From 90b7a5600fa239bf3350e96698d676c3fd98d510 Mon Sep 17 00:00:00 2001
From: Devaev Maxim <mdevaev@gmail.com>
Date: Sat, 22 Aug 2020 16:15:26 +0300
Subject: [PATCH] Issue #24: disable software framedrop if hw_fps ==
 desired_fps

---
 src/device.c | 19 ++++++++++++++++---
 src/device.h |  1 +
 src/stream.c | 15 +++++++++++----
 3 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/src/device.c b/src/device.c
index ecc9cdc..b6e397b 100644
--- a/src/device.c
+++ b/src/device.c
@@ -501,6 +501,8 @@ static int _device_open_format(struct device_t *dev) {
 static void _device_open_hw_fps(struct device_t *dev) {
 	struct v4l2_streamparm setfps;
 
+	dev->run->hw_fps = 0;
+
 	MEMSET_ZERO(setfps);
 	setfps.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
 
@@ -531,10 +533,21 @@ static void _device_open_hw_fps(struct device_t *dev) {
 		return;
 	}
 
-	if (dev->desired_fps != SETFPS_TPF(denominator)) {
-		LOG_INFO("Using HW FPS: %u -> %u (coerced)", dev->desired_fps, SETFPS_TPF(denominator));
+	if (SETFPS_TPF(numerator) != 1) {
+		LOG_ERROR("Invalid HW FPS numerator: %u != 1", SETFPS_TPF(numerator));
+		return;
+	}
+
+	if (SETFPS_TPF(denominator) == 0) { // Не знаю, бывает ли так, но пускай на всякий случай
+		LOG_ERROR("Invalid HW FPS denominator: 0");
+		return;
+	}
+
+	dev->run->hw_fps = SETFPS_TPF(denominator);
+	if (dev->desired_fps != dev->run->hw_fps) {
+		LOG_INFO("Using HW FPS: %u -> %u (coerced)", dev->desired_fps, dev->run->hw_fps);
 	} else {
-		LOG_INFO("Using HW FPS: %u", dev->desired_fps);
+		LOG_INFO("Using HW FPS: %u", dev->run->hw_fps);
 	}
 
 #	undef SETFPS_TPF
diff --git a/src/device.h b/src/device.h
index e564bbb..28df5ad 100644
--- a/src/device.h
+++ b/src/device.h
@@ -60,6 +60,7 @@ struct device_runtime_t {
 	unsigned			width;
 	unsigned			height;
 	unsigned			format;
+	unsigned			hw_fps;
 	size_t				raw_size;
 	unsigned			n_buffers;
 	unsigned			n_workers;
diff --git a/src/stream.c b/src/stream.c
index b783397..06b6ea7 100644
--- a/src/stream.c
+++ b/src/stream.c
@@ -350,11 +350,14 @@ static void _stream_expose_picture(struct stream_t *stream, unsigned buf_index,
 static struct _workers_pool_t *_workers_pool_init(struct stream_t *stream) {
 	struct _workers_pool_t *pool;
 
-	LOG_INFO("Creating pool with %u workers ...", stream->dev->run->n_workers);
+#	define DEV(_next) stream->dev->_next
+#	define RUN(_next) stream->dev->run->_next
+
+	LOG_INFO("Creating pool with %u workers ...", RUN(n_workers));
 
 	A_CALLOC(pool, 1);
 
-	pool->n_workers = stream->dev->run->n_workers;
+	pool->n_workers = RUN(n_workers);
 	A_CALLOC(pool->workers, pool->n_workers);
 
 	A_MUTEX_INIT(&pool->free_workers_mutex);
@@ -362,10 +365,13 @@ static struct _workers_pool_t *_workers_pool_init(struct stream_t *stream) {
 
 	atomic_init(&pool->workers_stop, false);
 
-	if (stream->dev->desired_fps > 0) {
-		pool->desired_frames_interval = (long double)1 / stream->dev->desired_fps;
+	if (DEV(desired_fps) > 0 && (DEV(desired_fps) < RUN(hw_fps) || RUN(hw_fps) == 0)) {
+		pool->desired_frames_interval = (long double)1 / DEV(desired_fps);
 	}
 
+#	undef RUN
+#	undef DEV
+
 	for (unsigned number = 0; number < pool->n_workers; ++number) {
 #		define WORKER(_next) pool->workers[number]._next
 
@@ -557,6 +563,7 @@ static long double _workers_pool_get_fluency_delay(struct _workers_pool_t *pool,
 
 	if (pool->desired_frames_interval > 0 && min_delay > 0 && pool->desired_frames_interval > min_delay) {
 		// Искусственное время задержки на основе желаемого FPS, если включен --desired-fps
+		// и аппаратный fps не попадает точно в желаемое значение
 		return pool->desired_frames_interval;
 	}
 	return min_delay;