Mercurial > sdl-ios-xcode

view docs/html/sdlaudiocvt.html @ 790:d39b74b8583c

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Date: Wed, 28 Jan 2004 20:25:54 +0100 From: Thomas Jarosch Subject: Re: [SDL] DSPF_RBG15 in src/video/directfb/SDL_DirectFB_video.c In my local DirectFB 0.1.19 copy, DSPF_RGB15 is an alias for DSPF_ARGB1555. They seem to have it removed in DirectFB CVS. As DSPF_RGB15 was only an alias, the attached patch can safely be applied to SDL and won't brake older DirectFB versions.
author Sam Lantinga <slouken@libsdl.org>
date Wed, 28 Jan 2004 22:01:02 +0000
parents e5bc29de3f0a
children 355632dca928
line wrap: on
line source

<HTML
><HEAD
><TITLE
>SDL_AudioCVT</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.64
"><LINK
REL="HOME"
TITLE="SDL Library Documentation"
HREF="index.html"><LINK
REL="UP"
TITLE="Audio"
HREF="audio.html"><LINK
REL="PREVIOUS"
TITLE="SDL_FreeWAV"
HREF="sdlfreewav.html"><LINK
REL="NEXT"
TITLE="SDL_BuildAudioCVT"
HREF="sdlbuildaudiocvt.html"></HEAD
><BODY
CLASS="REFENTRY"
BGCOLOR="#FFF8DC"
TEXT="#000000"
LINK="#0000ee"
VLINK="#551a8b"
ALINK="#ff0000"
><DIV
CLASS="NAVHEADER"
><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="sdlfreewav.html"
>Prev</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
></TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="sdlbuildaudiocvt.html"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><H1
><A
NAME="SDLAUDIOCVT"
>SDL_AudioCVT</A
></H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN6496"
></A
><H2
>Name</H2
>SDL_AudioCVT&nbsp;--&nbsp;Audio Conversion Structure</DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN6499"
></A
><H2
>Structure Definition</H2
><PRE
CLASS="PROGRAMLISTING"
>typedef struct{
  int needed;
  Uint16 src_format;
  Uint16 dest_format;
  double rate_incr;
  Uint8 *buf;
  int len;
  int len_cvt;
  int len_mult;
  double len_ratio;
  void (*filters[10])(struct SDL_AudioCVT *cvt, Uint16 format);
  int filter_index;
} SDL_AudioCVT;</PRE
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN6502"
></A
><H2
>Structure Data</H2
><DIV
CLASS="INFORMALTABLE"
><A
NAME="AEN6504"
></A
><P
></P
><TABLE
BORDER="0"
CLASS="CALSTABLE"
><TBODY
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>needed</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Set to one if the conversion is possible</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>src_format</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Audio format of the source</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>dest_format</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Audio format of the destination</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>rate_incr</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Rate conversion increment</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>buf</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Audio buffer</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>len</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Length of the original audio buffer in bytes</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>len_cvt</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Length of converted audio buffer in bytes (calculated)</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>len_mult</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>buf</I
></TT
> must be <TT
CLASS="STRUCTFIELD"
><I
>len</I
></TT
>*<TT
CLASS="STRUCTFIELD"
><I
>len_mult</I
></TT
> bytes in size(calculated)</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>len_ratio</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Final audio size is <TT
CLASS="STRUCTFIELD"
><I
>len</I
></TT
>*<TT
CLASS="STRUCTFIELD"
><I
>len_ratio</I
></TT
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>filters[10](..)</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Pointers to functions needed for this conversion</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>filter_index</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Current conversion function</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN6556"
></A
><H2
>Description</H2
><P
>The <SPAN
CLASS="STRUCTNAME"
>SDL_AudioCVT</SPAN
> is used to convert audio data between different formats. A <SPAN
CLASS="STRUCTNAME"
>SDL_AudioCVT</SPAN
> structure is created with the <A
HREF="sdlbuildaudiocvt.html"
><TT
CLASS="FUNCTION"
>SDL_BuildAudioCVT</TT
></A
> function, while the actual conversion is done by the <A
HREF="sdlconvertaudio.html"
><TT
CLASS="FUNCTION"
>SDL_ConvertAudio</TT
></A
> function.</P
><P
>Many of the fields in the <SPAN
CLASS="STRUCTNAME"
>SDL_AudioCVT</SPAN
> structure should be considered private and their function will not be discussed here.</P
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><SPAN
CLASS="TYPE"
>Uint8 *</SPAN
><TT
CLASS="STRUCTFIELD"
><I
>buf</I
></TT
></DT
><DD
><P
>This points to the audio data that will be used in the conversion. It is both the source and the destination, which means the converted audio data overwrites the original data. It also means that the converted data may be larger than the original data (if you were converting from 8-bit to 16-bit, for instance), so you must ensure <TT
CLASS="STRUCTFIELD"
><I
>buf</I
></TT
> is large enough. See below.</P
></DD
><DT
><SPAN
CLASS="TYPE"
>int</SPAN
> <TT
CLASS="STRUCTFIELD"
><I
>len</I
></TT
></DT
><DD
><P
>This is the length of the original audio data in bytes.</P
></DD
><DT
><SPAN
CLASS="TYPE"
>int</SPAN
> <TT
CLASS="STRUCTFIELD"
><I
>len_mult</I
></TT
></DT
><DD
><P
>As explained above, the audio buffer needs to be big enough to store the converted data, which may be bigger than the original audio data. The length of <TT
CLASS="STRUCTFIELD"
><I
>buf</I
></TT
> should be <TT
CLASS="STRUCTFIELD"
><I
>len</I
></TT
>*<TT
CLASS="STRUCTFIELD"
><I
>len_mult</I
></TT
>.</P
></DD
><DT
><SPAN
CLASS="TYPE"
>double</SPAN
> <TT
CLASS="STRUCTFIELD"
><I
>len_ratio</I
></TT
></DT
><DD
><P
>When you have finished converting your audio data, you need to know how much of your audio buffer is valid. <TT
CLASS="STRUCTFIELD"
><I
>len</I
></TT
>*<TT
CLASS="STRUCTFIELD"
><I
>len_ratio</I
></TT
> is the size of the converted audio data in bytes. This is very similar to <TT
CLASS="STRUCTFIELD"
><I
>len_mult</I
></TT
>, however when the convert audio data is shorter than the original <TT
CLASS="STRUCTFIELD"
><I
>len_mult</I
></TT
> would be 1. <TT
CLASS="STRUCTFIELD"
><I
>len_ratio</I
></TT
>, on the other hand, would be a fractional number between 0 and 1.</P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN6601"
></A
><H2
>See Also</H2
><P
><A
HREF="sdlbuildaudiocvt.html"
><TT
CLASS="FUNCTION"
>SDL_BuildAudioCVT</TT
></A
>,
<A
HREF="sdlconvertaudio.html"
><TT
CLASS="FUNCTION"
>SDL_ConvertAudio</TT
></A
>,
<A
HREF="sdlaudiospec.html"
><SPAN
CLASS="STRUCTNAME"
>SDL_AudioSpec</SPAN
></A
></P
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="sdlfreewav.html"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="sdlbuildaudiocvt.html"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>SDL_FreeWAV</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="audio.html"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>SDL_BuildAudioCVT</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>