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view docs/html/sdlbuildaudiocvt.html @ 773:da0a2ad35bf4
Date: Sun, 4 Jan 2004 23:48:19 +0100
From: Max Horn
Subject: Re: Again Audio CD patch
Am 04.01.2004 um 22:38 schrieb Sam Lantinga:
>
> Okay, I fixed the buffering problems by simply using a 4 second buffer
> instead of a 1 second buffer. However, using your code I can't play an
> entire CD - the playback stops after the first song.
>
Found the problem: FSReadFork returns eofErr when the file is finished.
However, we check its return value for errors, and if anything but
noErr occurs, the reader thread aborts its current iteration. That is
bad, because it aborts before it can ever set the flag which tells that
the file is over (also, any remaining data which FSRead did return is
lost - so you'd not hear about to 4 seconds from the end of the file.
Furthermore, the computed data size was 8 bytes to high (I forgot to
account for the fact that the size of an (A)IFF chunk always contains
the chunk header & size fields, too). This is enough to make it work.
However, the end condition is rather fragile, so I tuned some other
things to be pessimistic (check for <= 0 instead of == 0, when eofErr
is encountered enforce mReadFilePosition == mFileLength). You never
know...
The attached patch fixes the issue for me.
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Mon, 05 Jan 2004 00:57:51 +0000 |
parents | e5bc29de3f0a |
children | 355632dca928 |
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<HTML ><HEAD ><TITLE >SDL_BuildAudioCVT</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_AudioCVT" HREF="sdlaudiocvt.html"><LINK REL="NEXT" TITLE="SDL_ConvertAudio" HREF="sdlconvertaudio.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="sdlaudiocvt.html" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdlconvertaudio.html" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLBUILDAUDIOCVT" >SDL_BuildAudioCVT</A ></H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN6614" ></A ><H2 >Name</H2 >SDL_BuildAudioCVT -- Initializes a SDL_AudioCVT structure for conversion</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN6617" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN6618" ></A ><P ></P ><PRE CLASS="FUNCSYNOPSISINFO" >#include "SDL.h"</PRE ><P ><CODE ><CODE CLASS="FUNCDEF" >int <B CLASS="FSFUNC" >SDL_BuildAudioCVT</B ></CODE >(SDL_AudioCVT *cvt, Uint16 src_format, Uint8 src_channels, int src_rate, Uint16 dst_format, Uint8 dst_channels, int dst_rate);</CODE ></P ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN6624" ></A ><H2 >Description</H2 ><P >Before an <A HREF="sdlaudiocvt.html" ><SPAN CLASS="STRUCTNAME" >SDL_AudioCVT</SPAN ></A > structure can be used to convert audio data it must be initialized with source and destination information. </P ><P ><TT CLASS="PARAMETER" ><I >src_format</I ></TT > and <TT CLASS="PARAMETER" ><I >dst_format</I ></TT > are the source and destination format of the conversion. (For information on audio formats see <A HREF="sdlaudiospec.html" ><SPAN CLASS="STRUCTNAME" > SDL_AudioSpec</SPAN ></A >). <TT CLASS="PARAMETER" ><I >src_channels</I ></TT > and <TT CLASS="PARAMETER" ><I >dst_channels</I ></TT > are the number of channels in the source and destination formats. Finally, <TT CLASS="PARAMETER" ><I >src_rate</I ></TT > and <TT CLASS="PARAMETER" ><I >dst_rate</I ></TT > are the frequency or samples-per-second of the source and destination formats. Once again, see <A HREF="sdlaudiospec.html" ><SPAN CLASS="STRUCTNAME" >SDL_AudioSpec</SPAN ></A >.</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN6640" ></A ><H2 >Return Values</H2 ><P >Returns <SPAN CLASS="RETURNVALUE" >-1</SPAN > if the filter could not be built or 1 if it could.</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN6644" ></A ><H2 >Examples</H2 ><P >See <A HREF="sdlconvertaudio.html" ><TT CLASS="FUNCTION" >SDL_ConvertAudio</TT ></A >.</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN6649" ></A ><H2 >See Also</H2 ><P ><A HREF="sdlconvertaudio.html" ><TT CLASS="FUNCTION" >SDL_ConvertAudio</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="sdlaudiocvt.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="sdlconvertaudio.html" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_AudioCVT</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="audio.html" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SDL_ConvertAudio</TD ></TR ></TABLE ></DIV ></BODY ></HTML >