2 // A helper proxy to send data from bmusb to a V4L2 output.
3 // To get it as a V4L2 _input_, you can use v4l2loopback:
5 // sudo apt install v4l2loopback-dkms v4l2loopback-utils
6 // sudo modprobe v4l2loopback video_nr=2 card_label='Intensity Shuttle (bmusb)' max_width=1280 max_height=720 exclusive_caps=1
7 // ./bmusb-v4l2proxy /dev/video2
9 // There is currently no audio support.
15 #include <sys/ioctl.h>
16 #include <linux/videodev2.h>
17 #include <bmusb/bmusb.h>
19 #include <immintrin.h>
24 using namespace bmusb;
29 void frame_callback(uint16_t timecode,
30 FrameAllocator::Frame video_frame, size_t video_offset, VideoFormat video_format,
31 FrameAllocator::Frame audio_frame, size_t audio_offset, AudioFormat audio_format)
33 printf("0x%04x: %zu video bytes (format 0x%04x, %d x %d)\n",
35 video_frame.len - video_offset, video_format.id, video_format.width, video_format.height);
37 static unsigned last_width = 0, last_height = 0, last_stride = 0;
39 if (video_format.width != last_width ||
40 video_format.height != last_height ||
41 video_format.stride != last_stride) {
43 memset(&fmt, 0, sizeof(fmt));
44 fmt.type = V4L2_BUF_TYPE_VIDEO_OUTPUT;
45 fmt.fmt.pix.width = video_format.width;
46 fmt.fmt.pix.height = video_format.height;
48 // Chrome accepts YUYV, but not our native UYVY. We byteswap below.
49 fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
51 fmt.fmt.pix.field = V4L2_FIELD_NONE;
52 fmt.fmt.pix.bytesperline = video_format.stride;
53 fmt.fmt.pix.sizeimage = video_format.stride * video_format.height;
54 fmt.fmt.pix.colorspace = V4L2_COLORSPACE_SRGB;
55 int err = ioctl(video_fd, VIDIOC_S_FMT, &fmt);
57 perror("ioctl(VIDIOC_S_FMT)");
58 usb->get_video_frame_allocator()->release_frame(video_frame);
59 usb->get_audio_frame_allocator()->release_frame(audio_frame);
62 last_width = video_format.width;
63 last_height = video_format.height;
64 last_stride = video_format.stride;
68 if (video_frame.data != nullptr) {
69 uint8_t *origptr = video_frame.data + video_offset + video_format.extra_lines_top * video_format.stride;
71 __m128i *ptr = (__m128i *)origptr;
72 for (unsigned i = 0; i < video_format.stride * video_format.height / 16; ++i) {
73 __m128i val = _mm_loadu_si128(ptr);
74 val = _mm_slli_epi16(val, 8) | _mm_srli_epi16(val, 8);
75 _mm_storeu_si128(ptr, val);
79 uint8_t *ptr = origptr;
80 for (unsigned i = 0; i < video_format.stride * video_format.height / 4; ++i) {
87 write(video_fd, origptr, video_frame.len);
90 usb->get_video_frame_allocator()->release_frame(video_frame);
91 usb->get_audio_frame_allocator()->release_frame(audio_frame);
94 int main(int argc, char **argv)
96 const char *filename = (argc >= 2) ? argv[1] : "/dev/video2";
97 video_fd = open(filename, O_RDWR);
103 usb = new BMUSBCapture(0); // First card.
104 usb->set_frame_callback(frame_callback);
105 usb->configure_card();
106 BMUSBCapture::start_bm_thread();
107 usb->start_bm_capture();