Avisynth: How low/max bitrate for 480x576 resolution?
 

I was just wondering if I could drop the max.bitrate more if I'm doing encodes in 480x576? Since we could lower it from 2500 (704x576) to 2000 (528x576) I just thought we might get away with an even lower max.bitrate for 480x576 resolution? Or am I mistaken...? :roll:

Hi audioslave,

I use a MAX of 2,000Kbps for resolutions up to KVCDx3 (528x480).
So for 480x, 2,000 should be more than enough. At 704x480, 2,500Kbps is more appropiate.
And for MPEG-2 KDVD Full D-1, ~4,000Kbps works just fine ( with our matrix ).

-kwag

Yes, kwag, that's exactly what I mean "more than enough". :wink: Can I lower the max.bitrate until it's just "enough"? :) Let's say about 1800-1900?

Yes. You might want to simply do a "saturation test" with the encoder :idea:
Take a small (10 second) action scene of your movie, and encode with a CQ of about 90. Take a look at the maximum PEAK bitrate with Bitrate viewer. That will be basically the "ceiling" bitrate for your particular movie.
So you can use that bitrate as MAX :)

-kwag

So I can set the min.bitrate to 300, and the max.bitrate to 2500, the CQ to 90 and the check the peak value? Smart!
Once again, thank you for sharing your knowledge. :D

Just make sure you pick one of the highest action scenes of the movie.
That will guarantee that the bitrate will never go above that point on any other part of the movie.

-kwag

where can i download a bitrate viewer :?:

http://www.tecoltd.com/bitratev.htm

-kwag

Google sometimes can be the best friend ...

http://teco.emg.hu/bitratev/BV.EXE

I think it is the one .... I can't verify it cause im on a MAC in my office ;-)

EDIT: :oops: Kwag was faster :D....... :arrow: :arrow: :arrow: :arrow:

So, which is the trade-off between resolution, bitrate and CQ?
For example, at a fixed resolution, is it better to lower bitrate in order to get a higher CQ?

Max bitrage is tied the quality of high action scenes.
CQ is tied to the visual quality of the whole movie.

With this in mind, the choice is probably easier to do...

Personnaly I rather to have 3 or 4 scenes if a movie that are pixelated due to lack of bitrate that having mosquitoes in picture during 2 hours.

Can I just ask something here?

In an earlier post conversation with Dialhot
(http://www.kvcd.net/forum/viewtopic.php?t=11909), he'd said to me that he generally uses MIN 64/MAX 3000. As I'd previously been using MIN 300/MAX 2500 I decided to give his suggestion a try. I ended getting slightly higher CQ's and have stuck with 64/3000 ever since.

Are we now saying in this thread that MAX bitrates of 3000 or even 2500 are overly high? If 2000 is closer to the highest bitrate needed for most films, am I effectively wasting diskspace by encoding with too high a MAX?

HI Fingerbob

I,m not Phil but i am pretty sure what you are refering to is for DVD

I think he uses 64-3000 for KDVD and 64-2300 for KVCD

If you are talking about KVCD and you use the kvcd notch matrix and Kwag's optimal script and motion estimate in tmpge then alot of people were using 2000 as max ,but if you are doing avi and using Phil's script then its better to use high quality in tmpge and 2300-2500 max

Well in that thread he specifically says that its when he's using AVI sources.

Does that mean that an AVI source encoded to be burnt onto a DVDR can be done at a higher MAX (than to a CDR) whilst still giving the same output filesize (as a comparable KVCD done at the lower MAX)?

Or because its going onto a DVDR then the filesize is probably less of an issue - in which case you can boost the MAX to 3000?

Sorry - this is making me go cross-eyed thinkin about it.

HI Fingerbob

Yes in that thread its AVI to dvdr

i will try and explain a little

when using a cdr for video you are roughly going to have 700mbs of video while using a dvdr you will be having an average of 1300 mbs of video for the same movie

i realize that you probably know that already but as Phil said a few times for avi sources he just does mpeg2 kvcd vwith a higher max bitrate

this line confuses me a little but i think you have it correct

they way i look at it the way Phil does it is almost the same mpeg1 and mpeg2(excsept for the bitrate)except like you said with dvdr you have a lot more space for video

I'm sure if i am wrong Phil will clue us in