Advice to tweak this video8 -> DV footage

[neRok]

Hi. Ive been tasked by the family to convert all their video-8 footage to something digital. Ive got to get a couple of videos done before xmas & onto DVD (to be watched at the grandparents). Then I will tweak all the vids to x264 or something better. I've got a digital-8 camera and ripped DV AVI files with win-dv, so step 1 is done.

Ive done some reading on doom9 etc regarding the cleanup process, using avisynth, etc. Ive got a decent grasp of how to use avisynth (and avspmod, vdub, etc), just not what to do to these videos yet.


The DV AVI files are YV12 720x576 25.00fps interlaced BFF. Pretty standard stuff it seems. Attached is a screenshot showing a typical scene I need fixed. I can work on getting a snippet of vid if need be. Would the snippet of the photo suffice, or is it a 'bad scene' for testing?

Picture Size;
- Top has a black strip that changes in thickness. 4px gets rid of it always, 2px most of the time.
- Bottom seems to have the normal tape 'dodgy' section. 10px cleans it up.
- Left is gone with 12px.
- Right has black, which is gone with 12px. Then there is a 2px dodgy section (so 14px to clean that edge up).
So if I trim all those parts off, I am left with 694x562. Do I resize up to 720x576, or maybe 704x576, or just add a black border/frame around it and centre the picture (making it 720 or 704 overall)?

Luma; Since I am putting it on dvd, am I best just use ColorYUV(levels="PC->TV") to get the luma into the desired range? I have noticed that changing the luma with ColrYUV makes random spikes in the chart, much like the 1 seen (except there would be ~10)

Chroma: The chroma in the histagram look quite central. I take it this is quite good?

Color Blur; The bird on the left was in the centre, but the camera panned, and I think it left that green color streak along the jumper. This happens a lot in all the videos, usually with green and blue. Can anything be done about this? I tried some chroma rainbow reducers (ChromaShift for example), they didnt seem to do anything.

And for long term...
Stabilising (and remoing the time/date); I had a quick play with 'Freds 8mm script' on doom9, which had stabilising built in. It worked good, but the time/date stamp moved around. Any easy way to mask over this, or is a 'logo remover' the best option?

[jagabo]

Don't resize interlaced video, add borders to bring the frame back up to 720x576. Keep two of them mod8 if possible. If you really want to resize, use a sequence like:

(after cropping)
QTGMC()
BicubicResize(720,576)
SeparateFields()
SelectEvery(4,0,3)
Weave()

Your video has the typical over bright highlights of DV. PC->TV is not a good way to fix that as it will also lighten the darks. Judging by the sample image, ColorYUV(off_y=-20) will probably work better. Or maybe ColorYUV(gain_y=-20) .The super blacks in the histogram are probably the black border and a few oversharpening halos in the main image.

I don't think there's a lot you can do about the green streak from temporal blurring.

A delogo filter is probably best to cover the timestamp (to keep it from wandering around after stabilizing).

[sanlyn]

Picture Size;
- Top has a black strip that changes in thickness. 4px gets rid of it always, 2px most of the time.
- Bottom seems to have the normal tape 'dodgy' section. 10px cleans it up.
- Left is gone with 12px.
- Right has black, which is gone with 12px. Then there is a 2px dodgy section (so 14px to clean that edge up).
So if I trim all those parts off, I am left with 694x562. Do I resize up to 720x576, or maybe 704x576, or just add a black border/frame around it and centre the picture (making it 720 or 704 overall)?

To add to jagabo's very correct notes:

Interlaced YV12 requires that vertical cropping has to be mod-2 pixels at a shot, and the resulting frame must be mod-4 (the frame height must be evenly divisible by 4). This is due to the way YV12 stores chroma pixels. Horizontally, the crop can be only 2 pixels if that's all that's needed, but the frame width still has to be mod-4 as well.

If the desired result will eventually be DVD, frame width and height must be mod-8. Avoid resizing (and to echo jagabo, don't resize interlaced video). Crop followed by resize can distort the original frame aspect ratio, even by a small amount. Better to add black border pixels to restore the original frame size and center the frame if cropping is irregular.

Take a look at this Avisynth Help page on the Crop function, bottom of the page: http://avisynth.nl/index.php/Crop

[2Bdecided]

You don't need to fix the stuff in the borders if this is going to DVD to watch on a TV - it'll all be lost in the overscan.

However, if you want to fix it: crop + add borders (keeping all crops and borders mod2 horizontally and mod4 vertically due to YV12 chroma) as needed. A final framesize of 704x576 will leave smaller black borders than 720x576 and is a valid DVD resolution. Do not deinterlace for DVD. Do not wreck the interlacing by vertical resizing or non-mod2 cropping.


Make sure you're using the Cedocida DV decoder.


levels(0,1.0,255,2,235,coring=false)
will fix your levels, but it does look rather clipped even for that. I'm guessing there's nothing you can do about that?


You should keep your original captures.


Stabilising and delogo-ing are both error prone. Be careful. Stabilise+crop (to hide moving borders) can dramatically reduce quality.


Cheers,
David.

[neRok]

Thanks guys. I think I got the picture size sussed properly.
720x576 in
Crop(12, 4, -12, -12)
AddBorders(4, 8, 4, 8)
704x576 out
Is there anything negative about using 704, rather than 720? I figure that little bit less video will help with compression.

Everyones suggestion re luma makes sense. I will test out my favourite solution. off_y is the 'darkest', and seems to add a bit more contrast too (plants look a bit greener for example), so it is my favourite for this video (but need more testing on others). gain_y and levels solutions are similar.

Re interlace, do I need to swap the fields so the video is TFF for DVD?

Any suggestions re other filters to have a play with?

[jagabo]

Is there anything negative about using 704, rather than 720?

No.

I figure that little bit less video will help with compression.

Not really. Perfect black borders compress down to nearly nothing.

AddBorders(4, 8, 4, 8)

AddBorders(0,8,8,8) will give very slightly better compression and prevent DCT ringing artifacts at the borders.