#!/bin/sh
ffmpeg -threads 15 -i "$1" \
    -fflags +igndts \
    -copytb 1 \
    -vcodec mpeg4 -vtag XVID -b:v 400k  \
        -filter_complex "[0:v]setpts=0.8*PTS[v];[0:a]atempo=1.25[a]" \
        -map "[v]" -map "[a]" "$2"