From: Steinar H. Gunderson <sgunderson@bigfoot.com>
Date: Sun, 5 Apr 2020 15:34:02 +0000 (+0200)
Subject: Add a little program to proxy from bmusb to a V4L2 output.
X-Git-Tag: 0.7.5~5
X-Git-Url: https://git.sesse.net/?p=bmusb;a=commitdiff_plain;h=92bbe6548d1681d7cfae66e1c42f9770f3eec857

Add a little program to proxy from bmusb to a V4L2 output.
---

diff --git a/Makefile b/Makefile
index 23b458c..1c66611 100644
--- a/Makefile
+++ b/Makefile
@@ -11,13 +11,16 @@ SODEV := libbmusb.so
 SONAME := libbmusb.so.6
 SOLIB := libbmusb.so.6.0.0
 
-all: $(LIB) $(SOLIB) main
+all: $(LIB) $(SOLIB) main bmusb-v4l2proxy
 
 %.pic.o : %.cpp
 	$(CXX) $(CPPFLAGS) $(CXXFLAGS) -fPIC -o $@ -c $^
 
 main: bmusb.o main.o
-	$(CXX) -o main $^ $(LDFLAGS)
+	$(CXX) -o $@ $^ $(LDFLAGS)
+
+bmusb-v4l2proxy: bmusb.o v4l2proxy.o
+	$(CXX) -o $@ $^ $(LDFLAGS)
 
 # Static library.
 $(LIB): bmusb.o fake_capture.o
diff --git a/v4l2proxy.cpp b/v4l2proxy.cpp
new file mode 100644
index 0000000..2bb40aa
--- /dev/null
+++ b/v4l2proxy.cpp
@@ -0,0 +1,108 @@
+//
+// A helper proxy to send data from bmusb to a V4L2 output.
+// To get it as a V4L2 _input_, you can use v4l2loopback:
+//
+//   sudo apt install v4l2loopback-dkms v4l2loopback-utils
+//   sudo modprobe v4l2loopback video_nr=2 card_label='Intensity Shuttle (bmusb)' max_width=1280 max_height=720 exclusive_caps=1
+//   ./bmusb-v4l2proxy /dev/video2
+//
+// There is currently no audio support.
+
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <linux/videodev2.h>
+#include <bmusb/bmusb.h>
+#if __SSE2__
+#include <immintrin.h>
+#endif
+
+using namespace bmusb;
+
+BMUSBCapture *usb;
+int video_fd;
+
+void frame_callback(uint16_t timecode,
+                    FrameAllocator::Frame video_frame, size_t video_offset, VideoFormat video_format,
+                    FrameAllocator::Frame audio_frame, size_t audio_offset, AudioFormat audio_format)
+{
+	printf("0x%04x: %zu video bytes (format 0x%04x, %d x %d)\n",
+		timecode,
+		video_frame.len - video_offset, video_format.id, video_format.width, video_format.height);
+
+	static unsigned last_width = 0, last_height = 0, last_stride = 0;
+
+	if (video_format.width != last_width ||
+	    video_format.height != last_height ||
+	    video_format.stride != last_stride) {
+		v4l2_format fmt;
+		memset(&fmt, 0, sizeof(fmt));
+		fmt.type = V4L2_BUF_TYPE_VIDEO_OUTPUT;
+		fmt.fmt.pix.width = video_format.width;
+		fmt.fmt.pix.height = video_format.height;
+
+		// Chrome accepts YUYV, but not our native UYVY. We byteswap below.
+		fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
+
+		fmt.fmt.pix.field = V4L2_FIELD_NONE;
+		fmt.fmt.pix.bytesperline = video_format.stride;
+		fmt.fmt.pix.sizeimage = video_format.stride * video_format.height;
+		fmt.fmt.pix.colorspace = V4L2_COLORSPACE_SRGB;
+		int err = ioctl(video_fd, VIDIOC_S_FMT, &fmt);
+		if (err == -1) {
+			perror("ioctl(VIDIOC_S_FMT)");
+			usb->get_video_frame_allocator()->release_frame(video_frame);
+			usb->get_audio_frame_allocator()->release_frame(audio_frame);
+			return;
+		} else {
+			last_width = video_format.width;
+			last_height = video_format.height;
+			last_stride = video_format.stride;
+		}
+	}
+
+	if (video_frame.data != nullptr) {
+		uint8_t *origptr = video_frame.data + video_offset + video_format.extra_lines_top * video_format.stride;
+#if __SSE2__
+		__m128i *ptr = (__m128i *)origptr;
+		for (unsigned i = 0; i < video_format.width * video_format.height / 8; ++i) {
+			__m128i val = _mm_loadu_si128(ptr);
+			val = _mm_slli_epi16(val, 8) | _mm_srli_epi16(val, 8);
+			_mm_storeu_si128(ptr, val);
+			++ptr;
+		}
+#else
+		uint8_t *ptr = origptr;
+		for (unsigned i = 0; i < video_format.width * video_format.height; ++i) {
+			swap(ptr[0], ptr[1]);
+			swap(ptr[2], ptr[3]);
+			ptr += 4;
+		}
+#endif
+
+		write(video_fd, origptr, video_frame.len);
+	}
+
+	usb->get_video_frame_allocator()->release_frame(video_frame);
+	usb->get_audio_frame_allocator()->release_frame(audio_frame);
+}
+
+int main(int argc, char **argv)
+{
+	const char *filename = (argc >= 2) ? argv[1] : "/dev/video2";
+	video_fd = open(filename, O_RDWR);
+	if (video_fd == -1) {
+		perror(filename);
+		exit(1);
+	}
+
+	usb = new BMUSBCapture(0);  // First card.
+	usb->set_frame_callback(frame_callback);
+	usb->configure_card();
+	BMUSBCapture::start_bm_thread();
+	usb->start_bm_capture();
+	sleep(1000000);
+}
+