Mercurial > sdl-ios-xcode
annotate docs/html/guideaudioexamples.html @ 1260:80f8c94b5199
Date: 10 Jun 2003 15:30:59 -0400
From: Mike Shal
Subject: [SDL] Bug in SDL_wave.c?
Hey everyone, I'm not sure if this is a bug in SDL, or if I just have
incorrect WAV files. The problem I'm having is loading multiple
concatenated WAVs from SDL_LoadWAV_RW. Some WAV files put comments at
the end of the file (which may be bad form), and SDL doesn't skip past
them when reading from the RWops. So the next WAV I try to load will
start at the comment section of the previous WAV, which obviously
doesn't work. If anyone else is having this problem, one quick fix you
can do is run sox on the bad WAVs, which strips out all of the comment
sections.
Eg:
$ sox sound.wav tmp.wav
$ mv -f tmp.wav sound.wav
The other fix is to patch SDL_wave.c, which is included with this email.
(Assuming I made the patch correctly :). All it does is calculate how
much remaining space there is in the WAV file after the data chunk, and
does SDL_RWseek to skip it. I don't think it should interfere with
anything else, but if someone could check it that would be nice :). If
the bug is really with SDL and not with my WAVs, can someone work this
into the next version of SDL? Thanks,
-Mike Shal
author | Sam Lantinga <slouken@libsdl.org> |
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date | Tue, 24 Jan 2006 07:20:18 +0000 |
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0 | 1 <HTML |
2 ><HEAD | |
3 ><TITLE | |
4 >Audio Examples</TITLE | |
5 ><META | |
6 NAME="GENERATOR" | |
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7 CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ |
0 | 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 | |
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31 SUMMARY="Header navigation table" |
0 | 32 WIDTH="100%" |
33 BORDER="0" | |
34 CELLPADDING="0" | |
35 CELLSPACING="0" | |
36 ><TR | |
37 ><TH | |
38 COLSPAN="3" | |
39 ALIGN="center" | |
40 >SDL Library Documentation</TH | |
41 ></TR | |
42 ><TR | |
43 ><TD | |
44 WIDTH="10%" | |
45 ALIGN="left" | |
46 VALIGN="bottom" | |
47 ><A | |
48 HREF="guideeventexamples.html" | |
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49 ACCESSKEY="P" |
0 | 50 >Prev</A |
51 ></TD | |
52 ><TD | |
53 WIDTH="80%" | |
54 ALIGN="center" | |
55 VALIGN="bottom" | |
56 >Chapter 4. Examples</TD | |
57 ><TD | |
58 WIDTH="10%" | |
59 ALIGN="right" | |
60 VALIGN="bottom" | |
61 ><A | |
62 HREF="guidecdromexamples.html" | |
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63 ACCESSKEY="N" |
0 | 64 >Next</A |
65 ></TD | |
66 ></TR | |
67 ></TABLE | |
68 ><HR | |
69 ALIGN="LEFT" | |
70 WIDTH="100%"></DIV | |
71 ><DIV | |
72 CLASS="SECT1" | |
73 ><H1 | |
74 CLASS="SECT1" | |
75 ><A | |
76 NAME="GUIDEAUDIOEXAMPLES" | |
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77 ></A |
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78 >Audio Examples</H1 |
0 | 79 ><P |
80 ></P | |
81 ><DIV | |
82 CLASS="SECT2" | |
83 ><H2 | |
84 CLASS="SECT2" | |
85 ><A | |
55
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86 NAME="AEN382" |
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87 ></A |
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88 >Opening the audio device</H2 |
0 | 89 ><P |
90 ><PRE | |
91 CLASS="PROGRAMLISTING" | |
92 > SDL_AudioSpec wanted; | |
93 extern void fill_audio(void *udata, Uint8 *stream, int len); | |
94 | |
95 /* Set the audio format */ | |
96 wanted.freq = 22050; | |
97 wanted.format = AUDIO_S16; | |
98 wanted.channels = 2; /* 1 = mono, 2 = stereo */ | |
99 wanted.samples = 1024; /* Good low-latency value for callback */ | |
100 wanted.callback = fill_audio; | |
101 wanted.userdata = NULL; | |
102 | |
103 /* Open the audio device, forcing the desired format */ | |
104 if ( SDL_OpenAudio(&wanted, NULL) < 0 ) { | |
105 fprintf(stderr, "Couldn't open audio: %s\n", SDL_GetError()); | |
106 return(-1); | |
107 } | |
108 return(0);</PRE | |
109 ></P | |
110 ></DIV | |
111 ><DIV | |
112 CLASS="SECT2" | |
113 ><H2 | |
114 CLASS="SECT2" | |
115 ><A | |
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116 NAME="AEN386" |
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117 ></A |
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118 >Playing audio</H2 |
0 | 119 ><P |
120 ><PRE | |
121 CLASS="PROGRAMLISTING" | |
122 > static Uint8 *audio_chunk; | |
123 static Uint32 audio_len; | |
124 static Uint8 *audio_pos; | |
125 | |
126 /* The audio function callback takes the following parameters: | |
127 stream: A pointer to the audio buffer to be filled | |
128 len: The length (in bytes) of the audio buffer | |
129 */ | |
130 void fill_audio(void *udata, Uint8 *stream, int len) | |
131 { | |
132 /* Only play if we have data left */ | |
133 if ( audio_len == 0 ) | |
134 return; | |
135 | |
136 /* Mix as much data as possible */ | |
137 len = ( len > audio_len ? audio_len : len ); | |
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138 SDL_MixAudio(stream, audio_pos, len, SDL_MIX_MAXVOLUME); |
0 | 139 audio_pos += len; |
140 audio_len -= len; | |
141 } | |
142 | |
143 /* Load the audio data ... */ | |
144 | |
145 ;;;;; | |
146 | |
147 audio_pos = audio_chunk; | |
148 | |
149 /* Let the callback function play the audio chunk */ | |
150 SDL_PauseAudio(0); | |
151 | |
152 /* Do some processing */ | |
153 | |
154 ;;;;; | |
155 | |
156 /* Wait for sound to complete */ | |
157 while ( audio_len > 0 ) { | |
158 SDL_Delay(100); /* Sleep 1/10 second */ | |
159 } | |
160 SDL_CloseAudio();</PRE | |
161 ></P | |
162 ></DIV | |
163 ></DIV | |
164 ><DIV | |
165 CLASS="NAVFOOTER" | |
166 ><HR | |
167 ALIGN="LEFT" | |
168 WIDTH="100%"><TABLE | |
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169 SUMMARY="Footer navigation table" |
0 | 170 WIDTH="100%" |
171 BORDER="0" | |
172 CELLPADDING="0" | |
173 CELLSPACING="0" | |
174 ><TR | |
175 ><TD | |
176 WIDTH="33%" | |
177 ALIGN="left" | |
178 VALIGN="top" | |
179 ><A | |
180 HREF="guideeventexamples.html" | |
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181 ACCESSKEY="P" |
0 | 182 >Prev</A |
183 ></TD | |
184 ><TD | |
185 WIDTH="34%" | |
186 ALIGN="center" | |
187 VALIGN="top" | |
188 ><A | |
189 HREF="index.html" | |
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190 ACCESSKEY="H" |
0 | 191 >Home</A |
192 ></TD | |
193 ><TD | |
194 WIDTH="33%" | |
195 ALIGN="right" | |
196 VALIGN="top" | |
197 ><A | |
198 HREF="guidecdromexamples.html" | |
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199 ACCESSKEY="N" |
0 | 200 >Next</A |
201 ></TD | |
202 ></TR | |
203 ><TR | |
204 ><TD | |
205 WIDTH="33%" | |
206 ALIGN="left" | |
207 VALIGN="top" | |
208 >Event Examples</TD | |
209 ><TD | |
210 WIDTH="34%" | |
211 ALIGN="center" | |
212 VALIGN="top" | |
213 ><A | |
214 HREF="guideexamples.html" | |
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215 ACCESSKEY="U" |
0 | 216 >Up</A |
217 ></TD | |
218 ><TD | |
219 WIDTH="33%" | |
220 ALIGN="right" | |
221 VALIGN="top" | |
222 >CDROM Examples</TD | |
223 ></TR | |
224 ></TABLE | |
225 ></DIV | |
226 ></BODY | |
227 ></HTML | |
228 > |