When encoding to mpeg-2 with the "Decode with mplayer" and "Burn" options enabled, you can burn in the image a text-based subtitle, and use this control to set its position (0=top, 100=bottom). Use the "Preview" button to check the position and move subtitles interactively with keyboard controls R/T, and find the right value to use. See full list on roysac.com The 2nd output file, out2.srt, only accepts text-based subtitle streams. So, even though the first subtitle stream available belongs to C.mkv, it is image-based and hence skipped. The selected stream, "stream 2" in B.mp4, is the first text-based subtitle stream. Bitmap fonts are like image formats such as Windows Bitmap (.bmp), Portable Network Graphics (.png) and Tagged Image Format (.tif or .tiff), which store the image data as a grid of pixels, in some cases with compression. Computer font-Wikipedia