Gstreamer + OpenCV h264 编码和解码图像变形问题

Question

Hardware: Apalis IMX8 CPU(SOM) and Sensoray model-1012 video frame grabber

I am trying to save analog video with h264 coding and play it. The code has 3 parts. Reading camera, saving video with coding and playing video with decoding.

The problem i am facing is on decoding part. When i decode and show video it corrupts.

How i read analog video(Works fine):

cap = cv::VideoCapture(" v4l2src device=/dev/video4 ! video/x-raw, format=(string)YUY2, width=(int)720, height=(int)480, framerate=30/1, interlace-mode=interleaved ! deinterlace fields=1 method=2 ! videoconvert ! appsink ",cv::CAP_GSTREAMER);

How i compress and save video(Works fine):

cv::VideoWriter fixedVideo;
QString pipeTmp =  "appsrc ! videoconvert ! v4l2h264enc ! h264parse ! qtmux ! filesink location="+ FixedIMG_recordName +" sync=false ";
std::string pipe = pipeTmp.toUtf8().constData();
isOpen = fixedVideo.open(pipe , cv::CAP_GSTREAMER, (double)30, cv::Size(720,480), true);

How i decode and open video( DOESNT Work Fine ):

cv::VideoCapture cap_reader;
QString pipeTmp = " filesrc location=" + device + " ! qtdemux ! h264parse ! video/x-h264, width=720, height=480 ! v4l2h264dec ! videoconvert ! appsink ";
std::string pipe = pipeTmp.toUtf8().constData();
cap_reader.open(pipe , cv::CAP_GSTREAMER);

when i open cap_read pipe line to play same video from gstreamer command line pipe it works fine with some warnings. I put the GST_DEBUG output in log.txt Pipe line:

GST_DEBUG=3 gst-launch-1.0 -v filesrc location=test.mp4 ! qtdemux ! h264parse ! 'video/x-h264, width=720, height=480, framerate=30/1' ! v4l2h264dec ! videoconvert ! autovideosink

When i open the video from VLC it also works fine. But when i open the video from VideoCapture and the pipeline that i gave above it corrupts. The corrupted image example .

Answer 1

There is no problem in compression. When you decode mp4 file, you should use "imxvideoconvert_g2d".

Decode pipeline should be filesrc location=" + device + " ! qtdemux ! h264parse ! video/x-h264, width=720, height=480 ! v4l2h264dec ! imxvideoconverter_g2d ! video/x-raw,format=UYVY,width=720,height=480 ! videoconvert ! appsink