Calculated estimate of HVX200 CCD resolution

[Steve Mullen]

Originally Posted by Ash Greyson

Using this same logic... the Canon's 540 in 24F mode is likely effected the same way correct?

That's why Adam wobulated all cameras. Any camera that uses green-shift would measure worst-case resolution in the test. My my model estimates both the Sony and Canon to have far more than the measured resolution in real-world situation.

The 24F mode should not be different horizontally than the 60i mode.

[Steven Thomas]

Jarred posted this tonight:
http://www.dvxuser.com/V6/showpost.p...28&postcount=1

[Barlow Elton]

Saw it. Steve was money.

Now let's get over it and enjoy the creativity the camera will facilitate. No more pixel wars.

Canon should come clean about 24F IMHO. It's probably a very good 48i real-time deinterlace. Virtual 24p that works great too.

It's all good in the hood.

[Steve Mullen]

YOU CAN SKIP THIS POSTING AS I'M IN ERROR. BUT I'M LEAVING IT SO BARRY'S RESPONSE MAKES SENSE.

Questions:

How does the HVX200 get 1080i from the 1080p60 DSP buffer without line flicker or line twitter in the video. (Row-Pair summation seems NOT to be used because vertical resolution doesn't drop!) I've posted how I think it's done, but it was just a wild guess. And, if even my guess is correct -- see my earlier post -- the 1080i video has NO interlace artifacts. Will it look like HD "interlaced video?"


Also -- the question remains as to how NTSC and PAL are generated for DV, DVCPRO, and DVCPRO50.

1) Are both derived from the 1080p60 buffer in the DSP?

If so, then we have the same question about line flicker and twiter. Of course, Row-Pair Summation could be used during the downconversion to SD. However, effective vertical will then be only 435 TVL. Is that enough for PAL?

2) To obtain "real" SD interlaced video, like the DVX100 CCDs, the HVX200 CCDs could be switched to interlace mode. However, my computer model indicates that if interlaced" NTSC and PAL were pulled directly from the CCDs, effective vertical resolution would be only about 435 TVL. And, again I'm not sure this will be OK for PAL.

[Barry Green]

Originally Posted by Steve Mullen

1) Are both derived from the 1080p60 buffer in the DSP?

According to the article, yes. Everything starts at the 1920x1080 DSP buffer, and all other modes are downrezzed/created from that.

Of course, Row-Pair Summation could be used during the downconversion to SD. However, effective vertical will then be only 435 TVL. Is that enough for PAL?

Well, that's how many discernible lines PAL currently offers, so it should be. Applying the .75 interlace factor to 576, we get 432 TVL of resolution for interlaced PAL.

In any case, the "interlaced" NTSC and PAL video have NO interlace artifacts. Again, will it look like SD "interlaced video?"

Of course it does. In DV 60i mode it looks exactly like any other interlaced DV camera. And in 1080i mode it looks exactly like any other interlaced 1080 camera. I've got an FX1 and an HVX here right now, and in 1080i mode playing back on my interlaced 1080i set they look exactly the same as regards motion and interlacing).

2) To obtain "real" SD interlaced video, like the DVX100 CCDs, the HVX200 CCDs could be switched to interlace mode.

Not according to the article; there basically is no interlace mode on the CCD, it's all progressive all the time. Which is why interlaced mode doesn't get a boost in sensitivity, like the DVX does. But it looks exactly like interlaced mode. The DVX and the HVX, when both set to 4:3 60i, look extremely similar.

[Barry Green]

Oh, and by the way -- I sent you an e-mail, but I'll say it here too -- congrats on figuring out the pixel count down to the exact number. You did a great job on that!

[Steve Mullen]

Barry it was you insisting you had "non-wobulation" numbers that were significantly higher than Adam's numbers that made me realise that BOTH measurements had to be "valid."

Plus, you insisted the HVX200 LOOKED so much better than the worst-case tests. So Panasonic had to have designed a unique CCD + DSP "system." Which is what Jan was saying in her interview.

[Barry Green]

I enjoyed exchanging e-mails with you, it was interesting to see the process you went through to achieve your conclusions. But I'm really amazed at how well you nailed it. Your descriptions seemed to match all the evidence, but I still wanted to see official factory confirmation -- and that's exactly what we got.

Well done!

[Steve Mullen]

Originally Posted by Barry Green

Well, that's how many discernible lines PAL currently offers, so it should be. Applying the .75 interlace factor to 576, we get 432 TVL of resolution for interlaced PAL.

I've always used 75% but my model achieves minimum error with a value of 66%. That's one of many problems with any math model -- it can come up with a low overall error over a dozen camcorders -- yet have individual assumptions that don't match reality.

The model predicts NTSC to have 317 -- which actually comes close to the textbook answer of about 330. It estimates 380 for PAL.

So whichever number is "really" right -- 435 is greater than needed -- so the can DSP supply all. Very clever and a lot of number crunching!

You are also correct about interlace. For anyone who I totally confused:

With "real" interlace video -- when there is motion -- each field in a frame is different. We call them interlace artifacts -- and if you are going to film they are bad. But, when we view them on an interlaced display -- these slight differences between fields provide the eye with motion information at 1/60th second -- not 1/30th second intervals. So the artifacts actually help smooth motion.

When the HVX200 captures frames every 1/60th second, it obtains samples at a 60Hz rate. Each 1/60th second half the lines in a frame are discarded and the other half put into a field. So we generate 60i video exactly as we do when we have a camera that uses "interlace scanning."

[Justyn Rowe]

So what does it all mean?

[Barry Green]

It means we can quit worrying about it and go shoot now. :)

[Heath McKnight]

Green's layman translation is all I need!

heath

[Justyn Rowe]

Originally Posted by Barry Green

It means we can quit worrying about it and go shoot now. :)

Good enough for me! I just need the eagle to land...