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Date: Sun, 29 Feb 2004 15:14:22 +0200 From: Martin_Storsj Subject: Dynamic loading of ALSA I recently discovered that SDL can dynamically load ESD and aRts, and made a patch which adds this same functionality to ALSA. The update for configure.in isn't too good (it should e.g. look for libasound.so in other directories than /usr/lib), because I'm not too good at shellscripting and autoconf. The reason for using dlfcn.h and dlopen instead of SDL_LoadLibrary and SDL_LoadFunction is that libasound uses versioned symbols, and it is necessary to load the correct version using dlvsym. This isn't probably any real portability issue, because ALSA is linux-only.
author Sam Lantinga <slouken@libsdl.org>
date Tue, 02 Mar 2004 12:49:16 +0000
parents 355632dca928
children
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>SDL_MixAudio</TITLE
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><H1
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>SDL_MixAudio</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN7107"
></A
><H2
>Name</H2
>SDL_MixAudio&nbsp;--&nbsp;Mix audio data</DIV
><DIV
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></A
><H2
>Synopsis</H2
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><P
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><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>void <B
CLASS="FSFUNC"
>SDL_MixAudio</B
></CODE
>(Uint8 *dst, Uint8 *src, Uint32 len, int volume);</CODE
></P
><P
></P
></DIV
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><DIV
CLASS="REFSECT1"
><A
NAME="AEN7117"
></A
><H2
>Description</H2
><P
>This function takes two audio buffers of <TT
CLASS="PARAMETER"
><I
>len</I
></TT
> bytes each
of the playing audio format and mixes them, performing addition, volume
adjustment, and overflow clipping. The <TT
CLASS="PARAMETER"
><I
>volume</I
></TT
> ranges
from 0 to <TT
CLASS="LITERAL"
>SDL_MIX_MAXVOLUME</TT
> and should be set to the maximum
value for full audio volume. Note this does not change hardware volume. This is
provided for convenience -- you can mix your own audio data.</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
>Do not use this function for mixing together more than two streams of sample
data. The output from repeated application of this function may be distorted
by clipping, because there is no accumulator with greater range than the
input (not to mention this being an inefficient way of doing it).
Use mixing functions from SDL_mixer, OpenAL, or write your own mixer instead.</P
></BLOCKQUOTE
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><H2
>See Also</H2
><P
><A
HREF="sdlopenaudio.html"
><TT
CLASS="FUNCTION"
>SDL_OpenAudio</TT
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