==== Learn to use FFMPEG!!! ====

Simple default conversion:
ffmpeg -i {input} {output}

Specify codecs:
-c:v {vcodec} -c:a {acodec}

Scale the video:
-s {horz}x{vert}

Specify rates:
-r:a {audio rate} -b:v {video bitrate} -b:a {audio bitrate}

Or even better, use CRF with 26x:
-crf {crf rate}

Change duration:
-ss {hrs}:{mins}:{secs}.{msecs} -t {hrs}:{mins}:{secs}.{msecs}

Fun audio + image mix:
ffmpeg -i {audio} -i {image} {output}

•Site: https://denshi.org