Mercurial > sdl-ios-xcode
view docs/html/sdlconvertsurface.html @ 3880:74e828c64315 SDL-1.2
Fixed bug #292
I might be on crack here.
It looks like SDL_ConvertMono() in src/audio/SDL_audiocvt.c adds the left and
right channels of a stereo stream together, and clamps the new mono channel if
it would overflow.
Shouldn't it be dividing by 2 to average the two sample points instead of
clamping? Otherwise the mono sample point's volume doubles in the conversion.
This would also make the conversion faster, as it replaces two branches per
sample frame with a bitwise shift.
--ryan.
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Sun, 24 Sep 2006 15:45:37 +0000 |
parents | 355632dca928 |
children |
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<HTML ><HEAD ><TITLE >SDL_ConvertSurface</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ "><LINK REL="HOME" TITLE="SDL Library Documentation" HREF="index.html"><LINK REL="UP" TITLE="Video" HREF="video.html"><LINK REL="PREVIOUS" TITLE="SDL_GetClipRect" HREF="sdlgetcliprect.html"><LINK REL="NEXT" TITLE="SDL_BlitSurface" HREF="sdlblitsurface.html"></HEAD ><BODY CLASS="REFENTRY" BGCOLOR="#FFF8DC" TEXT="#000000" LINK="#0000ee" VLINK="#551a8b" ALINK="#ff0000" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >SDL Library Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="sdlgetcliprect.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdlblitsurface.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLCONVERTSURFACE" ></A >SDL_ConvertSurface</H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN2258" ></A ><H2 >Name</H2 >SDL_ConvertSurface -- Converts a surface to the same format as another surface.</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN2261" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN2262" ></A ><P ></P ><PRE CLASS="FUNCSYNOPSISINFO" >#include "SDL/SDL.h"</PRE ><P ><CODE ><CODE CLASS="FUNCDEF" >SDL_Surface *<B CLASS="FSFUNC" >SDL_ConvertSurface</B ></CODE >(SDL_Surface *src, SDL_PixelFormat *fmt, Uint32 flags);</CODE ></P ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN2268" ></A ><H2 >Description</H2 ><P >Creates a new surface of the specified format, and then copies and maps the given surface to it. If this function fails, it returns <TT CLASS="LITERAL" >NULL</TT >.</P ><P >The <TT CLASS="PARAMETER" ><I >flags</I ></TT > parameter is passed to <A HREF="sdlcreatergbsurface.html" ><TT CLASS="FUNCTION" >SDL_CreateRGBSurface</TT ></A > and has those semantics.</P ><P >This function is used internally by <A HREF="sdldisplayformat.html" ><TT CLASS="FUNCTION" >SDL_DisplayFormat</TT ></A >.</P ><P >This function can only be called after SDL_Init.</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN2280" ></A ><H2 >Return Value</H2 ><P >Returns either a pointer to the new surface, or <TT CLASS="LITERAL" >NULL</TT > on error.</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN2284" ></A ><H2 >See Also</H2 ><P ><A HREF="sdlcreatergbsurface.html" ><TT CLASS="FUNCTION" >SDL_CreateRGBSurface</TT ></A >, <A HREF="sdldisplayformat.html" ><TT CLASS="FUNCTION" >SDL_DisplayFormat</TT ></A >, <A HREF="sdlpixelformat.html" ><SPAN CLASS="STRUCTNAME" >SDL_PixelFormat</SPAN ></A >, <A HREF="sdlsurface.html" ><SPAN CLASS="STRUCTNAME" >SDL_Surface</SPAN ></A ></P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="sdlgetcliprect.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="sdlblitsurface.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_GetClipRect</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="video.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SDL_BlitSurface</TD ></TR ></TABLE ></DIV ></BODY ></HTML >