Mercurial > sdl-ios-xcode
diff src/audio/SDL_audio.c @ 1794:5605a9820134
Fixed bug #137
If SDL_OpenAudio() is passed zero for the desired format
fields, the following environment variables will be used
to fill them in:
SDL_AUDIO_FREQUENCY
SDL_AUDIO_FORMAT
SDL_AUDIO_CHANNELS
SDL_AUDIO_SAMPLES
If an environment variable is not specified, it will be set
to a reasonable default value.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Tue, 09 May 2006 08:52:54 +0000 |
| parents | 290b5baf2fca |
| children | c121d94672cb c1b6bb5205f1 |
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line diff
--- a/src/audio/SDL_audio.c Tue May 09 07:52:04 2006 +0000 +++ b/src/audio/SDL_audio.c Tue May 09 08:52:54 2006 +0000 @@ -285,6 +285,51 @@ SDL_mutexV(audio->mixer_lock); } +static Uint16 SDL_ParseAudioFormat(const char *string) +{ + Uint16 format = 0; + + switch (*string) { + case 'U': + ++string; + format |= 0x0000; + break; + case 'S': + ++string; + format |= 0x8000; + break; + default: + return 0; + } + switch (SDL_atoi(string)) { + case 8: + string += 1; + format |= 8; + break; + case 16: + string += 2; + format |= 16; + if ( SDL_strcmp(string, "LSB") == 0 +#if SDL_BYTEORDER == SDL_LIL_ENDIAN + || SDL_strcmp(string, "SYS") == 0 +#endif + ) { + format |= 0x0000; + } + if ( SDL_strcmp(string, "MSB") == 0 +#if SDL_BYTEORDER == SDL_BIG_ENDIAN + || SDL_strcmp(string, "SYS") == 0 +#endif + ) { + format |= 0x1000; + } + break; + default: + return 0; + } + return format; +} + int SDL_AudioInit(const char *driver_name) { SDL_AudioDevice *audio; @@ -386,6 +431,7 @@ int SDL_OpenAudio(SDL_AudioSpec *desired, SDL_AudioSpec *obtained) { SDL_AudioDevice *audio; + const char *env; /* Start up the audio driver, if necessary */ if ( ! current_audio ) { @@ -402,9 +448,35 @@ } /* Verify some parameters */ - if ( desired->callback == NULL ) { - SDL_SetError("SDL_OpenAudio() passed a NULL callback"); - return(-1); + if ( desired->freq == 0 ) { + env = SDL_getenv("SDL_AUDIO_FREQUENCY"); + if ( env ) { + desired->freq = SDL_atoi(env); + } + } + if ( desired->freq == 0 ) { + /* Pick some default audio frequency */ + desired->freq = 22050; + } + if ( desired->format == 0 ) { + env = SDL_getenv("SDL_AUDIO_FORMAT"); + if ( env ) { + desired->format = SDL_ParseAudioFormat(env); + } + } + if ( desired->format == 0 ) { + /* Pick some default audio format */ + desired->format = AUDIO_S16; + } + if ( desired->channels == 0 ) { + env = SDL_getenv("SDL_AUDIO_CHANNELS"); + if ( env ) { + desired->channels = SDL_atoi(env); + } + } + if ( desired->channels == 0 ) { + /* Pick a default number of channels */ + desired->channels = 2; } switch ( desired->channels ) { case 1: /* Mono */ @@ -416,6 +488,25 @@ SDL_SetError("1 (mono) and 2 (stereo) channels supported"); return(-1); } + if ( desired->samples == 0 ) { + env = SDL_getenv("SDL_AUDIO_SAMPLES"); + if ( env ) { + desired->samples = SDL_atoi(env); + } + } + if ( desired->samples == 0 ) { + /* Pick a default of ~46 ms at desired frequency */ + int samples = (desired->freq / 1000) * 46; + int power2 = 1; + while ( power2 < samples ) { + power2 *= 2; + } + desired->samples = power2; + } + if ( desired->callback == NULL ) { + SDL_SetError("SDL_OpenAudio() passed a NULL callback"); + return(-1); + } #if defined(__MACOS__) || (defined(__RISCOS__) && SDL_THREADS_DISABLED) /* FIXME: Need to implement PPC interrupt asm for SDL_LockAudio() */