Mercurial > sdl-ios-xcode

comparison src/audio/alsa/SDL_alsa_audio.c @ 1878:d7c9d7f42881

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Swizzle ALSA channels for 5.1 output to match DirectSound and CoreAudio. Untested, but potentially fixes Bugzilla #110.
author Ryan C. Gordon <icculus@icculus.org>
date Fri, 23 Jun 2006 08:35:48 +0000
parents 63fa37538842
children c121d94672cb a1b03ba2fcd0
comparison
equal deleted inserted replaced
1877:9b02a5b97f79 1878:d7c9d7f42881
262 } 262 }
263 } 263 }
264 } 264 }
265 } 265 }
266 266
267
268 /*
269 * http://bugzilla.libsdl.org/show_bug.cgi?id=110
270 * "For Linux ALSA, this is FL-FR-RL-RR-C-LFE
271 * and for Windows DirectX [and CoreAudio], this is FL-FR-C-LFE-RL-RR"
272 */
273 #define SWIZ6(T) \
274 T *ptr = (T *) mixbuf; \
275 const Uint32 count = (this->spec.samples / 6); \
276 Uint32 i; \
277 for (i = 0; i < count; i++, ptr += 6) { \
278 T tmp; \
279 tmp = ptr[2]; ptr[2] = ptr[4]; ptr[4] = tmp; \
280 tmp = ptr[3]; ptr[3] = ptr[5]; ptr[5] = tmp; \
281 }
282
283 static __inline__ void swizzle_alsa_channels_6_64bit(_THIS) { SWIZ6(Uint64); }
284 static __inline__ void swizzle_alsa_channels_6_32bit(_THIS) { SWIZ6(Uint32); }
285 static __inline__ void swizzle_alsa_channels_6_16bit(_THIS) { SWIZ6(Uint16); }
286 static __inline__ void swizzle_alsa_channels_6_8bit(_THIS) { SWIZ6(Uint8); }
287
288 #undef SWIZ6
289
290
291 /*
292 * Called right before feeding this->mixbuf to the hardware. Swizzle channels
293 * from Windows/Mac order to the format alsalib will want.
294 */
295 static __inline__ void swizzle_alsa_channels(_THIS)
296 {
297 if (this->spec.channels == 6) {
298 const Uint16 fmtsize = (this->spec.format & 0xFF); /* bits/channel. */
299 if (fmtsize == 16)
300 swizzle_alsa_channels_6_16bit(this);
301 else if (fmtsize == 8)
302 swizzle_alsa_channels_6_8bit(this);
303 else if (fmtsize == 32)
304 swizzle_alsa_channels_6_32bit(this);
305 else if (fmtsize == 64)
306 swizzle_alsa_channels_6_64bit(this);
307 }
308
309 /* !!! FIXME: update this for 7.1 if needed, later. */
310 }
311
312
267 static void ALSA_PlayAudio(_THIS) 313 static void ALSA_PlayAudio(_THIS)
268 { 314 {
269 int status; 315 int status;
270 int sample_len; 316 int sample_len;
271 signed short *sample_buf; 317 signed short *sample_buf;
272 318
319 swizzle_alsa_channels(this);
320
273 sample_len = this->spec.samples; 321 sample_len = this->spec.samples;
274 sample_buf = (signed short *)mixbuf; 322 sample_buf = (signed short *)mixbuf;
323
275 while ( sample_len > 0 ) { 324 while ( sample_len > 0 ) {
276 status = SDL_NAME(snd_pcm_writei)(pcm_handle, sample_buf, sample_len); 325 status = SDL_NAME(snd_pcm_writei)(pcm_handle, sample_buf, sample_len);
277 if ( status < 0 ) { 326 if ( status < 0 ) {
278 if ( status == -EAGAIN ) { 327 if ( status == -EAGAIN ) {
279 SDL_Delay(1); 328 SDL_Delay(1);