MPEG2 experts - i need tweeking options !!

[holistic]

Hello all

I have been doing the (NTSC)VHS to mpeg2 for a while now and have been satisfied with the results. Basically I have been putting 'above average' bitrates on CD's with approx 20 minute run times for archiving purposes.
I am now ready to do my family video Hi8 collection and am wondering if there is anything else to tweek for better results.

(other than lowering run times and increasing bitrates , as i don't want less that 20 minutes per 700Mb disk - my only cavet )

The 352*480 size has been chosen to keep in the 1/2 D1 DVD spec. (not the audio though). My plan is to transfer and archive about 30+ hours on to CD for future transfer to a better media years from now. Like the current dream - FMD WORM drive .
http://www.bbc.co.uk/dna/h2g2/A533143


** Current setup using TMPGEnc 2.5 **

Stream = MPEG2
Size = 352*480
Aspect Ratio = 4:3
Frame Rate = 29.97 (of course !)
Rate control = 2 Pass VBR MIN 1700 AVG 4500 (depends on length 20 to 21 minutes whenever i can fade out) MAX 7500
Profile / Level = MP@ML
YUV = 4:2:0
DC component precision = 10
Motion search precision = high quality (cannot tell visual difference between high and highest)
Encode mode = Interlaced - of course !
Field order = Bottom field - since the Hi8 is 'bridged' through my DV camcorder and tests show this to show no flickering.
No filters - color & picture seem good enough not to need them.
GOP = I - 1 , P - 5 , B - 2 closed

Audio is MPEG1 layer II @ 128 upsampled to 48Khz
(I tried 192 and could tell no difference .The extra bits saved from the audio help the video )


* something I noticed when I was doing research - NTSC DV is 4:1:1 - why doesen't TMPGEnc allow for that ?
* Any suggestions for a better GOP or different matrix ? I am guessing less 'P' frames will increase percived quality with a trade off in file size !


Thoughts on this appreciated.

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[The village idiot]

Well it looks like you are pretty much "on the ball" with this. Yes NTSC DV is 4:1:1. I don't use TMPGEnc, I've been using a mainconcept derivative, so I can't really help you there.

* Any suggestions for a better GOP or different matrix ? I am guessing less 'P' frames will increase percived quality with a trade off in file size !

That's what I was going to suggest. I have seen small (but more pleasing) differences in moving objects with using a smaller GOP, without a lot of increase in file size. Try GOP of 12, or I=1 P=3 B=2. Looks like BBIBBPBBPBBPBBIBBPBBPBBPBB etc.(for those not familiar). Most everything I do I use that GOP and when compared to the "standard" GOP of 15, the file sizes were in the tens to 1 or2 hundred of MB larger, depending on the lenght of the video at 720x480, and at least an average of 4500 - peak between 7000 - 8000, interlaced. If you are using an app. that allows overburn, you could easily make up the difference in file size.

Too bad you can't archive to something like DV where all frames are encoded. Or better still, uncompressed. With as much video as you have to do, would it make sense to buy a DVD recorder of some format? You could then get about 18 minutes of DV on a disk, or a whole bunch of mpeg. Even if you don't worry about playing on a DVD player, then you could get the cheapest machine out there. Or for ease of use, get a stand alone DVD recorder. That would make for a considerable time savings! But your time is your own, and if you a happy with the way you are doing it, don't let me try to change your methods.

[mikk]

I always turn on Floating Point on the Advanced tab. I also turn on No Motion Search For Still Picture. The other thing I do is tick the box for color scale. I use the TV scale in my source DVD2AVI, so I need to tick this box... it's so I get extra color info that's normally chopped off.

mikk

[snowmoon]

I use the following .avs script to clean up analog sources and reduce necessary bitrate.

main = SegmentedAVISource("ntcap_15.avi").SeparateFields( )
filteredEven = main.SelectEven().SpatialSoften(1,3,6).TemporalSof ten(1,4,8 ).Sharpen(.15)
filteredOdd = main.SelectOdd().SpatialSoften(1,3,6).TemporalSoft en(1,4,8 ).Sharpen(.15)
return Interleave(filteredEven,filteredOdd).Weave()


For 352x480 the max can be much lower, say 5500 or 6000. Your average is probably on the high side as well. I would say that with proper pre-filtering you could get 30-35 minutes per 80 minute disk.

[holistic]

The village idiot - thanks i have tried the GOP you suggested .No real difference over 20 minutes though. I will try a few more for comparison .


mikk -

Floating Point on the Advanced tab. I also turn on No Motion Search For Still Picture. The other thing - .... - I use the TV scale in my source DVD2AVI, so I need to tick this box... it's so I get extra color info that's normally chopped off.

Huh WTF are you talking about DVD2AVI ?.
Advanced tab !? - You must mean the 'quantize matrix' tab and yes thanks those two are selected.


snowmoon - intresting script - i will give it a try.

For 352x480 the max can be much lower, say 5500 or 6000. Your average is probably on the high side as well. I would say that with proper pre-filtering you could get 30-35 minutes per 80 minute disk

really ! - 30 minutes is about a bitrate of 3000kb/sec .No harm in adding it to the 'to be tested' list but doubt it will be better than 4500 (with same settings) - 20 minutes +/- 1 is OK form my archival needs as 1.CD's are cheap 2.I can wait for a better higher capacity storage format to copy the mpegs too.

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[snowmoon]

30 minutes on a 80 minute disk is a totla bitrate of 3674 ( including audio ).

Are you writing >MPG's to a mode 1 CD or writing them as some sort of SVCD?

[holistic]

To quote myself

The 352*480 size has been chosen to keep in the 1/2 D1 DVD spec. (not the audio though).

I will not be svcd the format will be a mpeg2 data disk and therefore mode 1.

[snowmoon]

Many people including myself write Half-d1 out to SVCD as a format since it does not change the mpeg-2. When you wish to move it up to another format all you do is de-multiplex and re-multiplex for DVD or other mpeg-2 format.

[holistic]

snowmoon - the script didn't work
It appears it is looking for yuv2 source .Since my source is DV - it is not yuv and I will need a different script.

I checked out the avisynth home page (and others) for some scripts and will try some of the noise filters (if they work !)

Tx for onfo regarding de-multiplex and re-multiplex for DVD but I have no intentions of making DVD .All i want is best quality mpeg2 archives (considering the Hi8 source of course). From that I will eventually copy all (100 + ) CD to a greater storage media a few years from now. Something like the FMD worm drive should be out by then !

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