Mercurial > sdl-ios-xcode
annotate docs/html/sdlmixaudio.html @ 4355:9b464226e541 SDL-1.2
Fixed bug #855
Ludwig Nussel 2009-10-18 06:31:52 PDT
an mprotect call was added to fix bug 528. However that results in a buffer
that allows writing and code execution. Ie the no-execute security features of
modern operating systems are defeated this way. Two mprotect calls are needed.
One to make the buffer executable but not writeable when done and another one
to make the buffer writeable again if the content needs to be changed.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Sun, 18 Oct 2009 17:31:37 +0000 |
| parents | 355632dca928 |
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| rev | line source |
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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 |
| 0 | 76 ><DIV |
| 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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87 NAME="AEN7110" |
| 0 | 88 ></A |
| 89 ><H2 | |
| 90 >Synopsis</H2 | |
| 91 ><DIV | |
| 92 CLASS="FUNCSYNOPSIS" | |
| 93 ><A | |
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94 NAME="AEN7111" |
| 0 | 95 ></A |
| 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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118 NAME="AEN7117" |
| 0 | 119 ></A |
| 120 ><H2 | |
| 121 >Description</H2 | |
| 122 ><P | |
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123 >This function takes two audio buffers of <TT |
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124 CLASS="PARAMETER" |
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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 |
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181
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142 ><DIV |
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143 CLASS="NOTE" |
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144 ><BLOCKQUOTE |
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145 CLASS="NOTE" |
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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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155 ></DIV |
| 0 | 156 ></DIV |
| 157 ><DIV | |
| 158 CLASS="REFSECT1" | |
| 159 ><A | |
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160 NAME="AEN7125" |
| 0 | 161 ></A |
| 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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178 SUMMARY="Footer navigation table" |
| 0 | 179 WIDTH="100%" |
| 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 > |