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view docs/html/sdlconvertaudio.html @ 821:30168104389f
Date: Sat, 14 Feb 2004 14:52:40 +0200
From: "Mike Gorchak"
Subject: Batch of the QNX6 fixes for the SDL
1. Updated readme.QNX
2. Fixed crashes during intensive window updating under fast machines (got over 200 rectangles for update).
3. Fixed double-buffered fullscreen modes, now it works as needed.
4. Fixed Photon detection algorithm.
5. Fixed HWSURFACE update function.
6. Added SDL_PHOTON_FULLSCREEN_REFRESH environment variable support for control refresh rates under Photon.
7. Added 640x400 fullscreen mode emulation via 640x480 (if videodriver not supports original 640x400 mode of course) shifted by 40 vertical pixels from begin, to center it. It's needed for some old DOS games which ran in doubled 320x200 mode.
8. Added available video ram amount support.
8. Added hardware surface allocation/deallocation support if current videomode and videodriver supports it.
9. Added hardware filling support.
10. Added hardware blits support (simple and colorkeyed).
And I've added to testvidinfo test color-keyed blits benchmark (maybe need to add alpha blits benchmark too ?). Currently Photon not supporting any alpha hardware blittings (all drivers lack of alpha blitting code support, only software alpha blitting exist in photon, which is hundreds times slowest than the SDL's one). So I've not added the alpha support. I suppose new QNX 6.3 will have the hardware alpha support, so when it will be done, I'll add alpha support.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Sat, 14 Feb 2004 20:22:21 +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 >