There is a bug in line 74 of the code which calculates outX wrong for input files with an aspect ratio != 4:3. I noticed because my video was 5:4 and the output file was not 16:9.
Fix for converting all input files to 16:9 is quite trivial tho, simply calculate outX from input height desired ratio:
outX := int(float64(specs.Streams[0].Height) (16.0 / 9.0)) / 2 * 2 // multiplier of 2
There is a bug in line 74 of the code which calculates outX wrong for input files with an aspect ratio != 4:3. I noticed because my video was 5:4 and the output file was not 16:9. Fix for converting all input files to 16:9 is quite trivial tho, simply calculate outX from input height desired ratio: outX := int(float64(specs.Streams[0].Height) (16.0 / 9.0)) / 2 * 2 // multiplier of 2