Just a parenthetical note: The article, in its ffmpeg encoding guide says, -f - Only used in the first pass. Specifies the format of the output file in the

Just a parenthetical note: The article, in its ffmpeg encoding guide says, -f - Only used in the first pass. Specifies the format of the output file in the second pass i.e. MP4 in this case This is not required to be the same as the intended output format. Using `-f null -` will work just as well, as long as the encoder is epxressly set, which it is, in the commands shown.