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• Flask app using OpenCv crash when i start recording

  17 mai 2023, par Mulham Darwish

  I build this flask app to live stream security cameras and the live stream works with the screenshot function but when start recording it crash but few times same code it worked and saved the video here the code. with the html file using js.

  


  from flask import Flask, render_template, Response, request
import cv2
import os
import time
import threading
import requests

app = Flask(__name__)

# Define the IP cameras
cameras = [
    {'url': 'rtsp://****:*****@******', 'name': 'Camera 1'},
    {'url': 'rtsp://****:*****@******', 'name': 'Camera 2'},
    {'url': 'rtsp://****:*****@******', 'name': 'Camera 3'},
    {'url': 'rtsp://****:*****@******', 'name': 'Camera 4'}
]

# Create a VideoCapture object for each camera
capture_objs = [cv2.VideoCapture(cam['url']) for cam in cameras]
stop_events = {i: threading.Event() for i in range(len(cameras))}
# Define the directory to save the recorded videos
recording_dir = os.path.join(os.getcwd(), 'recordings')

# Ensure the recording directory exists
if not os.path.exists(recording_dir):
    os.makedirs(recording_dir)

# Define the function to capture and save a video
def record_video(camera_index, stop_recording):
    # Define the codec and file extension
    fourcc = cv2.VideoWriter_fourcc(*'mp4v')
    file_extension = '.mp4'

    # Get the current timestamp for the filename
    timestamp = time.strftime("%Y%m%d-%H%M%S")

    # Define the filename and path
    filename = f'{cameras[camera_index]["name"]}_{timestamp}{file_extension}'
    filepath = os.path.join(recording_dir, filename)

    # Create a VideoWriter object to save the video
    width = int(capture_objs[camera_index].get(cv2.CAP_PROP_FRAME_WIDTH))
    height = int(capture_objs[camera_index].get(cv2.CAP_PROP_FRAME_HEIGHT))
    fps = int(capture_objs[camera_index].get(cv2.CAP_PROP_FPS))
    video_writer = cv2.VideoWriter(filepath, fourcc, fps, (width, height))

    # Capture frames and write them to the file
    while True:
        if stop_recording.is_set():
            break  # stop recording if stop_recording is set
        ret, frame = capture_objs[camera_index].read()
        if ret:
            video_writer.write(frame)
        else:
            break

    # Release the VideoWriter object and the VideoCapture object
    video_writer.release()
    capture_objs[camera_index].release()

@app.route('/')
def index():
    # Render the index page with the list of cameras
    return render_template('index.html', cameras=cameras)

def generate(camera_index):
    # Generate frames from the video feed
    while True:
        ret, frame = capture_objs[camera_index].read()
        if not ret:
            break

        # Encode the frame as JPEG
        _, jpeg = cv2.imencode('.jpg', frame)

        # Yield the frame as a Flask response
        yield (b'--frame\r\n'
               b'Content-Type: image/jpeg\r\n\r\n' + jpeg.tobytes() + b'\r\n')

@app.route('/video_feed')
def video_feed():
    # Get the camera index from the request arguments
    camera_index = int(request.args.get('camera_index'))

    # Generate the video feed
    return Response(generate(camera_index),
                    mimetype='multipart/x-mixed-replace; boundary=frame')

@app.route('/record', methods=['POST'])
def record():
    # Get the camera index from the request form
    camera_index = int(request.form['camera_index'])

    stop_recording = stop_events[camera_index]  # get the stop_recording event for the camera
    thread = threading.Thread(target=record_video, args=(camera_index, stop_recording))
    thread.start()  # start a thread to record video

    # Return a response indicating that the recording has started
    return 'Recording started.'

@app.route('/stop_record', methods=['POST'])
def stop_record():
    # Get the camera index from the request form
    camera_index = int(request.form['camera_index'])

    # Set the stop_recording event for the corresponding camera thread
    stop_events[camera_index].set()

    # Return a response indicating that recording has been stopped
    return 'Recording stopped.'

@app.route('/screenshot', methods=['POST'])
def take_screenshot():
    # Take a screenshot of the video stream and save it as a file
    camera = capture_objs[int(request.form['camera_id'])]
    success, frame = camera.read()
    if success:
        timestamp = time.strftime("%Y%m%d-%H%M%S")
        filename = f'screenshot_{timestamp}.jpg'
        cv2.imwrite(filename, frame)
        return 'Screenshot taken and saved'
    else:
        return 'Failed to take screenshot'

if __name__ == '__main__':
    app.run()


  


  I tried to update ffmpeg to the latest version and installed pip install opencv-python-headless and installed pip install opencv-python but most of the time i come to this crash code

  


  * Serving Flask app 'run'
* Debug mode: off
WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead.
 * Running on http://127.0.0.1:5000
Press CTRL+C to quit
127.0.0.1 - - [17/May/2023 13:24:11] "GET / HTTP/1.1" 200 -
127.0.0.1 - - [17/May/2023 13:24:11] "GET /video_feed?camera_index=0 HTTP/1.1" 200 -
127.0.0.1 - - [17/May/2023 13:24:11] "GET /video_feed?camera_index=1 HTTP/1.1" 200 -
127.0.0.1 - - [17/May/2023 13:24:11] "GET /video_feed?camera_index=2 HTTP/1.1" 200 -
127.0.0.1 - - [17/May/2023 13:24:11] "GET /video_feed?camera_index=3 HTTP/1.1" 200 -
127.0.0.1 - - [17/May/2023 13:24:44] "GET / HTTP/1.1" 200 -
127.0.0.1 - - [17/May/2023 13:24:45] "GET /video_feed?camera_index=3 HTTP/1.1" 200 -
127.0.0.1 - - [17/May/2023 13:24:45] "GET /video_feed?camera_index=0 HTTP/1.1" 200 -
127.0.0.1 - - [17/May/2023 13:24:45] "GET /video_feed?camera_index=1 HTTP/1.1" 200 -
127.0.0.1 - - [17/May/2023 13:24:45] "GET /video_feed?camera_index=2 HTTP/1.1" 200 -
[h264 @ 0x5605285fc5c0] error while decoding MB 28 29, bytestream -9
[h264 @ 0x560529110040] error while decoding MB 15 37, bytestream -6
[h264 @ 0x560528624980] error while decoding MB 45 45, bytestream -23
[h264 @ 0x5605286f1900] error while decoding MB 50 34, bytestream -7
[h264 @ 0x5605285fc5c0] error while decoding MB 25 9, bytestream -17
[h264 @ 0x5605292b0080] error while decoding MB 28 41, bytestream -5
[h264 @ 0x560528660040] error while decoding MB 101 45, bytestream -17
[h264 @ 0x5605285fc5c0] error while decoding MB 42 44, bytestream -5
[h264 @ 0x5605286f1900] error while decoding MB 118 42, bytestream -9
[h264 @ 0x560529110040] error while decoding MB 92 43, bytestream -5
[h264 @ 0x560528660040] error while decoding MB 99 34, bytestream -11
[h264 @ 0x56052932b0c0] error while decoding MB 92 36, bytestream -13
[h264 @ 0x560528667ac0] error while decoding MB 44 54, bytestream -5
[h264 @ 0x560529110040] error while decoding MB 93 33, bytestream -7
[h264 @ 0x5605286dd880] error while decoding MB 27 37, bytestream -19
[h264 @ 0x560528660040] error while decoding MB 66 56, bytestream -9
127.0.0.1 - - [17/May/2023 13:36:45] "POST /record HTTP/1.1" 200 -
Assertion fctx->async_lock failed at libavcodec/pthread_frame.c:175
Aborted (core dumped)


  


• ffmpeg HLS not append -hls_base_url to m3u8

  22 juin 2023, par user3378326

  When i use -hls_base_url http://10.10.10.1:5000/hls it's not append in the m3u8 Playlist.

  


  My command i use for generating the HLS Output on Windows cmd with ffmpeg 6.0-essentials_build :

  


  ffmpeg -y -i  Movie.ts  -c:v copy  -c:a:1 copy  -bsf:v h264_mp4toannexb  -f segment  -hls_base_url http:/10.10.10.1:5000/hls/  -segment_time 10  -segment_list  Movie.m3u8 hls\Movie-%03d.ts

  


  I try with :

  


  -hls_base_url http://10.10.10.1:5000/hls -hls_base_url 'http://10.10.10.1:5000/hls'   -hls_base_url "http://10.10.10.1:5000/hls"

  


• What's the purpose of the END field in files containing metadata for ffmpeg ?

  15 juillet 2023, par rdrg109

  Table of contents

  


  

  • The context

  


  • Minimal working example

    

    • no. 1

    


    • no. 2

    


    • no. 3

    


    


  


  • The questions

  


  


  


  The context

  


  I'm aware that it is possible to insert metadata of chapters into a video using ffmpeg (link to documentation). Minimal working example no. 1 shows this point.

  


  When I insert chapters that are not consecutive, ffmpeg doesn't use the end time that is specified in the metadata file through the END field. "Minimal working example no. 2" shows this point. In "Minimal working example no. 3", the END field of all chapters is 1 millisecond, yet we get the same result of Minimal working example no. 2. What is worth noting is that the END of the last chapter is the only one that is added correctly.

  


  


  Minimal working example

  


  


  no. 1

  


  Consider the following ffmpeg metadata file. It creates chapters in the following time ranges

  


  

  • From 0 to millisecond 9999, the chapter is This is my chapter one

  


  • From 10000 to millisecond 19999, the chapter is This is my chapter two

  


  • From 20000 to millisecond 29999, the chapter is This is my chapter three

  


  • From 30000 to millisecond 39999, the chapter is This is my chapter four

  


  


  ;FFMETADATA1
title=The title of my video

[CHAPTER]
TIMEBASE=1/1000
START=0
END=10000
title=This is my chapter one

[CHAPTER]
TIMEBASE=1/1000
START=10000
END=20000
title=This is my chapter two

[CHAPTER]
TIMEBASE=1/1000
START=20000
END=30000
title=This is my chapter three


  


  The following command creates a simple video and inserts the metadata shown above into that video.

  


  ffmpeg -v error -y -f lavfi -i 'testsrc=d=120:size=100x100' -i metadata.txt -map_metadata 1 output.mp4


  


  The following command shows information about the metadata in the video file that was created by the previous command.

  


  ffprobe -v error -show_chapters -print_format json output.mp4 | jq


  


  {
  "chapters": [
    {
      "id": 0,
      "time_base": "1/1000",
      "start": 0,
      "start_time": "0.000000",
      "end": 10000,
      "end_time": "10.000000",
      "tags": {
        "title": "This is my chapter one"
      }
    },
    {
      "id": 1,
      "time_base": "1/1000",
      "start": 10000,
      "start_time": "10.000000",
      "end": 20000,
      "end_time": "20.000000",
      "tags": {
        "title": "This is my chapter two"
      }
    },
    {
      "id": 2,
      "time_base": "1/1000",
      "start": 20000,
      "start_time": "20.000000",
      "end": 30000,
      "end_time": "30.000000",
      "tags": {
        "title": "This is my chapter three"
      }
    }
  ]
}


  


  No problem until here.

  


  


  no. 2

  


  ;FFMETADATA1
title=The title of my video

[CHAPTER]
TIMEBASE=1/1000
START=0
END=5000
title=This is my chapter one

[CHAPTER]
TIMEBASE=1/1000
START=10000
END=15000
title=This is my chapter two

[CHAPTER]
TIMEBASE=1/1000
START=20000
END=25000
title=This is my chapter three


  


  The following command creates a simple video and inserts the metadata shown above into that video.

  


  ffmpeg -v error -y -f lavfi -i 'testsrc=d=120:size=100x100' -i metadata.txt -map_metadata 1 output.mp4


  


  The following command shows information about the metadata in the video file that was created by the previous command.

  


  ffprobe -v error -show_chapters -print_format json output.mp4 | jq


  


  {
  "chapters": [
    {
      "id": 0,
      "time_base": "1/1000",
      "start": 0,
      "start_time": "0.000000",
      "end": 10000,
      "end_time": "10.000000",
      "tags": {
        "title": "This is my chapter one"
      }
    },
    {
      "id": 1,
      "time_base": "1/1000",
      "start": 10000,
      "start_time": "10.000000",
      "end": 20000,
      "end_time": "20.000000",
      "tags": {
        "title": "This is my chapter two"
      }
    },
    {
      "id": 2,
      "time_base": "1/1000",
      "start": 20000,
      "start_time": "20.000000",
      "end": 25000,
      "end_time": "25.000000",
      "tags": {
        "title": "This is my chapter three"
      }
    }
  ]
}


  


  From the output above, we can notice the following :

  


  

  • The end time of the chapter with title This is my chapter one is 10000 which should be 15000, since that is the value we specified in the END field

  


  • The end time of the chapter with title This is my chapter two is 20000 which should be 25000, since that is the value we specified in the END field

  


  • The end time of the last chapter is the only one that is the same to the value that we wrote in the metadata file

  


  


  I consider this unexpected behavior because ffmpeg should use the end time that we have specified in the metadata file.

  


  


  no. 3

  


  ;FFMETADATA1
title=The title of my video

[CHAPTER]
TIMEBASE=1/1000
START=0
END=1
title=This is my chapter one

[CHAPTER]
TIMEBASE=1/1000
START=10000
END=10001
title=This is my chapter two

[CHAPTER]
TIMEBASE=1/1000
START=20000
END=20001
title=This is my chapter three


  


  The following command creates a simple video and inserts the metadata shown above into that video.

  


  ffmpeg -v error -y -f lavfi -i 'testsrc=d=120:size=100x100' -i metadata.txt -map_metadata 1 output.mp4


  


  The following command shows information about the metadata in the video file that was created by the previous command.

  


  ffprobe -v error -show_chapters -print_format json output.mp4 | jq


  


  {
  "chapters": [
    {
      "id": 0,
      "time_base": "1/1000",
      "start": 0,
      "start_time": "0.000000",
      "end": 10000,
      "end_time": "10.000000",
      "tags": {
        "title": "This is my chapter one"
      }
    },
    {
      "id": 1,
      "time_base": "1/1000",
      "start": 10000,
      "start_time": "10.000000",
      "end": 20000,
      "end_time": "20.000000",
      "tags": {
        "title": "This is my chapter two"
      }
    },
    {
      "id": 2,
      "time_base": "1/1000",
      "start": 20000,
      "start_time": "20.000000",
      "end": 20001,
      "end_time": "20.001000",
      "tags": {
        "title": "This is my chapter three"
      }
    }
  ]
}


  


  From the output above, we can notice the following :

  


  

  • The end time of the chapter with title This is my chapter one is 10000, but it should be 15000, since that is the value we specified in the END field in the metadata file

  


  • The end time of the chapter with title This is my chapter two is 20000, but it should be 25000, since that is the value we specified in the END field in the metadata file

  


  • The end time of the last chapter is the only one that is the same to the value that we wrote in the metadata file

  


  


  I consider this unexpected behavior because ffmpeg should use the end time that we have specified in the metadata file.

  


  


  The questions

  


  In minimal working example no. 2 and minimal working example no. 3, we could see that although the metadata file sets END for each chapter, a different time is used (except for the last chapter). My questions are :

  


  

  • What's the purpose of having a field called END when it only serves a purpose in the last chapter ?

  


  • Given that ffmpeg only adds the correct value for END for the last chapter ? Wouldn't a better name for END be END_ONLY_FOR_LAST_CHAPTER ?

  


  • Am I doing something wrong that is casuing ffmpeg to use a different value for END in all chapters but the last one ?