How to record the 4k video in real time?

[cudawarped]

@credox

1. source is the /dev/video0

Ahh if it wasn’t hardware you could just directly read the raw encoded data and write to disk. I have done this on Windows with a slight modification but had limited success on linux see

VideoCapture from camera with CAP_PROP_FORMAT -1 (raw) and DSHOW/FFMPEG/windows

I performed a quick test and it appears that you can retrieve the raw encoded MJPEG data from directshow using CAP_FFMPEG if you slightly modify the source and link OpenCV against libavdevice. You need to add avdevice_register_all(); to void CvCapture_FFMPEG::init() and #include <libavdevice/avdevice.h>. Unfortunatley this means you need to build OpenCV against FFMPEG libs and not use the precompiled dll - opencv_videoio_ffmpegxxx_64.dll. Once the modification is in place you simply ne…

and

Not able to read Video from Capture Card with GPU (Unsupported Format) while Reading with CPU works fine

cv::cuda::VideoReader uses the FFMPEG backend so if you can’t use cv::VideoCapture(src, CAP_FFMPEG) then it won’t work with cv::cuda::VideoReader. That said I did manage to get the FFMPEG backend to work with direct show you may be able to follow a similar procedure with V4L2 devices on linux but I coudn’t guarantee it. An alternative would be to write your own parser to read the raw input from your stereo cams by inheriting from cv::cudacodec::RawVideoSource.

if you are interested.

@credox

3. output.mp4 with the mp4v fourcc .

Hopefully soon the cv::cudacodec::VideoWriter class will be fixed so if you have an Nvidia GPU this would be an option, however you would only be able to encode to raw h264|hevc files. To get container formats like mp4 you would have to post process the output files with FFmpeg or similar.