obs-studio/libobs/obs-video-gpu-encode.c

/******************************************************************************
    Copyright (C) 2023 by Lain Bailey <[email protected]>

    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 "obs-internal.h"

static void *gpu_encode_thread(struct obs_core_video_mix *video)
{
	uint64_t interval = video_output_get_frame_time(video->video);
	DARRAY(obs_encoder_t *) encoders;
	int wait_frames = NUM_ENCODE_TEXTURE_FRAMES_TO_WAIT;

	da_init(encoders);

	os_set_thread_name("obs gpu encode thread");

	while (os_sem_wait(video->gpu_encode_semaphore) == 0) {
		struct obs_tex_frame tf;
		uint64_t timestamp;
		uint64_t lock_key;
		uint64_t next_key;
		size_t lock_count = 0;

		if (os_atomic_load_bool(&video->gpu_encode_stop))
			break;

		if (wait_frames) {
			wait_frames--;
			continue;
		}

		os_event_reset(video->gpu_encode_inactive);

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

		pthread_mutex_lock(&video->gpu_encoder_mutex);

		circlebuf_pop_front(&video->gpu_encoder_queue, &tf, sizeof(tf));
		timestamp = tf.timestamp;
		lock_key = tf.lock_key;
		next_key = tf.lock_key;

		video_output_inc_texture_frames(video->video);

		for (size_t i = 0; i < video->gpu_encoders.num; i++) {
			obs_encoder_t *encoder = obs_encoder_get_ref(
				video->gpu_encoders.array[i]);
			if (encoder)
				da_push_back(encoders, &encoder);
		}

		pthread_mutex_unlock(&video->gpu_encoder_mutex);

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

		for (size_t i = 0; i < encoders.num; i++) {
			struct encoder_packet pkt = {0};
			bool received = false;
			bool success;
			uint32_t skip = 0;

			obs_encoder_t *encoder = encoders.array[i];
			struct obs_encoder *pair = encoder->paired_encoder;

			pkt.timebase_num = encoder->timebase_num *
					   encoder->frame_rate_divisor;
			pkt.timebase_den = encoder->timebase_den;
			pkt.encoder = encoder;

			if (!encoder->first_received && pair) {
				if (!pair->first_received ||
				    pair->first_raw_ts > timestamp) {
					continue;
				}
			}

			if (video_pause_check(&encoder->pause, timestamp))
				continue;

			if (encoder->reconfigure_requested) {
				encoder->reconfigure_requested = false;
				encoder->info.update(encoder->context.data,
						     encoder->context.settings);
			}

			// an explicit counter is used instead of remainder calculation
			// to allow multiple encoders started at the same time to start on
			// the same frame
			skip = encoder->frame_rate_divisor_counter++;
			if (encoder->frame_rate_divisor_counter ==
			    encoder->frame_rate_divisor)
				encoder->frame_rate_divisor_counter = 0;
			if (skip)
				continue;

			if (!encoder->start_ts)
				encoder->start_ts = timestamp;

			if (++lock_count == encoders.num)
				next_key = 0;
			else
				next_key++;

			success = encoder->info.encode_texture(
				encoder->context.data, tf.handle,
				encoder->cur_pts, lock_key, &next_key, &pkt,
				&received);
			send_off_encoder_packet(encoder, success, received,
						&pkt);

			lock_key = next_key;

			encoder->cur_pts += encoder->timebase_num *
					    encoder->frame_rate_divisor;
		}

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

		pthread_mutex_lock(&video->gpu_encoder_mutex);

		tf.lock_key = next_key;

		if (--tf.count) {
			tf.timestamp += interval;
			circlebuf_push_front(&video->gpu_encoder_queue, &tf,
					     sizeof(tf));

			video_output_inc_texture_skipped_frames(video->video);
		} else {
			circlebuf_push_back(&video->gpu_encoder_avail_queue,
					    &tf, sizeof(tf));
		}

		pthread_mutex_unlock(&video->gpu_encoder_mutex);

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

		os_event_signal(video->gpu_encode_inactive);

		for (size_t i = 0; i < encoders.num; i++)
			obs_encoder_release(encoders.array[i]);

		da_resize(encoders, 0);
	}

	da_free(encoders);
	return NULL;
}

bool init_gpu_encoding(struct obs_core_video_mix *video)
{
#ifdef _WIN32
	const struct video_output_info *info =
		video_output_get_info(video->video);

	video->gpu_encode_stop = false;

	circlebuf_reserve(&video->gpu_encoder_avail_queue, NUM_ENCODE_TEXTURES);
	for (size_t i = 0; i < NUM_ENCODE_TEXTURES; i++) {
		gs_texture_t *tex;
		gs_texture_t *tex_uv;

		if (info->format == VIDEO_FORMAT_P010) {
			gs_texture_create_p010(
				&tex, &tex_uv, info->width, info->height,
				GS_RENDER_TARGET | GS_SHARED_KM_TEX);
		} else {
			gs_texture_create_nv12(
				&tex, &tex_uv, info->width, info->height,
				GS_RENDER_TARGET | GS_SHARED_KM_TEX);
		}
		if (!tex) {
			return false;
		}

		uint32_t handle = gs_texture_get_shared_handle(tex);

		struct obs_tex_frame frame = {.tex = tex,
					      .tex_uv = tex_uv,
					      .handle = handle};

		circlebuf_push_back(&video->gpu_encoder_avail_queue, &frame,
				    sizeof(frame));
	}

	if (os_sem_init(&video->gpu_encode_semaphore, 0) != 0)
		return false;
	if (os_event_init(&video->gpu_encode_inactive, OS_EVENT_TYPE_MANUAL) !=
	    0)
		return false;
	if (pthread_create(&video->gpu_encode_thread, NULL, gpu_encode_thread,
			   video) != 0)
		return false;

	os_event_signal(video->gpu_encode_inactive);

	video->gpu_encode_thread_initialized = true;
	return true;
#else
	UNUSED_PARAMETER(video);
	return false;
#endif
}

void stop_gpu_encoding_thread(struct obs_core_video_mix *video)
{
	if (video->gpu_encode_thread_initialized) {
		os_atomic_set_bool(&video->gpu_encode_stop, true);
		os_sem_post(video->gpu_encode_semaphore);
		pthread_join(video->gpu_encode_thread, NULL);
		video->gpu_encode_thread_initialized = false;
	}
}

void free_gpu_encoding(struct obs_core_video_mix *video)
{
	if (video->gpu_encode_semaphore) {
		os_sem_destroy(video->gpu_encode_semaphore);
		video->gpu_encode_semaphore = NULL;
	}
	if (video->gpu_encode_inactive) {
		os_event_destroy(video->gpu_encode_inactive);
		video->gpu_encode_inactive = NULL;
	}

#define free_circlebuf(x)                                               \
	do {                                                            \
		while (x.size) {                                        \
			struct obs_tex_frame frame;                     \
			circlebuf_pop_front(&x, &frame, sizeof(frame)); \
			gs_texture_destroy(frame.tex);                  \
			gs_texture_destroy(frame.tex_uv);               \
		}                                                       \
		circlebuf_free(&x);                                     \
	} while (false)

	free_circlebuf(video->gpu_encoder_queue);
	free_circlebuf(video->gpu_encoder_avail_queue);
#undef free_circlebuf
}