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• How can I make windows "like" the mp4 files I create in Linux and sync with Rsync

  17 juillet 2019, par Geoff Fox

  I am a meteorologist on TV remotely from a studio I built. My control room uses a TriCaster, an amazing studio-in-a-box which runs on a Windows 7 variant. I make my weather maps myself on a Centos 7 machine — around 40,000/day.

  I don’t entirely understand the problem, but here’s a quote from someone helping me at NewTek (the TriCaster company)

  Rsync is built on a *nix based environment where all the file permissions and attributes are based on the Linux environment. There is no meaning for this in NTFS and Windows. The result is you get files that will most likely have the read-only flag set or no flag at all. Other attributes will be delivered as null. I’m sure from your own programming experience, programs don’t like null values and they generally have to be accounted for very specifically.

  And so the finely tuned TriCaster stumbles, meaning lost frames or other problems caused by my short weather animations.

  Here are some samples of the Rsync code I use

  rsync -r -t -s -v --no-p --chmod=ugo=rwX /var/www/html/output/loops/mp4/conus*.mp4 /mnt/tricaster/Clips/Import
rsync -r -t -s -v --no-p --chmod=ugo=rwX /var/www/html/output/loops/mp4/nebraska*.mp4 /mnt/tricaster/Clips/Import
rsync -r -t -s -v --no-p --chmod=ugo=rwX /var/www/html/output/loops/mp4/northernplains*.mp4 /mnt/tricaster/Clips/Import

  These are mp4 files. They are only used locally. I really don’t care what flags are checked and permissions filled as long as Windows 7 doesn’t care.

  At this point I always like to tell folks, though I do write some code my last computer class was in high school,’67-68 semester. Thanks in advance for your help.

• Play HLS segments through Media source extensions

  11 février 2018, par ler

  I got a list of m4s and init.mp4 from this FFMPEG command

  ffmpeg -i bunny.mp4 -f hls -hls_segment_type fmp4 -c:v copy playlist.m3u8

  I send those chunks using Socketand try to play them through MSE.
  When i send them in this order :

  init.mp4 + playlist0.m4s + playlist1.m4s ...

  They play without any problem, But when i want to start from the chunk number 3 meaning init.mp4 + playlist3.m4s for example i get this error :

  video frame with PTS 0us has negative DTS -80000us after applying timestampOffset, handling any discontinuity, and filtering against append window.

  I want to be able to start from any chunk, currently the only way to play the video is to star by init.mp4 + playlist0.m4s meaning playlist0.m4s because init.mp4 contain just headers of the video, This is the client code i’m using :

  var socket = io();
  
  var video = document.querySelector('video');
  
  var mimeCodec = 'video/mp4; codecs="avc1.64000d,mp4a.40.2"'; // true
  
  if ('MediaSource' in window && MediaSource.isTypeSupported(mimeCodec)) 
  
  {
  
      var mediaSource = new MediaSource;
  
      video.src = URL.createObjectURL(mediaSource);
  
      mediaSource.addEventListener('sourceopen', function () {
  
              var mediaSource = this;
  
              var sourceBuffer = mediaSource.addSourceBuffer(mimeCodec);
  
             sourceBuffer.mode = 'segments'; 
  
              sourceBuffer.addEventListener('updateend', function (_) { video.play().then(function() { }).catch(function(error) { }); });
  
              socket.on('broadcast', function (chunk) {
  
                  downloadData(chunk.uri, function(arrayBuffer) {
  
                      sourceBuffer.appendBuffer(arrayBuffer);
  
                  });
  
              });
  
      });
  
  } else {
  
      console.error('Unsupported MIME type or codec: ', mimeCodec);
  
  }
  
  function downloadData(url, cb) {
  
      var xhr = new XMLHttpRequest;
  
      xhr.open('get', url);
  
      xhr.responseType = 'arraybuffer';
  
      xhr.onload = function () {
  
          cb(new Uint8Array(xhr.response));
  
      };
  
      xhr.send();
  
  }

• Issues with Publishing and Subscribing Rates for H.264 Video Streaming over RabbitMQ

  7 octobre 2024, par Luis

  I am working on a project to stream an H.264 video file using RabbitMQ (AMQP protocol) and display it in a web application. The setup involves capturing video frames, encoding them, sending them to RabbitMQ, and then consuming and decoding them on the web application side using Flask and Flask-SocketIO.

  


  However, I am encountering performance issues with the publishing and subscribing rates in RabbitMQ. I cannot seem to achieve more than 10 messages per second. This is not sufficient for smooth video streaming.
I need help to diagnose and resolve these performance bottlenecks.

  


  Here is my code :

  


  

  • Video Capture and Publishing Script :

  


  


  # RabbitMQ setup
RABBITMQ_HOST = 'localhost'
EXCHANGE = 'DRONE'
CAM_LOCATION = 'Out_Front'
KEY = f'DRONE_{CAM_LOCATION}'
QUEUE_NAME = f'DRONE_{CAM_LOCATION}_video_queue'

# Path to the H.264 video file
VIDEO_FILE_PATH = 'videos/FPV.h264'

# Configure logging
logging.basicConfig(level=logging.INFO)

@contextmanager
def rabbitmq_channel(host):
    """Context manager to handle RabbitMQ channel setup and teardown."""
    connection = pika.BlockingConnection(pika.ConnectionParameters(host))
    channel = connection.channel()
    try:
        yield channel
    finally:
        connection.close()

def initialize_rabbitmq(channel):
    """Initialize RabbitMQ exchange and queue, and bind them together."""
    channel.exchange_declare(exchange=EXCHANGE, exchange_type='direct')
    channel.queue_declare(queue=QUEUE_NAME)
    channel.queue_bind(exchange=EXCHANGE, queue=QUEUE_NAME, routing_key=KEY)

def send_frame(channel, frame):
    """Encode the video frame using FFmpeg and send it to RabbitMQ."""
    ffmpeg_path = 'ffmpeg/bin/ffmpeg.exe'
    cmd = [
        ffmpeg_path,
        '-f', 'rawvideo',
        '-pix_fmt', 'rgb24',
        '-s', '{}x{}'.format(frame.shape[1], frame.shape[0]),
        '-i', 'pipe:0',
        '-f', 'h264',
        '-vcodec', 'libx264',
        '-pix_fmt', 'yuv420p',
        '-preset', 'ultrafast',
        'pipe:1'
    ]
    
    start_time = time.time()
    process = subprocess.Popen(cmd, stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    out, err = process.communicate(input=frame.tobytes())
    encoding_time = time.time() - start_time
    
    if process.returncode != 0:
        logging.error("ffmpeg error: %s", err.decode())
        raise RuntimeError("ffmpeg error")
    
    frame_size = len(out)
    logging.info("Sending frame with shape: %s, size: %d bytes", frame.shape, frame_size)
    timestamp = time.time()
    formatted_timestamp = datetime.fromtimestamp(timestamp).strftime('%H:%M:%S.%f')
    logging.info(f"Timestamp: {timestamp}") 
    logging.info(f"Formatted Timestamp: {formatted_timestamp[:-3]}")
    timestamp_bytes = struct.pack('d', timestamp)
    message_body = timestamp_bytes + out
    channel.basic_publish(exchange=EXCHANGE, routing_key=KEY, body=message_body)
    logging.info(f"Encoding time: {encoding_time:.4f} seconds")

def capture_video(channel):
    """Read video from the file, encode frames, and send them to RabbitMQ."""
    if not os.path.exists(VIDEO_FILE_PATH):
        logging.error("Error: Video file does not exist.")
        return
    cap = cv2.VideoCapture(VIDEO_FILE_PATH)
    if not cap.isOpened():
        logging.error("Error: Could not open video file.")
        return
    try:
        while True:
            start_time = time.time()
            ret, frame = cap.read()
            read_time = time.time() - start_time
            if not ret:
                break
            frame_rgb = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
            frame_rgb = np.ascontiguousarray(frame_rgb) # Ensure the frame is contiguous
            send_frame(channel, frame_rgb)
            cv2.imshow('Video', frame)
            if cv2.waitKey(1) & 0xFF == ord('q'):
                break
            logging.info(f"Read time: {read_time:.4f} seconds")
    finally:
        cap.release()
        cv2.destroyAllWindows()


  


  

  • the backend (flask) :

  


  


  app = Flask(__name__)
CORS(app)
socketio = SocketIO(app, cors_allowed_origins="*")

RABBITMQ_HOST = 'localhost'
EXCHANGE = 'DRONE'
CAM_LOCATION = 'Out_Front'
QUEUE_NAME = f'DRONE_{CAM_LOCATION}_video_queue'

def initialize_rabbitmq():
    connection = pika.BlockingConnection(pika.ConnectionParameters(RABBITMQ_HOST))
    channel = connection.channel()
    channel.exchange_declare(exchange=EXCHANGE, exchange_type='direct')
    channel.queue_declare(queue=QUEUE_NAME)
    channel.queue_bind(exchange=EXCHANGE, queue=QUEUE_NAME, routing_key=f'DRONE_{CAM_LOCATION}')
    return connection, channel

def decode_frame(frame_data):
    # FFmpeg command to decode H.264 frame data
    ffmpeg_path = 'ffmpeg/bin/ffmpeg.exe'
    cmd = [
        ffmpeg_path,
        '-f', 'h264',
        '-i', 'pipe:0',
        '-pix_fmt', 'bgr24',
        '-vcodec', 'rawvideo',
        '-an', '-sn',
        '-f', 'rawvideo',
        'pipe:1'
    ]
    process = subprocess.Popen(cmd, stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    start_time = time.time()  # Start timing the decoding process
    out, err = process.communicate(input=frame_data)
    decoding_time = time.time() - start_time  # Calculate decoding time
    
    if process.returncode != 0:
        print("ffmpeg error: ", err.decode())
        return None
    frame_size = (960, 1280, 3)  # frame dimensions expected by the frontend
    frame = np.frombuffer(out, np.uint8).reshape(frame_size)
    print(f"Decoding time: {decoding_time:.4f} seconds")
    return frame

def format_timestamp(ts):
    dt = datetime.fromtimestamp(ts)
    return dt.strftime('%H:%M:%S.%f')[:-3]

def rabbitmq_consumer():
    connection, channel = initialize_rabbitmq()
    for method_frame, properties, body in channel.consume(QUEUE_NAME):
        message_receive_time = time.time()  # Time when the message is received

        # Extract the timestamp from the message body
        timestamp_bytes = body[:8]
        frame_data = body[8:]
        publish_timestamp = struct.unpack('d', timestamp_bytes)[0]

        print(f"Message Receive Time: {message_receive_time:.4f} ({format_timestamp(message_receive_time)})")
        print(f"Publish Time: {publish_timestamp:.4f} ({format_timestamp(publish_timestamp)})")

        frame = decode_frame(frame_data)
        decode_time = time.time() - message_receive_time  # Calculate decode time

        if frame is not None:
            _, buffer = cv2.imencode('.jpg', frame)
            frame_data = buffer.tobytes()
            socketio.emit('video_frame', {'frame': frame_data, 'timestamp': publish_timestamp}, namespace='/')
            emit_time = time.time()  # Time after emitting the frame

            # Log the time taken to emit the frame and its size
            rtt = emit_time - publish_timestamp  # Calculate RTT from publish to emit
            print(f"Current Time: {emit_time:.4f} ({format_timestamp(emit_time)})")
            print(f"RTT: {rtt:.4f} seconds")
            print(f"Emit time: {emit_time - message_receive_time:.4f} seconds, Frame size: {len(frame_data)} bytes")
        channel.basic_ack(method_frame.delivery_tag)

@app.route('/')
def index():
    return render_template('index.html')

@socketio.on('connect')
def handle_connect():
    print('Client connected')

@socketio.on('disconnect')
def handle_disconnect():
    print('Client disconnected')

if __name__ == '__main__':
    consumer_thread = threading.Thread(target=rabbitmq_consumer)
    consumer_thread.daemon = True
    consumer_thread.start()
    socketio.run(app, host='0.0.0.0', port=5000)



  


  How can I optimize the publishing and subscribing rates to handle a higher number of messages per second ?

  


  Any help or suggestions would be greatly appreciated !

  


  I attempted to use threading and multiprocessing to handle multiple frames concurrently and I tried to optimize the frame decoding function to make it faster but with no success.