Mercurial > sdl-ios-xcode
annotate src/audio/alsa/SDL_alsa_audio.c @ 773:da0a2ad35bf4
Date: Sun, 4 Jan 2004 23:48:19 +0100
From: Max Horn
Subject: Re: Again Audio CD patch
Am 04.01.2004 um 22:38 schrieb Sam Lantinga:
>
> Okay, I fixed the buffering problems by simply using a 4 second buffer
> instead of a 1 second buffer. However, using your code I can't play an
> entire CD - the playback stops after the first song.
>
Found the problem: FSReadFork returns eofErr when the file is finished.
However, we check its return value for errors, and if anything but
noErr occurs, the reader thread aborts its current iteration. That is
bad, because it aborts before it can ever set the flag which tells that
the file is over (also, any remaining data which FSRead did return is
lost - so you'd not hear about to 4 seconds from the end of the file.
Furthermore, the computed data size was 8 bytes to high (I forgot to
account for the fact that the size of an (A)IFF chunk always contains
the chunk header & size fields, too). This is enough to make it work.
However, the end condition is rather fragile, so I tuned some other
things to be pessimistic (check for <= 0 instead of == 0, when eofErr
is encountered enforce mReadFilePosition == mFileLength). You never
know...
The attached patch fixes the issue for me.
author | Sam Lantinga <slouken@libsdl.org> |
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date | Mon, 05 Jan 2004 00:57:51 +0000 |
parents | b8d311d90021 |
children | 92615154bb68 |
rev | line source |
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0 | 1 /* |
2 SDL - Simple DirectMedia Layer | |
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3 Copyright (C) 1997-2004 Sam Lantinga |
0 | 4 |
5 This library is free software; you can redistribute it and/or | |
6 modify it under the terms of the GNU Library General Public | |
7 License as published by the Free Software Foundation; either | |
8 version 2 of the License, or (at your option) any later version. | |
9 | |
10 This library is distributed in the hope that it will be useful, | |
11 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 Library General Public License for more details. | |
14 | |
15 You should have received a copy of the GNU Library General Public | |
16 License along with this library; if not, write to the Free | |
17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
18 | |
19 Sam Lantinga | |
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20 slouken@libsdl.org |
0 | 21 */ |
22 | |
23 | |
24 | |
25 /* Allow access to a raw mixing buffer */ | |
26 | |
27 #include <stdlib.h> | |
28 #include <stdio.h> | |
29 #include <string.h> | |
30 #include <errno.h> | |
31 #include <unistd.h> | |
32 #include <fcntl.h> | |
33 #include <signal.h> | |
34 #include <sys/types.h> | |
35 #include <sys/time.h> | |
36 | |
37 #include "SDL_audio.h" | |
38 #include "SDL_error.h" | |
39 #include "SDL_audiomem.h" | |
40 #include "SDL_audio_c.h" | |
41 #include "SDL_timer.h" | |
42 #include "SDL_alsa_audio.h" | |
43 | |
44 /* The tag name used by ALSA audio */ | |
45 #define DRIVER_NAME "alsa" | |
46 | |
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47 /* The default ALSA audio driver */ |
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48 #define DEFAULT_DEVICE "default" |
0 | 49 |
50 /* Audio driver functions */ | |
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51 static int ALSA_OpenAudio(_THIS, SDL_AudioSpec *spec); |
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52 static void ALSA_WaitAudio(_THIS); |
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53 static void ALSA_PlayAudio(_THIS); |
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54 static Uint8 *ALSA_GetAudioBuf(_THIS); |
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55 static void ALSA_CloseAudio(_THIS); |
0 | 56 |
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57 static const char *get_audio_device() |
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58 { |
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59 const char *device; |
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60 |
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61 device = getenv("AUDIODEV"); /* Is there a standard variable name? */ |
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62 if ( device == NULL ) { |
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63 device = DEFAULT_DEVICE; |
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64 } |
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65 return device; |
0 | 66 } |
67 | |
68 /* Audio driver bootstrap functions */ | |
69 | |
70 static int Audio_Available(void) | |
71 { | |
72 int available; | |
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73 int status; |
0 | 74 snd_pcm_t *handle; |
75 | |
76 available = 0; | |
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77 status = snd_pcm_open(&handle, get_audio_device(), SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK); |
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78 if ( status >= 0 ) { |
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79 available = 1; |
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80 snd_pcm_close(handle); |
0 | 81 } |
82 return(available); | |
83 } | |
84 | |
85 static void Audio_DeleteDevice(SDL_AudioDevice *device) | |
86 { | |
87 free(device->hidden); | |
88 free(device); | |
89 } | |
90 | |
91 static SDL_AudioDevice *Audio_CreateDevice(int devindex) | |
92 { | |
93 SDL_AudioDevice *this; | |
94 | |
95 /* Initialize all variables that we clean on shutdown */ | |
96 this = (SDL_AudioDevice *)malloc(sizeof(SDL_AudioDevice)); | |
97 if ( this ) { | |
98 memset(this, 0, (sizeof *this)); | |
99 this->hidden = (struct SDL_PrivateAudioData *) | |
100 malloc((sizeof *this->hidden)); | |
101 } | |
102 if ( (this == NULL) || (this->hidden == NULL) ) { | |
103 SDL_OutOfMemory(); | |
104 if ( this ) { | |
105 free(this); | |
106 } | |
107 return(0); | |
108 } | |
109 memset(this->hidden, 0, (sizeof *this->hidden)); | |
110 | |
111 /* Set the function pointers */ | |
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112 this->OpenAudio = ALSA_OpenAudio; |
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113 this->WaitAudio = ALSA_WaitAudio; |
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114 this->PlayAudio = ALSA_PlayAudio; |
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115 this->GetAudioBuf = ALSA_GetAudioBuf; |
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116 this->CloseAudio = ALSA_CloseAudio; |
0 | 117 |
118 this->free = Audio_DeleteDevice; | |
119 | |
120 return this; | |
121 } | |
122 | |
123 AudioBootStrap ALSA_bootstrap = { | |
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124 DRIVER_NAME, "ALSA 0.9 PCM audio", |
0 | 125 Audio_Available, Audio_CreateDevice |
126 }; | |
127 | |
128 /* This function waits until it is possible to write a full sound buffer */ | |
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129 static void ALSA_WaitAudio(_THIS) |
0 | 130 { |
131 /* Check to see if the thread-parent process is still alive */ | |
132 { static int cnt = 0; | |
133 /* Note that this only works with thread implementations | |
134 that use a different process id for each thread. | |
135 */ | |
136 if (parent && (((++cnt)%10) == 0)) { /* Check every 10 loops */ | |
137 if ( kill(parent, 0) < 0 ) { | |
138 this->enabled = 0; | |
139 } | |
140 } | |
141 } | |
142 } | |
143 | |
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144 static void ALSA_PlayAudio(_THIS) |
0 | 145 { |
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146 int status; |
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147 int sample_len; |
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148 signed short *sample_buf; |
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149 |
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150 sample_len = this->spec.samples; |
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151 sample_buf = (signed short *)mixbuf; |
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152 while ( sample_len > 0 ) { |
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153 status = snd_pcm_writei(pcm_handle, sample_buf, sample_len); |
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154 if ( status < 0 ) { |
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155 if ( status == -EAGAIN ) { |
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156 SDL_Delay(1); |
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157 continue; |
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158 } |
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159 if ( status == -ESTRPIPE ) { |
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160 do { |
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161 SDL_Delay(1); |
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162 status = snd_pcm_resume(pcm_handle); |
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163 } while ( status == -EAGAIN ); |
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164 } |
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165 if ( status < 0 ) { |
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166 status = snd_pcm_prepare(pcm_handle); |
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167 } |
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168 if ( status < 0 ) { |
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169 /* Hmm, not much we can do - abort */ |
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170 this->enabled = 0; |
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171 return; |
0 | 172 } |
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173 continue; |
0 | 174 } |
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175 sample_buf += status * this->spec.channels; |
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176 sample_len -= status; |
0 | 177 } |
178 } | |
179 | |
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180 static Uint8 *ALSA_GetAudioBuf(_THIS) |
0 | 181 { |
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182 return(mixbuf); |
0 | 183 } |
184 | |
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185 static void ALSA_CloseAudio(_THIS) |
0 | 186 { |
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187 if ( mixbuf != NULL ) { |
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188 SDL_FreeAudioMem(mixbuf); |
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189 mixbuf = NULL; |
0 | 190 } |
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191 if ( pcm_handle ) { |
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192 snd_pcm_drain(pcm_handle); |
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193 snd_pcm_close(pcm_handle); |
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194 pcm_handle = NULL; |
0 | 195 } |
196 } | |
197 | |
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198 static int ALSA_OpenAudio(_THIS, SDL_AudioSpec *spec) |
0 | 199 { |
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200 int status; |
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201 snd_pcm_hw_params_t *params; |
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202 snd_pcm_format_t format; |
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203 snd_pcm_uframes_t frames; |
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204 Uint16 test_format; |
0 | 205 |
206 /* Open the audio device */ | |
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207 status = snd_pcm_open(&pcm_handle, get_audio_device(), SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK); |
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208 if ( status < 0 ) { |
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209 SDL_SetError("Couldn't open audio device: %s", snd_strerror(status)); |
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210 return(-1); |
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211 } |
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212 |
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213 /* Figure out what the hardware is capable of */ |
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214 snd_pcm_hw_params_alloca(¶ms); |
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215 status = snd_pcm_hw_params_any(pcm_handle, params); |
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216 if ( status < 0 ) { |
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217 SDL_SetError("Couldn't get hardware config: %s", snd_strerror(status)); |
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218 ALSA_CloseAudio(this); |
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219 return(-1); |
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220 } |
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221 |
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222 /* SDL only uses interleaved sample output */ |
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223 status = snd_pcm_hw_params_set_access(pcm_handle, params, SND_PCM_ACCESS_RW_INTERLEAVED); |
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224 if ( status < 0 ) { |
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225 SDL_SetError("Couldn't set interleaved access: %s", snd_strerror(status)); |
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226 ALSA_CloseAudio(this); |
0 | 227 return(-1); |
228 } | |
229 | |
230 /* Try for a closest match on audio format */ | |
354
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231 status = -1; |
0 | 232 for ( test_format = SDL_FirstAudioFormat(spec->format); |
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233 test_format && (status < 0); ) { |
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234 switch ( test_format ) { |
0 | 235 case AUDIO_U8: |
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236 format = SND_PCM_FORMAT_U8; |
0 | 237 break; |
238 case AUDIO_S8: | |
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239 format = SND_PCM_FORMAT_S8; |
0 | 240 break; |
241 case AUDIO_S16LSB: | |
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242 format = SND_PCM_FORMAT_S16_LE; |
0 | 243 break; |
244 case AUDIO_S16MSB: | |
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245 format = SND_PCM_FORMAT_S16_BE; |
0 | 246 break; |
247 case AUDIO_U16LSB: | |
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248 format = SND_PCM_FORMAT_U16_LE; |
0 | 249 break; |
250 case AUDIO_U16MSB: | |
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251 format = SND_PCM_FORMAT_U16_BE; |
0 | 252 break; |
253 default: | |
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254 format = 0; |
0 | 255 break; |
256 } | |
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257 if ( format != 0 ) { |
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258 status = snd_pcm_hw_params_set_format(pcm_handle, params, format); |
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259 } |
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260 if ( status < 0 ) { |
0 | 261 test_format = SDL_NextAudioFormat(); |
262 } | |
263 } | |
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264 if ( status < 0 ) { |
0 | 265 SDL_SetError("Couldn't find any hardware audio formats"); |
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266 ALSA_CloseAudio(this); |
0 | 267 return(-1); |
268 } | |
269 spec->format = test_format; | |
270 | |
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271 /* Set the number of channels */ |
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272 status = snd_pcm_hw_params_set_channels(pcm_handle, params, spec->channels); |
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273 if ( status < 0 ) { |
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274 status = snd_pcm_hw_params_get_channels(params); |
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275 if ( (status <= 0) || (status > 2) ) { |
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276 SDL_SetError("Couldn't set audio channels"); |
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277 ALSA_CloseAudio(this); |
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278 return(-1); |
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279 } |
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280 spec->channels = status; |
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281 } |
0 | 282 |
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283 /* Set the audio rate */ |
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284 status = snd_pcm_hw_params_set_rate_near(pcm_handle, params, spec->freq, NULL); |
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285 if ( status < 0 ) { |
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286 SDL_SetError("Couldn't set audio frequency: %s", snd_strerror(status)); |
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287 ALSA_CloseAudio(this); |
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288 return(-1); |
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289 } |
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290 spec->freq = status; |
0 | 291 |
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292 /* Set the buffer size, in samples */ |
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293 frames = spec->samples; |
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294 frames = snd_pcm_hw_params_set_period_size_near(pcm_handle, params, frames, NULL); |
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295 spec->samples = frames; |
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296 snd_pcm_hw_params_set_periods_near(pcm_handle, params, 2, NULL); |
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297 |
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298 /* "set" the hardware with the desired parameters */ |
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299 status = snd_pcm_hw_params(pcm_handle, params); |
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300 if ( status < 0 ) { |
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301 SDL_SetError("Couldn't set audio parameters: %s", snd_strerror(status)); |
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302 ALSA_CloseAudio(this); |
0 | 303 return(-1); |
304 } | |
305 | |
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306 /* Calculate the final parameters for this audio specification */ |
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307 SDL_CalculateAudioSpec(spec); |
0 | 308 |
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309 /* Allocate mixing buffer */ |
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310 mixlen = spec->size; |
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311 mixbuf = (Uint8 *)SDL_AllocAudioMem(mixlen); |
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312 if ( mixbuf == NULL ) { |
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313 ALSA_CloseAudio(this); |
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314 return(-1); |
0 | 315 } |
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316 memset(mixbuf, spec->silence, spec->size); |
0 | 317 |
318 /* Get the parent process id (we're the parent of the audio thread) */ | |
319 parent = getpid(); | |
320 | |
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321 /* Switch to blocking mode for playback */ |
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322 snd_pcm_nonblock(pcm_handle, 0); |
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323 |
0 | 324 /* We're ready to rock and roll. :-) */ |
325 return(0); | |
326 } |