In the custom parameters field, type: -vf "crop=1920:800:0:140" This removes letterboxing without re-encoding the timeline.

Contrary to modern "Max Quality" renders, version 1341 responds poorly to -preset p7 (slowest). The build's threading library favors the medium preset with a high bitrate ceiling. Trying to force veryslow on 1341 often results in render times slower than Adobe Media Encoder's default, defeating the purpose.