Official: HDMI 1080 IS INTERLACED ONLY
- Thread starter Stuart U
- Start date
According to the manual: the D4 is the same: 1080 HDMI is interlaced only. All other resolutions are Progressive. Page 281 @ http://www.nikonsupport.eu/europe/Manuals/D4/D4_En_01.pdf
dfreerider
Well-known member
That is not uncommon. I don't know of any camera available that does 1080p over HDMI. They all wrap the progressive frames in interlaced, but the fields are the same. It can be removed in post by different methods depending on the framerate. So it is not the old interlaced video look with 50/60 fields pr second, but progressive frames in an reversible interlaced stream.
From the Atomos website on how cameras deliver 1080 25p and 30p over HDMI
http://atomos.activehosted.com/kb/a...rates-24p-25p-30p-etc/25p-and-25psf-explained :
For 24p the way it is encoded is different. You can read more about this here: http://atomos.activehosted.com/kb/a...eras-output-24p-from-the-hdsdi-and-hdmi-ports
So for Nikon to deliver 1080p over HDMI, they would have to step outside of the standard method of transfer. Hopefully 1080p HDMI will become a standard soon, so we don't have to deal with pulldown removal in post. But if you use for instance a Atomos Samurai it can do the pulldown removal automatically when recording.
-Kyle
From the Atomos website on how cameras deliver 1080 25p and 30p over HDMI
http://atomos.activehosted.com/kb/a...rates-24p-25p-30p-etc/25p-and-25psf-explained :
For 24p the way it is encoded is different. You can read more about this here: http://atomos.activehosted.com/kb/a...eras-output-24p-from-the-hdsdi-and-hdmi-ports
So for Nikon to deliver 1080p over HDMI, they would have to step outside of the standard method of transfer. Hopefully 1080p HDMI will become a standard soon, so we don't have to deal with pulldown removal in post. But if you use for instance a Atomos Samurai it can do the pulldown removal automatically when recording.
-Kyle
Last edited:
md673
Member
Yep, you're exactly right. The solution to this is to use an external recorder that can perform the pulldown on the fly. I'm leaning towards the nanoFlash, but I'm sure more options will come out during NAB this year.
Matt
Last edited:
Thank you. That is a relief. My apologies for the overly dramatic headline.
I thought all was lost for a moment. Having said that, the 720P in camera mode looked very clean on John Wright's fashion shoot video: http://vimeo.com/38009435
I have high hopes for the D800 1080 HDMI
I thought all was lost for a moment. Having said that, the 720P in camera mode looked very clean on John Wright's fashion shoot video: http://vimeo.com/38009435
I have high hopes for the D800 1080 HDMI
Cosimo Bullo
Veteran
For the love of Christ, will SOMEONE just take the thing out and shoot a little moving footage with detail with the HDMI record???
Blackpeppers
Member
+1
Cosimo Bullo
Veteran
Thing also seems to have an intervolometer built in. Nice.
Zephyrnoid
Veteran
Yup AND Yup to both statements. NAB.... wonder if I should go there this year?
squig
Veteran
get a kickstarter going
md673
Member
I'll have the D800 in a week or two, but I'm still holding off on the external recorder to see what comes out at NAB. I'll be renting some in the near future to test them all out before I buy. When I do, I'll post some stuff on here.
Last edited:
md673
Member
I don't think so, but I'm not 100% sure. Most do not remove pull down. As far as I know the only two that do are the PIX240, PIX220, and the nanoFlash.
Last edited:
eteam
Well-known member
I am new here, at the prompting of a similar forum discussion on dpreview.com. My views -- yet to be confirmed or disproven -- are that the D4 and D800 are special and different, that expectations should not be (entirely) based on what has been done in current and previous dSLRs. Here's why:
I see a clear distinction between HDMI port used as a playback output and HDMI port used as a recording signal output port. The D800 (and D4) user manual makes a distinction between live recording and playback, but Nikon's implied distinction may be different than my implied distinction.
Even though this thread opened with a 'definitive' response from Nikon, perhaps this is not the final word on this question. The precisely correct question must be asked to obtain the accurate and useful answer. (again, can neither prove nor disprove what Nikon has said or written)
Let's be clear where this forum thread -- and the Atomos 'HDMI interface white paper' -- may both be wrong:
The D800 (and D4) is the first dSLR designed with the intent of using the HDMI output as a port for a recording signal, rather than a display signal.
For a display signal, no-one cares much whether the signal is 1080i60 or 1080p30 -- it doesn't matter much.
This has been the case for every dSLR until the D4 and D800. Up until now there had been no need to do anything more elaborate or more flexible than 1080i + 720p + 640p. And this may explain why Atomos has not seen anything other than 1080i + 720p + 640p HDMI signal sources.
Skip forward to the D4 and D800. Nikon is making a huge claim that uncompressed video can be recorded straight from the HDMI output port. This would put the finest Canon video output to utter shame. This is a feature which is squarely aimed at the video and film professionals at the highest levels. This represents the equivalent of "RAW" image format for video (not really, but it's a huge leap forward). This represents an upgrade from 30Mbit/second (bits, not bytes) compressed video to roughly 1.5Gbit/second uncompressed video.
Note: if you doubt me, inspect a single frame of video recorded by a Canon (or previous Nikon) camera. Pixel peep. What you will see are 8x8 pixel blocks which would be completely unacceptable for a still image from a $90 point & shoot, much less a professional dSLR.
It stands to reason that Nikon appreciates the difference between a playback display interface and a recording signal interface, and they understand that 1080i is not an acceptable substitute for 1080p30, 25, or 24. The complications include timecode, edit points, audio syncing, and 3:2 pulldown (forward and reverse) artifacts.
There are some excellent reasons for using 1080i for playback of 1080p24 video. Watching 24 fps video is incredibly annoying, and is the leading cause of epilepsy in land turtles. By the same token, 1080p24 is a much better recording signal format than 1080i, for 1080p24 source video. When you step into the world of recording format, and you claim the high ground for professional applications, the notion of 1080i wrappers and 3:2 pulldown makes you out to be a bit of a naive, unserious, and clueless pretender.
Let's look at the difficulty (and benefits) of implementing a 1080p30 signal interface instead of a 1080i interface:
- you can avoid the buffering of a frame to generate the two-field interlace sequence
- you can avoid fudging timecode (professionals like timecode)
- the pixel clock is the same (74.25MHz) in both formats
- the interface signals are clocked at the same frequency
- the data rates are identical
In fact, the clock frequencies and pixel data rates for all of the 1080i and 1080p video formats are identical. 1080i is the odd duck from the flock. The only difference in 'logic' among the various progressive formats is the counter which ticks off the number of pixel clock periods in the horizontal blanking period of each video line.
In sum, I am not convinced the answers offered by Atomos or gather by the dvxforum folks are the correct and final answer -- nor can I disprove them.
This question might be resolved in 10 minutes' time by connecting a proper HDMI widescreen monitor to a properly configured D4 or D800, generating 'uncompressed video' to the HDMI port, and pressing the 'signal information' button on the monitor.
[note: I am an experienced semi-pro still photographer, and a very experienced electronic design engineer with extensive background in HDMI and video signal interfaces. I am not, however, a camera designer or a Nikon employee]
-- Bob Elkind
Last edited:
eteam
Well-known member
1080p has been included in the HDMI standard for many many years. Does your computer monitor not support 1080p display over HDMI?
Both my (cheap) video display card and monitors support 1080p at 23, 24, 25, 59, and 60 (but not 30) FPS.
Not only does the HDMI spec include 1080p formats (and have for a looooong time), but the Atomos Ninja also supports 1080p over HDMI. The Atomos website seems wounded at the moment, but the B&H product page for the Atomos Ninja lists the input formats supported by the Ninja. According to B&H, the Ninja supports 1080i60, 1080i59.94, 1080i50, 1080p30, 1080p25, 1080p24, and 1080p23.98 -- all over HDMI.
The Samurai does not have an HDMI input port, only SDI/HD-SDI. The Ninja does have an HDMI input port.
2:2 pulldown from 1080p30/25 to 1080i60/50 isn't horrible. But there are some unsavory (visually noticeable) artifacts and editing limitations with 1080p24 converted to 1080i60 converted back to 1080p24.
-- Bob Elkind
Last edited:
PappasArts
Veteran
Hey Bob. You make good points on this subject as to whether the HDMI is "i" or "P". I agree since Nikon made it very clear that the port is designed for external recorders, and knowing that, Nikon surely would have done their research and consulted those who also are experts in that area. I believe that some have gotten that impression from others, as well from this recent test ( http://hdlndies.blogspot.com/2012/03/nikon-d800-vol01.html ) which said it was 1080i. However it also says that the output is 10bits 422. I can't see Nikon going to the lengths to design an external port for the purpose of a recorder, and make it 10bit 422, then make it 1080i only. There might be settings in camera that allow you to switch it to 1080i output for viewing and 1080P for external recorder mode. Until someone who knows what their doing tests it, or Nikon makes an official statement, it's unfortunately unknown.
Pappas
http://pappasarts.wordpress.com/
http://twitter.com/pappasarts
dfreerider
Well-known member
I forgot the word camera , but it should been pretty obvious that I was talking about the way video cameras transfer 1080 HDMI. The sad fact remains that as of today almost all commercially available cameras use 1080i over HDMI.
Yes your absolutely right. To use the Samurai you would need to convert the signal to SDI/HD-SDI.
Would be great if the D4/D800 is 1080p, guess we will just have to wait and see.
Last edited:
eteam
Well-known member
Amazingly, there are some folks posting in this forum who do not share your understanding.
Apologies for the unintended insult.
There's nothing wrong with using 1080i for a display signal format. Up until now, no camera (well, no Nikon camera, at least) has used HDMI as a primary recording interface.
-- Bob Elkind
Last edited:
dfreerider
Well-known member
I'd love to be proved wrong, but I still don't see a lot of cameras available that output 24p, 25p, or 30p in a HDMI 1080p stream. I'm not arguing that the HDMI standard may support it, but I'm saying that the camera manufacturers haven't been using it much. For Nikon to do so, it is a step beyond what is currently the standard for professional video cameras. Really hope they have though.
But it's a pointless argument of what is a standard or not a standard at this point. We will know in a few days how Nikon has done it. My original reply was meant to correct the impression that the video would be interlaced like old video. I'm sure we can all agree that that is highly unlikely.
Btw Bob, your expertise is much appreciated here. My experience is mainly as a user of cameras and recorders, and I don't have detailed technical knowledge like you.
Last edited:
eteam
Well-known member
In the dSLR market, I do not believe there are any (with open question for D4 and D800).
The RED and ARRI cameras do not output 1080p via HDMI without add-on encoders, either, based on a quick scan of their websites. HD-SDI is a standard recording signal interface for their products, not HDMI.
In another post in this forum, I made the comment that until now, HDMI was never intended (by dSLRs) for use as anything but a display monitor interface. The D4 and D800 are breaking new ground by establishing HDMI as a recording signal interface.
Correct me if I am wrong, but my understanding is that representing 1080p 30/25 video as 1080i 60/50 video on the HDMI output port represents a minor inconvenience to the operators, and nothing more. Alias-free conversion from 1080i 60/50 to 1080p 30/25 is well-understood and straightforward, and these interlaced and progressive formats are equally friendly for editing.
But in the case of 1080p24, conversion to 1080i 60 involves forward and reverse 3:2 pulldown, which introduces artifacts and compromises editing flexibility. If the D4 and D800 do not support 1080p24 output, then folks using this format will be the ones who will be 'rear-ended'.
As a design engineer, there is no added hardware cost in adding 1080p30/25/24 output support to 1080i 60/50. If anything, the implementation logic is a bit simpler for the progressive formats than for the interlaced formats. It makes little sense to provide one (or some), but not all, of these progressive signal output formats.
As you said, we shall see what the D4 and D800 provide before long.
-- Bob Elkind
Last edited: