Maximum and Minimum bitrates?

[SilverBlade]

I don't know if this has been asked before, but a couple of questions did pop into my mind a couple of weeks ago:\

1) What is the maximum bit rate for a movie before it becomes a waste of space/processing time? (As in, the quality of the movie won't get better after a certain point)

2) What is the minimum bit rate for a movie before you notice a definite loss in quality?

[jdobbs]

There's really no answer for those questions. It all depends on the source. Some sources require more bitrate than others (for example high action movies or very detailed scenes). Other movies require very little.

[JohnGalt]

What jdobbs says is, of course, absolutely true. If you want some (useless) guidelines, tho, you might use the following reductive and schematic rules of thumb: >4000 = pretty good; <2000 = really bad.

If you have a very low bitrate source, you might experiment with the Half-D1 option (which halves the width of the source, so your bits are used to encode less data), and with AviSynth plugins that soften the picture (less detail generally makes a source easier to encode, hence less macroblocking and so on). Of course, both of these options will decrease the quality of the source, but each option may well look better than the alternative.