Writing RGB frames into video

Python
1

Hello Everyone,

I have got a rookie question. I am receiving YUV420 frames from a picamera (YUV420 is required for acquisition speed), I convert them to RGB and then the frames are written into a video file. However the video file is not readable. Individual RGB frames can be displayed using imshow. I tried different conversion methods and video codecs. If I query RGB frames from the camera directly, videos are fine. If anyone has an idea, I would be very grateful.

import numpy as np
import cv2 
import time
from picamera2 import Picamera2


def setcam(resolutionLow,resolutionHigh):
    picam2 = Picamera2()
    preview_config = picam2.create_preview_configuration(lores={"size": resolutionLow})
    capture_config = picam2.create_still_configuration(main={"size": resolutionHigh, "format": "YUV420"})    
    return picam2,preview_config, capture_config



#some vars, to be arguments later on 
numFrames = 10
npName = 'test.csv'
videoName = 'testVideo.avi'
frameRate = 2
holdTime = 1/frameRate - 0.3
hiRes = (4056,3040)
loRes = (640,480)

#writer= cv2.VideoWriter(videoName, cv2.VideoWriter_fourcc('M', 'J', 'P', 'G'), frameRate, hiRes)
writer= cv2.VideoWriter(videoName, cv2.VideoWriter_fourcc('h','2','6','4'), frameRate, hiRes)
picam2,video_config,image_config = setcam(loRes,hiRes)
picam2.configure(image_config)
picam2.start()
time.sleep(2)


counter = 0
for i in range(0,numFrames):
    rgb = np.uint8(cv2.cvtColor(picam2.capture_array(), cv2.COLOR_YUV420p2RGB))  #COLOR_YUV420p2RGB
    writer.write(rgb)
    cv2.imshow('frame', rgb)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break
    if counter == numFrames:
        break
    counter = counter + 1
    time.sleep(holdTime)
    



picam2.close()
writer.release()
cv2.destroyAllWindows()
print('TERMINATED')
2

assert writer.isOpened()

3

writer.isOpened() returns True. rgb has the shape (3040, 4096, 3). Could there be anything wrong with the dimensions in the rgb array?

4

Yes. It needs to exactly match the size used in initializing the writer, so you need to resize the images.

5

Thanks! Is there any information out there which codec requires what structure? Any hint what codec is the fastest (no compression needed).