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Date: Mon, 11 Oct 2004 15:17:27 +0300 (EEST) From: Hannu Savolainen Subject: Re: SDL uses obsolete OSS features I did some work on getting OSS to work better with SDL. There have been some problems with select which should be fixed now. I'm having some problems in understanding what is the purpose of the DSP_WaitAudio() routine. I added a return to the very beginning of this routine and commendted out the define for USE_BLOCKING_WRITES. At least lbreakout2 seems to work as well as earlier. The latencies are the same. An ordinary blocking write does exactly the same thing than DSP_WaitAudio does. So I would recommend using the USE_BLOCKING_WRITES approach and removing everything from the DSP_WaitAudio routine. Also enabling USE_BLOCKING_WRITES makes it possible to simplify DSP_PlayAudio() because you don't need to handle the partial writes (the do-while loop). Attached is a patch against SDL-1.2.7. After these changes SDL will use OSS as it's designed to be used (make it as simple as possible). This code should work with all OSS implementations because it uses only the very fundamental features that have been there since the jurassic times.
author Sam Lantinga <slouken@libsdl.org>
date Fri, 12 Nov 2004 21:39:04 +0000
parents 355632dca928
children
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<HTML
><HEAD
><TITLE
>SDL_CDPlayTracks</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
"><LINK
REL="HOME"
TITLE="SDL Library Documentation"
HREF="index.html"><LINK
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TITLE="CD-ROM"
HREF="cdrom.html"><LINK
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TITLE="SDL_CDPlay"
HREF="sdlcdplay.html"><LINK
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><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><H1
><A
NAME="SDLCDPLAYTRACKS"
></A
>SDL_CDPlayTracks</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN7375"
></A
><H2
>Name</H2
>SDL_CDPlayTracks&nbsp;--&nbsp;Play the given CD track(s)</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN7378"
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><A
NAME="AEN7379"
></A
><P
></P
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int <B
CLASS="FSFUNC"
>SDL_CDPlayTracks</B
></CODE
>(SDL_CD *cdrom, int start_track, int start_frame, int ntracks, int nframes));</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN7385"
></A
><H2
>Description</H2
><P
><TT
CLASS="FUNCTION"
>SDL_CDPlayTracks</TT
> plays the given CD starting at track
<TT
CLASS="PARAMETER"
><I
>start_track</I
></TT
>, for <TT
CLASS="PARAMETER"
><I
>ntracks</I
></TT
> tracks.  </P
><P
><TT
CLASS="PARAMETER"
><I
>start_frame</I
></TT
> is the frame offset, from the beginning of the <TT
CLASS="PARAMETER"
><I
>start_track</I
></TT
>, at which to start. <TT
CLASS="PARAMETER"
><I
>nframes</I
></TT
> is the frame offset, from the beginning of the last track (<TT
CLASS="PARAMETER"
><I
>start_track</I
></TT
>+<TT
CLASS="PARAMETER"
><I
>ntracks</I
></TT
>), at which to end playing.</P
><P
><TT
CLASS="FUNCTION"
>SDL_CDPlayTracks</TT
> should only be called after calling 
<A
HREF="sdlcdstatus.html"
><TT
CLASS="FUNCTION"
>SDL_CDStatus</TT
></A
> 
to get track information about the CD.</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
>Data tracks are ignored.</P
></BLOCKQUOTE
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN7403"
></A
><H2
>Return Value</H2
><P
>Returns <SPAN
CLASS="RETURNVALUE"
>0</SPAN
>, or <SPAN
CLASS="RETURNVALUE"
>-1</SPAN
> 
if there was an error.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN7408"
></A
><H2
>Examples</H2
><P
><PRE
CLASS="PROGRAMLISTING"
>/* assuming cdrom is a previously opened device */
/* Play the entire CD */
if(CD_INDRIVE(SDL_CDStatus(cdrom)))
  SDL_CDPlayTracks(cdrom, 0, 0, 0, 0);

/* Play the first track */
if(CD_INDRIVE(SDL_CDStatus(cdrom)))
  SDL_CDPlayTracks(cdrom, 0, 0, 1, 0);

/* Play first 15 seconds of the 2nd track */
if(CD_INDRIVE(SDL_CDStatus(cdrom)))
  SDL_CDPlayTracks(cdrom, 1, 0, 0, CD_FPS*15);</PRE
>
&#13;</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN7412"
></A
><H2
>See Also</H2
><P
><A
HREF="sdlcdplay.html"
><TT
CLASS="FUNCTION"
>SDL_CDPlay</TT
></A
>,
<A
HREF="sdlcdstatus.html"
><TT
CLASS="FUNCTION"
>SDL_CDStatus</TT
></A
>,
<A
HREF="sdlcd.html"
><TT
CLASS="FUNCTION"
>SDL_CD</TT
></A
></P
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