obs-studio/libobs/obs-output-delay.c

/******************************************************************************
    Copyright (C) 2023 by Lain Bailey <lain@obsproject.com>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
******************************************************************************/

#include <inttypes.h>
#include "obs-internal.h"

static inline bool delay_active(const struct obs_output *output)
{
	return os_atomic_load_bool(&output->delay_active);
}

static inline bool delay_capturing(const struct obs_output *output)
{
	return os_atomic_load_bool(&output->delay_capturing);
}

static inline bool flag_encoded(const struct obs_output *output)
{
	return (output->info.flags & OBS_OUTPUT_ENCODED) != 0;
}

static inline bool log_flag_encoded(const struct obs_output *output,
				    const char *func_name, bool inverse_log)
{
	const char *prefix = inverse_log ? "n encoded" : " raw";
	bool ret = flag_encoded(output);
	if ((!inverse_log && !ret) || (inverse_log && ret))
		blog(LOG_WARNING, "Output '%s': Tried to use %s on a%s output",
		     output->context.name, func_name, prefix);
	return ret;
}

static inline void push_packet(struct obs_output *output,
			       struct encoder_packet *packet, uint64_t t)
{
	struct delay_data dd;

	dd.msg = DELAY_MSG_PACKET;
	dd.ts = t;
	obs_encoder_packet_create_instance(&dd.packet, packet);

	pthread_mutex_lock(&output->delay_mutex);
	circlebuf_push_back(&output->delay_data, &dd, sizeof(dd));
	pthread_mutex_unlock(&output->delay_mutex);
}

static inline void process_delay_data(struct obs_output *output,
				      struct delay_data *dd)
{
	switch (dd->msg) {
	case DELAY_MSG_PACKET:
		if (!delay_active(output) || !delay_capturing(output))
			obs_encoder_packet_release(&dd->packet);
		else
			output->delay_callback(output, &dd->packet);
		break;
	case DELAY_MSG_START:
		obs_output_actual_start(output);
		break;
	case DELAY_MSG_STOP:
		obs_output_actual_stop(output, false, dd->ts);
		break;
	}
}

void obs_output_cleanup_delay(obs_output_t *output)
{
	struct delay_data dd;

	while (output->delay_data.size) {
		circlebuf_pop_front(&output->delay_data, &dd, sizeof(dd));
		if (dd.msg == DELAY_MSG_PACKET) {
			obs_encoder_packet_release(&dd.packet);
		}
	}

	output->active_delay_ns = 0;
	os_atomic_set_long(&output->delay_restart_refs, 0);
}

static inline bool pop_packet(struct obs_output *output, uint64_t t)
{
	uint64_t elapsed_time;
	struct delay_data dd;
	bool popped = false;
	bool preserve;

	/* ------------------------------------------------ */

	preserve = (output->delay_cur_flags & OBS_OUTPUT_DELAY_PRESERVE) != 0;

	pthread_mutex_lock(&output->delay_mutex);

	if (output->delay_data.size) {
		circlebuf_peek_front(&output->delay_data, &dd, sizeof(dd));
		elapsed_time = (t - dd.ts);

		if (preserve && output->reconnecting) {
			output->active_delay_ns = elapsed_time;

		} else if (elapsed_time > output->active_delay_ns) {
			circlebuf_pop_front(&output->delay_data, NULL,
					    sizeof(dd));
			popped = true;
		}
	}

	pthread_mutex_unlock(&output->delay_mutex);

	/* ------------------------------------------------ */

	if (popped)
		process_delay_data(output, &dd);

	return popped;
}

void process_delay(void *data, struct encoder_packet *packet)
{
	struct obs_output *output = data;
	uint64_t t = os_gettime_ns();
	push_packet(output, packet, t);
	while (pop_packet(output, t))
		;
}

void obs_output_signal_delay(obs_output_t *output, const char *signal)
{
	struct calldata params;
	uint8_t stack[128];

	calldata_init_fixed(&params, stack, sizeof(stack));
	calldata_set_ptr(&params, "output", output);
	calldata_set_int(&params, "sec", output->active_delay_ns / 1000000000);
	signal_handler_signal(output->context.signals, signal, &params);
}

bool obs_output_delay_start(obs_output_t *output)
{
	struct delay_data dd = {
		.msg = DELAY_MSG_START,
		.ts = os_gettime_ns(),
	};

	if (!delay_active(output)) {
		bool can_begin = obs_output_can_begin_data_capture(output, 0);
		if (!can_begin)
			return false;
		if (!obs_output_initialize_encoders(output, 0))
			return false;
	}

	pthread_mutex_lock(&output->delay_mutex);
	circlebuf_push_back(&output->delay_data, &dd, sizeof(dd));
	pthread_mutex_unlock(&output->delay_mutex);

	os_atomic_inc_long(&output->delay_restart_refs);

	if (delay_active(output)) {
		do_output_signal(output, "starting");
		return true;
	}

	if (!obs_output_begin_data_capture(output, 0)) {
		obs_output_cleanup_delay(output);
		return false;
	}

	return true;
}

void obs_output_delay_stop(obs_output_t *output)
{
	struct delay_data dd = {
		.msg = DELAY_MSG_STOP,
		.ts = os_gettime_ns(),
	};

	pthread_mutex_lock(&output->delay_mutex);
	circlebuf_push_back(&output->delay_data, &dd, sizeof(dd));
	pthread_mutex_unlock(&output->delay_mutex);

	do_output_signal(output, "stopping");
}

void obs_output_set_delay(obs_output_t *output, uint32_t delay_sec,
			  uint32_t flags)
{
	if (!obs_output_valid(output, "obs_output_set_delay"))
		return;
	if (!log_flag_encoded(output, __FUNCTION__, false))
		return;

	output->delay_sec = delay_sec;
	output->delay_flags = flags;
}

uint32_t obs_output_get_delay(const obs_output_t *output)
{
	return obs_output_valid(output, "obs_output_set_delay")
		       ? output->delay_sec
		       : 0;
}

uint32_t obs_output_get_active_delay(const obs_output_t *output)
{
	return obs_output_valid(output, "obs_output_set_delay")
		       ? (uint32_t)(output->active_delay_ns / 1000000000ULL)
		       : 0;
}