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Tweak audio to reduce latency and allow user to override with cvars.

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This commit is contained in:
Ryan C. Gordon 2005-09-04 19:36:36 +00:00
parent 9266fccf79
commit 752d393daa
1 changed files with 66 additions and 8 deletions
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74
code/unix/sdl_snd.c
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@ -62,6 +62,8 @@ cvar_t *sndbits;
cvar_t *sndspeed;
cvar_t *sndchannels;
cvar_t *snddevice;
cvar_t *sdldevsamps;
cvar_t *sdlmixsamps;
static qboolean use_custom_memset = qfalse;
// https://zerowing.idsoftware.com/bugzilla/show_bug.cgi?id=371
@ -122,6 +124,28 @@ static void sdl_audio_callback(void *userdata, Uint8 *stream, int len)
dmapos = 0;
}
static void print_audiospec(const char *str, const SDL_AudioSpec *spec)
{
Com_Printf("%s:\n", str);
// I'm sorry this is nasty.
#define PRINT_AUDIO_FMT(x) \
if (spec->format == x) Com_Printf("Format: %s\n", #x); else
PRINT_AUDIO_FMT(AUDIO_U8)
PRINT_AUDIO_FMT(AUDIO_S8)
PRINT_AUDIO_FMT(AUDIO_U16LSB)
PRINT_AUDIO_FMT(AUDIO_S16LSB)
PRINT_AUDIO_FMT(AUDIO_U16MSB)
PRINT_AUDIO_FMT(AUDIO_S16MSB)
Com_Printf("Format: UNKNOWN\n");
#undef PRINT_AUDIO_FMT
Com_Printf("Freq: %d\n", (int) spec->freq);
Com_Printf("Samples: %d\n", (int) spec->samples);
Com_Printf("Channels: %d\n", (int) spec->channels);
Com_Printf("\n");
}
qboolean SNDDMA_Init(void)
{
char drivername[128];
@ -139,6 +163,8 @@ qboolean SNDDMA_Init(void)
sndspeed = Cvar_Get("sndspeed", "0", CVAR_ARCHIVE);
sndchannels = Cvar_Get("sndchannels", "2", CVAR_ARCHIVE);
snddevice = Cvar_Get("snddevice", "/dev/dsp", CVAR_ARCHIVE);
sdldevsamps = Cvar_Get("sdldevsamps", "0", CVAR_ARCHIVE);
sdlmixsamps = Cvar_Get("sdlmixsamps", "0", CVAR_ARCHIVE);
}
if (!SDL_WasInit(SDL_INIT_AUDIO))
@ -169,14 +195,20 @@ qboolean SNDDMA_Init(void)
// I dunno if this is the best idea, but I'll give it a try...
// should probably check a cvar for this...
if (desired.freq <= 11025)
desired.samples = 512;
else if (desired.freq <= 22050)
desired.samples = 1024;
else if (desired.freq <= 44100)
desired.samples = 2048;
if (sdldevsamps->value)
desired.samples = sdldevsamps->value;
else
desired.samples = 4096; // (*shrug*)
{
// just pick a sane default.
if (desired.freq <= 11025)
desired.samples = 256;
else if (desired.freq <= 22050)
desired.samples = 512;
else if (desired.freq <= 44100)
desired.samples = 1024;
else
desired.samples = 2048; // (*shrug*)
}
desired.channels = (int) sndchannels->value;
desired.callback = sdl_audio_callback;
@ -188,10 +220,36 @@ qboolean SNDDMA_Init(void)
return qfalse;
} // if
print_audiospec("Format we requested from SDL audio device", &desired);
print_audiospec("Format we actually got", &obtained);
// dma.samples needs to be big, or id's mixer will just refuse to
// work at all; we need to keep it significantly bigger than the
// amount of SDL callback samples, and just copy a little each time
// the callback runs.
// 32768 is what the OSS driver filled in here on my system. I don't
// know if it's a good value overall, but at least we know it's
// reasonable...this is why I let the user override.
tmp = sdlmixsamps->value;
if (!tmp)
tmp = (obtained.samples * obtained.channels) * 4;
if (tmp & (tmp - 1)) // not a power of two? Seems to confuse something.
{
int val = 1;
while (val < tmp)
val <<= 1;
val >>= 1;
Com_Printf("WARNING: sdlmixsamps wasn't a power of two (%d),"
" so we made it one (%d).\n", tmp, val);
tmp = val;
}
dmapos = 0;
dma.samplebits = obtained.format & 0xFF; // first byte of format is bits.
dma.channels = obtained.channels;
dma.samples = 32768; //obtained.samples * obtained.channels;
dma.samples = tmp;
dma.submission_chunk = 1;
dma.speed = obtained.freq;
dmasize = (dma.samples * (dma.samplebits/8));