Mercurial > sdl-ios-xcode
annotate docs/html/sdllockaudio.html @ 765:4c2ba6161939
Editors Note: The original patch was modified to use SDL_Delay() instead of
nanosleep because nanosleep may not be portable to all systems
using SDL with the ALSA backend. This may be a moot point with
the switch to blocking writes anyway...
Date: Sat, 27 Dec 2003 21:47:36 +0100
From: Michel Daenzer
To: Debian Bug Tracking System
Subject: [SDL] Bug#225252: [PATCH] ALSA fixes
Package: libsdl1.2debian-all
Version: 1.2.6-2
Severity: normal
Tags: patch
For SDL 1.2.6, the ALSA backend was changed to call snd_pcm_open() with
SND_PCM_NONBLOCK. That's a good idea per se, however, it causes high CPU
usage, interrupted sound and stuttering in some games here. Taking a nanosleep
whenever snd_pcm_writei() returns -EAGAIN fixes this, but I think it's more
efficient to use blocking mode for the actual sound playback. Feedback from the
SDL and ALSA lists appreciated.
The patch also fixes the default ALSA device to be used.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Sun, 04 Jan 2004 15:40:50 +0000 |
| parents | e5bc29de3f0a |
| children | 355632dca928 |
| rev | line source |
|---|---|
| 0 | 1 <HTML |
| 2 ><HEAD | |
| 3 ><TITLE | |
| 4 >SDL_LockAudio</TITLE | |
| 5 ><META | |
| 6 NAME="GENERATOR" | |
|
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7 CONTENT="Modular DocBook HTML Stylesheet Version 1.64 |
| 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_MixAudio" | |
| 17 HREF="sdlmixaudio.html"><LINK | |
| 18 REL="NEXT" | |
| 19 TITLE="SDL_UnlockAudio" | |
| 20 HREF="sdlunlockaudio.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 | |
| 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="sdlmixaudio.html" | |
| 48 >Prev</A | |
| 49 ></TD | |
| 50 ><TD | |
| 51 WIDTH="80%" | |
| 52 ALIGN="center" | |
| 53 VALIGN="bottom" | |
| 54 ></TD | |
| 55 ><TD | |
| 56 WIDTH="10%" | |
| 57 ALIGN="right" | |
| 58 VALIGN="bottom" | |
| 59 ><A | |
| 60 HREF="sdlunlockaudio.html" | |
| 61 >Next</A | |
| 62 ></TD | |
| 63 ></TR | |
| 64 ></TABLE | |
| 65 ><HR | |
| 66 ALIGN="LEFT" | |
| 67 WIDTH="100%"></DIV | |
| 68 ><H1 | |
| 69 ><A | |
| 70 NAME="SDLLOCKAUDIO" | |
| 71 >SDL_LockAudio</A | |
| 72 ></H1 | |
| 73 ><DIV | |
| 74 CLASS="REFNAMEDIV" | |
| 75 ><A | |
|
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76 NAME="AEN6746" |
| 0 | 77 ></A |
| 78 ><H2 | |
| 79 >Name</H2 | |
| 80 >SDL_LockAudio -- Lock out the callback function</DIV | |
| 81 ><DIV | |
| 82 CLASS="REFSYNOPSISDIV" | |
| 83 ><A | |
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84 NAME="AEN6749" |
| 0 | 85 ></A |
| 86 ><H2 | |
| 87 >Synopsis</H2 | |
| 88 ><DIV | |
| 89 CLASS="FUNCSYNOPSIS" | |
| 90 ><A | |
|
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91 NAME="AEN6750" |
| 0 | 92 ></A |
| 93 ><P | |
| 94 ></P | |
| 95 ><PRE | |
| 96 CLASS="FUNCSYNOPSISINFO" | |
| 97 >#include "SDL.h"</PRE | |
| 98 ><P | |
| 99 ><CODE | |
| 100 ><CODE | |
| 101 CLASS="FUNCDEF" | |
| 102 >void <B | |
| 103 CLASS="FSFUNC" | |
| 104 >SDL_LockAudio</B | |
| 105 ></CODE | |
| 106 >(void);</CODE | |
| 107 ></P | |
| 108 ><P | |
| 109 ></P | |
| 110 ></DIV | |
| 111 ></DIV | |
| 112 ><DIV | |
| 113 CLASS="REFSECT1" | |
| 114 ><A | |
|
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115 NAME="AEN6756" |
| 0 | 116 ></A |
| 117 ><H2 | |
| 118 >Description</H2 | |
| 119 ><P | |
| 120 >The lock manipulated by these functions protects the callback function. | |
| 121 During a LockAudio period, you can be guaranteed that the | |
| 122 callback function is not running. Do not call these from the callback | |
| 123 function or you will cause deadlock.</P | |
| 124 ></DIV | |
| 125 ><DIV | |
| 126 CLASS="REFSECT1" | |
| 127 ><A | |
|
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128 NAME="AEN6759" |
| 0 | 129 ></A |
| 130 ><H2 | |
| 131 >See Also</H2 | |
| 132 ><P | |
| 133 ><A | |
| 134 HREF="sdlopenaudio.html" | |
| 135 ><TT | |
| 136 CLASS="FUNCTION" | |
| 137 >SDL_OpenAudio</TT | |
| 138 ></A | |
| 139 ></P | |
| 140 ></DIV | |
| 141 ><DIV | |
| 142 CLASS="NAVFOOTER" | |
| 143 ><HR | |
| 144 ALIGN="LEFT" | |
| 145 WIDTH="100%"><TABLE | |
| 146 WIDTH="100%" | |
| 147 BORDER="0" | |
| 148 CELLPADDING="0" | |
| 149 CELLSPACING="0" | |
| 150 ><TR | |
| 151 ><TD | |
| 152 WIDTH="33%" | |
| 153 ALIGN="left" | |
| 154 VALIGN="top" | |
| 155 ><A | |
| 156 HREF="sdlmixaudio.html" | |
| 157 >Prev</A | |
| 158 ></TD | |
| 159 ><TD | |
| 160 WIDTH="34%" | |
| 161 ALIGN="center" | |
| 162 VALIGN="top" | |
| 163 ><A | |
| 164 HREF="index.html" | |
| 165 >Home</A | |
| 166 ></TD | |
| 167 ><TD | |
| 168 WIDTH="33%" | |
| 169 ALIGN="right" | |
| 170 VALIGN="top" | |
| 171 ><A | |
| 172 HREF="sdlunlockaudio.html" | |
| 173 >Next</A | |
| 174 ></TD | |
| 175 ></TR | |
| 176 ><TR | |
| 177 ><TD | |
| 178 WIDTH="33%" | |
| 179 ALIGN="left" | |
| 180 VALIGN="top" | |
| 181 >SDL_MixAudio</TD | |
| 182 ><TD | |
| 183 WIDTH="34%" | |
| 184 ALIGN="center" | |
| 185 VALIGN="top" | |
| 186 ><A | |
| 187 HREF="audio.html" | |
| 188 >Up</A | |
| 189 ></TD | |
| 190 ><TD | |
| 191 WIDTH="33%" | |
| 192 ALIGN="right" | |
| 193 VALIGN="top" | |
| 194 >SDL_UnlockAudio</TD | |
| 195 ></TR | |
| 196 ></TABLE | |
| 197 ></DIV | |
| 198 ></BODY | |
| 199 ></HTML | |
| 200 > |