[MPlayer-dev-eng] Bogus numbers for NUT overhead

[D Richard Felker III]

While trying to figure out how to improve the nut design, I've been
doing overhead calculation on paper, and discovered that most of
Michael's numbers are totally bogus. It's IMPOSSIBLE for any container
to have less than ~0.25% overhead for 128kbit mp3, because the packet
size is 418 bytes, meaning that even a 1byte header gives ~0.25%
overhead! But Michael's original "NUT preview" email on ffmpeg-devel
reported:

> -rw-r--r--    1 michael  michael   4592134 2004-04-01 19:57 test3.nut
> -rw-r--r--    1 michael  michael   4582922 2004-04-01 19:57 test3.mp3

So either his muxer was dropping some frames, or it's packing multiple
frames together (which is illegal). Other reports since then have
repored similarly incredible results. So what's up?

If we want to correctly evaluate different designs, we first have to
make sure we're using a valid muxer, or else do all the calculations
theoretically. And IMO the current muxer is broken.

I think a reasonal target overhead for audio-only files is 0.5%-2%.
For audio+video it should be more like 0.25%.

Rich