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annotate docs/html/sdlmixaudio.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 |
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0 | 1 <HTML |
2 ><HEAD | |
3 ><TITLE | |
4 >SDL_MixAudio</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="Audio" | |
14 HREF="audio.html"><LINK | |
15 REL="PREVIOUS" | |
16 TITLE="SDL_ConvertAudio" | |
17 HREF="sdlconvertaudio.html"><LINK | |
18 REL="NEXT" | |
19 TITLE="SDL_LockAudio" | |
20 HREF="sdllockaudio.html"></HEAD | |
21 ><BODY | |
22 CLASS="REFENTRY" | |
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="sdlconvertaudio.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 ></TD | |
57 ><TD | |
58 WIDTH="10%" | |
59 ALIGN="right" | |
60 VALIGN="bottom" | |
61 ><A | |
62 HREF="sdllockaudio.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 ><H1 | |
72 ><A | |
73 NAME="SDLMIXAUDIO" | |
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74 ></A |
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75 >SDL_MixAudio</H1 |
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77 CLASS="REFNAMEDIV" | |
78 ><A | |
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79 NAME="AEN7107" |
0 | 80 ></A |
81 ><H2 | |
82 >Name</H2 | |
83 >SDL_MixAudio -- Mix audio data</DIV | |
84 ><DIV | |
85 CLASS="REFSYNOPSISDIV" | |
86 ><A | |
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90 >Synopsis</H2 | |
91 ><DIV | |
92 CLASS="FUNCSYNOPSIS" | |
93 ><A | |
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96 ><P | |
97 ></P | |
98 ><PRE | |
99 CLASS="FUNCSYNOPSISINFO" | |
100 >#include "SDL.h"</PRE | |
101 ><P | |
102 ><CODE | |
103 ><CODE | |
104 CLASS="FUNCDEF" | |
105 >void <B | |
106 CLASS="FSFUNC" | |
107 >SDL_MixAudio</B | |
108 ></CODE | |
109 >(Uint8 *dst, Uint8 *src, Uint32 len, int volume);</CODE | |
110 ></P | |
111 ><P | |
112 ></P | |
113 ></DIV | |
114 ></DIV | |
115 ><DIV | |
116 CLASS="REFSECT1" | |
117 ><A | |
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121 >Description</H2 | |
122 ><P | |
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123 >This function takes two audio buffers of <TT |
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125 ><I |
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126 >len</I |
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127 ></TT |
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128 > bytes each |
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129 of the playing audio format and mixes them, performing addition, volume |
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130 adjustment, and overflow clipping. The <TT |
0 | 131 CLASS="PARAMETER" |
132 ><I | |
133 >volume</I | |
134 ></TT | |
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135 > ranges |
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136 from 0 to <TT |
0 | 137 CLASS="LITERAL" |
138 >SDL_MIX_MAXVOLUME</TT | |
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139 > and should be set to the maximum |
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140 value for full audio volume. Note this does not change hardware volume. This is |
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141 provided for convenience -- you can mix your own audio data.</P |
181
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142 ><DIV |
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146 ><P |
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147 ><B |
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148 >Note: </B |
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149 >Do not use this function for mixing together more than two streams of sample |
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150 data. The output from repeated application of this function may be distorted |
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151 by clipping, because there is no accumulator with greater range than the |
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152 input (not to mention this being an inefficient way of doing it). |
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153 Use mixing functions from SDL_mixer, OpenAL, or write your own mixer instead.</P |
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154 ></BLOCKQUOTE |
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158 CLASS="REFSECT1" | |
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160 NAME="AEN7125" |
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162 ><H2 | |
163 >See Also</H2 | |
164 ><P | |
165 ><A | |
166 HREF="sdlopenaudio.html" | |
167 ><TT | |
168 CLASS="FUNCTION" | |
169 >SDL_OpenAudio</TT | |
170 ></A | |
171 ></P | |
172 ></DIV | |
173 ><DIV | |
174 CLASS="NAVFOOTER" | |
175 ><HR | |
176 ALIGN="LEFT" | |
177 WIDTH="100%"><TABLE | |
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180 BORDER="0" | |
181 CELLPADDING="0" | |
182 CELLSPACING="0" | |
183 ><TR | |
184 ><TD | |
185 WIDTH="33%" | |
186 ALIGN="left" | |
187 VALIGN="top" | |
188 ><A | |
189 HREF="sdlconvertaudio.html" | |
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190 ACCESSKEY="P" |
0 | 191 >Prev</A |
192 ></TD | |
193 ><TD | |
194 WIDTH="34%" | |
195 ALIGN="center" | |
196 VALIGN="top" | |
197 ><A | |
198 HREF="index.html" | |
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199 ACCESSKEY="H" |
0 | 200 >Home</A |
201 ></TD | |
202 ><TD | |
203 WIDTH="33%" | |
204 ALIGN="right" | |
205 VALIGN="top" | |
206 ><A | |
207 HREF="sdllockaudio.html" | |
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208 ACCESSKEY="N" |
0 | 209 >Next</A |
210 ></TD | |
211 ></TR | |
212 ><TR | |
213 ><TD | |
214 WIDTH="33%" | |
215 ALIGN="left" | |
216 VALIGN="top" | |
217 >SDL_ConvertAudio</TD | |
218 ><TD | |
219 WIDTH="34%" | |
220 ALIGN="center" | |
221 VALIGN="top" | |
222 ><A | |
223 HREF="audio.html" | |
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224 ACCESSKEY="U" |
0 | 225 >Up</A |
226 ></TD | |
227 ><TD | |
228 WIDTH="33%" | |
229 ALIGN="right" | |
230 VALIGN="top" | |
231 >SDL_LockAudio</TD | |
232 ></TR | |
233 ></TABLE | |
234 ></DIV | |
235 ></BODY | |
236 ></HTML | |
237 > |