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alsa: rework timing

Browse source 
Use a DLL to track the hardware pointer and use this to set the
timer.
Handle XRUN and recover.
This commit is contained in:
Wim Taymans 2018-11-16 17:00:40 +01:00
parent 5444b850d2
commit 0343297257
4 changed files with 270 additions and 232 deletions
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55
spa/plugins/alsa/alsa-utils.h
View file

@ -64,11 +64,15 @@ struct buffer {
struct spa_list link;
};
#define DLL_BW_MAX 0.256
#define DLL_BW_MIN 0.05
#define DLL_BW_PERIOD 4.0
struct dll {
double T;
double b, c;
double n0;
int count;
double w1, w2;
double base, t0, dt;
double bw;
int count;
};
struct state {
@ -95,7 +99,6 @@ struct state {
bool have_format;
struct spa_audio_info current_format;
struct dll dll;
double bw;
snd_pcm_uframes_t buffer_frames;
snd_pcm_uframes_t period_frames;
@ -109,6 +112,7 @@ struct state {
struct spa_io_range *range;
struct spa_io_clock *clock;
struct spa_io_position *position;
struct spa_io_sequence *notify;
struct buffer buffers[MAX_BUFFERS];
unsigned int n_buffers;
@ -127,9 +131,14 @@ struct state {
snd_htimestamp_t now;
int64_t sample_count;
int64_t filled;
int64_t sample_time;
uint64_t last_time;
uint64_t next_time;
uint64_t underrun;
double old_dt;
double safety;
};
int
@ -141,40 +150,42 @@ spa_alsa_enum_format(struct state *state,
int spa_alsa_set_format(struct state *state, struct spa_audio_info *info, uint32_t flags);
int spa_alsa_start(struct state *state, bool xrun_recover);
int spa_alsa_pause(struct state *state, bool xrun_recover);
int spa_alsa_start(struct state *state);
int spa_alsa_pause(struct state *state);
int spa_alsa_close(struct state *state);
int spa_alsa_write(struct state *state, snd_pcm_uframes_t silence);
static inline void dll_bandwidth(struct dll *dll, double period, double rate, double bandwidth)
static inline void dll_bandwidth(struct dll *dll, double bandwidth)
{
double w = 2 * M_PI * bandwidth * period / rate;
dll->b = 1.0 - exp(-M_SQRT2 * w);
dll->c = (1.0 - exp(-w * w)) / period;
double w = 2 * M_PI * bandwidth;
dll->w1 = w * M_SQRT2;
dll->w2 = w * w;
dll->bw = bandwidth;
dll->base = dll->t0;
}
static inline void dll_init(struct dll *dll, double period, double rate, double bandwidth)
static inline void dll_init(struct dll *dll, double bandwidth)
{
dll->T = 1000000.0 / rate;
dll->dt = 1.0;
dll->count = 0;
dll_bandwidth(dll, period, rate, bandwidth);
dll_bandwidth(dll, bandwidth);
}
static inline double dll_update(struct dll *dll, double system_time, double period)
static inline double dll_update(struct dll *dll, double tw, double period)
{
double e;
if (dll->count++ == 0) {
dll->n0 = system_time;
dll->t0 = dll->base = tw;
} else {
dll->n0 += period * dll->T;
e = system_time - dll->n0;
dll->n0 += SPA_MAX(dll->b, 1.0 / dll->count) * e;
dll->T += dll->c * e;
dll->t0 += dll->dt * period;
e = (tw - dll->t0) * period;
dll->t0 += dll->w1 * e;
dll->dt += dll->w2 * e;
}
return dll->n0;
return dll->t0;
}
#ifdef __cplusplus