[参考译文] [TDA4VM] V4L2支持的输入格式

root@j7-evm:~# v4l2-ctl --list-devices
vxd-dec (platform:vxd-dec):
        /dev/video0

vxe-enc (platform:vxe-enc):
        /dev/video1

mfc_fd = open(/dev/video1, O_RDWR | O_NONBLOCK, 0);
v4l2_capability cap = { 0 };
int ret = ioctl(mfc_fd, VIDIOC_QUERYCAP, &cap);
fprintf(stderr, "Querycaps: fd=%#x driver=%s card=%s bus_info=%s\n", mfc_fd, cap.driver, cap.card, cap.bus_info);
fprintf(stderr, "Querycaps: device_caps=%#08x capabilities=%#08x\n", cap.device_caps, cap.capabilities);
{
    struct v4l2_fmtdesc desc = {0};
    struct v4l2_frmsizeenum frmsize = {0};
    desc.index = 0;
    desc.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
    fprintf(stderr, "Calling VIDIOC_ENUM_FMT on CAPTURE:\n");
    while ((ret = ioctl(mfc_fd, VIDIOC_ENUM_FMT, &desc)) == 0)
    {
      fprintf(stderr, "\tdesc.index = %d, pixelformat=0x%x, description = %s\n", desc.index, desc.pixelformat, desc.description);
      desc.index++;
    }

    desc.index = 0;
    desc.type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
    fprintf(stderr, "Calling VIDIOC_ENUM_FMT on OUTPUT:\n");
    while((ret = ioctl(mfc_fd, VIDIOC_ENUM_FMT, &desc))==0)
    {
      fprintf(stderr, "\tdesc.index = %d, pixelformat=0x%x, description = %s\n", desc.index, desc.pixelformat, desc.description);
      desc.index++;
    }

    frmsize.index = 0;
    fprintf(stderr, "Calling VIDIOC_ENUM_FRAMESIZES:\n");
    ret = ioctl(mfc_fd, VIDIOC_ENUM_FRAMESIZES, &frmsize);
    if (ret)
    {
      throw Exception("VIDIOC_ENUM_FRAMESIZES failed.");
    }
    else if (frmsize.type == V4L2_FRMSIZE_TYPE_DISCRETE)
    {
      fprintf(stderr, "VIDIOC_ENUM_FRAMESIZES got DISCRETE\n");
      fprintf(stderr, "\tfrmsizes[%d] width=%d height=%d\n", frmsize.index, frmsize.discrete.width, frmsize.discrete.height);
      frmsize.index++;
      while ((ret = ioctl(mfc_fd, VIDIOC_ENUM_FRAMESIZES, &frmsize)) == 0)
      {
        fprintf(stderr, "\t\tfrmsizes[%d] width=%d height=%d\n", frmsize.index, frmsize.discrete.width, frmsize.discrete.height);
        frmsize.index++;
      }
    }
    else
    {
      fprintf(stderr, "VIDIOC_ENUM_FRAMESIZES types got %d\n", frmsize.type);
      fprintf(stderr, "\tfrmsizes[%d] width=%d height=%d\n", frmsize.index, frmsize.discrete.width, frmsize.discrete.height);
      frmsize.index++;
    }
}

Querycaps: fd=0x7f driver=vxe-enc card=vxe-enc bus_info=platform:vxe-enc
Querycaps: device_caps=0x4204000 capabilities=0x84204000
Calling VIDIOC_ENUM_FMT on CAPTURE:
        desc.index = 0, pixelformat=0x34363248, description = H.264
Calling VIDIOC_ENUM_FMT on OUTPUT:
        desc.index = 0, pixelformat=0x3231564e, description = Y/CbCr 4:2:0
        desc.index = 1, pixelformat=0x34424752, description = 32-bit A/XRGB 8-8-8-8
Calling VIDIOC_ENUM_FRAMESIZES:
VIDIOC_ENUM_FRAMESIZES types got 2
        frmsizes[0] width=1 height=1920
VIDIOC_ENUM_FRAMEINTERVALS got DISCRETE
fival[0] numerator=1 denominator=15 framerate=15