Official: HDMI 1080 IS INTERLACED ONLY

Okay, I feel compelled to re-iterate the points I made in my first posting in this thread, this time in bullet point form, as I don't want what was stated in that initial post to just become "Jon Thorn says it outputs 1080p 23.98" because that would be an oversimplification of what I stated.

1) My tests were performed with neither a QXD or CompactFlash card inserted in the Nikon D4.
2) The Nikon D4 HDMI output was set to "Auto" for the HDMI output in terms of format.
3) The "Auto" setting allows items connected via HDMI to initiate a "handshake" that may allow the output to be interpreted/received as 1080p 23.98; if the receiving device does not report support for 1080p 23.98, then it is quite likely that the receiving device may simply report 1080i 29.97. In the case of the AJA Ki Pro Mini recorder, special EDID work was done, in collaboration with Nikon, for version 3.0 firmware to support this; if you use a Ki Pro Mini with earlier firmware, it will likely only report 1080i 29.97. Because of this, it is likely unwise to assume that all recorders/converters will report/detect/record 1080p 23.98 if they have not done this EDID work.
4) The camera's output of the Menu, even if "1920x1080; 24fps" has been selected in the Nikon D4 menu, will be 1080i 29.97 until "Live View" is enabled.

I am reposting this information, again, because it isn't sufficient to assume that the camera "just outputs 1080p 23.98" and I don't want that to be the impression that might be relayed as a "soundbite" from my initial posting; there are series of conditions that would need to be met for this to be the case. "Auto", with respect to the HDMI output setting, implies an "auto-negotiation" with the HDMI receiving device. Note that among the Nikon D4 HDMI output choices, 1080p is not explicitly listed; the "Auto" setting and a device that "handshakes" would result in 1080p 23.98.

I hope this additional clarification/re-statement is helpful,
Jon Thorn
Senior Product Manager
AJA Video Systems, Inc.
 
@Jon Thorn,

Your reports are very much appreciated. There is a great deal of interest in the D4 and D800 (and some other camera with a '5' and a '3' attached to it...), both of which come with user manuals which spare no details in some areas and spend no details in others.

Granted that our primary interest is in the camera rather than the video recorder, for the moment, this will not persist. There is a great deal of mis-information and conjecture (masquerading as insight) being tossed about and repeated, including suggestions that conversion from 24p to 60i and back again is simple and harmless. The information you have provided makes it clear that conversion to and from 1080i60 is not inevitable, is entirely avoidable, and the AJA product is proven capable and compatible.

I extend to you an invitation to discuss the reasons why 24p->1080i->24p conversion is worth avoiding. This would be a helpful discussion topic, based on some recent posts and inquiries.

I am surprised that special EDID coordination was needed to establish a solid interface between the Nikon and AJA designs. I have studied the HDMI specification, and its description of EDID entries seems simple enough (plus... it's simple enough to reverse engineer without causing harm).

Going forward, I have interests in both the Nikon cameras and the related peripherals. As you have already posted in these forums, you are as close as 'we' might get to being our new 'best friend'. We will grow old and lonely waiting for a post from Nikon!

Here are some low-hanging-fruit questions which touch both the camera side and the recorder side:

  • Does Nikon transmit 10-bit or 12-bit 4:2:2 YCrCb?
  • With 4:2:2 YCrCb input, how many bits does AJA record?
  • Does AJA presume only 10-bit or 8-bit YCrCb on input, or do you presume 12-bit (always) and round to fewer than 12 bits?


  • Does AJA record any portions of the HDMI input stream without compression? (e.g. audio, aux data packets)
  • Does AJA record anything more than active video?


  • Are there plans for adding 1080p24 4:4:4 RGB device support to the AJA recorder?

Just because I am brazen enough to ask all these questions does not mean that I think you are obligated to answer them. Far from it.
You are a busy guy, and you have a business unit to run and corporate interests to protect and defend.

If you are wondering what 'intelligence' might be salaciously interesting to we who are in the forum mob, consider these questions (above) as -- simply -- suggestions for you to consider :)

Perhaps sometime in the not-too-distant future, one or more of us may be able to repay the favours you have already provided.

Regards,

Bob Elkind
 
The HDMI out with the cards removed is indeed 1080p 4:2:2 8bits, but it seems that the video out is not down-sampled, but some form like skipping this and that, resulting in a resolution worse than the MK3.
 
Kenny_G said:
The HDMI out with the cards removed is indeed 1080p 4:2:2 8bits, but it seems that the video out is not down-sampled, but some form like skipping this and that, resulting in a resolution worse than the MK3.
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The 4:2:2 YCrCb HDMI formats provide for 12-bit data values. How did you conclude the D4 HDMI output is 8-bit rather than 10-bit or 12-bit?

-- Bob Elkind
 
http://www.imaging-resource.com/PRODS/nikon-d4/nikon-d4A.HTM they've posted the transcript of a Q&A session with Nikon just scroll down within the pane

"(Dave Etchells, IR) - 8-bit is correct, 4:2:2 is a standard digital video format. The numbers refer to the sub-sampling of the various channels (Luminance, and two chroma channels). 4:2:2 subsamples the chroma channels 2:1 along each line vs the luminance channel. The subsampling is only along each horizontal video line; there's no sub-sampling between video lines. by Dave Etchells"
 
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ok now we're getting somewhere but I think its pointless to buy a 6,000$ full frame stills cam to use it in 2.7 crop mode. I guess no one has a Ninja or Pix 220 to try it with.

Nikon D4 test 3/5 : Crop Modes, 4:2:2 output http://vimeo.com/39133762

"And in this test, I hooked up the D4 to Blackmagic Design Ultra Studio 3D, trying to capture uncompressed 4:2:2 signal through HDMI. But for some unknown reason, it didn't work (or did it?). All I got was gamma shift, not image improvement."
 
resonance_image said:
but I think its pointless to buy a 6,000$ full frame stills cam to use it in 2.7 crop mode
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why not when it ostensibly gives you the effect of multiple focal lengths, without having to lug several lenses around. My guess in the ENG and photojournalists shooting for Youtube & print will really groove to that feature. Then and Wedding, Event and run of the mill corporate material, not to mention soccer moms ;)
Does this crop feature exists on the D800 as well as far as you know?
 
eteam said:
The 4:2:2 YCrCb HDMI formats provide for 12-bit data values. How did you conclude the D4 HDMI output is 8-bit rather than 10-bit or 12-bit?

-- Bob Elkind
Click to expand...

Been in Nikon's own description on their website for several months:

"Built-in HDMI lets you view footage on an external monitor or record uncompressed 8-bit 4.2.2 footage directly to an external recording device. "

Right here (scroll down to video description): http://www.nikonusa.com/Nikon-Produ...4.html#tab-ProductDetail-ProductTabs-Overview

Anyway, great posts, Bob. Thanks.

Personally, I'm more interested in what the Sound Devices PIX 240 can do with the D800, since it has both timecode and great sound inputs. I've asked them, in their forum, to look at this thread. Hopefully they will chime in at some point.
 
It would be really great to have someone from Nikon come here to do a Q&A ...i dont know if that would be possible ? maybe some one could ask ? as you would think it be in there best intrest. Its a high probability im a bit slow but does anyone else find these camera companies a little ambiguas when it comes to precise details.
I have sent nikon the direct question they gave me a reference number and said "A member of our support team will get back to you soon"
 
Zephyrnoid said:
why not when it ostensibly gives you the effect of multiple focal lengths, without having to lug several lenses around. My guess in the ENG and photojournalists shooting for Youtube & print will really groove to that feature. Then and Wedding, Event and run of the mill corporate material, not to mention soccer moms ;)
Does this crop feature exists on the D800 as well as far as you know?
Click to expand...

Well this is the idea I had originally; to achieve multiple focal lengths at the touch of a button. The problem is that only the 2.7 crop mode yields usable results, so you have soft fx, soft dx, and then nice and sharp 2.7 crop. check out the Vienna University video just posted up here in another thread, the shooter only used the 2.7 crop mode and considers the others unusable for broadcast.

The D800 can switch between FX and DX so that still lets you punch in a bit.
 
resonance_image said:
check out the Vienna University video just posted up here in another thread, the shooter only used the 2.7 crop mode and considers the others unusable for broadcast.
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Please point out where he said anything about usability for broadcast. His preproduction D4 had problems with FX video, and Nikon told him 2.7x is best. He has not tested a production model D4 and will be testing a D800 next week. That's what I read here: http://vimeo.com/39035275

I will be watching out for his tests and pay attention to his opinion. He clearly knows how to shoot and light, and thus should give a fair idea of what the camera can do under controlled conditions. I'm sure he'll also test the HDMI out, which wasn't working on his preproduction D4.
 
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3:2 pulldown introduces artifacts - explanation

3:2 pulldown introduces artifacts - explanation

Well, this is almost like politics.

The sentence quoted below is true, but irrelevant for the topic being discussed.
I will explain why.

If you convert 24p video to 60i video using 3:2 pull down, it really introduces artifacts WHEN WATCHED AS 60i.
What some posters here try to explain is that from that 60i signal you can convert the video BACK TO 24p using reverse pull down, and it will be exactly identical to the original 24p video, WITH NO ARTIFACTS.

So this is to explain why what you have posted is both true and irrelevant at the same time.

BUT, the important question is, if you do 24p to 60i conversion, THEN COMPRESS THE VIDEO, and AFTER THE COMPRESSION you try to apply reverse telecine, can the "odd" and "even" interlaced sub-frames be combined together, after the compression ? I have no idea how compression of interlaced video is implemented, but in case that both interlaced sub-frames are compressed separately, I have the feeling that it could be problematic to blend those two compressed sub frames to create one compressed full frame. Maybe some decompression/re-compression is needed to do that. I do not know.

eteam said:
First, 3:2 pulldown represents a temporal distortion artifact which can be quite noticeable in the form of smooth motion which appears to lurch.

-- Bob Elkind
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This is the test I wanted to see

This is the test I wanted to see

Test with a TV is the best to do. With external recorders you never know if the are converting from 1080i to 1080p, or if they are really receiving 1080p. A consumer TV will never do any conversion, so this, I believe, is the truth.
Let's hope it is the same with D4.

md673 said:
Gents! I'm happy to report that the HDMI output w/o cards in the D800 is progressive. That is according to my Panasonic plasma. Picked up the camera this morning, plugged it in first thing, and the TV says 1080p. The TV doesn't report the frame rate, but the camera shows 24, so I'm assuming that's correct. What's weird is that the camera menu says HDMI is 1080i, but the TV says 1080p. Who knows why, but I'll take it!
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grecner said:
The sentence quoted below is true, but irrelevant for the topic being discussed. I will explain why.
Click to expand...
I think you do a fair job of explaining (in part) why this warning is relevant for the topic being discussed (i.e. can the D4/D800 camera provide progressive format video on the HDMI port when operating in LIVE VIDEO mode?).
If you convert 24p video to 60i video using 3:2 pull down, it really introduces artifacts WHEN WATCHED AS 60i.
Click to expand...
Agreed, so far.
What some posters here try to explain is that from that 60i signal you can convert the video BACK TO 24p using reverse pull down, and it will be exactly identical to the original 24p video, WITH NO ARTIFACTS.
Click to expand...
Martin,

I think you have unintentionally re-phrased the issue and thereby (inadvertently) distorted its meaning. Here is my interpretation, and the forum readers can decide for themselves which (if not both) are worthy of consideration:

  • You can convert the video BACK TO 24p using reverse pull down, and if done correctly it will be exactly identical to the original 24p video, WITH NO ARTIFACTS. If not done correctly, artifacts will remain and may even worsen. If you avoid 3:2 pulldown entirely, you have no worries. If you cannot avoid 3:2 pulldown, then you should be keenly interested in how, where, when, and if you plan to reverse the 3:2 pulldown and progressive => interlaced conversion.

Is this a reasonable and fair concern? Or do you think this is a piddling nit which should be dismissed?

BUT, the important question is, if you do 24p to 60i conversion, THEN COMPRESS THE VIDEO, and AFTER THE COMPRESSION you try to apply reverse telecine, can the "odd" and "even" interlaced sub-frames be combined together, after the compression? I have no idea how compression of interlaced video is implemented, but in case that both interlaced sub-frames are compressed separately, I have the feeling that it could be problematic to blend those two compressed sub frames to create one compressed full frame. Maybe some decompression/re-compression is needed to do that. I do not know.
Click to expand...
Intentionally or not, you have described the typical use of the Atomos Ninja with the Nikon D4/D800 camera, and have captured the primary concerns which are at the root of the original question: Does the D4/D800 support only 1080i50/60 HDMI output? We all now know that the answer to this question is no, 1080p24/25/30 output can be provided. There are certain keys and clues in the video which are essential for a 'perfect' (loss-free or, at least, artifact-free) restoration of interlaced video to its original non-pulldown, progressive format. As you eloquently explain, these clues and keys are most likely lost forever in a number of different ways, including (and particularly) applying lossy compression as used in such devices as the Atomos Ninja.

The secondary question, which must then be asked, is: Which devices are presently suitable for avoiding P => I conversion (and the dreaded pulldown) in use with the D4/D800 camera(s)?

Note that the questions primarily at hand are made in the pursuit of keeping the 'pristine' HDMI output signal pristine. For the casual weekend videographer, this is not worth a second thought. For the most meticulous and demanding users, I don't think either you or I have exaggerated the potential problems which attend pulldown (especially 3:2 pulldown) and P => I => [???] => P processing. If anything, we have neglected to mention the editing and switching hazards and restrictions whilst in interlaced format.

Grecner, your post started with a declaration that the alarmist warning of 3:2 pulldown artifacts is irrelevant, but you finished with a strong case for ignoring such warnings at your own peril.

-- Bob Elkind
 
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grecner said:
Let's hope it is the same with D4.
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Martin,

If you look through this thread, you should see a post (#62 in this thread) written by Jon Thorn, Sr Product manager at AJA, where he directly confirms use of AJA product (Kiwi Mini?) recording directly from a D4 24p 4:2:2 HDMI signal.

-- Bob Elkind
 
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Hopefully this information can be of use. I've tested the D800 with both AJA and BM hardware and so far can only get the 24p option to work with the Decklink, but it DOES WORK--THE D800 spits out a true 24p signal. Problem is, I can't get it to add a normal pulldown in 1080i mode. This is an issue if your recording device doesn't support 24p input via HDMI (like AJA's IOHD) and you want to reverse pulldown later. (Tried with cards in and out of camera--no difference). See details here: http://fennworld.blogspot.com/
 
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