Mercurial > sdl-ios-xcode
view src/audio/SDL_audiodev.c @ 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 | 12b6d331d82a |
children | 782fd950bd46 c121d94672cb a1b03ba2fcd0 |
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/* SDL - Simple DirectMedia Layer Copyright (C) 1997-2006 Sam Lantinga This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA Sam Lantinga slouken@libsdl.org */ #include "SDL_config.h" /* Get the name of the audio device we use for output */ #if SDL_AUDIO_DRIVER_BSD || SDL_AUDIO_DRIVER_OSS || SDL_AUDIO_DRIVER_SUNAUDIO #include <fcntl.h> #include <sys/types.h> #include <sys/stat.h> #include "SDL_stdinc.h" #include "SDL_audiodev_c.h" #ifndef _PATH_DEV_DSP #if defined(__NETBSD__) || defined(__OPENBSD__) #define _PATH_DEV_DSP "/dev/audio" #else #define _PATH_DEV_DSP "/dev/dsp" #endif #endif #ifndef _PATH_DEV_DSP24 #define _PATH_DEV_DSP24 "/dev/sound/dsp" #endif #ifndef _PATH_DEV_AUDIO #define _PATH_DEV_AUDIO "/dev/audio" #endif int SDL_OpenAudioPath(char *path, int maxlen, int flags, int classic) { const char *audiodev; int audio_fd; char audiopath[1024]; /* Figure out what our audio device is */ if ( ((audiodev=SDL_getenv("SDL_PATH_DSP")) == NULL) && ((audiodev=SDL_getenv("AUDIODEV")) == NULL) ) { if ( classic ) { audiodev = _PATH_DEV_AUDIO; } else { struct stat sb; /* Added support for /dev/sound/\* in Linux 2.4 */ if ( ((stat("/dev/sound", &sb) == 0) && S_ISDIR(sb.st_mode)) && ((stat(_PATH_DEV_DSP24, &sb) == 0) && S_ISCHR(sb.st_mode)) ) { audiodev = _PATH_DEV_DSP24; } else { audiodev = _PATH_DEV_DSP; } } } audio_fd = open(audiodev, flags, 0); /* If the first open fails, look for other devices */ if ( (audio_fd < 0) && (SDL_strlen(audiodev) < (sizeof(audiopath)-3)) ) { int exists, instance; struct stat sb; instance = 1; do { /* Don't use errno ENOENT - it may not be thread-safe */ SDL_snprintf(audiopath, SDL_arraysize(audiopath), "%s%d", audiodev, instance++); exists = 0; if ( stat(audiopath, &sb) == 0 ) { exists = 1; audio_fd = open(audiopath, flags, 0); } } while ( exists && (audio_fd < 0) ); audiodev = audiopath; } if ( path != NULL ) { SDL_strlcpy(path, audiodev, maxlen); path[maxlen-1] = '\0'; } return(audio_fd); } #elif SDL_AUDIO_DRIVER_PAUD /* Get the name of the audio device we use for output */ #include <sys/types.h> #include <sys/stat.h> #include "SDL_stdinc.h" #include "SDL_audiodev_c.h" #ifndef _PATH_DEV_DSP #define _PATH_DEV_DSP "/dev/%caud%c/%c" #endif char devsettings[][3] = { { 'p', '0', '1' }, { 'p', '0', '2' }, { 'p', '0', '3' }, { 'p', '0', '4' }, { 'p', '1', '1' }, { 'p', '1', '2' }, { 'p', '1', '3' }, { 'p', '1', '4' }, { 'p', '2', '1' }, { 'p', '2', '2' }, { 'p', '2', '3' }, { 'p', '2', '4' }, { 'p', '3', '1' }, { 'p', '3', '2' }, { 'p', '3', '3' }, { 'p', '3', '4' }, { 'b', '0', '1' }, { 'b', '0', '2' }, { 'b', '0', '3' }, { 'b', '0', '4' }, { 'b', '1', '1' }, { 'b', '1', '2' }, { 'b', '1', '3' }, { 'b', '1', '4' }, { 'b', '2', '1' }, { 'b', '2', '2' }, { 'b', '2', '3' }, { 'b', '2', '4' }, { 'b', '3', '1' }, { 'b', '3', '2' }, { 'b', '3', '3' }, { 'b', '3', '4' }, { '\0', '\0', '\0' } }; static int OpenUserDefinedDevice(char *path, int maxlen, int flags) { const char *audiodev; int audio_fd; /* Figure out what our audio device is */ if ((audiodev=SDL_getenv("SDL_PATH_DSP")) == NULL) { audiodev=SDL_getenv("AUDIODEV"); } if ( audiodev == NULL ) { return -1; } audio_fd = open(audiodev, flags, 0); if ( path != NULL ) { SDL_strlcpy(path, audiodev, maxlen); path[maxlen-1] = '\0'; } return audio_fd; } int SDL_OpenAudioPath(char *path, int maxlen, int flags, int classic) { struct stat sb; int audio_fd; char audiopath[1024]; int cycle; audio_fd = OpenUserDefinedDevice(path,maxlen,flags); if ( audio_fd != -1 ) { return audio_fd; } cycle = 0; while( devsettings[cycle][0] != '\0' ) { SDL_snprintf( audiopath, SDL_arraysize(audiopath), _PATH_DEV_DSP, devsettings[cycle][0], devsettings[cycle][1], devsettings[cycle][2]); if ( stat(audiopath, &sb) == 0 ) { audio_fd = open(audiopath, flags, 0); if ( audio_fd > 0 ) { if ( path != NULL ) { SDL_strlcpy( path, audiopath, maxlen ); } return audio_fd; } } } return -1; } #endif /* Audio driver selection */