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Initial revision
author Sam Lantinga <slouken@lokigames.com>
date Thu, 26 Apr 2001 16:45:43 +0000
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children 55f1f1b3e27d
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-1:000000000000 0:74212992fb08
1 <HTML
2 ><HEAD
3 ><TITLE
4 >Audio Examples</TITLE
5 ><META
6 NAME="GENERATOR"
7 CONTENT="Modular DocBook HTML Stylesheet Version 1.61
8 "><LINK
9 REL="HOME"
10 TITLE="SDL Library Documentation"
11 HREF="index.html"><LINK
12 REL="UP"
13 TITLE="Examples"
14 HREF="guideexamples.html"><LINK
15 REL="PREVIOUS"
16 TITLE="Event Examples"
17 HREF="guideeventexamples.html"><LINK
18 REL="NEXT"
19 TITLE="CDROM Examples"
20 HREF="guidecdromexamples.html"></HEAD
21 ><BODY
22 CLASS="SECT1"
23 BGCOLOR="#FFF8DC"
24 TEXT="#000000"
25 LINK="#0000ee"
26 VLINK="#551a8b"
27 ALINK="#ff0000"
28 ><DIV
29 CLASS="NAVHEADER"
30 ><TABLE
31 WIDTH="100%"
32 BORDER="0"
33 CELLPADDING="0"
34 CELLSPACING="0"
35 ><TR
36 ><TH
37 COLSPAN="3"
38 ALIGN="center"
39 >SDL Library Documentation</TH
40 ></TR
41 ><TR
42 ><TD
43 WIDTH="10%"
44 ALIGN="left"
45 VALIGN="bottom"
46 ><A
47 HREF="guideeventexamples.html"
48 >Prev</A
49 ></TD
50 ><TD
51 WIDTH="80%"
52 ALIGN="center"
53 VALIGN="bottom"
54 >Chapter 4. Examples</TD
55 ><TD
56 WIDTH="10%"
57 ALIGN="right"
58 VALIGN="bottom"
59 ><A
60 HREF="guidecdromexamples.html"
61 >Next</A
62 ></TD
63 ></TR
64 ></TABLE
65 ><HR
66 ALIGN="LEFT"
67 WIDTH="100%"></DIV
68 ><DIV
69 CLASS="SECT1"
70 ><H1
71 CLASS="SECT1"
72 ><A
73 NAME="GUIDEAUDIOEXAMPLES"
74 >Audio Examples</A
75 ></H1
76 ><P
77 ></P
78 ><DIV
79 CLASS="SECT2"
80 ><H2
81 CLASS="SECT2"
82 ><A
83 NAME="AEN343"
84 >Opening the audio device</A
85 ></H2
86 ><P
87 ><PRE
88 CLASS="PROGRAMLISTING"
89 > SDL_AudioSpec wanted;
90 extern void fill_audio(void *udata, Uint8 *stream, int len);
91
92 /* Set the audio format */
93 wanted.freq = 22050;
94 wanted.format = AUDIO_S16;
95 wanted.channels = 2; /* 1 = mono, 2 = stereo */
96 wanted.samples = 1024; /* Good low-latency value for callback */
97 wanted.callback = fill_audio;
98 wanted.userdata = NULL;
99
100 /* Open the audio device, forcing the desired format */
101 if ( SDL_OpenAudio(&#38;wanted, NULL) &#60; 0 ) {
102 fprintf(stderr, "Couldn't open audio: %s\n", SDL_GetError());
103 return(-1);
104 }
105 return(0);</PRE
106 ></P
107 ></DIV
108 ><DIV
109 CLASS="SECT2"
110 ><H2
111 CLASS="SECT2"
112 ><A
113 NAME="AEN347"
114 >Playing audio</A
115 ></H2
116 ><P
117 ><PRE
118 CLASS="PROGRAMLISTING"
119 > static Uint8 *audio_chunk;
120 static Uint32 audio_len;
121 static Uint8 *audio_pos;
122
123 /* The audio function callback takes the following parameters:
124 stream: A pointer to the audio buffer to be filled
125 len: The length (in bytes) of the audio buffer
126 */
127 void fill_audio(void *udata, Uint8 *stream, int len)
128 {
129 /* Only play if we have data left */
130 if ( audio_len == 0 )
131 return;
132
133 /* Mix as much data as possible */
134 len = ( len &#62; audio_len ? audio_len : len );
135 SDL_MixAudio(stream, audio_pos, len, SDL_MIX_MAXVOLUME)
136 audio_pos += len;
137 audio_len -= len;
138 }
139
140 /* Load the audio data ... */
141
142 ;;;;;
143
144 audio_pos = audio_chunk;
145
146 /* Let the callback function play the audio chunk */
147 SDL_PauseAudio(0);
148
149 /* Do some processing */
150
151 ;;;;;
152
153 /* Wait for sound to complete */
154 while ( audio_len &#62; 0 ) {
155 SDL_Delay(100); /* Sleep 1/10 second */
156 }
157 SDL_CloseAudio();</PRE
158 ></P
159 ></DIV
160 ></DIV
161 ><DIV
162 CLASS="NAVFOOTER"
163 ><HR
164 ALIGN="LEFT"
165 WIDTH="100%"><TABLE
166 WIDTH="100%"
167 BORDER="0"
168 CELLPADDING="0"
169 CELLSPACING="0"
170 ><TR
171 ><TD
172 WIDTH="33%"
173 ALIGN="left"
174 VALIGN="top"
175 ><A
176 HREF="guideeventexamples.html"
177 >Prev</A
178 ></TD
179 ><TD
180 WIDTH="34%"
181 ALIGN="center"
182 VALIGN="top"
183 ><A
184 HREF="index.html"
185 >Home</A
186 ></TD
187 ><TD
188 WIDTH="33%"
189 ALIGN="right"
190 VALIGN="top"
191 ><A
192 HREF="guidecdromexamples.html"
193 >Next</A
194 ></TD
195 ></TR
196 ><TR
197 ><TD
198 WIDTH="33%"
199 ALIGN="left"
200 VALIGN="top"
201 >Event Examples</TD
202 ><TD
203 WIDTH="34%"
204 ALIGN="center"
205 VALIGN="top"
206 ><A
207 HREF="guideexamples.html"
208 >Up</A
209 ></TD
210 ><TD
211 WIDTH="33%"
212 ALIGN="right"
213 VALIGN="top"
214 >CDROM Examples</TD
215 ></TR
216 ></TABLE
217 ></DIV
218 ></BODY
219 ></HTML
220 >