From c7466ef67f76efdd9e8a151e8d0f38281199c2a9 Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
Date: Sat, 10 Dec 2016 12:10:04 +0100
Subject: [PATCH] Add timestamps on each received frame.

Note that this breaks the ABI.
---
 Makefile         | 4 ++--
 bmusb.cpp        | 5 +++++
 bmusb/bmusb.h    | 9 +++++++++
 fake_capture.cpp | 4 ++++
 4 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index ee0ba10..e1c33ec 100644
--- a/Makefile
+++ b/Makefile
@@ -7,8 +7,8 @@ INSTALL := install
 PREFIX := /usr/local
 LIB := libbmusb.a
 SODEV := libbmusb.so
-SONAME := libbmusb.so.1
-SOLIB := libbmusb.so.1.0.0
+SONAME := libbmusb.so.2
+SOLIB := libbmusb.so.2.0.0
 
 all: $(LIB) $(SOLIB) main
 
diff --git a/bmusb.cpp b/bmusb.cpp
index 2900709..9decbc9 100644
--- a/bmusb.cpp
+++ b/bmusb.cpp
@@ -25,6 +25,7 @@
 
 #include <algorithm>
 #include <atomic>
+#include <chrono>
 #include <condition_variable>
 #include <cstddef>
 #include <cstdint>
@@ -37,6 +38,7 @@
 #include <thread>
 
 using namespace std;
+using namespace std::chrono;
 using namespace std::placeholders;
 
 #define USB_VENDOR_BLACKMAGIC 0x1edb
@@ -362,6 +364,8 @@ void BMUSBCapture::start_new_frame(const uint8_t *start)
 	uint16_t timecode = (start[1] << 8) | start[0];
 
 	if (current_video_frame.len > 0) {
+		current_video_frame.received_timestamp = steady_clock::now();
+
 		// If format is 0x0800 (no signal), add a fake (empty) audio
 		// frame to get it out of the queue.
 		// TODO: Figure out if there are other formats that come with
@@ -405,6 +409,7 @@ void BMUSBCapture::start_new_audio_block(const uint8_t *start)
 	uint16_t format = (start[3] << 8) | start[2];
 	uint16_t timecode = (start[1] << 8) | start[0];
 	if (current_audio_frame.len > 0) {
+		current_audio_frame.received_timestamp = steady_clock::now();
 		//dump_audio_block();
 		queue_frame(format, timecode, current_audio_frame, &pending_audio_frames);
 	}
diff --git a/bmusb/bmusb.h b/bmusb/bmusb.h
index f4af6aa..6aabd51 100644
--- a/bmusb/bmusb.h
+++ b/bmusb/bmusb.h
@@ -4,6 +4,7 @@
 #include <libusb.h>
 #include <stdint.h>
 #include <atomic>
+#include <chrono>
 #include <condition_variable>
 #include <deque>
 #include <functional>
@@ -39,6 +40,14 @@ class FrameAllocator {
 		// If so, <len> and <size> are still about the number of total bytes
 		// so if size == 1024, there's 512 bytes in data and 512 in data2.
 		bool interleaved = false;
+
+		// At what point this frame was received. Note that this marks the
+		// _end_ of the frame being received, not the beginning.
+		// Thus, if you want to measure latency, you'll also need to include
+		// the time the frame actually took to transfer (usually 1/fps,
+		// ie., the frames are typically transferred in real time).
+		std::chrono::steady_clock::time_point received_timestamp =
+			std::chrono::steady_clock::time_point::min();
 	};
 
 	virtual ~FrameAllocator();
diff --git a/fake_capture.cpp b/fake_capture.cpp
index 5f53e95..fbcfedd 100644
--- a/fake_capture.cpp
+++ b/fake_capture.cpp
@@ -13,6 +13,7 @@
 #if __SSE2__
 #include <immintrin.h>
 #endif
+#include <chrono>
 #include <cstddef>
 
 #include "bmusb/bmusb.h"
@@ -26,6 +27,7 @@ constexpr uint8_t cbs[NUM_COLORS] = { 90, 54, 240, 128 };
 constexpr uint8_t crs[NUM_COLORS] = { 240, 34, 110, 128 };
 
 using namespace std;
+using namespace std::chrono;
 
 namespace bmusb {
 namespace {
@@ -255,6 +257,7 @@ void FakeCapture::producer_thread_func()
 				memset4(video_frame.data, ycbcr, width * height / 2);
 			}
 			video_frame.len = width * height * 2;
+			video_frame.received_timestamp = steady_clock::now();
 		}
 
 		AudioFormat audio_format;
@@ -266,6 +269,7 @@ void FakeCapture::producer_thread_func()
 			const unsigned num_stereo_samples = audio_sample_frequency / fps;
 			assert(audio_frame.size >= audio_format.num_channels * sizeof(int32_t) * num_stereo_samples);
 			audio_frame.len = audio_format.num_channels * sizeof(int32_t) * num_stereo_samples;
+			audio_frame.received_timestamp = steady_clock::now();
 
 			if (audio_sin == 0.0f) {
 				// Silence.
-- 
2.39.2