NvVideoEncoder: different between output and capture plane format

Robotics & Edge Computing Jetson & Embedded Systems Jetson Nano
1

Hello!
I see tegra_multimedia_api/samples/common/classes/NvVideoEncoder.cpp and I have question

int
NvVideoEncoder::setOutputPlaneFormat(uint32_t pixfmt, uint32_t width,
        uint32_t height)
{
    struct v4l2_format format;
    uint32_t num_bufferplanes;
    NvBuffer::NvBufferPlaneFormat planefmts[MAX_PLANES];

    if (pixfmt != V4L2_PIX_FMT_YUV420M && pixfmt != V4L2_PIX_FMT_YUV444M &&
        pixfmt != V4L2_PIX_FMT_P010M)
    {
........

NvVideoEncoder::setCapturePlaneFormat(uint32_t pixfmt, uint32_t width,
        uint32_t height, uint32_t sizeimage)
{
    struct v4l2_format format;

    memset(&format, 0, sizeof(struct v4l2_format));
    format.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
    switch (pixfmt)
    {
        case V4L2_PIX_FMT_H264:
        case V4L2_PIX_FMT_H265:
        case V4L2_PIX_FMT_VP8:
        case V4L2_PIX_FMT_VP9:
.........

According to this code capture plane format is a encoder output, output plane format is encoder input, right?
But at same time setFrameRate() apply parameters to output plane, but if it encoder input this configure sensor framerate? So I can’t capture from sensor 60 fps and encode 30 fps?
Thank you.

2

Hi,

Yes.

setFrameRate() is to provide information of bitrate control. To encode 30fps and bitrate 4Mbps in constant bit rate mode, each frame has rough 4M/30 bits. For 60fps, it is 4M/60 bits. Sensor frame rate can be arbitrary and not required to be same as setFrameRate().