Mercurial > sdl-ios-xcode
view docs/html/sdlmaprgba.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_MapRGBA</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_MapRGB" HREF="sdlmaprgb.html"><LINK REL="NEXT" TITLE="SDL_GetRGB" HREF="sdlgetrgb.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="sdlmaprgb.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdlgetrgb.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLMAPRGBA" ></A >SDL_MapRGBA</H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN1687" ></A ><H2 >Name</H2 >SDL_MapRGBA -- Map a RGBA color value to a pixel format.</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN1690" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN1691" ></A ><P ></P ><PRE CLASS="FUNCSYNOPSISINFO" >#include "SDL.h"</PRE ><P ><CODE ><CODE CLASS="FUNCDEF" >Uint32 <B CLASS="FSFUNC" >SDL_MapRGBA</B ></CODE >(SDL_PixelFormat *fmt, Uint8 r, Uint8 g, Uint8 b, Uint8 a);</CODE ></P ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN1697" ></A ><H2 >Description</H2 ><P >Maps the RGBA color value to the specified pixel format and returns the pixel value as a 32-bit int.</P ><P >If the format has a palette (8-bit) the index of the closest matching color in the palette will be returned.</P ><P >If the specified pixel format has no alpha component the alpha value will be ignored (as it will be in formats with a palette).</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN1702" ></A ><H2 >Return Value</H2 ><P >A pixel value best approximating the given RGBA color value for a given pixel format. If the pixel format bpp (color depth) is less than 32-bpp then the unused upper bits of the return value can safely be ignored (e.g., with a 16-bpp format the return value can be assigned to a <SPAN CLASS="TYPE" >Uint16</SPAN >, and similarly a <SPAN CLASS="TYPE" >Uint8</SPAN > for an 8-bpp format).</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN1707" ></A ><H2 >See Also</H2 ><P ><A HREF="sdlgetrgb.html" >SDL_GetRGB</A >, <A HREF="sdlgetrgba.html" >SDL_GetRGBA</A >, <A HREF="sdlmaprgb.html" >SDL_MapRGB</A >, <A HREF="sdlpixelformat.html" >SDL_PixelFormat</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="sdlmaprgb.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="sdlgetrgb.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_MapRGB</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_GetRGB</TD ></TR ></TABLE ></DIV ></BODY ></HTML >