FORUMS: list search recent posts

Aliasing/twittering EX1

COW Forums : Sony XDCAM - EX & Related

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
Olly Lawer
Aliasing/twittering EX1
on Feb 28, 2009 at 5:16:59 pm

Hi,

Just wondered if anyone has figured out a solution to minimize aliasing/twittering with the EX1?

I thought aliasing was less when working with Progressive, although there seems no discernible difference with either one.

I guess there must be a way to minimalise this effect as I rarely notice it on TV.

Any help would be appreciated.

Thanks


Return to posts index

Don Greening
Re: Aliasing/twittering EX1
on Feb 28, 2009 at 6:40:53 pm

Olly, have you tried adjusting the detail setting down to minus 20 or minus 25? I think minus 25 effectively reduces the detail setting to nothing without actually turning it off and greying out other settings such as aperture correction, etc. The edge detail and detail frequency settings that Sony dials in at the factory are excessive. There does seem to be a correlation between EX line twitter and how much edge detail the camera is using. Are you noticing this more with your SD down converts or when watching the native EX files?

- Don


Return to posts index

Olly Lawer
Re: Aliasing/twittering EX1
on Feb 28, 2009 at 6:52:14 pm

Thanks for your reply.

I have only just purchased the EX1, so am doing some SD down converts now...and having a few heart stopping moments reading threads (http://www.dvinfo.net/conf/sony-xdcam-ex-cinealta/116196-how-your-ex1-sd-dvds-looking-3.html) that say you cannot get good looking XDCAM down converts to SD...surely this cannot be true?

I am using this guide to down convert to SD (http://www.kenstone.net/fcp_homepage/ex1_sd_output_young.html) although the image has now been made into a 4:3 instead of 16:9, so has squashed the image, even though this isn't what I selected.

Have you managed to get acceptable SD DVDs from the EX1 footage, if so how?

I will do as you suggested and lower the detail - does this have a big affect on the image quality also?





Return to posts index


Don Greening
Re: Aliasing/twittering EX1
on Feb 28, 2009 at 6:58:13 pm

[Olly Lawer] "does this have a big affect on the image quality also? "

No. It actually makes the picture look more organic and natural. Less like video and more film-like. Here's a recent discussion on successfully down converting from HD to SD. At least for users of Final Cut Pro:

http://forums.creativecow.net/thread/142/862811

- Don



Return to posts index

Olly Lawer
Re: Aliasing/twittering EX1
on Feb 28, 2009 at 7:04:40 pm

Thanks.

I will have a look through this. Just to set my mind at rest, have you managed to get good looking SD DVDs from the EX1?





Return to posts index

Don Greening
Re: Aliasing/twittering EX1
on Feb 28, 2009 at 7:08:43 pm

[Olly Lawer] "Just to set my mind at rest, have you managed to get good looking SD DVDs from the EX1? "

I continue to experiment but for the most part I'm satisfied with the SD results.

- Don



Return to posts index


Olly Lawer
Re: Aliasing/twittering EX1
on Feb 28, 2009 at 7:12:25 pm

Not hugely reassuring.

Better then other Cams like Z1?

Would you say for someone that will need to produce SD DVDs the EX! is not a good option?



Return to posts index

Don Greening
Re: Aliasing/twittering EX1
on Feb 28, 2009 at 7:33:23 pm

Since I haven't down converted anything else other than EX footage I have no frame of reference with regard to cameras like the Z1U. I have a friend with a the Sony Z7U that continues to have down convert and line twitter issues using Premiere Pro on a Windows machine.

My down converts are a lot better than they used to be with only a trace of line twitter and only once in a while. My next experiment will be to turn the edge detail all the way down to nothing and do another test. Right now it's set at minus 20. The last project was combining footage from the EX and my XL2 for DVD. The result was that the viewer will be hard pressed see a quality difference.

Keep in mind that if you stay in HD there's no line twitter from the EX.

- Don


Return to posts index

Craig Seeman
Re: Aliasing/twittering EX1
on Feb 28, 2009 at 7:22:30 pm

I think turning down the detail is a good suggestion.

I've had the twitter issue myself. What I think is happening is when you're shooting 1080p and part of the subject resolves to only a scan line or two and you downconvert to SD interlace the resultant subject is about a scanline or less. Hence it will twitter as the fields alternate.

In my case the twitter was at its worst when shooting thin tree branches while executing a slow zoom.

Part of the issue is that the EX resolves to a much higher resolution than most cameras (including many more expensive cameras). I believe Adam Wilt did some chart tests and found it resolving to about 1000 lines. When you have an object resolving to just one scan line at that resolution and downconvert the result may be as I note above. You get a one scan line object that appears only one one of two fields.

I believe ideally one would have some Edge Detection Interpolation on the downscale so only such lines are "treated" (softened to spread beyond one scan line in the resultant downconvert).



Return to posts index


Olly Lawer
Re: Aliasing/twittering EX1
on Feb 28, 2009 at 7:38:42 pm


I am at a cross roads of whether to send the EX1 back and get another camera. Before I do, I want to understand if anyone has managed to get a decent SD DVD from EX1 footage.

Noah has a DVD detailing how to down convert to SD (http://www.callboxlive.com)- but before I buy it, I wanted to find out if the EX1 is best for purpose.

I must admit, I did know the problems associated before I brought the Camera, but I was hoping the kenstone solution would work - the image looks good (before it goes to compressor that is and apart from the aliasing) although unfortunately it changes the aspect when I view it (even tho I haven't selected 4:3) and squashes the image.



Return to posts index

Don Greening
Re: Aliasing/twittering EX1
on Feb 28, 2009 at 7:47:20 pm

[Olly Lawer] "the image looks good (before it goes to compressor that is and apart from the aliasing) although unfortunately it changes the aspect when I view it (even tho I haven't selected 4:3) and squashes the image. "

If you've selected 720x480 Anamorphic then it will be squished when you view it in Quicktime Player and before you send it to Compressor. If you exported from FCP as a square pixel 854X480 self-contained movie then Quicktime Player will display the movie correctly.

When you use Compressor to encode your Anamorphic movie just make sure you've selected Anamorphic (16:9) in the encoder tab when you're setting everything up.

- Don



Return to posts index

Craig Seeman
Re: Aliasing/twittering EX1
on Feb 28, 2009 at 8:03:47 pm

[Olly Lawer] "I am at a cross roads of whether to send the EX1 back and get another camera."

Imagine sending a camera back because the resolution is too high.
BTW if you look at the Vortex training DVD that's all EX downconverted to SD. Doug Jensen mentions on some forums he does this all the time without issue.

Like any good DP you need to know what your target is. The problem is thin lines and the camera's excellent ability to resolve them in HD.

There are a number of possible solutions ranging from turning down edge detail, softening the image slightly in post maybe shooting 720p rather than 1080p, getting higher end downconversion software or hardware.

Yes having a higher quality source does require a bit more thinking.




Return to posts index


Olly Lawer
Re: Aliasing/twittering EX1
on Feb 28, 2009 at 8:19:55 pm

I know sending it back because the resolution is too high would be nuts, but if you read through the threads, then it seems there is no solution to getting good quality SD DVDs from the EX1...even extending to the review pro video coalition did on the EX1. (http://provideocoalition.com/index.php/awilt/story/review_sony_pmw_ex1_1_2_3_cmos_hd_camcorder)

The Vortex DVD does look better then some other SD down converts i've seen, but his DVD contains a lot of aliasing, which spoils the image.

I have just read an inspiring post where it seems someone has had some success. Thanks for your help.

Everyone has to start somewhere...



Return to posts index

Craig Seeman
Re: Aliasing/twittering EX1
on Feb 28, 2009 at 8:54:55 pm

Adam Wilt's comment in the comments below the article:

Eero: solving DVD creation problems is too big a topic for the comments section of a camera review (!); best start a thread in the forums: http://provideocoalition.com/index.php/forums/. All I can suggest (and all I’ll say here) is that you probably need to filter the high detail frequencies, especially vertically, to get the picture to look clean and quiescent on a standard-def interlaced display; HD downscaled to SD without prefiltering can alias severely, cause cross-color on composite feeds, and twitter insanely on CRTs.

You really just need to know what to do and have the right software/hardware to get good results.
That you think there is "no solution" itself doesn't make sense. If that were true you'd never see a good DVD coming from F23 or RED ONE cameras. You need to understand the workflow and get the right software/hardware to do a proper downconversion.



Return to posts index

Olly Lawer
Re: Aliasing/twittering EX1
on Feb 28, 2009 at 9:04:00 pm

I meant more no easy solution that doesn't cost an arm and a leg or rather no solution with the current set-up I have EX1/FCP/COMPRESSOR/DVDPRO.

Although having dug a bit deeper there is hope that I can get quality results with the kit I have. Noah's DVD should provide a good way of doing this.

As I said, everyone starts somewhere and as technology gets better, it also gets a damn lot more complicated. Thankfully, these forums exist and people like yourself are willing to give their knowledge to help, if i was stuck with the manual...



Return to posts index


Don Greening
Re: Aliasing/twittering EX1
on Mar 1, 2009 at 1:51:26 am

It would seem that Adam Wilt's recommendation for reducing line twitter with a Final Cut Pro HD to SD down convert is to use the motion blur filter with a sample setting of 1 (one). This apparently makes FCP do a much better job during the down conversion process. He also suggests experimenting with varying amounts of the flicker filter.

- Don


Return to posts index

Will Griffith
Re: Aliasing/twittering EX1
on Mar 1, 2009 at 4:16:48 am

For me FCP has always been a horrible converter.

The only way we could fix HDV conversions for BetaSP
was to use a Kona and its hardware downconvert.

Right now I don't even bother with FCP or Compressor's
conversions and just use the IOHD with the EX3.
It also saves on rendering.


Return to posts index

Steve Connor
Re: Aliasing/twittering EX1
on Mar 1, 2009 at 6:13:59 pm

Olly,

I'm just finishing my 3rd commercial DVD release that was partially shot with EX1/EX3's in 50i mode alongside an HDcam HDW790. To date we have sold some 5000 copies of the first two releases without a single mention of any problems with the pictures, in fact we get great comments about picture quality I simply edit in FCP and make an SD Mpeg 2 file directly from the HD timeline and the results have no problems at all.

If you check my e-bay store and look at my feedback on the following titles "The Shuttleworth Collection 2008" and "Flying Legends 2008" you will see people are very happy with the results!

http://stores.ebay.co.uk/Aviation-DVD-Store


I also have some web videos here which have EX content on, I know they aren't SD as such, but if there was a downconversion problem then it would show with Web Video as well.

http://www.vimeo.com/user542524/videos The B17 video on this site was entirely shot on the EX1

I have even made NTSC versions of the discs with no issues.

Yes, you should turn the detail down, I'm not quite sure what all the hysteria is about the EX not doing good SD. I'm more than happy with it.

Steve Connor
Adrenalin Television

Have you tried "Search Posts"? Enlightenment may be there.


Return to posts index


Olly Lawer
Re: Aliasing/twittering EX1
on Mar 1, 2009 at 6:27:44 pm

Thanks Steve,

It's good to hear that you are getting pleasing results without the need for expensive equipment.

So are you simply editing in HD and then using compressor to downconvert to SD using MPEG-2? Are you rending in ProRes?

Thanks - after putting my debts to the limit to make this happen (a childhood dream and if you don't try, you never know!) I did panic a bit reading those posts and not getting good results from the supposive KenStone fix - unless I was doing wrong of course.



Return to posts index

Steve Connor
Re: Aliasing/twittering EX1
on Mar 1, 2009 at 6:33:49 pm

I just simply use compressor to make an Mpeg2 from my HD timeline, I actually use DVCPro HD on these projects because of the smaller disc space, but the reults are even better in ProRes.

The EX is a great camera, dial down or switch off the detail and you shouldn't have any problems.

Steve Connor
Adrenalin Television

Have you tried "Search Posts"? Enlightenment may be there.


Return to posts index

Olly Lawer
Re: Aliasing/twittering EX1
on Mar 1, 2009 at 7:47:54 pm

Steve,

I tried your method, but I must be going wrong somewhere as I DVD Pro doesn't recognize the format when I encode to MPEG-2 Elementary Stream.

Basically, I edited in HD in FCP - rendering to ProRes. I then sent the file to Compressor and selected MPEG-2 (I didn't change any of the settings). When I import the finished encode into DVD Pro, it tells me the format is invalid.

I think I need a good book on compressor!



Return to posts index

Steve Connor
Re: Aliasing/twittering EX1
on Mar 1, 2009 at 8:08:21 pm

Use the "mpeg2 6.2mbps 1 pass setting" in the "DVD Fastest encode 90 minutes" folder and the dolby digital professional 2.0 setting for the audio

Steve Connor
Adrenalin Television

Have you tried "Search Posts"? Enlightenment may be there.


Return to posts index

Olly Lawer
Re: Aliasing/twittering EX1
on Mar 1, 2009 at 8:15:20 pm

Great, I will try this.

Are you increasing the average bit rate for better quality and changing the frame controls in any way?






Return to posts index

Steve Connor
Re: Aliasing/twittering EX1
on Mar 1, 2009 at 8:20:05 pm

depending on the length of the video I may tweak the data rate to 6.7 or 6.8

Steve Connor
Adrenalin Television

Have you tried "Search Posts"? Enlightenment may be there.


Return to posts index

Olly Lawer
Re: Aliasing/twittering EX1
on Mar 1, 2009 at 9:11:22 pm

Thanks for this workflow. Image looks a LOT better then it did the first time.

Just to throw another workflow I discovered into the mix. Have you tried this?

Edit as normal in HD in FCP
Choose File>Export to XDCAM. This will create a BAPV folder with your project in it.
Launch XDCAM EX Clip Browser and open the BAPV folder
Choose File>Export>Raw DV
Use the newly created DV file to create your DVD using standard DVD software.

Apparently people are getting some very good results.



Return to posts index

Steve Connor
Re: Aliasing/twittering EX1
on Mar 1, 2009 at 10:23:14 pm

I wouldn't encode to SD from a DV codec, wastes information, at least I'd convert to DV50

Steve Connor
Adrenalin Television

Have you tried "Search Posts"? Enlightenment may be there.


Return to posts index

Michael Slowe
Re: Aliasing/twittering EX1
on Mar 2, 2009 at 2:32:06 pm

Very good thread, one of the best for years, thanks fellows.

I have had brilliant DVD's from the EX1 but, I have to say, the best were from material shot in the SP mode (HDV)! I then upscaled through Convergent Design's box to HD and edited in Media 100. That application does a really good downscale and then the DVD is encoded with BitVice (VBR ave. 7.5, formatted in Studio Pro and burnt in Toast. I am sure that BitVice does a far better job in encoding than does Compressor.

Lately, now I'm shooting in the HQ mode, I have experienced all the edge twitter described in the thread. Obviously the camera is too good! I propose now to experiment with the detail turned down to -20 as suggested and hope for improved DVD quality. I have compared the BitVice downscale with that in Media 100 and the latter is visibly superior.

Michael Slowe


Return to posts index

Olly Lawer
Re: Aliasing/twittering EX1
on Mar 2, 2009 at 8:06:50 pm

Hi Michael,

It has been hugely beneficial. I have been searching forums for the answers for many days and not found my answer, until this thread.

I will try shooting in SP mode and see what results I get from that, but I have to say, the results look pretty good from Steve's workflow. Maybe a little bit blurred on low light shots, but then again, that could be my shooting.

For information, when I turned the detail off, I experienced no twitter/aliasing at all. Although I am going to test the camera again tomorrow by burning a variation of shots, SP, HQ, Progressive/Interlaced with varying degrees of detail and see what results I get.





Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2017 CreativeCOW.net All Rights Reserved
[TOP]