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• Play video using ffmpeg

  17 juin 2023, par MCD

  The following code stuck in the middle of the video. I want to play the video start at start_seconds and end at end_seconds.

  


  import subprocess
import cv2
import numpy as np
import subprocess

def play_video_with_ffmpeg(video_path, start_seconds, end_seconds):
print(start_seconds)

    # Set the desired frame size
    width = 920
    height = 600
    
    # Set the window position
    print("here")
    window_x = 600  # X position
    window_y = 10  # Y position
    cv2.namedWindow('Video Player', cv2.WINDOW_NORMAL)
    cv2.moveWindow('Video Player', window_x, window_y)
    
    # Build the ffmpeg command to skip to the desired start time and end time
    command = [
        'ffmpeg',
        '-ss', str(start_seconds),
        '-i', video_path,
        '-t', str((end_seconds - start_seconds)),
        '-vf', f'scale={width}:{height}',
        '-r', '30',
        '-f', 'image2pipe',
        '-pix_fmt', 'bgr24',
        '-vcodec', 'rawvideo',
        '-'
    ]
    
    # Open a subprocess to execute the ffmpeg command
    process = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    
    # Create a buffer to hold the frame data
    buffer_size = width * height * 3
    frame_buffer = bytearray(buffer_size)
    
    while process.poll() is None:
        # Read the frame from the subprocess stdout into the buffer
        bytes_read = process.stdout.readinto(frame_buffer)
    
        if bytes_read == buffer_size:
            # Convert the frame buffer to a numpy array
            frame = np.frombuffer(frame_buffer, dtype='uint8').reshape((height, width, 3))
    
            # Resize the frame
            frame_resized = cv2.resize(frame, (width, height), interpolation=cv2.INTER_AREA)
    
            # Display the frame
            cv2.imshow('Video Player', frame_resized)
    
            if cv2.waitKey(1) & 0xFF == ord('q'):
                break
    
    process.stdout.close()
    process.stderr.close()
    cv2.destroyAllWindows()


  


  I expect to play the video start from start_second and end at end_second. I used cv2.set but it took long time to play from start_second.

  


• Play audio out through specific output device with ffplay

  4 février 2018, par ComedicChimera

  I just have a quick question regarding ffplay (extension of ffmpeg) for Windows. I am trying to get it to allow me to play audio out of specific device (ie. a virtual audio cable), and I cannot find any documentation on how to do it.

  Here is my current command :

  "ffplay -loglevel panic -nodisp -volume volume -i url"

  I could not find any documentation of how to do this.

  If it is not possible to do this ffplay, I would like to ask if there is away to set a specific audio output device in Python 3 (as that is the language I am using to call ffplay)

  Thanks

• Is using QtFFmpegWrapper+QLabel+QTimer a good way to play video in a Qt application ?

  21 décembre 2012, par Vi.

  I'm looking how to portably play video on Qt, but not Phonon.

  Using ffmpeg seems to be a good idea (it should work the same way on all platforms).

  Currently It uses QLabel for video output and does QPixmap::fromImage for each frame ; frames which are decoded and buffered by QtFFmpegWrapper in a background thread. QTimer decides when to show the next frame.

  The whole thing looks a bit hacky (Video ? In a label ?). Am I doing it right ? Is there a better portable way of playing ffmpeg-decoded video in a Qt application ?