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Date: 10 Jun 2003 15:30:59 -0400 From: Mike Shal Subject: [SDL] Bug in SDL_wave.c? Hey everyone, I'm not sure if this is a bug in SDL, or if I just have incorrect WAV files. The problem I'm having is loading multiple concatenated WAVs from SDL_LoadWAV_RW. Some WAV files put comments at the end of the file (which may be bad form), and SDL doesn't skip past them when reading from the RWops. So the next WAV I try to load will start at the comment section of the previous WAV, which obviously doesn't work. If anyone else is having this problem, one quick fix you can do is run sox on the bad WAVs, which strips out all of the comment sections. Eg: $ sox sound.wav tmp.wav $ mv -f tmp.wav sound.wav The other fix is to patch SDL_wave.c, which is included with this email. (Assuming I made the patch correctly :). All it does is calculate how much remaining space there is in the WAV file after the data chunk, and does SDL_RWseek to skip it. I don't think it should interfere with anything else, but if someone could check it that would be nice :). If the bug is really with SDL and not with my WAVs, can someone work this into the next version of SDL? Thanks, -Mike Shal
author Sam Lantinga <slouken@libsdl.org>
date Tue, 24 Jan 2006 07:20:18 +0000
parents 355632dca928
children
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<HTML
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><TITLE
>SDL_AddTimer</TITLE
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><H1
><A
NAME="SDLADDTIMER"
></A
>SDL_AddTimer</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN8482"
></A
><H2
>Name</H2
>SDL_AddTimer&nbsp;--&nbsp;Add a timer which will call a callback after the specified number of milliseconds has
elapsed.</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN8485"
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><A
NAME="AEN8486"
></A
><P
></P
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>SDL_TimerID <B
CLASS="FSFUNC"
>SDL_AddTimer</B
></CODE
>(Uint32 interval, SDL_NewTimerCallback callback, void *param);</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="SDLNEWTIMERCALLBACK"
></A
><H2
>Callback</H2
><PRE
CLASS="PROGRAMLISTING"
>/* type definition for the "new" timer callback function */
typedef Uint32 (*SDL_NewTimerCallback)(Uint32 interval, void *param);</PRE
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8495"
></A
><H2
>Description</H2
><P
>Adds a callback function to be run after the specified number of
milliseconds has elapsed. The callback function is passed the current
timer interval and the user supplied parameter from the
<TT
CLASS="FUNCTION"
>SDL_AddTimer</TT
> call and returns the next timer
interval. If the returned value from the callback is the same as the one
passed in, the periodic alarm continues, otherwise a new alarm is
scheduled.</P
><P
>To cancel a currently running timer call
<A
HREF="sdlremovetimer.html"
>SDL_RemoveTimer</A
> with the
timer ID returned from
<TT
CLASS="FUNCTION"
>SDL_AddTimer</TT
>.</P
><P
>The timer callback function may run in a different thread than your
main program, and so shouldn't call any functions from within itself.
You may always call <A
HREF="sdlpushevent.html"
>SDL_PushEvent</A
>, however.</P
><P
>The granularity of the timer is platform-dependent, but you should count
on it being at least 10 ms as this is the most common number.
This means that if
you request a 16 ms timer, your callback will run approximately 20 ms
later on an unloaded system.  If you wanted to set a flag signaling
a frame update at 30 frames per second (every 33 ms), you might set a
timer for 30 ms (see example below).

If you use this function, you need to pass <TT
CLASS="LITERAL"
>SDL_INIT_TIMER</TT
>
to <A
HREF="sdlinit.html"
>SDL_Init</A
>.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8507"
></A
><H2
>Return Value</H2
><P
>Returns an ID value for the added timer or
<SPAN
CLASS="RETURNVALUE"
>NULL</SPAN
> if there was an error.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8511"
></A
><H2
>Examples</H2
><P
><PRE
CLASS="PROGRAMLISTING"
>my_timer_id = SDL_AddTimer((33/10)*10, my_callbackfunc, my_callback_param);</PRE
></P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8515"
></A
><H2
>See Also</H2
><P
><A
HREF="sdlremovetimer.html"
><TT
CLASS="FUNCTION"
>SDL_RemoveTimer</TT
></A
>,
<A
HREF="sdlpushevent.html"
><TT
CLASS="FUNCTION"
>SDL_PushEvent</TT
></A
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