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Old 19 Apr 2002, 04:29 AM   #1
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Default Just found out...May be useful

I have found out a couple of things by encoding:

1) Dark movies don't compress well
2) Dark movies need the newer codec. So DivX 5.01 will work
better then M$MPEG V2 & DivX 3.

Any other tips you would like 2 share are welcome
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Old 19 Apr 2002, 05:03 AM   #2
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I knew this. Thanks for clearing it up.

I always brighten the video in MPEG2 then to DIVX 3.11alpha nd therefore it compresses ALOT and good quality!

I would be happy if anyone would like a preview of a clip, but they must be able to upload it on their own server, as I have a low bandwidth!

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Old 19 Apr 2002, 11:53 PM   #3
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When you mean by brightening it up
are you referring to the luminance correction in nandub?
becoz if that is the case i might give it a go
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Old 19 Apr 2002, 11:54 PM   #4
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Yes, that too.



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Old 20 Apr 2002, 12:45 AM   #5
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Uhh, there seems to be a bit of misunderstanding on the use of Luminance Correction of nandub. Here's an extract from Doom9's guide. It will explain what I would like to say:

Luma correction corrects luma values (hence the name). During the first pass each frame is measured for "luma noise". Frames with a great deal of contrast will have a high luma noise, frames with little contrast will have a low luma noise so we have to correct or add bits to the low luma noise frames. Frames underneath the threshold get more bits. The further away they are from the threshold, the more bits they get up to threshold over 2, then they start getting less correction. If you have a threshold of 10 and 30% correction then luma noise 9 will get 6%, luma noise 8 12%, luma noise 7 18%, luma noise 6 24%, luma noise 5 30%, luma noise 4 25%, luma noise 3 18%, luma noise 2 12% and luma noise 1 6%. So as you can see it's a proportional triangle which has the gain (max) value at threshold/2 and it decreases proportionally on both sides. Furthermore frames on top of the curve lose bits depending on luma noise. After the frames have been corrected a frame with luma noise 20 loses more than a frame with luma noise 15. Suggested values are 10 for threshold and 30 for gain.

So this has nothing to do with brightening the video. You will need to load up a Brightness/Contrast filter in nandub to achieve the goal.
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Old 20 Apr 2002, 12:49 AM   #6
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Enchanter - This is what I meant! Sorry for the bad english

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Old 20 Apr 2002, 04:39 AM   #7
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i just found out by experimenting that it is best to encode in DVD2AVI and not just use it as a frameserver if you are not using M$MPEG V2 or DivX 3 for 2 pass encoding (via nandub). So try it out if your using DivX4/5 or Xvid etc...

The good thing is it is easy to resize in it

However i do have a problem. How do i change the resolution. For eg i want 2 change it from 720*480 to 640*... But i don't want to recode it all again as it will take twice as long
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Old 20 Apr 2002, 05:42 AM   #8
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I don't think there is a way?

or maybe do a 1pass with the resize filter in action?

I dunno, just guessing

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Old 21 Apr 2002, 08:46 PM   #9
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thanx for the long reply enchanter
so if if do brighten the video with (not luminance correction hence the explanation cleared things out)
would it make the video easier 2 compress?
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