Mercurial > sdl-ios-xcode
view docs/html/sdlconvertaudio.html @ 1643:51038e80ae59
More general fix for bug #189
The clipping is done at a higher level, and the low level functions are
passed clipped rectangles. Drivers which don't support source clipping
have not been changed, so the image will be squished instead of clipped,
but at least they will no longer crash when the destination rect was out
of bounds.
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Mon, 17 Apr 2006 06:47:23 +0000 |
parents | 355632dca928 |
children |
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<HTML ><HEAD ><TITLE >SDL_ConvertAudio</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="Audio" HREF="audio.html"><LINK REL="PREVIOUS" TITLE="SDL_BuildAudioCVT" HREF="sdlbuildaudiocvt.html"><LINK REL="NEXT" TITLE="SDL_MixAudio" HREF="sdlmixaudio.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="sdlbuildaudiocvt.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdlmixaudio.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLCONVERTAUDIO" ></A >SDL_ConvertAudio</H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN7048" ></A ><H2 >Name</H2 >SDL_ConvertAudio -- Convert audio data to a desired audio format.</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN7051" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN7052" ></A ><P ></P ><PRE CLASS="FUNCSYNOPSISINFO" >#include "SDL.h"</PRE ><P ><CODE ><CODE CLASS="FUNCDEF" >int <B CLASS="FSFUNC" >SDL_ConvertAudio</B ></CODE >(SDL_AudioCVT *cvt);</CODE ></P ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN7058" ></A ><H2 >Description</H2 ><P ><TT CLASS="FUNCTION" >SDL_ConvertAudio</TT > takes one parameter, <TT CLASS="PARAMETER" ><I >cvt</I ></TT >, which was previously initilized. Initilizing a <A HREF="sdlaudiocvt.html" ><SPAN CLASS="STRUCTNAME" >SDL_AudioCVT</SPAN ></A > is a two step process. First of all, the structure must be passed to <A HREF="sdlbuildaudiocvt.html" ><TT CLASS="FUNCTION" >SDL_BuildAudioCVT</TT ></A > along with source and destination format parameters. Secondly, the <SPAN CLASS="STRUCTNAME" >cvt</SPAN >-><TT CLASS="STRUCTFIELD" ><I >buf</I ></TT > and <SPAN CLASS="STRUCTNAME" >cvt</SPAN >-><TT CLASS="STRUCTFIELD" ><I >len</I ></TT > fields must be setup. <SPAN CLASS="STRUCTNAME" >cvt</SPAN >-><TT CLASS="STRUCTFIELD" ><I >buf</I ></TT > should point to the audio data and <SPAN CLASS="STRUCTNAME" >cvt</SPAN >-><TT CLASS="STRUCTFIELD" ><I >len</I ></TT > should be set to the length of the audio data in bytes. Remember, the length of the buffer pointed to by <TT CLASS="STRUCTFIELD" ><I >buf</I ></TT > show be <TT CLASS="STRUCTFIELD" ><I >len</I ></TT >*<TT CLASS="STRUCTFIELD" ><I >len_mult</I ></TT > bytes in length.</P ><P >Once the <SPAN CLASS="STRUCTNAME" >SDL_AudioCVT</SPAN >structure is initilized then we can pass it to <TT CLASS="FUNCTION" >SDL_ConvertAudio</TT >, which will convert the audio data pointer to by <SPAN CLASS="STRUCTNAME" >cvt</SPAN >-><TT CLASS="STRUCTFIELD" ><I >buf</I ></TT >. If <TT CLASS="FUNCTION" >SDL_ConvertAudio</TT > returned <SPAN CLASS="RETURNVALUE" >0</SPAN > then the conversion was completed successfully, otherwise <SPAN CLASS="RETURNVALUE" >-1</SPAN > is returned.</P ><P >If the conversion completed successfully then the converted audio data can be read from <SPAN CLASS="STRUCTNAME" >cvt</SPAN >-><TT CLASS="STRUCTFIELD" ><I >buf</I ></TT >. The amount of valid, converted, audio data in the buffer is equal to <SPAN CLASS="STRUCTNAME" >cvt</SPAN >-><TT CLASS="STRUCTFIELD" ><I >len</I ></TT >*<TT CLASS="STRUCTFIELD" ><I >cvt</I ></TT >-><SPAN CLASS="STRUCTNAME" >len_ratio</SPAN >.</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN7093" ></A ><H2 >Examples</H2 ><PRE CLASS="PROGRAMLISTING" >/* Converting some WAV data to hardware format */ void my_audio_callback(void *userdata, Uint8 *stream, int len); SDL_AudioSpec *desired, *obtained; SDL_AudioSpec wav_spec; SDL_AudioCVT wav_cvt; Uint32 wav_len; Uint8 *wav_buf; int ret; /* Allocated audio specs */ desired = malloc(sizeof(SDL_AudioSpec)); obtained = malloc(sizeof(SDL_AudioSpec)); /* Set desired format */ desired->freq=22050; desired->format=AUDIO_S16LSB; desired->samples=8192; desired->callback=my_audio_callback; desired->userdata=NULL; /* Open the audio device */ if ( SDL_OpenAudio(desired, obtained) < 0 ){ fprintf(stderr, "Couldn't open audio: %s\n", SDL_GetError()); exit(-1); } free(desired); /* Load the test.wav */ if( SDL_LoadWAV("test.wav", &wav_spec, &wav_buf, &wav_len) == NULL ){ fprintf(stderr, "Could not open test.wav: %s\n", SDL_GetError()); SDL_CloseAudio(); free(obtained); exit(-1); } /* Build AudioCVT */ ret = SDL_BuildAudioCVT(&wav_cvt, wav_spec.format, wav_spec.channels, wav_spec.freq, obtained->format, obtained->channels, obtained->freq); /* Check that the convert was built */ if(ret==-1){ fprintf(stderr, "Couldn't build converter!\n"); SDL_CloseAudio(); free(obtained); SDL_FreeWAV(wav_buf); } /* Setup for conversion */ wav_cvt.buf = malloc(wav_len * wav_cvt.len_mult); wav_cvt.len = wav_len; memcpy(wav_cvt.buf, wav_buf, wav_len); /* We can delete to original WAV data now */ SDL_FreeWAV(wav_buf); /* And now we're ready to convert */ SDL_ConvertAudio(&wav_cvt); /* do whatever */ . . . . </PRE ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN7096" ></A ><H2 >See Also</H2 ><P ><A HREF="sdlbuildaudiocvt.html" ><TT CLASS="FUNCTION" >SDL_BuildAudioCVT</TT ></A >, <A HREF="sdlaudiocvt.html" ><TT CLASS="FUNCTION" >SDL_AudioCVT</TT ></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="sdlbuildaudiocvt.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="sdlmixaudio.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_BuildAudioCVT</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="audio.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SDL_MixAudio</TD ></TR ></TABLE ></DIV ></BODY ></HTML >