CQ_VBR and the Maxbitrate
 

Kwag,
i try increase a CQ_VBR and/or reduce the Maxbitrate.

for a sample,i use a simple chapter(03minuts,23seconds)and with:

OffsetFixed CQ_VBR Value=25 and MaxBitrate=1150
final size: 22,4mb

OffsetFixed CQ_VBR Value=25 and MaxBitrate=2300
final size: 20,8mb (*1)

OffsetFixed CQ_VBR Value=30 and MaxBitrate=1150
final size: 24,9mb (*2)

OffsetFixed CQ_VBR Value=30 and MaxBitrate=2300
final size: 23,7mb

i'm confuse with the results:
less CQ and more Maxbitrate= less size. (*1)meaning worse quality?
more CQ and less Maxbitrate= more size. (*2)

i can't see a "visible" difference in quality,but i ask:
what is better, more or less (cq and Maxbitrate)?
and about the size in a movie?(more than 130minuts)
and if i want two movies of 70 minuts in one cd?

(:-@ ..."it's driving me mad".

thanks in advance! :wink:

Hi jorel,

As a rule of thumb, the minimum MAX bit rate you should use are 1,150 for 352x240, 2,300 for 352x480 to 544x480, and 2,500 ( or more if your player can handle it ) for 704x480.

Those are the bit rates I use. For the LBR, which is set to 1,150, I use 1,800 if the movie is ~2 hours ( or use the KVCD 352x240 PLUS which is already set to 1,800). For longer movies, I drop back to 1,150.
The way CQ_VBR works (I assume) has to do with the fluctuations between MIN and MAX bit rates. So the more you close the gap between MIN and MAX ( MIN and MAX closer together ), it aproaches constant bit rate. The more you separate the MIN and MAX, the wider the fluctuations for the encoder to work, and less quality will be produced.

Do not pass GO, do not collect 200 dollars. :!: :mrgreen:

This is my opinion based on my own tests and many (many) encodes, so I assume this is the way TMPEG works internally.

-kwag

What would be a good method to guesstimate the min/max bitrate you use? Say for a movie of ~2 to a bit over 2 hours, encoded at 480x352 or 352x480 (to use as an example)? How do you determine the best bitrate range?

I don't guess, I use file size prediction CQ_VBR with fixed MIN and MAX :wink:

-kwag

Kwag,
how can i encode two movies of 70 minuts in one cd?
thanks in advance.

Of course :D
Try the LBR and then burn each movie as a separate track. :wink:

-kwag

yes but,
i encode one movie first....than the second movie.
how can i know the final size of one and other?
if i encode the first ,he don't get the total size of the cd? :?

ps: about "why don't you use some "soldiers" to help you?"
i "see" the news....do you remember this?
http://www.kvcd.net/forum/viewtopic....487b72c6711d75
:wink:

Hi jorel,

You would select a target of 400MB minus your audio size, instead of 800MB. This way, you are prediction "Half CD-R" size for each movie.

-kwag

:D thanks Kwag! (again and again.....)

editing:

ammck55,from doom9,help me with this link:


http://forum.doom9.org/showthread.php?s=&threadid=39117

in special:
6. I then click the "..." button and add all the other vob files.

it's a solution to encode different vobs :wink: