25PsF: deinterlacing progressive

[Piotr Wozniacki]

I found and interesting article for those of you wondering about aliasing and twittering in the V1E/P when fed into a HD display through deinterlacing interface (HDMI or component):

http://www.100fps.com/video_resolution_vs_fluidity.htm

In some examples shown there, you can find aliasing identical to what you'll find in a snapshot, taken from VLC playing a 25PsF clip and bobbing it.

[Timo Mukari]

I noticed discussion of this same topic on some other forums and seems some TV sets have some way of controlling interleacing (film mode, movie mode). On my TV it did not seem to have any impact on your shots. Also they claimed some TV channels (e.g. "The Voice" ) sends both progressive (music videos) and interleaced (scrolling text) material mixtured. Testing these channels is a good/quick way to test how your TV's deinterleacer performs.

[Piotr Wozniacki]

An idea occured to me that I think is worth sharing:

Will the Canon XH-A1 play progressive tapes from the V1E? I don't see why it wouldn't as it is basicalyy still just a 50i stream. If it will, does anyone of you guys have access to both, and could check whether the line twitter is present on a HD viewing device when played from the Canon?

Tony?

[Chris Medico]

Yes it will and you are correct that its encoded just as a normal 50i stream would be.

On my side of the pond, video shot in 24p plays fine on my HC3. I tried it as a test even though I don't use that feature on the camera for my normal shooting.

Test away!

[Piotr Wozniacki]

Good news to everybody using the R50 version of V1!

I hope I'm not re-inventing the wheel, but I think I have just found the way to produce perfect progressive MPEGs in Vegas, from 25PsF video shot with whatever sharpness you want. Apart from setting the Project (timeline) properties to Progressive, it's important to also right-click the clip already in the timeline, open Properties, and in the "Media" tab choose "Progressive" in the Field order field again. It looks like - even though, as stated before, Vegas does recognize 25PsF clips as Progressive, it doesn't treat them as such actually - and the Field order is Upper first unless you change it explicitely in the way described above.

Having set both the Project and the Media Field order to progressive, I have rendered an MPEG-2 from clips whose sharpness varied from zero to 12. I played them back in the Nero Showtime player; even with deinterlacing=bob, there is no line twitter whatsoever (I used the "garage" clips with those fine horizontal lines).

What I don't get, though, is that VLC still shows the twitter when bobbing. Anyway, the result shows again that twitter-free display of 25PsF video is possible!

Here is a link to such MPEG-2 clip:
http://rapidshare.com/files/23814815...from_Vegas.m2t

Max (or anybody using the HVR-HD60),
May I ask you for a favour? Please download this clip and copy it to your HVR-HD60 directly from your computer, then connect the drive to your V1E, the camera to your HDTV via component or HDMI - and try to play it back. If you posted the results, I'd appreciate it very much (though I guess it won't play at all).

[Steve Mullen]

"Apart from setting the Project (timeline) properties to Progressive, it's important to also righ-click the clip already in the timeline, open Properties, and in the "Media" tab choose "Progressive" in the Field order field again."

Looks like there is a disconnect between the captured properties and what is used in the timeline. However, before I yell Vegas bug -- I'm not sure what difference this can make in a timeline unless one is applying FX?

Unless, field-order were reversed. That would cause a display issue -- I think.

1) Is there any way to select all your source clips and make the change?

2) Is there any way to select all clips in a timeline and change them.

I ran a series of export performance tests as part as an upcoming Vegas review. Guess what? The same timeline in three formats was exported. The 24p timeline took almost 2X longer!!!

[Timo Mukari]

Originally Posted by Piotr Wozniacki

Good news to everybody using the R50 version of V1!
Having set both the Project and the Media Field order to progressive, I have rendered an MPEG-2 from clips whose sharpness varied from zero to 12. I played them back in the Nero Showtime player; even with deinterlacing=bob, there is no line twitter whatsoever (I used the "garage" clips with those fine horizontal lines).

What I don't get, though, is that VLC still shows the twitter when bobbing. Anyway, the result shows again that twitter-free display of 25PsF video is possible!.

I tried this your new clip also on my HD-DVD player and I believe the quality was little better, but there is still some twitter, on the wall lines. Not as bad as using VLC with bob on (and this varies also what PC and/or display I am using). If someone has the HD-XE1 player supporting 1080p with true 1080p TV - would be nice to repeat this test with full progressive signal path (I have only the HD-E1 1080i version). As stated on Sony V1E pages you need a full progressive path to get best quality out of the 25p mode.

[Piotr Wozniacki]

The other artefact, apart from line twitter, that still is present in 25PsF video from the V1E, is the noise in fine detail area, known as "mosquito noise", "marching ants" or "busy pixels". I must say that it is this artefact that prevents me from shooting in progressive with sharpness setting higher than 5 (from 7 up, it becomes unacceptable at some contents; at 3 it's completely gone). The problem is that it doesn't go away with deinterlacing, ie. is still visible even on a computer monitor without deinterlacing.

Today I shot from a tripod some scene that - when shot hand-held - showed excessive amount of busy pixels; what I found interesting is that with the camera well stabilized and OIS off, the problem is much less pronounced and rises the safe sharpness level by 2 stops (5 being quite clean, 7 acceptable).

[Timo Mukari]

Piotr, did you try the Nero player with the older clips you had ? Was the twitter gone with bob on there as well ? I was just speculating why this does not show on the VLC any better with bob on and wondering if it is just the Nero player determining "better" when to deinterlace (independently of the settings) vs. VLC obeying your settings as such ?

[Steve Mullen]

Originally Posted by Piotr Wozniacki

I must say that it is this artefact that prevents me from shooting in progressive with sharpness setting higher than 5 (from 7 up, it becomes unacceptable at some contents; at 3 it's completely gone).

Today I shot from a tripod some scene that - when shot hand-held - showed excessive amount of busy pixels; what I found interesting is that with the camera well stabilized and OIS off, the problem is much less pronounced and rises the safe sharpness level by 2 stops (5 being quite clean, 7 acceptable).

As I remember, S needed to be 6 in order to have enough detail. Which means you need to deal with the issue either at the time of shooting or in post.

You found that a stable, no vertical jitter, prevents excessive aliasing even at 7 -- so 6 is fine.

You found that filtering cuts twitter at 6 -- so did it remove aliasing as well? If it did, you are all set.

[Piotr Wozniacki]

Timo,

Older clips do twitter with deinteralcing=bob in both the Nero and VLC players.

Steve,

Unfortnately, I've only done with line twitter; the mosquito noise is still there (in order to completely avoid it, the sharpness must be at 3 max with some contents and hand-held shooting, at 5-6 with contents of no fine detail and the camera well stabilized). But yes - it can be removed with filtering in post, though I don't find this solution very ettractive as it also removes detail in perfectly clean areas!

I've noticed that even minor camera movement causes sort of pixel unstability in fine detail near contrasty edges; the pixels stabilize for a second only to "fall apart" again, and start moving around like ants. The same happens wih changes other than movement, as well - for instance, when changing exposure. This is not present when the camera is rock stable, and the exposure, zoom etc don't change - how do you account for that? I think that DNR is still not optimally used - even after the V1E fix!