Pipe Opencv Images To Ffmpeg Using Python

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 each frame. im

Solution 1:

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()
    ifnot ret:
        break
    proc.stdin.write(frame.tostring())

cap.release()
proc.stdin.close()
proc.stderr.close()
proc.wait()

Solution 2:

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 librariesfrom 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 loopwhileTrue:
    
    (grabbed, frame) = stream.read()
    # read frames# check if frame emptyifnotis grabbed:
        #if True break the infinite loopbreak# {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-pressif key == ord("q"):
        #if 'q' key-pressed break outbreak

cv2.destroyAllWindows()
# close output window

stream.release()
# safely close video stream
writer.close()
# safely close writer

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

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

Hope that helps!