[MEncoder-users] Suggestions invited for encoder options for varying qualities

[Joe Emenaker]

I'm tinkering with a script... intended to be a front-end to mencoder to 
make it easier to use. Yeah, yeah... you hear this once a month, I 
know....  here's what I intend mine to do:

Basically, you'd provided up to four bits of info to the script:
 - A list of input sources (ie, dvd://1, pr0n.avi, goldfinger.mp4... 
whatever)
 - A destination device or format (ie, "ipod", "psp", "treo", "vcd", etc.)
    this would determine container, codecs, resolution, color-depth, and 
possibly frame-rate
 - A preference regarding the file-size/quality tradeoff (ie, "basic", 
"good", "extreme"...)
    this would determine bitrate
 - A preference regarding the encoding-time/quality tradeoff (ie, 
"quick", "normal", "extreme"...)
    this would determine encoding parms like, number of passes, and 
other options like maybe vhq?, qpel?, etc.

I'm in need of the community's input in two areas:

First, I'd like to get a consensus regarding which options for *each* 
codec library (ie, lavcopts, x264opts, xvidencopts, faacopts, etc) fall 
into the size-versus-quality category (any other than bitrate?) and 
which are in the encoding-time-versus-quality category. Furthermore, I'd 
like to know which ones everyone feels should be turned on or off for 
"quick", "normal", "extreme", etc. preferences.

Secondly, I'd like some input on strategies for determining bitrates for 
the various target devices. I'm currently thinking of two ways to do 
this. 1) Estimate suitable bitrates based solely upon resolution, 
color-depth, and codec, or 2) Actually have some "normal" bitrate for 
each target device and then "basic" or "extreme" would be some 
percentage higher or lower than the normal one. A few weeks ago, it was 
mentioned that bitrate, instead of varying directly with the number of 
the resolution, is better varying with the square-root of the 
resolution. Is this still considered barely suitable, or is this a 
fairly good strategy when compared with the hassle of manually 
determining a good bitrate for every target device?

Lastly, as an aside, does anybody want to suggest good terms to use for 
the various qualities (ie, basic/good/extreme, or low/medium/high, or 
1/2/3, etc.)? And how many quality levels should there be? 3? 5?

- Joe