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annotate docs/html/audio.html @ 1982:3b4ce57c6215
First shot at new audio data types (int32 and float32).
Notable changes:
- Converters between types are autogenerated. Instead of making multiple
passes over the data with seperate filters for endianess, size, signedness,
etc, converting between data types is always one specialized filter. This
simplifies SDL_BuildAudioCVT(), which otherwise had a million edge cases
with the new types, and makes the actually conversions more CPU cache
friendly. Left a stub for adding specific optimized versions of these
routines (SSE/MMX/Altivec, assembler, etc)
- Autogenerated converters are built by SDL/src/audio/sdlgenaudiocvt.pl. This
does not need to be run unless tweaking the code, and thus doesn't need
integration into the build system.
- Went through all the drivers and tried to weed out all the "Uint16"
references that are better specified with the new SDL_AudioFormat typedef.
- Cleaned out a bunch of hardcoded bitwise magic numbers and replaced them
with new SDL_AUDIO_* macros.
- Added initial float32 and int32 support code. Theoretically, existing
drivers will push these through converters to get the data they want to
feed to the hardware.
Still TODO:
- Optimize and debug new converters.
- Update the CoreAudio backend to accept float32 data directly.
- Other backends, too?
- SDL_LoadWAV() needs to be updated to support int32 and float32 .wav files
(both of which exist and can be generated by 'sox' for testing purposes).
- Update the mixer to handle new datatypes.
- Optionally update SDL_sound and SDL_mixer, etc.
author | Ryan C. Gordon <icculus@icculus.org> |
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date | Thu, 24 Aug 2006 12:10:46 +0000 |
parents | 355632dca928 |
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rev | line source |
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0 | 1 <HTML |
2 ><HEAD | |
3 ><TITLE | |
4 >Audio</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="SDL Reference" | |
14 HREF="reference.html"><LINK | |
15 REL="PREVIOUS" | |
16 TITLE="SDL_JoystickClose" | |
17 HREF="sdljoystickclose.html"><LINK | |
18 REL="NEXT" | |
19 TITLE="SDL_AudioSpec" | |
20 HREF="sdlaudiospec.html"><META | |
21 NAME="KEYWORD" | |
22 CONTENT="audio"><META | |
23 NAME="KEYWORD" | |
24 CONTENT="function"></HEAD | |
25 ><BODY | |
26 CLASS="CHAPTER" | |
27 BGCOLOR="#FFF8DC" | |
28 TEXT="#000000" | |
29 LINK="#0000ee" | |
30 VLINK="#551a8b" | |
31 ALINK="#ff0000" | |
32 ><DIV | |
33 CLASS="NAVHEADER" | |
34 ><TABLE | |
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35 SUMMARY="Header navigation table" |
0 | 36 WIDTH="100%" |
37 BORDER="0" | |
38 CELLPADDING="0" | |
39 CELLSPACING="0" | |
40 ><TR | |
41 ><TH | |
42 COLSPAN="3" | |
43 ALIGN="center" | |
44 >SDL Library Documentation</TH | |
45 ></TR | |
46 ><TR | |
47 ><TD | |
48 WIDTH="10%" | |
49 ALIGN="left" | |
50 VALIGN="bottom" | |
51 ><A | |
52 HREF="sdljoystickclose.html" | |
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53 ACCESSKEY="P" |
0 | 54 >Prev</A |
55 ></TD | |
56 ><TD | |
57 WIDTH="80%" | |
58 ALIGN="center" | |
59 VALIGN="bottom" | |
60 ></TD | |
61 ><TD | |
62 WIDTH="10%" | |
63 ALIGN="right" | |
64 VALIGN="bottom" | |
65 ><A | |
66 HREF="sdlaudiospec.html" | |
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67 ACCESSKEY="N" |
0 | 68 >Next</A |
69 ></TD | |
70 ></TR | |
71 ></TABLE | |
72 ><HR | |
73 ALIGN="LEFT" | |
74 WIDTH="100%"></DIV | |
75 ><DIV | |
76 CLASS="CHAPTER" | |
77 ><H1 | |
78 ><A | |
79 NAME="AUDIO" | |
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80 ></A |
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81 >Chapter 10. Audio</H1 |
0 | 82 ><DIV |
83 CLASS="TOC" | |
84 ><DL | |
85 ><DT | |
86 ><B | |
87 >Table of Contents</B | |
88 ></DT | |
89 ><DT | |
90 ><A | |
91 HREF="sdlaudiospec.html" | |
92 >SDL_AudioSpec</A | |
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93 > -- Audio Specification Structure</DT |
0 | 94 ><DT |
95 ><A | |
96 HREF="sdlopenaudio.html" | |
97 >SDL_OpenAudio</A | |
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98 > -- Opens the audio device with the desired parameters.</DT |
0 | 99 ><DT |
100 ><A | |
101 HREF="sdlpauseaudio.html" | |
102 >SDL_PauseAudio</A | |
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103 > -- Pauses and unpauses the audio callback processing</DT |
0 | 104 ><DT |
105 ><A | |
106 HREF="sdlgetaudiostatus.html" | |
107 >SDL_GetAudioStatus</A | |
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108 > -- Get the current audio state</DT |
0 | 109 ><DT |
110 ><A | |
111 HREF="sdlloadwav.html" | |
112 >SDL_LoadWAV</A | |
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113 > -- Load a WAVE file</DT |
0 | 114 ><DT |
115 ><A | |
116 HREF="sdlfreewav.html" | |
117 >SDL_FreeWAV</A | |
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118 > -- Frees previously opened WAV data</DT |
0 | 119 ><DT |
120 ><A | |
121 HREF="sdlaudiocvt.html" | |
122 >SDL_AudioCVT</A | |
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123 > -- Audio Conversion Structure</DT |
0 | 124 ><DT |
125 ><A | |
126 HREF="sdlbuildaudiocvt.html" | |
127 >SDL_BuildAudioCVT</A | |
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128 > -- Initializes a SDL_AudioCVT structure for conversion</DT |
0 | 129 ><DT |
130 ><A | |
131 HREF="sdlconvertaudio.html" | |
132 >SDL_ConvertAudio</A | |
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133 > -- Convert audio data to a desired audio format.</DT |
0 | 134 ><DT |
135 ><A | |
136 HREF="sdlmixaudio.html" | |
137 >SDL_MixAudio</A | |
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138 > -- Mix audio data</DT |
0 | 139 ><DT |
140 ><A | |
141 HREF="sdllockaudio.html" | |
142 >SDL_LockAudio</A | |
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143 > -- Lock out the callback function</DT |
0 | 144 ><DT |
145 ><A | |
146 HREF="sdlunlockaudio.html" | |
147 >SDL_UnlockAudio</A | |
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148 > -- Unlock the callback function</DT |
0 | 149 ><DT |
150 ><A | |
151 HREF="sdlcloseaudio.html" | |
152 >SDL_CloseAudio</A | |
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153 > -- Shuts down audio processing and closes the audio device.</DT |
0 | 154 ></DL |
155 ></DIV | |
156 ><P | |
157 >Sound on the computer is translated from waves that you hear into a series of | |
158 values, or samples, each representing the amplitude of the wave. When these | |
159 samples are sent in a stream to a sound card, an approximation of the original | |
160 wave can be recreated. The more bits used to represent the amplitude, and the | |
161 greater frequency these samples are gathered, the closer the approximated | |
162 sound is to the original, and the better the quality of sound.</P | |
163 ><P | |
164 >This library supports both 8 and 16 bit signed and unsigned sound samples, | |
165 at frequencies ranging from 11025 Hz to 44100 Hz, depending on the | |
166 underlying hardware. If the hardware doesn't support the desired audio | |
167 format or frequency, it can be emulated if desired (See | |
168 <A | |
169 HREF="sdlopenaudio.html" | |
170 ><TT | |
171 CLASS="FUNCTION" | |
172 >SDL_OpenAudio()</TT | |
173 ></A | |
174 >)</P | |
175 ><P | |
176 >A commonly supported audio format is 16 bits per sample at 22050 Hz.</P | |
177 ></DIV | |
178 ><DIV | |
179 CLASS="NAVFOOTER" | |
180 ><HR | |
181 ALIGN="LEFT" | |
182 WIDTH="100%"><TABLE | |
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183 SUMMARY="Footer navigation table" |
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185 BORDER="0" | |
186 CELLPADDING="0" | |
187 CELLSPACING="0" | |
188 ><TR | |
189 ><TD | |
190 WIDTH="33%" | |
191 ALIGN="left" | |
192 VALIGN="top" | |
193 ><A | |
194 HREF="sdljoystickclose.html" | |
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195 ACCESSKEY="P" |
0 | 196 >Prev</A |
197 ></TD | |
198 ><TD | |
199 WIDTH="34%" | |
200 ALIGN="center" | |
201 VALIGN="top" | |
202 ><A | |
203 HREF="index.html" | |
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204 ACCESSKEY="H" |
0 | 205 >Home</A |
206 ></TD | |
207 ><TD | |
208 WIDTH="33%" | |
209 ALIGN="right" | |
210 VALIGN="top" | |
211 ><A | |
212 HREF="sdlaudiospec.html" | |
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213 ACCESSKEY="N" |
0 | 214 >Next</A |
215 ></TD | |
216 ></TR | |
217 ><TR | |
218 ><TD | |
219 WIDTH="33%" | |
220 ALIGN="left" | |
221 VALIGN="top" | |
222 >SDL_JoystickClose</TD | |
223 ><TD | |
224 WIDTH="34%" | |
225 ALIGN="center" | |
226 VALIGN="top" | |
227 ><A | |
228 HREF="reference.html" | |
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229 ACCESSKEY="U" |
0 | 230 >Up</A |
231 ></TD | |
232 ><TD | |
233 WIDTH="33%" | |
234 ALIGN="right" | |
235 VALIGN="top" | |
236 >SDL_AudioSpec</TD | |
237 ></TR | |
238 ></TABLE | |
239 ></DIV | |
240 ></BODY | |
241 ></HTML | |
242 > |