Mercurial > sdl-ios-xcode
annotate sdl.m4 @ 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 | a5defa3b93e1 |
| children | 65f4b2dd46b7 |
| rev | line source |
|---|---|
| 0 | 1 # Configure paths for SDL |
| 2 # Sam Lantinga 9/21/99 | |
| 3 # stolen from Manish Singh | |
| 4 # stolen back from Frank Belew | |
| 5 # stolen from Manish Singh | |
| 6 # Shamelessly stolen from Owen Taylor | |
| 7 | |
| 8 dnl AM_PATH_SDL([MINIMUM-VERSION, [ACTION-IF-FOUND [, ACTION-IF-NOT-FOUND]]]) | |
| 9 dnl Test for SDL, and define SDL_CFLAGS and SDL_LIBS | |
| 10 dnl | |
|
794
a5defa3b93e1
Updated for the latest version of automake
Sam Lantinga <slouken@libsdl.org>
parents:
489
diff
changeset
|
11 AC_DEFUN([AM_PATH_SDL], |
| 0 | 12 [dnl |
| 13 dnl Get the cflags and libraries from the sdl-config script | |
| 14 dnl | |
| 15 AC_ARG_WITH(sdl-prefix,[ --with-sdl-prefix=PFX Prefix where SDL is installed (optional)], | |
| 16 sdl_prefix="$withval", sdl_prefix="") | |
| 17 AC_ARG_WITH(sdl-exec-prefix,[ --with-sdl-exec-prefix=PFX Exec prefix where SDL is installed (optional)], | |
| 18 sdl_exec_prefix="$withval", sdl_exec_prefix="") | |
| 19 AC_ARG_ENABLE(sdltest, [ --disable-sdltest Do not try to compile and run a test SDL program], | |
| 20 , enable_sdltest=yes) | |
| 21 | |
| 22 if test x$sdl_exec_prefix != x ; then | |
| 23 sdl_args="$sdl_args --exec-prefix=$sdl_exec_prefix" | |
| 24 if test x${SDL_CONFIG+set} != xset ; then | |
| 25 SDL_CONFIG=$sdl_exec_prefix/bin/sdl-config | |
| 26 fi | |
| 27 fi | |
| 28 if test x$sdl_prefix != x ; then | |
| 29 sdl_args="$sdl_args --prefix=$sdl_prefix" | |
| 30 if test x${SDL_CONFIG+set} != xset ; then | |
| 31 SDL_CONFIG=$sdl_prefix/bin/sdl-config | |
| 32 fi | |
| 33 fi | |
| 34 | |
|
172
37e3ca9254c7
Date: Sat, 8 Sep 2001 04:42:23 +0200
Sam Lantinga <slouken@libsdl.org>
parents:
168
diff
changeset
|
35 AC_REQUIRE([AC_CANONICAL_TARGET]) |
|
489
d90349051cab
Fixed path problem with sdl.m4 macro file
Sam Lantinga <slouken@libsdl.org>
parents:
452
diff
changeset
|
36 PATH="$prefix/bin:$prefix/usr/bin:$PATH" |
|
d90349051cab
Fixed path problem with sdl.m4 macro file
Sam Lantinga <slouken@libsdl.org>
parents:
452
diff
changeset
|
37 AC_PATH_PROG(SDL_CONFIG, sdl-config, no, [$PATH]) |
| 0 | 38 min_sdl_version=ifelse([$1], ,0.11.0,$1) |
| 39 AC_MSG_CHECKING(for SDL - version >= $min_sdl_version) | |
| 40 no_sdl="" | |
| 41 if test "$SDL_CONFIG" = "no" ; then | |
| 42 no_sdl=yes | |
| 43 else | |
| 44 SDL_CFLAGS=`$SDL_CONFIG $sdlconf_args --cflags` | |
| 45 SDL_LIBS=`$SDL_CONFIG $sdlconf_args --libs` | |
| 46 | |
| 47 sdl_major_version=`$SDL_CONFIG $sdl_args --version | \ | |
| 48 sed 's/\([[0-9]]*\).\([[0-9]]*\).\([[0-9]]*\)/\1/'` | |
| 49 sdl_minor_version=`$SDL_CONFIG $sdl_args --version | \ | |
| 50 sed 's/\([[0-9]]*\).\([[0-9]]*\).\([[0-9]]*\)/\2/'` | |
| 51 sdl_micro_version=`$SDL_CONFIG $sdl_config_args --version | \ | |
| 52 sed 's/\([[0-9]]*\).\([[0-9]]*\).\([[0-9]]*\)/\3/'` | |
| 53 if test "x$enable_sdltest" = "xyes" ; then | |
| 54 ac_save_CFLAGS="$CFLAGS" | |
| 55 ac_save_LIBS="$LIBS" | |
| 56 CFLAGS="$CFLAGS $SDL_CFLAGS" | |
| 57 LIBS="$LIBS $SDL_LIBS" | |
| 58 dnl | |
| 59 dnl Now check if the installed SDL is sufficiently new. (Also sanity | |
| 60 dnl checks the results of sdl-config to some extent | |
| 61 dnl | |
| 62 rm -f conf.sdltest | |
| 63 AC_TRY_RUN([ | |
| 64 #include <stdio.h> | |
| 65 #include <stdlib.h> | |
| 66 #include <string.h> | |
| 67 #include "SDL.h" | |
| 68 | |
| 69 char* | |
| 70 my_strdup (char *str) | |
| 71 { | |
| 72 char *new_str; | |
| 73 | |
| 74 if (str) | |
| 75 { | |
| 76 new_str = (char *)malloc ((strlen (str) + 1) * sizeof(char)); | |
| 77 strcpy (new_str, str); | |
| 78 } | |
| 79 else | |
| 80 new_str = NULL; | |
| 81 | |
| 82 return new_str; | |
| 83 } | |
| 84 | |
| 85 int main (int argc, char *argv[]) | |
| 86 { | |
| 87 int major, minor, micro; | |
| 88 char *tmp_version; | |
| 89 | |
| 90 /* This hangs on some systems (?) | |
| 91 system ("touch conf.sdltest"); | |
| 92 */ | |
| 93 { FILE *fp = fopen("conf.sdltest", "a"); if ( fp ) fclose(fp); } | |
| 94 | |
| 95 /* HP/UX 9 (%@#!) writes to sscanf strings */ | |
| 96 tmp_version = my_strdup("$min_sdl_version"); | |
| 97 if (sscanf(tmp_version, "%d.%d.%d", &major, &minor, µ) != 3) { | |
| 98 printf("%s, bad version string\n", "$min_sdl_version"); | |
| 99 exit(1); | |
| 100 } | |
| 101 | |
| 102 if (($sdl_major_version > major) || | |
| 103 (($sdl_major_version == major) && ($sdl_minor_version > minor)) || | |
| 104 (($sdl_major_version == major) && ($sdl_minor_version == minor) && ($sdl_micro_version >= micro))) | |
| 105 { | |
| 106 return 0; | |
| 107 } | |
| 108 else | |
| 109 { | |
| 110 printf("\n*** 'sdl-config --version' returned %d.%d.%d, but the minimum version\n", $sdl_major_version, $sdl_minor_version, $sdl_micro_version); | |
| 111 printf("*** of SDL required is %d.%d.%d. If sdl-config is correct, then it is\n", major, minor, micro); | |
| 112 printf("*** best to upgrade to the required version.\n"); | |
| 113 printf("*** If sdl-config was wrong, set the environment variable SDL_CONFIG\n"); | |
| 114 printf("*** to point to the correct copy of sdl-config, and remove the file\n"); | |
| 115 printf("*** config.cache before re-running configure\n"); | |
| 116 return 1; | |
| 117 } | |
| 118 } | |
| 119 | |
| 120 ],, no_sdl=yes,[echo $ac_n "cross compiling; assumed OK... $ac_c"]) | |
| 121 CFLAGS="$ac_save_CFLAGS" | |
| 122 LIBS="$ac_save_LIBS" | |
| 123 fi | |
| 124 fi | |
| 125 if test "x$no_sdl" = x ; then | |
| 126 AC_MSG_RESULT(yes) | |
| 127 ifelse([$2], , :, [$2]) | |
| 128 else | |
| 129 AC_MSG_RESULT(no) | |
| 130 if test "$SDL_CONFIG" = "no" ; then | |
| 131 echo "*** The sdl-config script installed by SDL could not be found" | |
| 132 echo "*** If SDL was installed in PREFIX, make sure PREFIX/bin is in" | |
| 133 echo "*** your path, or set the SDL_CONFIG environment variable to the" | |
| 134 echo "*** full path to sdl-config." | |
| 135 else | |
| 136 if test -f conf.sdltest ; then | |
| 137 : | |
| 138 else | |
| 139 echo "*** Could not run SDL test program, checking why..." | |
| 140 CFLAGS="$CFLAGS $SDL_CFLAGS" | |
| 141 LIBS="$LIBS $SDL_LIBS" | |
| 142 AC_TRY_LINK([ | |
| 143 #include <stdio.h> | |
| 144 #include "SDL.h" | |
|
1
cf2af46e9e2a
Changes since SDL 1.2.0 release
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
|
145 |
|
cf2af46e9e2a
Changes since SDL 1.2.0 release
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
|
146 int main(int argc, char *argv[]) |
|
cf2af46e9e2a
Changes since SDL 1.2.0 release
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
|
147 { return 0; } |
|
cf2af46e9e2a
Changes since SDL 1.2.0 release
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
|
148 #undef main |
|
cf2af46e9e2a
Changes since SDL 1.2.0 release
Sam Lantinga <slouken@lokigames.com>
parents:
0
diff
changeset
|
149 #define main K_and_R_C_main |
| 0 | 150 ], [ return 0; ], |
| 151 [ echo "*** The test program compiled, but did not run. This usually means" | |
| 152 echo "*** that the run-time linker is not finding SDL or finding the wrong" | |
| 153 echo "*** version of SDL. If it is not finding SDL, you'll need to set your" | |
| 154 echo "*** LD_LIBRARY_PATH environment variable, or edit /etc/ld.so.conf to point" | |
| 155 echo "*** to the installed location Also, make sure you have run ldconfig if that" | |
| 156 echo "*** is required on your system" | |
| 157 echo "***" | |
| 158 echo "*** If you have an old version installed, it is best to remove it, although" | |
| 159 echo "*** you may also be able to get things to work by modifying LD_LIBRARY_PATH"], | |
| 160 [ echo "*** The test program failed to compile or link. See the file config.log for the" | |
| 161 echo "*** exact error that occured. This usually means SDL was incorrectly installed" | |
| 162 echo "*** or that you have moved SDL since it was installed. In the latter case, you" | |
| 163 echo "*** may want to edit the sdl-config script: $SDL_CONFIG" ]) | |
| 164 CFLAGS="$ac_save_CFLAGS" | |
| 165 LIBS="$ac_save_LIBS" | |
| 166 fi | |
| 167 fi | |
| 168 SDL_CFLAGS="" | |
| 169 SDL_LIBS="" | |
| 170 ifelse([$3], , :, [$3]) | |
| 171 fi | |
| 172 AC_SUBST(SDL_CFLAGS) | |
| 173 AC_SUBST(SDL_LIBS) | |
| 174 rm -f conf.sdltest | |
| 175 ]) |