view docs/html/cdrom.html @ 3880:74e828c64315 SDL-1.2

Fixed bug #292 I might be on crack here. It looks like SDL_ConvertMono() in src/audio/SDL_audiocvt.c adds the left and right channels of a stereo stream together, and clamps the new mono channel if it would overflow. Shouldn't it be dividing by 2 to average the two sample points instead of clamping? Otherwise the mono sample point's volume doubles in the conversion. This would also make the conversion faster, as it replaces two branches per sample frame with a bitwise shift. --ryan.
author Sam Lantinga <slouken@libsdl.org>
date Sun, 24 Sep 2006 15:45:37 +0000
parents 355632dca928
children
line wrap: on
line source

<HTML
><HEAD
><TITLE
>CD-ROM</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="SDL Reference"
HREF="reference.html"><LINK
REL="PREVIOUS"
TITLE="SDL_CloseAudio"
HREF="sdlcloseaudio.html"><LINK
REL="NEXT"
TITLE="SDL_CDNumDrives"
HREF="sdlcdnumdrives.html"><META
NAME="KEYWORD"
CONTENT="cdrom"><META
NAME="KEYWORD"
CONTENT="function"></HEAD
><BODY
CLASS="CHAPTER"
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="sdlcloseaudio.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
></TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="sdlcdnumdrives.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="CHAPTER"
><H1
><A
NAME="CDROM"
></A
>Chapter 11. CD-ROM</H1
><DIV
CLASS="TOC"
><DL
><DT
><B
>Table of Contents</B
></DT
><DT
><A
HREF="sdlcdnumdrives.html"
>SDL_CDNumDrives</A
>&nbsp;--&nbsp;Returns the number of CD-ROM drives on the system.</DT
><DT
><A
HREF="sdlcdname.html"
>SDL_CDName</A
>&nbsp;--&nbsp;Returns a human-readable, system-dependent identifier for the CD-ROM.</DT
><DT
><A
HREF="sdlcdopen.html"
>SDL_CDOpen</A
>&nbsp;--&nbsp;Opens a CD-ROM drive for access.</DT
><DT
><A
HREF="sdlcdstatus.html"
>SDL_CDStatus</A
>&nbsp;--&nbsp;Returns the current status of the given drive.</DT
><DT
><A
HREF="sdlcdplay.html"
>SDL_CDPlay</A
>&nbsp;--&nbsp;Play a CD</DT
><DT
><A
HREF="sdlcdplaytracks.html"
>SDL_CDPlayTracks</A
>&nbsp;--&nbsp;Play the given CD track(s)</DT
><DT
><A
HREF="sdlcdpause.html"
>SDL_CDPause</A
>&nbsp;--&nbsp;Pauses a CDROM</DT
><DT
><A
HREF="sdlcdresume.html"
>SDL_CDResume</A
>&nbsp;--&nbsp;Resumes a CDROM</DT
><DT
><A
HREF="sdlcdstop.html"
>SDL_CDStop</A
>&nbsp;--&nbsp;Stops a CDROM</DT
><DT
><A
HREF="sdlcdeject.html"
>SDL_CDEject</A
>&nbsp;--&nbsp;Ejects a CDROM</DT
><DT
><A
HREF="sdlcdclose.html"
>SDL_CDClose</A
>&nbsp;--&nbsp;Closes a SDL_CD handle</DT
><DT
><A
HREF="sdlcd.html"
>SDL_CD</A
>&nbsp;--&nbsp;CDROM Drive Information</DT
><DT
><A
HREF="sdlcdtrack.html"
>SDL_CDtrack</A
>&nbsp;--&nbsp;CD Track Information Structure</DT
></DL
></DIV
><P
>SDL supports audio control of up to 32 local CD-ROM drives at once.</P
><P
>You use this API to perform all the basic functions of a CD player,
including listing the tracks, playing, stopping, and ejecting the CD-ROM.
(Currently, multi-changer CD drives are not supported.)</P
><P
>Before you call any of the SDL CD-ROM functions, you must first call
"<TT
CLASS="FUNCTION"
>SDL_Init(SDL_INIT_CDROM)</TT
>", which scans the system for
CD-ROM drives, and sets the program up for audio control.  Check the 
return code, which should be <SPAN
CLASS="RETURNVALUE"
>0</SPAN
>, to see if there 
were any errors in starting up.</P
><P
>After you have initialized the library, you can find out how many drives
are available using the <TT
CLASS="FUNCTION"
>SDL_CDNumDrives()</TT
> function.  
The first drive listed is the system default CD-ROM drive.  After you have 
chosen a drive, and have opened it with <TT
CLASS="FUNCTION"
>SDL_CDOpen()</TT
>, 
you can check the status and start playing if there's a CD in the drive.</P
><P
>A CD-ROM is organized into one or more tracks, each consisting of a certain
number of "frames".  Each frame is ~2K in size, and at normal playing speed,
a CD plays 75 frames per second.  SDL works with the number of frames on a
CD, but this can easily be converted to the more familiar minutes/seconds
format by using the <TT
CLASS="FUNCTION"
>FRAMES_TO_MSF()</TT
> macro.</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="sdlcloseaudio.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="sdlcdnumdrives.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>SDL_CloseAudio</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="reference.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>SDL_CDNumDrives</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>