720p30 downconvert to BetaCam has 'interlace ripping' at DVinfo.net

George Strother · May 25th, 2007, 05:04 PM

Has anyone had success with the realtime downconvert to uncompressed 8 or 10 bit BetaCam component feature of the Kona LH from an HDV 720p30 timeline?

Link to a frame showing the effect I am getting -

http://briefcase.yahoo.com/bc/twosun...ase.yahoo.com/

This b&w image shows the coarse serations on the vertical edges of the animated block. In the animation it just moves left and right. 720p30 footage from JVC HD100U and HD250 cameras have the same "fringe", but it's not as clear on the scenes I'm testing.

Anyone know how to make this work?

Stephen L. Noe · May 25th, 2007, 07:55 PM

Are you previewing on a CRT or LCD?

Stephan Ahonen · May 25th, 2007, 10:23 PM

That's just an interlacing artifact. Don't worry about it, perfectly normal, and it disappears when you view the picture on an interlaced screen.

Just make sure you set your field precedence right.

George Strother · May 26th, 2007, 10:27 AM

Quote:

Originally Posted by Stephen L. Noe

Are you previewing on a CRT or LCD?

Sony PVM1344Q SMPTE pro/broadcast CRT over component from the Kona LH.

AJA support hasn't been able to figure it out yet. I am hoping someone here has seen this before and has found a way around it.

George Strother · May 26th, 2007, 10:34 AM

Quote:

Originally Posted by Stephan Ahonen

That's just an interlacing artifact. Don't worry about it, perfectly normal, and it disappears when you view the picture on an interlaced screen.

Just make sure you set your field precedence right.

This isn't a normal interlace artifact. It isn't a field dominance order issue either.

The error is visable on a broadcast CRT interlace monitor. It doesn't show on a progressive computer display.

This error looks just like this when the tape is playing, but smooths when the tape is paused. Backwards for normal interlace.

Normal interlace artifacts pop out when the tape is paused, smooth out when the tape is playing.

Stephan Ahonen · May 26th, 2007, 11:53 AM

It really does sound like interlacing to me. What you describe are some of the peculiarities of interlaced material that has been sourced from progressive material.

If you're downconverting 30p material, the interlacing artifacts will go away when you pause because it will pause on a full frame. However, in motion you will see interlacing artifacts *between* frames because it will paint the first field from the next frame while the second field from the previous frame is still visible.

It's not showing up on your progressive display because it's showing the full progressive frames.

If you're still not convinced it's interlacing, zoom in on the image you provided. The mouse teeth in the picture alternate to the left and right line by line.

George Strother · May 26th, 2007, 02:59 PM

Quote:

Originally Posted by Stephan Ahonen

It really does sound like interlacing to me. What you describe are some of the peculiarities of interlaced material that has been sourced from progressive material.

If you're downconverting 30p material, the interlacing artifacts will go away when you pause because it will pause on a full frame. However, in motion you will see interlacing artifacts *between* frames because it will paint the first field from the next frame while the second field from the previous frame is still visible.

It's not showing up on your progressive display because it's showing the full progressive frames.

If you're still not convinced it's interlacing, zoom in on the image you provided. The mouse teeth in the picture alternate to the left and right line by line.

OK, yes it is interlaced. And it is interlaced wrong. And the BetaCamSP footage that results is unusable. During playback everything moving across the screen has distinct "fingers" sticking out of it on both sides. Pause and they go away. Correct interlace displays the opposite way on a pro/broadcast CRT SD monitor.

AJA support is trying to find a way to fix it. I'm just looking for someone who has found a way around this while AJA works on it.

The problem is apparently tied to HDV or AIC sequences or anything that been through the HDV codec used by our JVC cameras.

It may be just another issue with the ProHD cameras and one more workflow they simply can't do.

Or maybe someone here knows a workaround.

Stephan Ahonen · May 27th, 2007, 02:12 AM

Just curious, have you tried reversing the field dominance? It's worth a shot.

It's also possible that the AJA is working 100% correctly and that what's happening is simply an unavoidable consequence of pulling down 30p into 60i.

Scott Jaco · May 27th, 2007, 07:32 AM

I've gone from a 720/30p timeline to Betacam without any problems. I selected 10-bit uncompressed for video playback using a Blackmagic card.

It seemed to look quite nice.

Glen Vandermolen · May 27th, 2007, 09:23 AM

I'm planning on purchasing an HD200 with a BR-HD50 deck, which I will then edit with FCP 5.1.4. on a G5. For workflow, I plan on sometimes shooting 720/24P and 720/30p, editing in HDV, then outputting in standard video onto a Betacam SP deck.
Since I don't yet have the gear I'm not totally clear on how your problem originated. But with my set-up, is it possible I'll experience this problem? Does it occur when mastering to a Beta SP format?
If this is an inherent flaw with the JVC ProHD set, then this could definitely affect my purchasing plans. Do I need some type of card between the BR-HD50 deck and FCP to digitize HDV? I was under the impression I could digitize directly into a ProMac FCP without further hardware.

George Strother · May 27th, 2007, 06:33 PM

Quote:

Originally Posted by Stephan Ahonen

Just curious, have you tried reversing the field dominance? It's worth a shot.

It's also possible that the AJA is working 100% correctly and that what's happening is simply an unavoidable consequence of pulling down 30p into 60i.

Yes, I tried that first. It has no effect at all, which seems even more like some problem in the interlace conversion. It should make a mess of the video if it's set the wrong way round.

I don't know enough about the interlacing process being used to guess if the fault is AJA, Apple, JVC or the HDV 1 codec. As you say, the HDV 720p30 codec may not allow clean interlace conversion. But just below your post, Scott Jaco says he's getting good results with a Black Magic card.

So I'm still looking for someone who has found a workaround, whether it's going into and out of another codec, hopping up and down on one foot, switching cards, or ...

George Strother · May 27th, 2007, 06:38 PM

Quote:

Originally Posted by Scott Jaco

I've gone from a 720/30p timeline to Betacam without any problems. I selected 10-bit uncompressed for video playback using a Blackmagic card.

It seemed to look quite nice.

Scott

Are you viewing the feed to the BetaCam tape or the BetaCam playback on an interlaced CRT monitor?

If everything looks good on a pro/broadcast CRT I'll need to take a close look at a Black Magic card.

George Strother · May 27th, 2007, 06:46 PM

Quote:

Originally Posted by Glen Vandermolen

I'm planning on purchasing an HD200 with a BR-HD50 deck, which I will then edit with FCP 5.1.4. on a G5. For workflow, I plan on sometimes shooting 720/24P and 720/30p, editing in HDV, then outputting in standard video onto a Betacam SP deck.
Since I don't yet have the gear I'm not totally clear on how your problem originated. But with my set-up, is it possible I'll experience this problem? Does it occur when mastering to a Beta SP format?
If this is an inherent flaw with the JVC ProHD set, then this could definitely affect my purchasing plans. Do I need some type of card between the BR-HD50 deck and FCP to digitize HDV? I was under the impression I could digitize directly into a ProMac FCP without further hardware.

Glen

This is a new issue for me. I hadn't tried 720p30 to BetaSP until a couple of days ago. The Kona LH card supports realtime conversion for BetaSP mastering, it's just not working right for me at the moment.

Still too early to say what the problem is, but someone on this forum may have already run into it and have the workaround.

As far as capture to FCP 5.1.4, you can go direct to the Mac by firewire into the HDV or AIC codec. With a capture card you can capture to several other formats, if they are better for your workflow.

Scott Jaco · May 27th, 2007, 08:35 PM

Quote:

Originally Posted by George Strother

Scott

Are you viewing the feed to the BetaCam tape or the BetaCam playback on an interlaced CRT monitor?

If everything looks good on a pro/broadcast CRT I'll need to take a close look at a Black Magic card.

I'm viewing a CRT monitor off the Betacam's monitor feed output.

George Strother · May 28th, 2007, 06:13 AM

Quote:

Originally Posted by Scott Jaco

I'm viewing a CRT monitor off the Betacam's monitor feed output.

What model Black Magic card are you using?

May 25th, 2007, 05:04 PM	#1
George Strother Major Player Join Date: Jun 2006 Location: San Diego, CA Posts: 204	720p30 downconvert to BetaCam has 'interlace ripping' Has anyone had success with the realtime downconvert to uncompressed 8 or 10 bit BetaCam component feature of the Kona LH from an HDV 720p30 timeline? Link to a frame showing the effect I am getting - http://briefcase.yahoo.com/bc/twosun...ase.yahoo.com/ This b&w image shows the coarse serations on the vertical edges of the animated block. In the animation it just moves left and right. 720p30 footage from JVC HD100U and HD250 cameras have the same "fringe", but it's not as clear on the scenes I'm testing. Anyone know how to make this work?

May 25th, 2007, 07:55 PM	#2
Stephen L. Noe Trustee Join Date: Apr 2005 Location: Chicago Posts: 1,214	Are you previewing on a CRT or LCD? __________________ Advanced Avid Liquid Training found Here

May 25th, 2007, 10:23 PM	#3
Stephan Ahonen Major Player Join Date: Apr 2005 Posts: 512	That's just an interlacing artifact. Don't worry about it, perfectly normal, and it disappears when you view the picture on an interlaced screen. Just make sure you set your field precedence right.

May 26th, 2007, 11:53 AM	#6
Stephan Ahonen Major Player Join Date: Apr 2005 Posts: 512	It really does sound like interlacing to me. What you describe are some of the peculiarities of interlaced material that has been sourced from progressive material. If you're downconverting 30p material, the interlacing artifacts will go away when you pause because it will pause on a full frame. However, in motion you will see interlacing artifacts between frames because it will paint the first field from the next frame while the second field from the previous frame is still visible. It's not showing up on your progressive display because it's showing the full progressive frames. If you're still not convinced it's interlacing, zoom in on the image you provided. The mouse teeth in the picture alternate to the left and right line by line.

May 27th, 2007, 02:12 AM	#8
Stephan Ahonen Major Player Join Date: Apr 2005 Posts: 512	Just curious, have you tried reversing the field dominance? It's worth a shot. It's also possible that the AJA is working 100% correctly and that what's happening is simply an unavoidable consequence of pulling down 30p into 60i.

May 27th, 2007, 07:32 AM	#9
Scott Jaco Major Player Join Date: Mar 2006 Location: Sherman Oaks, CA Posts: 471	I've gone from a 720/30p timeline to Betacam without any problems. I selected 10-bit uncompressed for video playback using a Blackmagic card. It seemed to look quite nice.

May 27th, 2007, 09:23 AM	#10
Glen Vandermolen Space Hipster Join Date: Jun 2003 Location: Jacksonville, FL Posts: 1,596	I'm planning on purchasing an HD200 with a BR-HD50 deck, which I will then edit with FCP 5.1.4. on a G5. For workflow, I plan on sometimes shooting 720/24P and 720/30p, editing in HDV, then outputting in standard video onto a Betacam SP deck. Since I don't yet have the gear I'm not totally clear on how your problem originated. But with my set-up, is it possible I'll experience this problem? Does it occur when mastering to a Beta SP format? If this is an inherent flaw with the JVC ProHD set, then this could definitely affect my purchasing plans. Do I need some type of card between the BR-HD50 deck and FCP to digitize HDV? I was under the impression I could digitize directly into a ProMac FCP without further hardware.