FFMPEG - convert video to Black & White with threshold?

Question

I'd like to convert videos to black and white but also specify the threshold of what to convert to black/white.

I'm currently using cv2 to do this successfully using the 2 lines below (first converts to grayscale then B&W). But it would help my workflow to do everything with FFMPEG if possible.

    grayFrame = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    (thresh, BW) = cv2.threshold(grayFrame, 10, 255, cv2.THRESH_BINARY)

Answer 1

Use the threshold filter:

ffmpeg -i main_1280x720.mp4 -f lavfi -i color=gray:s=1280x720 -f lavfi -i color=black:s=1280x720 -f lavfi -i color=white:s=1280x720 -filter_complex threshold output.mkv

This filter requires four video streams to perform thresholding:

1. main input
2. threshold
3. min
4. max

You can optionally add the format filter for a grayscale pixel format: threshold,format=gray (assuming your output format supports that otherwise additional pixel format conversion will automatically take place).

Answer 2

The main answer didn't work for me, this did:

ffmpeg -i input.mkv -f lavfi -i color=gray:s=1280x720 -f lavfi -i color=black:s=1280x720 -f lavfi -i color=white:s=1280x720 -filter_complex "[0:v]scale=1280x720,threshold" output.mkv