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List:       mjpeg-users
Subject:    Re: [Mjpeg-users] Re: 24fps vs 30fps - why bother? :)
From:       "Steven M. Schultz" <sms () 2BSD ! COM>
Date:       2005-06-28 4:57:19
Message-ID: 200506280457.j5S4vJQ00637 () moe ! 2bsd ! com
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	Let's try this again and sorry for breaking the threading but SF.Net's
	bogus verification (probing the <> user) bounced yet another mail item
	on me :(

On Tue, 28 Jun 2005, Steven Ellis wrote:

> Really interesting thread on the strengths and weaknesses of different 
> ways to encode material.

	A bit heated (my fault) but interesting ;)

> Have any of you looked at the two pass MPEG2 code used in avidemux2. Its 

	No thanks.  Most of my encoding runs already are in the 14 to 16 hour 
	range.  I've no real desire to double that :)  

> For example I take an off air D1 PAL video capture, edit out adverts to 
> 45 minutes approx

	As one of my brothers keeps reminding me D1 is a digital tape recorder
	format (as is D-5, D-9 and so on).  In the "biz" (broadcast TV) they
	call it "601" (as in Rec.601) video :)

> 1. Clean up the black borders, ie remove non-visible junk.

	Good idea - but I wouldn't have thought digital TV would have much
	junk.

> Yes I know I should leave it interlaced, but a lot of my material was a 
> film -> TV transfer and de-interlaces really well.

	Ummm, I make a distinction between reverting a pulldown and 
	deinterlacing.  It sounds like what you're doing is reverting the 2:2
	pulldown used by PAL much as I, in NTSC-land, would revert the 3:2 
	pulldown.  

	To me that's not deinterlacing.  I think of Deinterlacing as taking
	a ~30fps interlaced (non-pulldown) video and creating a ~24fps new
	video stream.  That's a lot harder to do than matching pairs of
	fields from a pulldown processed stream :)

> 3. Use the Mplayer HQ Denoise filter.

	Hmmm, on the MPlayer mailinglists I've seen that filter disparaged
	and  mention made of not using it.  When I was using 'mencoder' to
	do encoding I did use it and thought it was ok (seemed to be mild,
	almost not noticeable in effect).

> 4. Encode to MPEG 2, target filesize of 1300 (3 episodes per DVD with 
> Audio), Max Bitrate 8000

	Just as easy would be to take the number of minutes of video and
	divide into 560 :)  I'll skip all the boring arithmetic but the
	rule of thumb given in DVD Studio Pro's documentation is to take
	(560 / minutes) to get the average bit rate in megabits/sec.  So for
	3x45 minutes you get 4.148 or ~4148Kbit/sec

> With the deinterlaced video I get an average Q of 3-4 and pretty damn 
> good video quality.

	Undoing the pulldown and encoding the progressive frames for some
	of the VHS tapes I've done recently I've gotten down around 2-3 :)
	Pretty amazing what doing a 10bit uncompressed capture and 
	pre-processing the data with FinalCutPro can do :-)

> Have a play and see what you think. It also has useful filters for 
> telecine etc.

	yuvkineco works quite well too once the field order is switched to
	top field first.

	One possible problem that hasn't been encountered yet (but no doubt
	will eventually) is a video that has mixed telecined film and NTSC
	video.  The tools I've seen don't know how to deal with mixed frame 
	rates - switching between 24 and 30.

	For now I think I'll take a break and go on vacation for a couple
	weeks :-)

	Cheers,
	Steven Schultz


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