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>
date Mon, 05 Jan 2004 00:57:51 +0000
parents b8d311d90021
children 92615154bb68
rev   line source
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1 /*
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2 SDL - Simple DirectMedia Layer
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3 Copyright (C) 1997-2004 Sam Lantinga
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4
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5 This library is free software; you can redistribute it and/or
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6 modify it under the terms of the GNU Library General Public
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7 License as published by the Free Software Foundation; either
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8 version 2 of the License, or (at your option) any later version.
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9
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10 This library is distributed in the hope that it will be useful,
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11 but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 Library General Public License for more details.
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14
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15 You should have received a copy of the GNU Library General Public
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16 License along with this library; if not, write to the Free
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17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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18
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19 Sam Lantinga
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20 slouken@libsdl.org
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21 */
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22
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23
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24
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25 /* Allow access to a raw mixing buffer */
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26
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27 #include <stdlib.h>
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28 #include <stdio.h>
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29 #include <string.h>
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30 #include <errno.h>
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31 #include <unistd.h>
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32 #include <fcntl.h>
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33 #include <signal.h>
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34 #include <sys/types.h>
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35 #include <sys/time.h>
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36
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37 #include "SDL_audio.h"
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38 #include "SDL_error.h"
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39 #include "SDL_audiomem.h"
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40 #include "SDL_audio_c.h"
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41 #include "SDL_timer.h"
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42 #include "SDL_alsa_audio.h"
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43
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44 /* The tag name used by ALSA audio */
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45 #define DRIVER_NAME "alsa"
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46
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47 /* The default ALSA audio driver */
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48 #define DEFAULT_DEVICE "default"
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49
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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);
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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;
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66 }
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67
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68 /* Audio driver bootstrap functions */
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69
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70 static int Audio_Available(void)
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71 {
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72 int available;
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73 int status;
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74 snd_pcm_t *handle;
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75
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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);
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81 }
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82 return(available);
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83 }
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84
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85 static void Audio_DeleteDevice(SDL_AudioDevice *device)
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86 {
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87 free(device->hidden);
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88 free(device);
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89 }
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90
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91 static SDL_AudioDevice *Audio_CreateDevice(int devindex)
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92 {
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93 SDL_AudioDevice *this;
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94
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95 /* Initialize all variables that we clean on shutdown */
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96 this = (SDL_AudioDevice *)malloc(sizeof(SDL_AudioDevice));
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97 if ( this ) {
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98 memset(this, 0, (sizeof *this));
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99 this->hidden = (struct SDL_PrivateAudioData *)
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100 malloc((sizeof *this->hidden));
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101 }
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102 if ( (this == NULL) || (this->hidden == NULL) ) {
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103 SDL_OutOfMemory();
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104 if ( this ) {
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105 free(this);
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106 }
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107 return(0);
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108 }
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109 memset(this->hidden, 0, (sizeof *this->hidden));
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110
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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;
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117
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118 this->free = Audio_DeleteDevice;
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119
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120 return this;
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121 }
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122
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123 AudioBootStrap ALSA_bootstrap = {
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124 DRIVER_NAME, "ALSA 0.9 PCM audio",
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125 Audio_Available, Audio_CreateDevice
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126 };
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127
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128 /* This function waits until it is possible to write a full sound buffer */
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129 static void ALSA_WaitAudio(_THIS)
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130 {
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131 /* Check to see if the thread-parent process is still alive */
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132 { static int cnt = 0;
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133 /* Note that this only works with thread implementations
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134 that use a different process id for each thread.
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135 */
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136 if (parent && (((++cnt)%10) == 0)) { /* Check every 10 loops */
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137 if ( kill(parent, 0) < 0 ) {
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138 this->enabled = 0;
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139 }
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140 }
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141 }
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142 }
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143
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144 static void ALSA_PlayAudio(_THIS)
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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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diff changeset
157 continue;
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158 }
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diff changeset
159 if ( status == -ESTRPIPE ) {
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diff changeset
160 do {
765
4c2ba6161939 Editors Note: The original patch was modified to use SDL_Delay() instead of
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diff changeset
161 SDL_Delay(1);
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diff changeset
162 status = snd_pcm_resume(pcm_handle);
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diff changeset
163 } while ( status == -EAGAIN );
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diff changeset
164 }
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diff changeset
165 if ( status < 0 ) {
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diff changeset
166 status = snd_pcm_prepare(pcm_handle);
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167 }
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diff changeset
168 if ( status < 0 ) {
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diff changeset
169 /* Hmm, not much we can do - abort */
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diff changeset
170 this->enabled = 0;
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diff changeset
171 return;
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172 }
356
a1e54d1ba16f *** empty log message ***
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diff changeset
173 continue;
0
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174 }
354
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diff changeset
175 sample_buf += status * this->spec.channels;
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diff changeset
176 sample_len -= status;
0
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177 }
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178 }
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179
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180 static Uint8 *ALSA_GetAudioBuf(_THIS)
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181 {
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182 return(mixbuf);
0
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183 }
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184
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185 static void ALSA_CloseAudio(_THIS)
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186 {
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187 if ( mixbuf != NULL ) {
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188 SDL_FreeAudioMem(mixbuf);
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189 mixbuf = NULL;
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190 }
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191 if ( pcm_handle ) {
357
5868b0f832f2 *** empty log message ***
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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;
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195 }
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196 }
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197
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198 static int ALSA_OpenAudio(_THIS, SDL_AudioSpec *spec)
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199 {
354
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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;
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205
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206 /* Open the audio device */
547
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207 status = snd_pcm_open(&pcm_handle, get_audio_device(), SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
354
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diff changeset
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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diff changeset
213 /* Figure out what the hardware is capable of */
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diff changeset
214 snd_pcm_hw_params_alloca(&params);
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215 status = snd_pcm_hw_params_any(pcm_handle, params);
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diff changeset
216 if ( status < 0 ) {
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217 SDL_SetError("Couldn't get hardware config: %s", snd_strerror(status));
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diff changeset
218 ALSA_CloseAudio(this);
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219 return(-1);
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diff changeset
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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diff changeset
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);
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227 return(-1);
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228 }
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229
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230 /* Try for a closest match on audio format */
354
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diff changeset
231 status = -1;
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232 for ( test_format = SDL_FirstAudioFormat(spec->format);
354
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diff changeset
233 test_format && (status < 0); ) {
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diff changeset
234 switch ( test_format ) {
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235 case AUDIO_U8:
354
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diff changeset
236 format = SND_PCM_FORMAT_U8;
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237 break;
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238 case AUDIO_S8:
354
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diff changeset
239 format = SND_PCM_FORMAT_S8;
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240 break;
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241 case AUDIO_S16LSB:
354
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diff changeset
242 format = SND_PCM_FORMAT_S16_LE;
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243 break;
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244 case AUDIO_S16MSB:
354
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diff changeset
245 format = SND_PCM_FORMAT_S16_BE;
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246 break;
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247 case AUDIO_U16LSB:
354
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diff changeset
248 format = SND_PCM_FORMAT_U16_LE;
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249 break;
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250 case AUDIO_U16MSB:
354
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diff changeset
251 format = SND_PCM_FORMAT_U16_BE;
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252 break;
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253 default:
354
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diff changeset
254 format = 0;
0
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255 break;
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256 }
354
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diff changeset
257 if ( format != 0 ) {
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diff changeset
258 status = snd_pcm_hw_params_set_format(pcm_handle, params, format);
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diff changeset
259 }
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diff changeset
260 if ( status < 0 ) {
0
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261 test_format = SDL_NextAudioFormat();
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262 }
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263 }
354
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diff changeset
264 if ( status < 0 ) {
0
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265 SDL_SetError("Couldn't find any hardware audio formats");
354
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diff changeset
266 ALSA_CloseAudio(this);
0
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267 return(-1);
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268 }
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269 spec->format = test_format;
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270
354
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diff changeset
271 /* Set the number of channels */
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diff changeset
272 status = snd_pcm_hw_params_set_channels(pcm_handle, params, spec->channels);
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diff changeset
273 if ( status < 0 ) {
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diff changeset
274 status = snd_pcm_hw_params_get_channels(params);
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diff changeset
275 if ( (status <= 0) || (status > 2) ) {
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diff changeset
276 SDL_SetError("Couldn't set audio channels");
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diff changeset
277 ALSA_CloseAudio(this);
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diff changeset
278 return(-1);
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diff changeset
279 }
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diff changeset
280 spec->channels = status;
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diff changeset
281 }
0
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282
354
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diff changeset
283 /* Set the audio rate */
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diff changeset
284 status = snd_pcm_hw_params_set_rate_near(pcm_handle, params, spec->freq, NULL);
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diff changeset
285 if ( status < 0 ) {
30935e76acb5 Updated ALSA audio support for ALSA 0.9
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diff changeset
286 SDL_SetError("Couldn't set audio frequency: %s", snd_strerror(status));
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diff changeset
287 ALSA_CloseAudio(this);
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diff changeset
288 return(-1);
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diff changeset
289 }
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diff changeset
290 spec->freq = status;
0
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291
354
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diff changeset
292 /* Set the buffer size, in samples */
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diff changeset
293 frames = spec->samples;
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diff changeset
294 frames = snd_pcm_hw_params_set_period_size_near(pcm_handle, params, frames, NULL);
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diff changeset
295 spec->samples = frames;
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diff changeset
296 snd_pcm_hw_params_set_periods_near(pcm_handle, params, 2, NULL);
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diff changeset
297
30935e76acb5 Updated ALSA audio support for ALSA 0.9
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diff changeset
298 /* "set" the hardware with the desired parameters */
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diff changeset
299 status = snd_pcm_hw_params(pcm_handle, params);
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diff changeset
300 if ( status < 0 ) {
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diff changeset
301 SDL_SetError("Couldn't set audio parameters: %s", snd_strerror(status));
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diff changeset
302 ALSA_CloseAudio(this);
0
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diff changeset
303 return(-1);
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diff changeset
304 }
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305
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306 /* Calculate the final parameters for this audio specification */
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307 SDL_CalculateAudioSpec(spec);
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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);
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315 }
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316 memset(mixbuf, spec->silence, spec->size);
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317
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318 /* Get the parent process id (we're the parent of the audio thread) */
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319 parent = getpid();
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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
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324 /* We're ready to rock and roll. :-) */
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325 return(0);
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326 }