A few queries

[grvce]

I have encoded three movies with Gknot and I feel that this tool really rocks. Hats off to the author.

I have a few questions though. Pardon me for the n00b touch to the questions.

1) Somewhere on the forums it was mentioned that a compressibility check would save around 6 hours of my time. I didnt understand the reason behind that. A compressibility check would only determine the best setting for the movie, why would it save time ?

2) I am basically a BW movie (classics) fan, i believe I can achieve higher compression on those. Is this assumption valid ?

3) Also the movies that I encode with Divx5 pro ( i always use divx 5 pro) look really nice in Divx5 Player 2.0 Alpha 5. In others, like WMP 6.4 and the playa, i can see the blocks (tiny little squares, i think they are called macroblocks). I want to ask whether anyone else has experienced this. I will attach a few screenshots later on.

Thanx in advance,
Seeker

[N_F]

1) He probably meant that if you're final movie turns out bad you could have made a comp. test from the beginnning and saved the time a remake will take (if you decide to do one). I disagree, but that's another thing.

2) It's been my experience that the difference is small between color and b&w, but don't take my word for it.

[hakko504]

A compression test will save time if you use it to avoid undersized files. If a compression test shows 100% or more you can never achieve the desired bitrate, thus saving you a full encode to find this out. With b-frames enabled max bitrate will be even lower, and anything over 75% will most likely give you undersized files. The exact point is not fixed but depends on the movie.
Yes, and no. By using greyscale() or Levels() in AviSynth you can get rid of all color parts, thus increasing compressability. On the other hand, old B/W movies are often quite noisy, with a lot of contrasts, and 4:3 format, and these are factors that make it harder to compress the movie. Using a number of filters can improve this matter considerably, and should be tried. It can take a while to find the best settings for that though. A reasonably new film in B/W like Ed Wood or Young Frankenstein should be very easy to compress really hard.
This is probably because they use different settings and functions for post-processing. In WMP you can right-click in the picture and go into properties to change that. If you want more control then I recommend ffdshow as decompressor. Also, if you experience this you are probably using a little too low bitrate for that particular movie, and should increase it, or add a smoothing filter to increase compressability.