xvid not giving a accurate final size with 2 pass

[gavogavo]

I'm currently encodeing a hd source video. It encoded in VC1 15mbp. I used this script here to resize it to standard defition.

crop( 0, 140, 0, -140)
Lanczos4Resize(720,304) # Lanczos4 (Sharp)
Undot() # Minimal Noise

When I go to xvid 1.21 in vitualdubmod. I do a 1 pass then do a 2 pass and use their built in bitrate calculator However even with the bitrate calculator this movie is never acurate being the bitrate alot lower then what I chose and the file size is lower. Say I shot for 4gb total I will get a 2.7gb file. I'm thinking it because the vc1 is easier to compress then mpeg 2 so the bitrate calculator is not accurate. I'm doing 2 pass so it should be pretty close. Does anyone now of a way of calculateing that takes going from hd to sd into account and the vc1. If so it be much apperiated. One more question do you guys even brother using undot on hd sources?

-gavo

[BigDid]

I'm currently encodeing a hd source video. It encoded in VC1 15mbp. I used this script here to resize it to standard defition.
... this movie is never acurate being the bitrate alot lower then what I chose and the file size is lower. Say I shot for 4gb total I will get a 2.7gb file.
Hi and welcome to the forum,

From the numbers you give it seems you are maxxing out xvid (Codec cannot give more bits so it give an undersize final file)

If so, some settings and tips could help:
- Do not use B-frames => uncheck "B-VOPs" in xvid codec configuration/profile window
- Do not use VAQ => uncheck "Adaptative quantization" also in xvid codec configuration/profile

-Use another matrix (same window as above) than the standard one; for SAP use have a look at Sharktooth ASP cqm like EQM v3 HR, non SAP even more bitrate hungry cqm like EQM v3 UHR or Didée 6of9; see:
http://forum.doom9.org/showthread.php?s=&threadid=83125

Also, be sure to use job control and 2pass-1st pass followed by 2pass-2nd pass in Vdubmod

One more question do you guys even brother using undot on hd sources?

undot() or removegrain(mode=1) won't harm your source see read me; if stronger denoising is needed see the different denoiser threads to get infos.

Did

[gavogavo]

Thank you for the wonderful replie you are very helpful:D one more question my video bitrate is 3510, is EQM V3UHR (revision 2) the right matrix for me or should I just use EQM V3UHR?

[BigDid]

...one more question my video bitrate is 3510, is EQM V3UHR (revision 2) the right matrix for me or should I just use EQM V3UHR?
OMG, 3510Kbp/s :scared:

We don't play in the same yard, for SD I usually encode xvid at 1000/1500Kbps and x264 at +/- 2000kbp/s

UHR rev2 is the one indicated in the link previously provided, it's the right one :)

I am afraid even with the tips you will get an undersized final size, but be assured that it will be difficult to get a better xvid encode with these settings :D

Good luck

Did

[gavogavo]

it's for xbmc so it will play and interesting I turned on gmc and it looked worse. GMC bad at big bit rates maybe?

[BigDid]

Hi,

At this point (and such high bitrate) it is up to you to experiment and see what suits you best. I don't use GMC nor QPEL cause these options are not SAP compatible.

Another option would be to encode xvid-anamorphic if accepted by your box, I do it with x264 SD not xvid but it may help you (Megui can do it).

My new box is a Western Digital TV-HD and even if I don't have time to test it extensively I am positively impressed by that tiny box (and low price).

Did

[gavogavo]

Xbmc wont play h264 at the bitrate high enough to make it worth my while I will keep playing around and let you now what I can come up with.

[gavogavo]

what is xvid-anamorphic and clever tm anamoprhic enccoding resizing in megui. that help xvid encodes? is Trellis quantization enabled or disabled for bitrates of 4700 and 720x340 resolution? i enabled chorma motion to thinking that helps.

[FlimsyFeet]

I do a 1 pass then do a 2 pass and use their built in bitrate calculator However even with the bitrate calculator this movie is never acurate being the bitrate alot lower then what I chose and the file size is lower.
In older versions of Xvid, the bitrate calculator was broken. Try working it out and entering the numbers by hand.

[gavogavo]

with the settings I get to 3.8gb close enough. Thanks alot. Plays super great on xbmc. One more question on a regular crt tv is there any point going to resolutions higher then 720x?

[BigDid]

... One more question on a regular crt tv is there any point going to resolutions higher then 720x?
Hi,

I suppose by regular you mean a 4:3 CRT; if so the answer is no unless you encode for your future LCD/Plasma.. tv :cool:

If you have a widescreen (16:9) CRT it can (natively*) display up to 850*480/NTSC or 1024*576/PAL; good for anamorphic dvd :)

For more technical data, see:
http://www.winvistatips.com/widescreen-crt-question-which-resolution-t384672.html
http://en.wikipedia.org/wiki/File:Vector_Video_Standards2.svg
http://en.wikipedia.org/wiki/Full_screen_anamorphic
http://en.wikipedia.org/wiki/Display_resolution

Did

* CRT will display whatever signal/resolution you feed to it's native/max resolution

[gavogavo]

meant regular old school tv with rca jacks plugged in. like regular xbox xbmc hooked up to tv 480i. is going to even 720x480 overkill for a regular tv?