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view docs/html/sdlloadwav.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 |
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<HTML ><HEAD ><TITLE >SDL_LoadWAV</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.64 "><LINK REL="HOME" TITLE="SDL Library Documentation" HREF="index.html"><LINK REL="UP" TITLE="Audio" HREF="audio.html"><LINK REL="PREVIOUS" TITLE="SDL_GetAudioStatus" HREF="sdlgetaudiostatus.html"><LINK REL="NEXT" TITLE="SDL_FreeWAV" HREF="sdlfreewav.html"></HEAD ><BODY CLASS="REFENTRY" BGCOLOR="#FFF8DC" TEXT="#000000" LINK="#0000ee" VLINK="#551a8b" ALINK="#ff0000" ><DIV CLASS="NAVHEADER" ><TABLE WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >SDL Library Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="sdlgetaudiostatus.html" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdlfreewav.html" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLLOADWAV" >SDL_LoadWAV</A ></H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN6428" ></A ><H2 >Name</H2 >SDL_LoadWAV -- Load a WAVE file</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN6431" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN6432" ></A ><P ></P ><PRE CLASS="FUNCSYNOPSISINFO" >#include "SDL.h"</PRE ><P ><CODE ><CODE CLASS="FUNCDEF" >SDL_AudioSpec *<B CLASS="FSFUNC" >SDL_LoadWAV</B ></CODE >(const char *file, SDL_AudioSpec *spec, Uint8 **audio_buf, Uint32 *audio_len);</CODE ></P ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN6438" ></A ><H2 >Description</H2 ><P ><TT CLASS="FUNCTION" >SDL_LoadWAV</TT > This function loads a WAVE <TT CLASS="PARAMETER" ><I >file</I ></TT > into memory.</P ><P >If this function succeeds, it returns the given <A HREF="sdlaudiospec.html" ><TT CLASS="FUNCTION" >SDL_AudioSpec</TT ></A >, filled with the audio data format of the wave data, and sets <TT CLASS="PARAMETER" ><I >audio_buf</I ></TT > to a <TT CLASS="FUNCTION" >malloc</TT >'d buffer containing the audio data, and sets <TT CLASS="PARAMETER" ><I >audio_len</I ></TT > to the length of that audio buffer, in bytes. You need to free the audio buffer with <A HREF="sdlfreewav.html" ><TT CLASS="FUNCTION" >SDL_FreeWAV</TT ></A > when you are done with it.</P ><P >This function returns <TT CLASS="LITERAL" >NULL</TT > and sets the SDL error message if the wave file cannot be opened, uses an unknown data format, or is corrupt. Currently raw, MS-ADPCM and IMA-ADPCM WAVE files are supported.</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN6453" ></A ><H2 >Example</H2 ><PRE CLASS="PROGRAMLISTING" >SDL_AudioSpec wav_spec; Uint32 wav_length; Uint8 *wav_buffer; /* Load the WAV */ if( SDL_LoadWAV("test.wav", &wav_spec, &wav_buffer, &wav_length) == NULL ){ fprintf(stderr, "Could not open test.wav: %s\n", SDL_GetError()); exit(-1); } . . . /* Do stuff with the WAV */ . . /* Free It */ SDL_FreeWAV(wav_buffer);</PRE ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN6456" ></A ><H2 >See Also</H2 ><P ><A HREF="sdlaudiospec.html" ><SPAN CLASS="STRUCTNAME" >SDL_AudioSpec</SPAN ></A >, <A HREF="sdlopenaudio.html" ><TT CLASS="FUNCTION" >SDL_OpenAudio</TT ></A >, <A HREF="sdlfreewav.html" ><TT CLASS="FUNCTION" >SDL_FreeWAV</TT ></A ></P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="sdlgetaudiostatus.html" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="sdlfreewav.html" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_GetAudioStatus</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="audio.html" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SDL_FreeWAV</TD ></TR ></TABLE ></DIV ></BODY ></HTML >