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.
16 #include <sys/ioctl.h>
17 #include <linux/videodev2.h>
18 #include <bmusb/bmusb.h>
20 #include <immintrin.h>
25 using namespace bmusb;
30 void frame_callback(uint16_t timecode,
31 FrameAllocator::Frame video_frame, size_t video_offset, VideoFormat video_format,
32 FrameAllocator::Frame audio_frame, size_t audio_offset, AudioFormat audio_format)
34 printf("0x%04x: %zu video bytes (format 0x%04x, %d x %d)\n",
36 video_frame.len - video_offset, video_format.id, video_format.width, video_format.height);
38 static unsigned last_width = 0, last_height = 0, last_stride = 0;
40 if (video_format.width != last_width ||
41 video_format.height != last_height ||
42 video_format.stride != last_stride) {
44 memset(&fmt, 0, sizeof(fmt));
45 fmt.type = V4L2_BUF_TYPE_VIDEO_OUTPUT;
46 fmt.fmt.pix.width = video_format.width;
47 fmt.fmt.pix.height = video_format.height;
49 // Chrome accepts YUYV, but not our native UYVY. We byteswap below.
50 fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
52 fmt.fmt.pix.field = V4L2_FIELD_NONE;
53 fmt.fmt.pix.bytesperline = video_format.stride;
54 fmt.fmt.pix.sizeimage = video_format.stride * video_format.height;
55 fmt.fmt.pix.colorspace = V4L2_COLORSPACE_SRGB;
56 int err = ioctl(video_fd, VIDIOC_S_FMT, &fmt);
58 perror("ioctl(VIDIOC_S_FMT)");
59 usb->get_video_frame_allocator()->release_frame(video_frame);
60 usb->get_audio_frame_allocator()->release_frame(audio_frame);
63 last_width = video_format.width;
64 last_height = video_format.height;
65 last_stride = video_format.stride;
69 if (video_frame.data != nullptr) {
70 uint8_t *origptr = video_frame.data + video_offset + video_format.extra_lines_top * video_format.stride;
72 __m128i *ptr = (__m128i *)origptr;
73 for (unsigned i = 0; i < video_format.stride * video_format.height / 16; ++i) {
74 __m128i val = _mm_loadu_si128(ptr);
75 val = _mm_slli_epi16(val, 8) | _mm_srli_epi16(val, 8);
76 _mm_storeu_si128(ptr, val);
80 uint8_t *ptr = origptr;
81 for (unsigned i = 0; i < video_format.stride * video_format.height / 4; ++i) {
88 size_t len = video_frame.len;
90 ssize_t ret = write(video_fd, origptr, len);
96 break; // Hope for better luck next frame.
104 usb->get_video_frame_allocator()->release_frame(video_frame);
105 usb->get_audio_frame_allocator()->release_frame(audio_frame);
108 int main(int argc, char **argv)
110 const char *filename = (argc >= 2) ? argv[1] : "/dev/video2";
111 video_fd = open(filename, O_RDWR);
112 if (video_fd == -1) {
117 usb = new BMUSBCapture(0); // First card.
118 usb->set_frame_callback(frame_callback);
119 usb->configure_card();
120 BMUSBCapture::start_bm_thread();
121 usb->start_bm_capture();