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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><H1
><A
NAME="SDLLOADWAV"
>SDL_LoadWAV</A
></H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN6428"
></A
><H2
>Name</H2
>SDL_LoadWAV&nbsp;--&nbsp;Load a WAVE file</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN6431"
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><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
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><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
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></DIV
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><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
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><H2
>Example</H2
><PRE
CLASS="PROGRAMLISTING"
>SDL_AudioSpec wav_spec;
Uint32 wav_length;
Uint8 *wav_buffer;

/* Load the WAV */
if( SDL_LoadWAV("test.wav", &#38;wav_spec, &#38;wav_buffer, &#38;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
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>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
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