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Recommendation from Lennart Poettering: In ALSA_OpenAudio(): instead of setting period_size+n_periods OR buffer_size I'd recommend copying the hwparams stuff before you do this, then first try period_size+n_periods, and then apply it with snd_pcm_hw_params() and check if that works. If it didn't you should take the copy of hwparams and try setting buffer_size and apply that via snd_pcm_hw_params() and check if that worked. And if that failed too, then take the copy and don't apply neither period nor buffer settings and see if that works.
author Sam Lantinga <slouken@libsdl.org>
date Mon, 19 Oct 2009 02:23:21 +0000
parents 355632dca928
children
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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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><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
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></DIV
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><DIV
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><A
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><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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>See Also</H2
><P
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><TT
CLASS="FUNCTION"
>SDL_OpenAudio</TT
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