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//
// 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 <errno.h>
#include <sys/ioctl.h>
#include <linux/videodev2.h>
#include <bmusb/bmusb.h>
#if __SSE2__
#include <immintrin.h>
#endif
#include <algorithm>
using namespace std;
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.stride * video_format.height / 16; ++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.stride * video_format.height / 4; ++i) {
swap(ptr[0], ptr[1]);
swap(ptr[2], ptr[3]);
ptr += 4;
}
#endif
size_t len = video_frame.len;
while (len > 0) {
ssize_t ret = write(video_fd, origptr, len);
if (ret == -1) {
if (errno == EINTR) {
continue;
} else {
perror("write");
break; // Hope for better luck next frame.
}
}
origptr += ret;
len -= ret;
}
}
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);
}
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