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v4l2: use dll to track rate difference

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Track the difference between the configured and real framerate and use
that as the rate correction to adjust the next_nsec clock field.
This commit is contained in:
Wim Taymans 2024-11-26 17:14:26 +01:00
parent 043245ca11
commit 41e35c7b17
5 changed files with 40 additions and 5 deletions
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19
spa/plugins/v4l2/v4l2-utils.c
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@ -1429,7 +1429,21 @@ static int mmap_read(struct impl *this)
pts = SPA_TIMEVAL_TO_NSEC(&buf.timestamp);
if (this->clock) {
double target = (double)port->info.rate.num / port->info.rate.denom;
double corr;
if (this->dll.bw == 0.0) {
spa_dll_set_bw(&this->dll, SPA_DLL_BW_MAX, port->info.rate.denom, port->info.rate.denom);
this->clock->next_nsec = pts;
corr = 1.0;
} else {
double diff = ((double)this->clock->next_nsec - (double)pts) / SPA_NSEC_PER_SEC;
double error = port->info.rate.denom * (diff - target);
corr = spa_dll_update(&this->dll, SPA_CLAMPD(error, -128., 128.));
}
/* FIXME, we should follow the driver clock and target_ values.
* for now we ignore and use our own. */
this->clock->target_rate = port->info.rate;
@ -1440,8 +1454,8 @@ static int mmap_read(struct impl *this)
this->clock->position = buf.sequence;
this->clock->duration = 1;
this->clock->delay = 0;
this->clock->rate_diff = 1.0;
this->clock->next_nsec = pts + port->info.rate.num * SPA_NSEC_PER_SEC / port->info.rate.denom;
this->clock->rate_diff = corr;
this->clock->next_nsec += (uint64_t) (target * SPA_NSEC_PER_SEC * corr);
}
b = &port->buffers[buf.index];
@ -1856,6 +1870,7 @@ static int spa_v4l2_stream_on(struct impl *this)
spa_log_error(this->log, "'%s' VIDIOC_STREAMON: %m", this->props.device);
return -errno;
}
this->dll.bw = 0.0;
port->source.func = v4l2_on_fd_events;
port->source.data = this;