Pipe opencv images to ffmpeg using python

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深忆病人
深忆病人 2021-02-04 14:22

How can I pipe openCV images to ffmpeg (running ffmpeg as a subprocess)? (I am using spyder/anaconda)

I am reading frames from a video file and do some processing on eac

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  • 2021-02-04 14:46

    I'm Kind of late, But my powerful VidGear Python Library automates the process of pipelining OpenCV frames into FFmpeg on any platform with its WriteGear API's Compression Mode. OP, You can implement your answer as follows:

    # import libraries
    from vidgear.gears import WriteGear
    import cv2
    
    output_params = {"-s":"2048x2048", "-r":30} #define FFmpeg tweak parameters for writer
    
    stream = cv2.VideoCapture(0) #Open live webcam video stream on first index(i.e. 0) device
    
    writer = WriteGear(output_filename = 'Output.mp4', compression_mode = True, logging = True, **output_params) #Define writer with output filename 'Output.mp4' 
    
    # infinite loop
    while True:
        
        (grabbed, frame) = stream.read()
        # read frames
    
        # check if frame empty
        if not is grabbed:
            #if True break the infinite loop
            break
        
    
        # {do something with frame here}
            gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    
        # write a modified frame to writer
        writer.write(gray) 
           
        # Show output window
        cv2.imshow("Output Frame", frame)
    
        key = cv2.waitKey(1) & 0xFF
        # check for 'q' key-press
        if key == ord("q"):
            #if 'q' key-pressed break out
            break
    
    cv2.destroyAllWindows()
    # close output window
    
    stream.release()
    # safely close video stream
    writer.close()
    # safely close writer
    

    Source: https://abhitronix.github.io/vidgear/gears/writegear/compression/usage/#using-compression-mode-with-opencv

    You can check out VidGear Docs for more advanced applications and features.

    Hope that helps!

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  • 2021-02-04 14:52

    I had similar problem once. I opened an issue on Github, turns out it may be a platform issue.

    Related to your question, you can as well pipe OpenCV images to FFMPEG. Here's a sample code:

    # This script copies the video frame by frame
    import cv2
    import subprocess as sp
    
    input_file = 'input_file_name.mp4'
    output_file = 'output_file_name.mp4'
    
    cap = cv2.VideoCapture(input_file)
    ret, frame = cap.read()
    height, width, ch = frame.shape
    
    ffmpeg = 'FFMPEG'
    dimension = '{}x{}'.format(width, height)
    f_format = 'bgr24' # remember OpenCV uses bgr format
    fps = str(cap.get(cv2.CAP_PROP_FPS))
    
    command = [ffmpeg,
            '-y',
            '-f', 'rawvideo',
            '-vcodec','rawvideo',
            '-s', dimension,
            '-pix_fmt', 'bgr24',
            '-r', fps,
            '-i', '-',
            '-an',
            '-vcodec', 'mpeg4',
            '-b:v', '5000k',
            output_file ]
    
    proc = sp.Popen(command, stdin=sp.PIPE, stderr=sp.PIPE)
    
    while True:
        ret, frame = cap.read()
        if not ret:
            break
        proc.stdin.write(frame.tostring())
    
    cap.release()
    proc.stdin.close()
    proc.stderr.close()
    proc.wait()
    
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