view docs/html/sdlbuildaudiocvt.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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>SDL_BuildAudioCVT</A
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><H2
>Name</H2
>SDL_BuildAudioCVT&nbsp;--&nbsp;Initializes a SDL_AudioCVT structure for conversion</DIV
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>Synopsis</H2
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><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int <B
CLASS="FSFUNC"
>SDL_BuildAudioCVT</B
></CODE
>(SDL_AudioCVT *cvt, Uint16 src_format, Uint8 src_channels, int src_rate, Uint16 dst_format, Uint8 dst_channels, int dst_rate);</CODE
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><H2
>Description</H2
><P
>Before an <A
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><SPAN
CLASS="STRUCTNAME"
>SDL_AudioCVT</SPAN
></A
> structure can be used to convert audio data it must be initialized with source and destination information. </P
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><TT
CLASS="PARAMETER"
><I
>src_format</I
></TT
> and <TT
CLASS="PARAMETER"
><I
>dst_format</I
></TT
> are the source and destination format of the conversion. (For information on audio formats see <A
HREF="sdlaudiospec.html"
><SPAN
CLASS="STRUCTNAME"
> SDL_AudioSpec</SPAN
></A
>). <TT
CLASS="PARAMETER"
><I
>src_channels</I
></TT
> and <TT
CLASS="PARAMETER"
><I
>dst_channels</I
></TT
> are the number of channels in the source and destination formats. Finally, <TT
CLASS="PARAMETER"
><I
>src_rate</I
></TT
> and <TT
CLASS="PARAMETER"
><I
>dst_rate</I
></TT
> are the frequency or samples-per-second of the source and destination formats. Once again, see <A
HREF="sdlaudiospec.html"
><SPAN
CLASS="STRUCTNAME"
>SDL_AudioSpec</SPAN
></A
>.</P
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><H2
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>Returns <SPAN
CLASS="RETURNVALUE"
>-1</SPAN
> if the filter could not be built or 1 if it could.</P
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>See <A
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>SDL_ConvertAudio</TT
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>SDL_ConvertAudio</TT
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>SDL_AudioCVT</TT
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