v4l2-ctl --set-ctrl preferred_stride=64
python ./v4l2dev_2_opencv_show_grey.py --width 2432--height 2048

我刚刚找了linux代码仓库 发现没有preferred_stride 的关键字相关搜索结果

如果在Google和baidu bing等上搜索stride的话，出来的全是深度学习的步长stride

但是，这样的话，虽然一张图片被分配了25602048个字节，但其实像素还是只有24482048？

你需要按照25602048来预览。25602048=5242880字节

你好 在使用了

v4l2-ctl -d /dev/video3 --set-ctrl preferred_stride=2560 --set-fmt-video=width=2448,height=2048,pixelformat=GREY --stream-mmap --stream-count=30 --stream-to=v3.raw

之后，我得到了v3.raw，然后我发现效果像是preferred_stride设置并没有生效

jetson-tx2@ubuntu:/usr/local/src/nvidia_jetson_veye_bsp/samples/opencv/raw_camera$ cat 5wb-cam.py
import cv2
import argparse
import subprocess

def main():
    # Set up command-line argument parser
    parser = argparse.ArgumentParser(description='Real-time display of GREY image from /dev/video0')
    parser.add_argument('--roix', type=int, default=0, help='roi start x (default: 0)')
    parser.add_argument('--roiy', type=int, default=0, help='roi start y (default: 0)')
    parser.add_argument('--width', type=int, default=2448, help='image width (default: 1280)')
    parser.add_argument('--height', type=int, default=2048, help='image height (default: 960)')
    parser.add_argument('--fps', type=int, default=30, help='frame rate (default: 30)')
    parser.add_argument('--preferred_stride', type=int, default=2560,help='preferred stride(default: 2560)')
    args = parser.parse_args()

    v4l2_cmd = "v4l2-ctl -d /dev/video0 --set-ctrl roi_x=%d" % args.roix
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl -d /dev/video0 --set-ctrl roi_y=%d" % args.roiy
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl -d /dev/video0 --set-fmt-video=width=%d,height=%d,pixelformat=GREY" % (args.width,args.height)
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl -d /dev/video0 --set-ctrl frame_rate=%d" % args.fps
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl --set-ctrl preferred_stride=%d " % args.preferred_stride
    subprocess.call(v4l2_cmd, shell=True)


    v4l2_cmd = "v4l2-ctl -d /dev/video1 --set-ctrl roi_x=%d" % args.roix
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl -d /dev/video1 --set-ctrl roi_y=%d" % args.roiy
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl -d /dev/video1 --set-fmt-video=width=%d,height=%d,pixelformat=GREY" % (args.width,args.height)
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl -d /dev/video1 --set-ctrl frame_rate=%d" % args.fps
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl --set-ctrl preferred_stride=%d " % args.preferred_stride
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl -d /dev/video2 --set-ctrl roi_x=%d" % args.roix
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl -d /dev/video2 --set-ctrl roi_y=%d" % args.roiy
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl -d /dev/video2 --set-fmt-video=width=%d,height=%d,pixelformat=GREY" % (args.width,args.height)
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl -d /dev/video2 --set-ctrl frame_rate=%d" % args.fps
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl --set-ctrl preferred_stride=%d " % args.preferred_stride
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl -d /dev/video3 --set-ctrl roi_x=%d" % args.roix
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl -d /dev/video3 --set-ctrl roi_y=%d" % args.roiy
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl -d /dev/video3 --set-fmt-video=width=%d,height=%d,pixelformat=GREY" % (args.width,args.height)
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl -d /dev/video3 --set-ctrl frame_rate=%d" % args.fps
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl --set-ctrl preferred_stride=%d " % args.preferred_stride
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl -d /dev/video4 --set-ctrl roi_x=%d" % args.roix
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl -d /dev/video4 --set-ctrl roi_y=%d" % args.roiy
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl -d /dev/video4 --set-fmt-video=width=%d,height=%d,pixelformat=GREY" % (args.width,args.height)
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl -d /dev/video4 --set-ctrl frame_rate=%d" % args.fps
    subprocess.call(v4l2_cmd, shell=True)

    v4l2_cmd = "v4l2-ctl --set-ctrl preferred_stride=%d " % args.preferred_stride
    subprocess.call(v4l2_cmd, shell=True)


    # Open the /dev/video0 device
    cap0 = cv2.VideoCapture('/dev/video0',cv2.CAP_V4L)
    cap1 = cv2.VideoCapture('/dev/video1',cv2.CAP_V4L)
    cap2 = cv2.VideoCapture('/dev/video2',cv2.CAP_V4L)
    cap3 = cv2.VideoCapture('/dev/video3',cv2.CAP_V4L)
    cap4 = cv2.VideoCapture('/dev/video4',cv2.CAP_V4L)
    if not cap0.isOpened():
        print("Failed to open /dev/video0")
        return

    if not cap1.isOpened():
        print("Failed to open /dev/video1")
        return


    if not cap2.isOpened():
        print("Failed to open /dev/video2")
        return


    if not cap3.isOpened():
        print("Failed to open /dev/video3")
        return

    if not cap3.isOpened():
        print("Failed to open /dev/video4")
        return
    # Set the image size
    cap0.set(cv2.CAP_PROP_FRAME_WIDTH, 2560)
    cap0.set(cv2.CAP_PROP_FRAME_HEIGHT, args.height)

    cap1.set(cv2.CAP_PROP_FRAME_WIDTH, 2560)
    cap1.set(cv2.CAP_PROP_FRAME_HEIGHT, args.height)

    cap2.set(cv2.CAP_PROP_FRAME_WIDTH, 2560)
    cap2.set(cv2.CAP_PROP_FRAME_HEIGHT, args.height)

    cap3.set(cv2.CAP_PROP_FRAME_WIDTH, 2560)
    cap3.set(cv2.CAP_PROP_FRAME_HEIGHT, args.height)

    cap4.set(cv2.CAP_PROP_FRAME_WIDTH, 2560)
    cap4.set(cv2.CAP_PROP_FRAME_HEIGHT, args.height)

    # Calculate the aligned width
    #aligned_width = (args.width + 3)& ~3

    # Loop over frames and display them
    while True:
        # Read a frame
        ret0, frame0   = cap0.read()
        ret1, frame1   = cap1.read()
        ret2, frame2   = cap2.read()
        ret3, frame3   = cap3.read()
        ret4, frame4   = cap4.read()
        # Check if reading was successful
        if not ret0:
            print("Failed to read frame from /dev/video0")
            break

        if not ret1:
            print("Failed to read frame from /dev/video1")
            break

        if not ret2:
            print("Failed to read frame from /dev/video2")
            break

        if not ret3:
            print("Failed to read frame from /dev/video3")
            break

        if not ret4:
            print("Failed to read frame from /dev/video4")
            break
        #if frame.shape[1]!= aligned_width:
        #    aligned_frame = np.zeros((args.height, aligned_width), dtype=np.uint8)
        #    aligned_frame[:, args.width] = frame
        #    frame = aligned_frame
        # Display the frame
        cv2.imshow('preview (video0)', frame0)
        cv2.imshow('preview (video1)', frame1)
        cv2.imshow('preview (video2)', frame2)
        cv2.imshow('preview (video3)', frame3)
        cv2.imshow('preview (video4)', frame4)
        # Exit if 'q' key is pressed
        if cv2.waitKey(1) & 0xFF == ord('q'):
            break

    # Release resources
    cap0.release()
    cap1.release()
    cap2.release()
    cap3.release()
    cap4.release()
    cv2.destroyAllWindows()

if __name__ == '__main__':
    main()
jetson-tx2@ubuntu:/usr/local/src/nvidia_jetson_veye_bsp/samples/opencv/raw_camera$ python 5wb-cam.py
VIDEOIO ERROR: V4L2: Pixel format of incoming image is unsupported by OpenCV
VIDEOIO ERROR: V4L2: Pixel format of incoming image is unsupported by OpenCV
VIDEOIO ERROR: V4L2: Pixel format of incoming image is unsupported by OpenCV
VIDEOIO ERROR: V4L2: Pixel format of incoming image is unsupported by OpenCV
VIDEOIO ERROR: V4L2: Pixel format of incoming image is unsupported by OpenCV
VIDIOC_STREAMON: Invalid argument
VIDIOC_STREAMON: Invalid argument
VIDIOC_STREAMON: Invalid argument
VIDIOC_STREAMON: Invalid argument
VIDIOC_STREAMON: Invalid argument
Failed to read frame from /dev/video0
jetson-tx2@ubuntu:/usr/local/src/nvidia_jetson_veye_bsp/samples/opencv/raw_camera$

这样修改之后 opencv就报错了 它不支持2560这样一个比较大的参数