A Tegra X2/X1 camera recorder, implemented in python

tegra-cam-rec.py

# --------------------------------------------------------
# Camera Recorder for Tegra X2/X1
#
# This program captures video from IP CAM, USB webcam,
# or the Tegra onboard camera, adds some watermark on
# the video frames and then records it into a TS file.
# The code demonstrates how to use cv2.VideoWriter()
# while taking advantage of TX2/TX1's H.264 H/W encoder
# capabilities.
#
# Refer to the following blog post for how to set up
# and run the code:
#   https://jkjung-avt.github.io/tx2-camera-recorder/
#
# Written by JK Jung <jkjung13@gmail.com>
# --------------------------------------------------------


import sys
import argparse
import subprocess

import cv2


def parse_args():
    # Parse input arguments
    desc = 'Capture and record live camera video on Jetson TX2/TX1'
    parser = argparse.ArgumentParser(description=desc)
    parser.add_argument('--rtsp', dest='use_rtsp',
                        help='use IP CAM (remember to also set --uri)',
                        action='store_true')
    parser.add_argument('--uri', dest='rtsp_uri',
                        help='RTSP URI, e.g. rtsp://192.168.1.64:554',
                        default=None, type=str)
    parser.add_argument('--latency', dest='rtsp_latency',
                        help='latency in ms for RTSP [200]',
                        default=200, type=int)
    parser.add_argument('--usb', dest='use_usb',
                        help='use USB webcam (remember to also set --vid)',
                        action='store_true')
    parser.add_argument('--vid', dest='video_dev',
                        help='device # of USB webcam (/dev/video?) [1]',
                        default=1, type=int)
    parser.add_argument('--width', dest='image_width',
                        help='image width [640]',
                        default=640, type=int)
    parser.add_argument('--height', dest='image_height',
                        help='image height [480]',
                        default=480, type=int)
    parser.add_argument('--ts', dest='ts_file',
                        help='output .ts file name ["output"]',
                        default='output', type=str)
    parser.add_argument('--fps', dest='fps',
                        help='fps of the output .ts video [30]',
                        default=30, type=int)
    parser.add_argument('--rec', dest='rec_sec',
                        help='recording length in seconds [5]',
                        default=5, type=int)
    parser.add_argument('--text', dest='text',
                        help='text overlayed on the video ["TX2 DEMO"]',
                        default='TX2 DEMO', type=str)
    args = parser.parse_args()
    return args


def open_cam_rtsp(uri, width, height, latency):
    gst_str = ('rtspsrc location={} latency={} ! '
               'rtph264depay ! h264parse ! omxh264dec ! '
               'nvvidconv ! '
               'video/x-raw, width=(int){}, height=(int){}, '
               'format=(string)BGRx ! '
               'videoconvert ! appsink').format(uri, latency, width, height)
    return cv2.VideoCapture(gst_str, cv2.CAP_GSTREAMER)


def open_cam_usb(dev, width, height):
    # We want to set width and height here, otherwise we could just do:
    #     return cv2.VideoCapture(dev)
    gst_str = ('v4l2src device=/dev/video{} ! '
               'video/x-raw, width=(int){}, height=(int){} ! '
               'videoconvert ! appsink').format(dev, width, height)
    return cv2.VideoCapture(gst_str, cv2.CAP_GSTREAMER)


def open_cam_onboard(width, height):
    gst_elements = str(subprocess.check_output('gst-inspect-1.0'))
    if 'nvcamerasrc' in gst_elements:
        # On versions of L4T prior to 28.1, add 'flip-method=2' into gst_str
        gst_str = ('nvcamerasrc ! '
                   'video/x-raw(memory:NVMM), '
                   'width=(int)2592, height=(int)1458, '
                   'format=(string)I420, framerate=(fraction)30/1 ! '
                   'nvvidconv ! '
                   'video/x-raw, width=(int){}, height=(int){}, '
                   'format=(string)BGRx ! '
                   'videoconvert ! appsink').format(width, height)
    elif 'nvarguscamerasrc' in gst_elements:
        gst_str = ('nvarguscamerasrc ! '
                   'video/x-raw(memory:NVMM), '
                   'width=(int)1920, height=(int)1080, '
                   'format=(string)NV12, framerate=(fraction)30/1 ! '
                   'nvvidconv flip-method=2 ! '
                   'video/x-raw, width=(int){}, height=(int){}, '
                   'format=(string)BGRx ! '
                   'videoconvert ! appsink').format(width, height)
    else:
        raise RuntimeError('onboard camera source not found!')
    return cv2.VideoCapture(gst_str, cv2.CAP_GSTREAMER)


def get_video_writer(fname, fps, width, height):
    gst_str = ('appsrc ! videoconvert ! omxh264enc ! mpegtsmux ! '
               'filesink location={}.ts').format(fname)
    return cv2.VideoWriter(gst_str, cv2.CAP_GSTREAMER, 0, fps,
                           (width, height))


def main():
    args = parse_args()
    print('Called with args:')
    print(args)
    print('OpenCV version: {}'.format(cv2.__version__))

    if args.use_rtsp:
        cap = open_cam_rtsp(args.rtsp_uri,
                            args.image_width,
                            args.image_height,
                            args.rtsp_latency)
    elif args.use_usb:
        cap = open_cam_usb(args.video_dev,
                           args.image_width,
                           args.image_height)
    else: # by default, use the Jetson onboard camera
        cap = open_cam_onboard(args.image_width,
                               args.image_height)
    if not cap.isOpened():
        sys.exit('Failed to open camera!')

    writer = get_video_writer(args.ts_file, args.fps,
                              args.image_width, args.image_height)
    if not writer.isOpened():
        cap.release()
        sys.exit('Failed to open "{}.ts"!'.format(args.ts_file))

    for _ in range(args.fps * args.rec_sec): # assuming python3 here...
        _, img = cap.read() # read image
        if img is None:
            print('No more image from camera, exiting...')
            break
        # put watermark on image
        cv2.putText(img, args.text, (10, 60),
                    fontFace=cv2.FONT_HERSHEY_COMPLEX, fontScale=2.0,
                    color=(0, 240, 0), thickness=6, lineType=cv2.LINE_AA)
        cv2.imshow('REC', img)
        if cv2.waitKey(1) == 27: # ESC key: quit program
            break
        writer.write(img) # write current image to the ts file

    writer.release()
    cap.release()


if __name__ == '__main__':
    main()

I am trying to read the onboard camera on my jetson tx2 through python using the string provided above:
gst_str = ('nvarguscamerasrc ! ' 'video/x-raw(memory:NVMM), ' 'width=(int)1920, height=(int)1080, ' 'format=(string)NV12, framerate=(fraction)30/1 ! ' 'nvvidconv flip-method=2 ! ' 'video/x-raw, width=(int)640, height=(int)480, ' 'format=(string)BGRx ! ' 'videoconvert ! appsink')

cap.isOpened() is returning false.

my gst-inspect shows nvarguscamerasrc. CV version 3.2.0 and python version is 3.6.9.

Strangely, this works which uses the same string as above except for the sink:

gst-launch-1.0 nvarguscamerasrc ! 'video/x-raw(memory:NVMM), width=(int)1920, height=(int)1080, format=(string)NV12, framerate=(fraction)30/1' ! nvvidconv flip-method=2 ! 'video/x-raw, width=(int)640, height=(int)480, format=(string)BGRx' ! videoconvert ! nveglglessink -e

Any ideas how do I debug this issue?

Refererence:

1. https://devtalk.nvidia.com/default/topic/1070636/jetson-nano/dynamic-nvarguscamerasrc-nvcompositor-failed-to-create-capturesession/
2. https://gstreamer.freedesktop.org/documentation/tutorials/basic/debugging-tools.html?gi-language=c

You could try to set "GST_DEBUG" environment variable to enable debug messages of GStreamer pipelines.

Thank you for your work.I have a similar need：Use the hardware codec on jetson nano with gstreamer to push the video stream (usb camera, IP camera and other video input devices) to the rtmp or rtsp server in real time (I don't know which is better), no need to play video on nano. Can you help me, I don't know how to modify the code. Thank you