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tweak sound buffering and timing to better match pandora's refresh.
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this also changes how direct sound channels are started and
sample step precision is increased to hopefully fix gbc + direct
channel desync that has been reported on the forums.
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notaz committed Sep 7, 2011
1 parent a231964 commit 2f1c528
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Showing 4 changed files with 48 additions and 55 deletions.
7 changes: 7 additions & 0 deletions common.h
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Original file line number Diff line number Diff line change
Expand Up @@ -180,6 +180,7 @@


typedef u32 fixed16_16;
typedef u32 fixed8_24;

#define float_to_fp16_16(value) \
(fixed16_16)((value) * 65536.0) \
Expand All @@ -196,6 +197,12 @@ typedef u32 fixed16_16;
#define fp16_16_fractional_part(value) \
((value) & 0xFFFF) \

#define float_to_fp8_24(value) \
(fixed8_24)((value) * 16777216.0) \

#define fp8_24_fractional_part(value) \
((value) & 0xFFFFFF) \

#define fixed_div(numerator, denominator, bits) \
(((numerator * (1 << bits)) + (denominator / 2)) / denominator) \

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9 changes: 4 additions & 5 deletions main.h
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Original file line number Diff line number Diff line change
Expand Up @@ -48,7 +48,7 @@ typedef struct
u32 reload;
u32 prescale;
u32 stop_cpu_ticks;
fixed16_16 frequency_step;
fixed8_24 frequency_step;
timer_ds_channel_type direct_sound_channels;
timer_irq_type irq;
timer_status_type status;
Expand Down Expand Up @@ -132,8 +132,7 @@ static u32 prescale_table[] = { 0, 6, 8, 10 };
if(timer[timer_number].direct_sound_channels & (0x01 << channel)) \
{ \
direct_sound_channel[channel].buffer_index = \
(direct_sound_channel[channel].buffer_index + buffer_adjust) % \
BUFFER_SIZE; \
(gbc_sound_buffer_index + buffer_adjust) % BUFFER_SIZE; \
} \

#define trigger_timer(timer_number) \
Expand Down Expand Up @@ -164,8 +163,8 @@ static u32 prescale_table[] = { 0, 6, 8, 10 };
if(timer_number < 2) \
{ \
u32 buffer_adjust = \
(u32)(((float)(cpu_ticks - timer[timer_number].stop_cpu_ticks) * \
sound_frequency) / 16777216.0) * 2; \
(u32)(((float)(cpu_ticks - gbc_sound_last_cpu_ticks) * \
sound_frequency) / GBC_BASE_RATE) * 2; \
\
sound_update_frequency_step(timer_number); \
adjust_sound_buffer(timer_number, 0); \
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64 changes: 26 additions & 38 deletions sound.c
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Original file line number Diff line number Diff line change
Expand Up @@ -84,31 +84,31 @@ void sound_timer_queue32(u32 channel, u32 value)

#define render_sample_left() \
sound_buffer[buffer_index] += current_sample + \
fp16_16_to_u32((next_sample - current_sample) * fifo_fractional) \
fp16_16_to_u32((next_sample - current_sample) * (fifo_fractional >> 8)) \

#define render_sample_right() \
sound_buffer[buffer_index + 1] += current_sample + \
fp16_16_to_u32((next_sample - current_sample) * fifo_fractional) \
fp16_16_to_u32((next_sample - current_sample) * (fifo_fractional >> 8)) \

#define render_sample_both() \
dest_sample = current_sample + \
fp16_16_to_u32((next_sample - current_sample) * fifo_fractional); \
fp16_16_to_u32((next_sample - current_sample) * (fifo_fractional >> 8)); \
sound_buffer[buffer_index] += dest_sample; \
sound_buffer[buffer_index + 1] += dest_sample \

#define render_samples(type) \
while(fifo_fractional <= 0xFFFF) \
while(fifo_fractional <= 0xFFFFFF) \
{ \
render_sample_##type(); \
fifo_fractional += frequency_step; \
buffer_index = (buffer_index + 2) % BUFFER_SIZE; \
} \

void sound_timer(fixed16_16 frequency_step, u32 channel)
void sound_timer(fixed8_24 frequency_step, u32 channel)
{
direct_sound_struct *ds = direct_sound_channel + channel;

fixed16_16 fifo_fractional = ds->fifo_fractional;
fixed8_24 fifo_fractional = ds->fifo_fractional;
u32 buffer_index = ds->buffer_index;
s16 current_sample, next_sample, dest_sample;

Expand Down Expand Up @@ -149,7 +149,7 @@ void sound_timer(fixed16_16 frequency_step, u32 channel)
}

ds->buffer_index = buffer_index;
ds->fifo_fractional = fp16_16_fractional_part(fifo_fractional);
ds->fifo_fractional = fp8_24_fractional_part(fifo_fractional);

if(((ds->fifo_top - ds->fifo_base) % 32) <= 16)
{
Expand Down Expand Up @@ -264,8 +264,8 @@ u32 gbc_sound_master_volume;
if(rate > 2048) \
rate = 2048; \
\
frequency_step = float_to_fp16_16(((131072.0 / (2048 - rate)) * 8.0) / \
sound_frequency); \
frequency_step = float_to_fp16_16(((131072.0f / (2048 - rate)) * 8.0f) \
/ sound_frequency); \
\
gs->frequency_step = frequency_step; \
gs->rate = rate; \
Expand Down Expand Up @@ -309,13 +309,6 @@ u32 gbc_sound_master_volume;

#define update_tone_noenvelope() \

#define gbc_sound_synchronize() \
while(((gbc_sound_buffer_index - sound_buffer_base) % BUFFER_SIZE) > \
(audio_buffer_size * 2)) \
{ \
SDL_CondWait(sound_cv, sound_mutex); \
} \

#define update_tone_counters(envelope_op, sweep_op) \
tick_counter += gbc_sound_tick_step; \
if(tick_counter > 0xFFFF) \
Expand Down Expand Up @@ -428,19 +421,10 @@ u32 gbc_sound_master_volume;
wave_bank[i2 + 1] = ((current_sample & 0x0F) - 8); \
} \

void synchronize_sound()
{
SDL_LockMutex(sound_mutex);

gbc_sound_synchronize();

SDL_UnlockMutex(sound_mutex);
}

void update_gbc_sound(u32 cpu_ticks)
{
fixed16_16 buffer_ticks = float_to_fp16_16(((float)(cpu_ticks -
gbc_sound_last_cpu_ticks) * sound_frequency) / 16777216.0);
fixed16_16 buffer_ticks = float_to_fp16_16((float)(cpu_ticks -
gbc_sound_last_cpu_ticks) * sound_frequency / GBC_BASE_RATE);
u32 i, i2;
gbc_sound_struct *gs = gbc_sound_channel;
fixed16_16 sample_index, frequency_step;
Expand All @@ -466,8 +450,8 @@ void update_gbc_sound(u32 cpu_ticks)
SDL_LockMutex(sound_mutex);
if(synchronize_flag)
{
if(((gbc_sound_buffer_index - sound_buffer_base) % BUFFER_SIZE) >
(audio_buffer_size * 3 / 2))
if(((gbc_sound_buffer_index - sound_buffer_base) % BUFFER_SIZE) >=
(audio_buffer_size * 2))
{
while(((gbc_sound_buffer_index - sound_buffer_base) % BUFFER_SIZE) >
(audio_buffer_size * 3 / 2))
Expand Down Expand Up @@ -705,10 +689,12 @@ void reset_sound()
gbc_sound_struct *gs = gbc_sound_channel;
u32 i;

SDL_LockMutex(sound_mutex);

sound_on = 0;
sound_buffer_base = 0;
sound_last_cpu_ticks = 0;
memset(sound_buffer, 0, audio_buffer_size);
memset(sound_buffer, 0, sizeof(sound_buffer));

for(i = 0; i < 2; i++, ds++)
{
Expand Down Expand Up @@ -736,6 +722,8 @@ void reset_sound()
gs->sample_data = square_pattern_duty[2];
gs->active_flag = 0;
}

SDL_UnlockMutex(sound_mutex);
}

void sound_exit()
Expand Down Expand Up @@ -772,14 +760,6 @@ void init_sound()
NULL
};

gbc_sound_tick_step =
float_to_fp16_16(256.0 / sound_frequency);

init_noise_table(noise_table15, 32767, 14);
init_noise_table(noise_table7, 127, 6);

reset_sound();

sound_mutex = SDL_CreateMutex();
sound_cv = SDL_CreateCond();

Expand All @@ -793,6 +773,14 @@ void init_sound()
printf("audio: freq %d, size %d\n", sound_frequency, audio_buffer_size);
#endif

gbc_sound_tick_step =
float_to_fp16_16(256.0f / sound_frequency);

init_noise_table(noise_table15, 32767, 14);
init_noise_table(noise_table7, 127, 6);

reset_sound();

SDL_PauseAudio(0);
}

Expand Down
23 changes: 11 additions & 12 deletions sound.h
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Original file line number Diff line number Diff line change
Expand Up @@ -22,17 +22,14 @@

#define BUFFER_SIZE 65536

// A lot of sound cards on PC can't handle such small buffers but this
// seems to work well on PSP.

#ifdef PSP_BUILD

#define SOUND_BUFFER_SIZE 4096
#define GBA_XTAL 16777216.0f
#define GBA_60HZ_RATE 16853760.0f /* 228*(272+960)*60 */

#if !defined(PSP_BUILD) && !defined(WIZ_BUILD)
// run GBA at 60Hz (~0.5% faster) to better match host display
#define GBC_BASE_RATE GBA_60HZ_RATE
#else

#define SOUND_BUFFER_SIZE 16384

#define GBC_BASE_RATE GBA_XTAL
#endif

typedef enum
Expand All @@ -54,7 +51,7 @@ typedef struct
s8 fifo[32];
u32 fifo_base;
u32 fifo_top;
fixed16_16 fifo_fractional;
fixed8_24 fifo_fractional;
// The + 1 is to give some extra room for linear interpolation
// when wrapping around.
u32 buffer_index;
Expand Down Expand Up @@ -109,6 +106,8 @@ extern s8 square_pattern_duty[4][8];
extern u32 gbc_sound_master_volume_left;
extern u32 gbc_sound_master_volume_right;
extern u32 gbc_sound_master_volume;
extern u32 gbc_sound_buffer_index;
extern u32 gbc_sound_last_cpu_ticks;

extern u32 sound_frequency;
extern u32 sound_on;
Expand All @@ -122,7 +121,7 @@ extern SDL_mutex *sound_mutex;
void sound_timer_queue8(u32 channel, u8 value);
void sound_timer_queue16(u32 channel, u16 value);
void sound_timer_queue32(u32 channel, u32 value);
void sound_timer(fixed16_16 frequency_step, u32 channel);
void sound_timer(fixed8_24 frequency_step, u32 channel);
void sound_reset_fifo(u32 channel);
void update_gbc_sound(u32 cpu_ticks);
void init_sound();
Expand Down Expand Up @@ -320,7 +319,7 @@ static u32 gbc_sound_wave_volume[4] = { 0, 16384, 8192, 4096 };

#define sound_update_frequency_step(timer_number) \
timer[timer_number].frequency_step = \
float_to_fp16_16(16777216.0 / (timer_reload * sound_frequency)) \
float_to_fp8_24(GBC_BASE_RATE / (timer_reload * sound_frequency)) \

#endif // IN_MEMORY_C

Expand Down

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