_UnlockRenderBuffer (void)
 228 {
 229         SDL_UnlockAudioDevice(audio_device);
 230 }
 231
 232 /*
 233 ====================
 234 SndSys_SendKeyEvents
 235
 236 Send keyboard events originating from the sound system (e.g. MIDI)
 237 ====================
 238 */
 239 void SndSys_SendKeyEvents(void)
 240 {
 241         // not supported
 242 }