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Always use an SDL buffer size that is a power of two. Reduce buffer size

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to 70ms.

Subversion-branch: /trunk/chocolate-doom
Subversion-revision: 1524
This commit is contained in:
Simon Howard 2009-05-17 13:54:19 +00:00
parent 144849eee5
commit e80490d431
2 changed files with 58 additions and 8 deletions
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31
pcsound/pcsound_sdl.c
View file

@ -32,7 +32,7 @@
#include "pcsound.h"
#include "pcsound_internal.h"
#define SOUND_SLICE_TIME 100 /* ms */
#define MAX_SOUND_SLICE_TIME 70 /* ms */
#define SQUARE_WAVE_AMP 0x2000
// If true, we initialised SDL and have the responsibility to shut it
@ -164,6 +164,33 @@ static void PCSound_SDL_Shutdown(void)
}
}
// Calculate slice size, based on MAX_SOUND_SLICE_TIME.
// The result must be a power of two.
static int GetSliceSize(void)
{
int limit;
int n;
limit = (pcsound_sample_rate * MAX_SOUND_SLICE_TIME) / 1000;
// Try all powers of two, not exceeding the limit.
for (n=0;; ++n)
{
// 2^n <= limit < 2^n+1 ?
if ((1 << (n + 1)) > limit)
{
return (1 << n);
}
}
// Should never happen?
return 1024;
}
static int PCSound_SDL_Init(pcsound_callback_func callback_func)
{
int slicesize;
@ -179,7 +206,7 @@ static int PCSound_SDL_Init(pcsound_callback_func callback_func)
return 0;
}
slicesize = (SOUND_SLICE_TIME * pcsound_sample_rate) / 1000;
slicesize = GetSliceSize();
if (Mix_OpenAudio(pcsound_sample_rate, AUDIO_S16SYS, 2, slicesize) < 0)
{

35
src/i_sdlsound.c
View file

@ -49,7 +49,7 @@
#include "doomdef.h"
#define LOW_PASS_FILTER
#define SOUND_SLICE_TIME 100 /* ms */
#define MAX_SOUND_SLICE_TIME 70 /* ms */
#define NUM_CHANNELS 16
static boolean sound_initialised = false;
@ -65,7 +65,6 @@ int use_libsamplerate = 0;
extern int mb_used;
// When a sound stops, check if it is still playing. If it is not,
// we can mark the sound data as CACHE to be freed back for other
// means.
@ -667,10 +666,36 @@ static void I_SDL_ShutdownSound(void)
sound_initialised = false;
}
// Calculate slice size, based on MAX_SOUND_SLICE_TIME.
// The result must be a power of two.
static int GetSliceSize(void)
{
int limit;
int n;
limit = (snd_samplerate * MAX_SOUND_SLICE_TIME) / 1000;
// Try all powers of two, not exceeding the limit.
for (n=0;; ++n)
{
// 2^n <= limit < 2^n+1 ?
if ((1 << (n + 1)) > limit)
{
return (1 << n);
}
}
// Should never happen?
return 1024;
}
static boolean I_SDL_InitSound(void)
{
int i;
int slicesize;
// No sounds yet
@ -690,9 +715,7 @@ static boolean I_SDL_InitSound(void)
return false;
}
slicesize = (snd_samplerate * SOUND_SLICE_TIME) / 1000;
if (Mix_OpenAudio(snd_samplerate, AUDIO_S16SYS, 2, slicesize) < 0)
if (Mix_OpenAudio(snd_samplerate, AUDIO_S16SYS, 2, GetSliceSize()) < 0)
{
fprintf(stderr, "Error initialising SDL_mixer: %s\n", Mix_GetError());
return false;