[MEncoder-users] MEncoder and computation of frame-by-frame decoding time

[Andrea Guidi]

Hi!
I'm using MEncoder in a work in order to evaluate how frame-by-frame and
average DECODING times vary, changing resolution of the video input.
In particular, I'm now working only on mpeg1-2 and what I'm doing is take as
input an avi file with a certain resolution (during these days, my tests are
on a Scrubs episode encoded with xvid with resolution 512*384), encode this
file in mpeg2 with mencoder (following help here
http://www.mplayerhq.hu/DOCS/HTML/en/menc-feat-vcd-dvd.html) with different
resolutions and to compute average and frame-by-frame decoding time.

I have two questions.

1) given a certain resolution in input for an avi file, what are the only
significant resolutions for coding in mpeg2 such that the video is still
mpeg2 "compliant" and aspect ratio is not altered?
I ask you this because I've chosen the resolutions for mpeg2 format
specified in the paragraph "Format Constraint" in that page of the link
above but some of them are not "significant"...what's the principle to
follow in order to choose mpeg2 resolution?

2) if I want to make some decoding tests, encoding my video input file in
mpeg2 also with B-frame, what are the correct setting for "vmax_b_frames",
"vb_strategy" and "b_sensitivity" options?
<http://www.mplayerhq.hu/DOCS/HTML/en/menc-feat-vcd-dvd.html>

Thank you in advance.