Pipe raw OpenCV images to FFmpeg

I'm Kind of late, But my powerful VidGear Python Library automates the process of pipelining OpenCV frames into FFmpeg on any platform. Here's a basic python example:

# import libraries
from vidgear.gears import WriteGear
import cv2

output_params = {"-vcodec":"libx264", "-crf": 0, "-preset": "fast"} #define (Codec,CRF,preset) 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/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!

Took a bunch of fiddling but I figured it out using the FFmpeg rawvideo demuxer:

python capture.py | ffmpeg -f rawvideo -pixel_format bgr24 -video_size 640x480 -framerate 30 -i - foo.avi

Since there is no header in raw video specifying the assumed video parameters, the user must specify them in order to be able to decode the data correctly:

• -framerate Set input video frame rate. Default value is 25.
• -pixel_format Set the input video pixel format. Default value is yuv420p.
• -video_size Set the input video size. There is no default, so this value must be specified explicitly.

And here's a little something extra for the power users. Same thing but using VLC to stream the live output to the web, Flash format:

python capture.py | cvlc --demux=rawvideo --rawvid-fps=30 --rawvid-width=320 --rawvid-height=240  --rawvid-chroma=RV24 - --sout "#transcode{vcodec=h264,vb=200,fps=30,width=320,height=240}:std{access=http{mime=video/x-flv},mux=ffmpeg{mux=flv},dst=:8081/stream.flv}"

Edit: Create a webm stream using ffmpeg and ffserver

python capture.py | ffmpeg -f rawvideo -pixel_format rgb24 -video_size 640x480 -framerate 25 -i - http://localhost:8090/feed1.ffm