Is it possible to permanently letterbox a video (add black bars)while transcoding it?

Is it possible to permanently letterbox a video (add black bars to top and bottom) while transcoding it? (For example, add black bars to top and bottom of 2.35:1 aspect ratio video so that it becomes a 16:9 video with a 2.35:1 image area?)

Many thanks.

Yes, the Panasonic Viera (2011 Models, Adjusted Aspect Ratio) profile does this. What device are you using?

Thanks! I am using a Samsung from approx 2014.

If it's not possible to do this with this device, it's OK, I've found it's not that inconvenient to just add the black bars by re-encoding the file with AviDemux before playback - easier than I thought it would be.