FFMPEG and drawtext

Several years ago I wrote a program that consolidates time-lapse pictures into a directory and calls FFMPEG to create a video.

I had been wanting the time-code from when each picture was taken printed on the screen while the video was playing but had not figured out how to get it done until this weekend.

Video TimeCode

Frame from video showing the DateTimeOriginal timecode embedded.

I’d gone down multiple paths in an attempt to get this result before finally getting the drawtext feature to work. My program manually pulled the metadata from the images before feeding them to ffmpg. I’d tried creating both text files and image files for overlaying. none of those got the result that I was looking for.

When I finally got everything working, it seems simple, but the underlying problem has to do with the amount of string escaping required to get the command to work.

Here’s an example command I was issuing to ffmpeg that got the result I was looking for.

ffmpeg.exe -hide_banner -r 30 -i Wim%05d.JPG -vf crop=in_w:3/4*in_h,drawtext=fontfile=C\\:/WINDOWS/Fonts/OCRAEXT.ttf:fontcolor=white:fontsize=160:y=main_h-text_h-50:x=main_w-text_w-50:text=WimsWorld,drawtext=fontfile=C\\:/WINDOWS/Fonts/OCRAEXT.ttf:fontcolor=white:fontsize=160:y=main_h-text_h-50:x=50:text=%{metadata\\:DateTimeOriginal} -s 3840x2160 -pix_fmt yuv420p -n Test-2160p30-cropped.mp4

If you look at the -vf option parameter, I’m cropping my input pictures to 3/4 their original height, then using the drawtext feature twice. First I write the static text to the bottom right of the frame, then I extract metadata from the source image and write it to the bottom left of the frame.

Because I’m calling this from a program, I had extra escaping of the \ character in my code. All of the escaping required a lot of trial and error to get things working. I’m using OCRAEXT as my font, but I could be using any fixed spacing font. because of the fact that the time is changing every frame, it’s important that the font not be proportional to make it easy to read.

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