Mercurial > sdl-ios-xcode
diff docs/html/sdlconvertaudio.html @ 0:74212992fb08
Initial revision
| author | Sam Lantinga <slouken@lokigames.com> |
|---|---|
| date | Thu, 26 Apr 2001 16:45:43 +0000 |
| parents | |
| children | 55f1f1b3e27d |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/docs/html/sdlconvertaudio.html Thu Apr 26 16:45:43 2001 +0000 @@ -0,0 +1,399 @@ +<HTML +><HEAD +><TITLE +>SDL_ConvertAudio</TITLE +><META +NAME="GENERATOR" +CONTENT="Modular DocBook HTML Stylesheet Version 1.61 +"><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 +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" +>Prev</A +></TD +><TD +WIDTH="80%" +ALIGN="center" +VALIGN="bottom" +></TD +><TD +WIDTH="10%" +ALIGN="right" +VALIGN="bottom" +><A +HREF="sdlmixaudio.html" +>Next</A +></TD +></TR +></TABLE +><HR +ALIGN="LEFT" +WIDTH="100%"></DIV +><H1 +><A +NAME="SDLCONVERTAUDIO" +>SDL_ConvertAudio</A +></H1 +><DIV +CLASS="REFNAMEDIV" +><A +NAME="AEN6426" +></A +><H2 +>Name</H2 +>SDL_ConvertAudio -- Convert audio data to a desired audio format.</DIV +><DIV +CLASS="REFSYNOPSISDIV" +><A +NAME="AEN6429" +></A +><H2 +>Synopsis</H2 +><DIV +CLASS="FUNCSYNOPSIS" +><A +NAME="AEN6430" +></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="AEN6436" +></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="AEN6471" +></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=(SDL_AudioSpec *)malloc(sizeof(SDL_AudioSpec)); +obtained=(SDL_AudioSpec *)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=(Uint8 *)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="AEN6474" +></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 +WIDTH="100%" +BORDER="0" +CELLPADDING="0" +CELLSPACING="0" +><TR +><TD +WIDTH="33%" +ALIGN="left" +VALIGN="top" +><A +HREF="sdlbuildaudiocvt.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="sdlmixaudio.html" +>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" +>Up</A +></TD +><TD +WIDTH="33%" +ALIGN="right" +VALIGN="top" +>SDL_MixAudio</TD +></TR +></TABLE +></DIV +></BODY +></HTML +> \ No newline at end of file