view README.MacOSX @ 942:41a59de7f2ed

Here are patches for SDL12 and SDL_mixer for 4 or 6 channel surround sound on Linux using the Alsa driver. To use them, naturally you need a sound card that will do 4 or 6 channels and probably also a recent version of the Alsa drivers and library. Since the only SDL output driver that knows about surround sound is the Alsa driver, you���ll want to choose it, using: export SDL_AUDIODRIVER=alsa There are no syntactic changes to the programming API. No new library calls, no differences in arguments. There are two semantic changes: (1) For library calls with number of channels as an argument, formerly you could use only 1 or 2 for the number of channels. Now you can also use 4 or 6. (2) The two "left" and "right" arguments to Mix_SetPanning, for the case of 4 or 6 channels, no longer simply control the volumes of the left and right channels. Now the "left" argument is converted to an angle and Mix_SetPosition is called, and the "right" argu- ment is ignored. With two exceptions, so far as I know, the modified SDL12 and SDL_mixer work the same way as the original versions, when opened for 1 or 2 channel output. The two exceptions are bugs which I fixed. Well, the first, anyway, is a bug for sure. When rate conversions up or down by a factor of two are applied (in src/audio/SDL_audiocvt.c), streams with different numbers of channels (that is, mono and stereo) are treated the same way: either each sample is copied or every other sample is omitted. This is ok for mono, but for stereo, it is frames that should be copied or omitted, where by "frame" I mean a portion of the stream containing one sample for each channel. (In the SDL source, confusingly, sometimes frames are called "samples".) So for these rate conversions, stereo streams have to be treated differently, and they are, in my modified version. The other problem that might be characterized as a bug arises when SDL_mixer is passed a multichannel chunk which does not have an integral number of frames. Due to the way the effect_position code loops over frames, when the chunk ends with a partial frame, memory outside the chunk buffer will be accessed. In the case of stereo, it���s possible that because malloc may give more memory than requested, this potential problem never actually causes a segment fault. I don���t know. For 6 channel chunks, I do know, and it does cause segment faults. If SDL_mixer is passed defective chunks and this causes a segment fault, arguably, that���s not a bug in SDL_mixer. Still, whether or not it counts as a bug, it���s easy to protect against, so why not? I added code in mixer.c to discard any partial frame at the end of a chunk. Then what about when SDL or SDL_mixer is opened for 4 or 6 chan- nel output? What happens with the parts of the current library designed for stereo? I don���t know whether I���ve covered all the bases, but I���ve tried: (1) For playing 2 channel waves, or other cases where SDL knows it has to match up a 2 channel source with a 4 or 6 channel output, I���ve added code in SDL_audiocvt.c to make the necessary conversions. (2) For playing midis using timidity, I���ve converted timidity to do 4 or 6 channel output, upon request. (3) For playing mods using mikmod, I put ad hoc code in music.c to convert the stereo output that mikmod produces to 4 or 6 chan- nels. Obviously it would be better to change the mikmod code to mix down into 4 or 6 channels, but I have a hard time following the code in mikmod, so I didn���t do that. (4) For playing mp3s, I put ad hoc code in smpeg to copy channels in the case when 4 or 6 channel output is needed. (5) There seems to be no problem with .ogg files - stereo .oggs can be up converted as .wavs are. (6) The effect_position code in SDL_mixer is now generalized to in- clude the cases of 4 and 6 channel streams. I���ve done a very limited amount of compatibility testing for some of the games using SDL I happen to have. For details, see the file TESTS. I���ve put into a separate archive, Surround-SDL-testfiles.tgz, a couple of 6 channel wave files for testing and a 6 channel ogg file. If you have the right hardware and version of Alsa, you should be able to play the wave files with the Alsa utility aplay (and hear all channels, except maybe lfe, for chan-id.wav, since it���s rather faint). Don���t expect aplay to give good sound, though. There���s something wrong with the current version of aplay. The canyon.ogg file is to test loading of 6 channel oggs. After patching and compiling, you can play it with playmus. (My version of ogg123 will not play it, and I had to patch mplayer to get it to play 6 channel oggs.) Greg Lee <greg@ling.lll.hawaii.edu> Thus, July 1, 2004
author Sam Lantinga <slouken@libsdl.org>
date Sat, 21 Aug 2004 12:27:02 +0000
parents ae4ab3ac89a9
children 3d9a199d2a70
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==============================================================================
Using the Simple DirectMedia Layer with Mac OS X
==============================================================================

These instructions are for people using Apple's Mac OS X (pronounced
"ten").

From the developer's point of view, OS X is a sort of hybrid Mac and
Unix system, and you have the option of using either traditional
command line tools or Apple's IDE ProjectBuilder (PB).

To build SDL using the command line, use the standard configure and make
process:

	./configure
	make
	sudo make install

(You may need to create the subdirs of /usr/local manually.)

To use the library once it's built, you essential have two possibilities:
use the traditional autoconf/automake/make method, or use Project Builder.

==============================================================================
Using the Simple DirectMedia Layer with a traditional Makefile
==============================================================================

An existing autoconf/automake build system for your SDL app has good chances
to work almost unchanged on OS X. However, to produce a "real" MacOS X binary
that you can distribute to users, you need to put the generated binary into a
so called "bundle", which basically is a fancy folder with a name like
"MyCoolGame.app".

To get this build automatically, add something like the following rule to
your Makefile.am:

bundle_contents = APP_NAME.app/Contents
APP_NAME_bundle: EXE_NAME
	mkdir -p $(bundle_contents)/MacOS
	mkdir -p $(bundle_contents)/Resources
	echo "APPL????" > $(bundle_contents)/PkgInfo
	$(INSTALL_PROGRAM) $< $(bundle_contents)/MacOS/

You should replace EXE_NAME with the name of the executable. APP_NAME is what
will be visible to the user in the Finder. Usually it will be the same
as EXE_NAME but capitalized. E.g. if EXE_NAME is "testgame" then APP_NAME 
usually is "TestGame". You might also want to use @PACKAGE@ to use the package
name as specified in your configure.in file.

If your project builds more than one application, you will have to do a bit
more.  For each of your target applications, you need a seperate rule.

If you want the created bundles to be installed, you may want to add this
rule to your Makefile.am:

install-exec-hook: APP_NAME_bundle
	rm -rf $(DESTDIR)$(prefix)/Applications/APP_NAME.app
	mkdir -p $(DESTDIR)$(prefix)/Applications/
	cp -r $< /$(DESTDIR)$(prefix)Applications/

This rule takes the Bundle created by the rule from step 3 and installs them
into $(DESTDIR)$(prefix)/Applications/.

Again, if you want to install multiple applications, you will have to augment
the make rule accordingly.


But beware! That is only part of the story! With the above, you end up with
a bare bone .app bundle, which is double clickable from the Finder. But
there are some  more things you should do before shipping yor product...

1) The bundle right now probably is dynamically linked against SDL. That 
   means that when you copy it to another computer, *it will not run*,
   unless you also install SDL on that other computer. A good solution
   for this dilemma is to static link against SDL. On OS X, you can
   achieve that by linkinag against the libraries listed by
     sdl-config --static-libs
   instead of those listed by
     sdl-config --libs
   Depending on how exactly SDL is integrated into your build systems, the
   way to achieve that varies, so I won't describe it here in detail
2) Add an 'Info.plist' to your application. That is a special XML file which
   contains some meta-information about your application (like some copyright
   information, the version of your app, the name of an optional icon file,
   and other things). Part of that information is displayed by the Finder
   when you click on the .app, or if you look at the "Get Info" window.
   More information about Info.plist files can be found on Apple's homepage.


As a final remark, let me add that I use some of the techniques (and some
variations of them) in Exult and ScummVM; both are available in source on
the net, so feel free to take a peek at them for inspiration!


==============================================================================
Using the Simple DirectMedia Layer with Project Builder
==============================================================================

These instructions are for using Apple's Project Builder IDE to build SDL
applications.

- First steps

The first thing to do is to unpack the PBProjects.tar.gz archive in the
top level SDL directory (where the PBProjects.tar.gz archive resides).
Because Stuffit Expander will unpack the archive into a subdirectory,
you should unpack the archive manually from the command line:
	cd [path_to_SDL_source]
	tar zxf PBProjects.tar.gz
This will create a new folder called PBProjects, which you can browse
normally from the Finder.

- Building the Framework

The SDL Library is packaged as a framework bundle, an organized
relocatable folder heirarchy of executible code, interface headers, 
and additional resources. For practical purposes, you can think of a 
framework as a more user and system-friendly shared library, whose library
file behaves more or less like a standard UNIX shared library.

To build the framework, simply open the framework project and build it. 
By default, the framework bundle "SDL.framework" is installed in 
~/Library/Frameworks. Therefore, the testers and project stationary expect
it to be located there. However, it will function the same in any of the
following locations:

    ~/Library/Frameworks
    /Local/Library/Frameworks
    /System/Library/Frameworks

- Build Options
    There are two "Build Styles" (See the "Targets" tab) for SDL.
    "Deployment" should be used if you aren't tweaking the SDL library.
    "Development" should be used to debug SDL apps or the library itself.

- Building the Testers
    Open the SDLTest project and build away!

- Using the Project Stationary
    Copy the stationary to the indicated folders to access it from
    the "New Project" and "Add target" menus. What could be easier?

- Setting up a new project by hand
    Some of you won't want to use the Stationary so I'll give some tips:
    * Create a new "Cocoa Application"
    * Add src/main/macosx/SDLMain.m , .h and .nib to your project
    * Remove "main.c" from your project
    * Remove "MainMenu.nib" from your project
    * Add "$(HOME)/Library/Frameworks/SDL.framework/Headers" to include path
    * Add "$(HOME)/Library/Frameworks" to the frameworks search path
    * Add "-framework SDL -framework Foundation -framework AppKit" to "OTHER_LDFLAGS"
    * Set the "Main Nib File" under "Application Settings" to "SDLMain.nib"
    * Add your files
    * Clean and build

- Building from command line
    Use pbxbuild in the same directory as your .pbproj file
         
- Running your app
    You can send command line args to your app by either invoking it from
    the command line (in *.app/Contents/MacOS) or by entering them in the
    "Executibles" panel of the target settings.
    
- Implementation Notes
    Some things that may be of interest about how it all works...
    * Working directory
        As defined in the SDL_main.m file, the working directory of your SDL app
        is by default set to its parent. You may wish to change this to better
        suit your needs.
    * You have a Cocoa App!
        Your SDL app is essentially a Cocoa application. When your app
        starts up and the libraries finish loading, a Cocoa procedure is called,
        which sets up the working directory and calls your main() method.
        You are free to modify your Cocoa app with generally no consequence 
        to SDL. You cannot, however, easily change the SDL window itself.
        Functionality may be added in the future to help this.
	

Known bugs are listed in the file "BUGS"