ffmpeg - how to set histogram size?

Question

I'm trying to add a histogram to a video using ffmpeg, I'm following this example, but I'm having trouble setting the size of the histogram, this is the code I'm using:

ffmpeg -y -report -i input.mp4 -vf "split[a][b];[a]format=gray,histogram=mode=waveform:waveform_mode=column,vflip,split[c][d];[b]pad=iw:ih+256[padded];[c]geq=g=1:b=1[red];[d]geq=r=1:b=1,crop=in_w:220:0:16[mid];[red][mid]overlay=0:16[wave];[padded][wave]overlay=0:H-h"  output.mp4

I've tried to play around with the pad and crop values without luck. How can I set the size of histogram to 100 pixels only?

Answer 1

I've solved my problem adding a scale value:

scale=1280:100

1280 being the width and 100 the height (output video is 1280x720)

The final code looks like this:

ffmpeg -y -report -i input.mp4 -vf "split[a][b];[a]format=gray,histogram=mode=waveform:waveform_mode=column,vflip,scale=1280:100,split[c][d];[b]pad=iw:ih+256[padded];[c]geq=g=1:b=1[red];[d]geq=r=1:b=1,crop=in_w:220:0:16[mid];[red][mid]overlay=0:16[wave];[padded][wave]overlay=0:H-h"  output.mp4