Exploring Nikon D5200 HDMI output - review update

[chauffeurdevan]

To be noted :

 

On my post about Bayer and 4:2:2. All I wrote is valid in 1:1 Bayer resolution to final resolution, meaning a 1920x1080 Bayer for a 1080 final resolution.

 

If you have higher resolution Bayer this change. Ideally, a bayer sensor should double (or quadruple) the final resolution, eg. 3840x2160 for a 1080 video. From there, you could get a nice 4:4:4 (slighlty oversampled in the green.)

[HurtinMinorKey]

The chroma sample X:Y:Z is a just a reference for ratios of information The use of "4" for "X" is just convention. So in other words, to get 4:4:4 from a Bayer, you need to down sample, then throw away some green, right?

 

Thanks for everyone's input.

[chauffeurdevan]

The chroma sample X:Y:Z is a just a reference for ratios of information The use of "4" for "X" is just convention. So in other words, to get 4:4:4 from a Bayer, you need to down sample, then throw away some green, right?

 

Thanks for everyone's input.

 

No you don't throw away extra green. It is just part of the bayer process.

 

What I meant is to have 4:4:4 in 1920x1080 on a FoveOn  for example, or tri CCD, you need a 1920x1080 x 3 sensor providing 6220800 photosites or 6mpx.

 

 

On a Bayer, you don't have that 1-1-1 red, green, blue ratio. but a 1-.5-.5. So you need to double the resolution to get at least each color for a final pixel. This is 8294400 photosites or 8mpix for a 1920x1080.

[jgharding]

@jgharding why are you talking about RGB 444 and then showing a YCbCr color model diagram?

 

I was addressing to two different things in that post. I think we're all confusing each other now which was never the point of my post, so I shall bow out!

[markm]

Chauffeurdevan or anyone who knows :)

 

 

Could you explain

 

Wny does the BMC 2.5K have to be downsampled to 1920 x1080

 

What I think I understand

The sensor is 2.5K and not 4K then it has to be downsampled to maintain its integrety because of bayer processing.

 

 What I want to do

 

Use super 16mm lenses and either crop or debayer down to a resolution that means I dont need to crop. So what is the best option for maintaining highest 1920 resolution.

1) Debayer the 2.5K down to 1920 and crop that.

2) Crop the 2.5 k image to super 16mm size then debayer that to 1920

 

I have a feeling the answer will be 2)  But how much resolution or quality hit would there be?

[theSuede]

There are some serious amounts of (des)information in this thread... Both regarding how chroma subsampling schemes are laid out, and how normal Bayer based sensors record video images in consumer-grade DSLR devices.

 

Now, in order from capture to recording:

 

Each manufacturer (and also separate models of cameras!) have their own way to read a sensor to create an initial image to "build" the video image from.

*Some cameras line-skip, since that's a very easy (and bandwidth-economically good) way to read a sensor FAST. Unfortunately, this gives lots of noise (much of the actual recorded information on the sensor is just thrown out unused) and lots of orientation dependent aliasing. This exact aliasing depends on how the manufacturer choses to scale the image from the original resolution of the sensor.

*Some cameras have other means of restricting the amount of pixels/second it has to read. Those can include true binning, patterned subsampling and many other schemes. Most of those schemes can also be reverse-engineered if you know what you're doing.

 

Almost ALL consumer-oriented cameras do after this initial sifting of information. Most of the quality loss except for the compression and chroma sub-sampling occurs here! At the second leg in the image pipeline you have a complete RGB 4-4-4 image at some (smaller) pixel scale. This depends on the original resolution of the sensor vs the subsampling method chosen. But it's often around 1200-1350 pixels on the X-axis and 800-950 pixels on the Y-axis.

 

Those are true 4-4-4 RGB images! But they aren't true HD resolution... Which is why most DSLR images are quite a lot softer and less detailed than true 1080p video.

 

The video compression engine accepts RGB as input, doing YCbCr(YUV) transform before sending the image stream to the encoder is just a big waste of effort. In the encoder input, the 4-4-4 RGB image is subsampled into 1920x1080 Y-channel data and [some] resolution CbCr(UV) data before it's sent in to the compression encoding.

 

So, no - you don't need an area of 4x4 Bayer-coded pixels to make 4-4-4 video. You need 2x2 pixels to get full-resolution images for ALL CHANNELS, the definition of 4-4-4. If you do a Bayer interpolation before coding, you only need ONE pixel to get 4-4-4 video... See Nikon D4 1:1 crop video mode next.

 

One instance is the 1:1 pixel crop video you can get from a Nikon D4. The video image in that mode is made from a 1920x1080 crop from the central part of the sensor. That image needs to be Bayer-interpolated before it's a full RGB image, but at least it's a full-res image. That's why it's so much better than the large modes in that camera - the large crop modes use line-skipping and lower actual image resolution. The loss from that is much bigger than the loss from having to do a Bayer interpolation.

 

If you want to read more about chroma subsampling and the exact layouts used, I'd recommend this:

http://dougkerr.net/pumpkin/articles/Subsampling.pdf

[RRRoger]

Have you tried setting HDMI to 1080p instead of auto?

When I do this I get a true progressive feed but it is 29.97 frames (30p) even though the camera is set to PAL / 25p.

 

What about trying it in NTSC and trying 24p from 60i? <Quote<<<

I am very surprised to learn that you can get any "clean" HDMI out of a D5200.

I am also surprised that the Video quality is so good.

 

I am using a V1, D7100, D600, and D800 for my "Home Movies".

 

With the D7100 I had to cycle with the info button to get clean output that filled my Camax monitor

and recorded to my Shuttle II without any info showing.

What you see on the external monitor is what you get.

 

That camera does not have a 1080P setting for the HDMI output so I have to use Auto.

This works fine if the in-camera Video settings are set for 1080P at 30fps

and record to DNxHD 220 (I had to download the free codec pac from AVID to use the files on my PC).

With ProRes the recordings are at 60fps, slightly lower quality, and much more difficult to deal with in  PowerDirector 11.

[Vitalis_Cameltoe]

HOW about Moire and alias in 422 hdmi? Gone?

[PaulTV]

Hi everyone,

 

I have a new D5200, and am having an issue getting FULL FRAME 1080 out of the hdmi socket - yes I get a cropped 1080 which needs post processing to bring it to full frame, thereby losing quality.

 

I've read all the above thread about camera settings, I'm simply not able to get a full raster image.

 

I spoke to Nikon, they say the camera has this as a limitation - so, can someone explain this to me:

 

Does the Nikon D5200 output 1920x1080 via the HDMI socket at full raster? Yes or No, and how did you achieve this?

 

thanks 

 

Paul :-)

[PaulTV]

After again speaking with Nikon, and further testing with my camera firmware C1.00 L1.006 - it appears impossible to externally record full HD from the D5200.

 

I've connected the camera to a Black Magic Intensity Pro HDMI capture card - result: 1920x1080 file with black bars around a size reduced image.

 

Connected to a Grass Valley HD Storm card yields exactly the same results.

 

Viewing on an external monitor produces the same results.

 

It looks like this entire thread is based on a myth - unless of course you like working with silly cropped images.

 

I'm in conversation with Atomos, who make both the Ninja and Samuri Blade capture devices. They say that they are having success, but maybe this is at 720.... as they quote the D800 as a working source, which does say in its specification that it has full, clean HDMI output expressly for external recording.

 

Paul :-)

[Reiner Damisch]

You have to press the "info" button, next to record button a few times to get the full picture, not the <i> button.

I also had to RTFM to find out.

page 98 reference manual

[RRRoger]

@Andrew: Also, if you find the time/possibilities, I'd like to learn more about shooting with an external recorder. Never done this before. What are the options, prices, drawbacks etc. What would you suggest for a budget shooter in combination with the D5200?

 

The BlackMagic Shuttle seems to be the cheapest option. I really like the Atomos Ninja 2 with built in monitor, but it's pricey... It would be nice if there was something in between with monitoring options.

 I use a CaMax 5.6" HD monitor mounted on my TriPod Leg and pluged into the Shuttle II.

I get a superior view and a cheaper recording solution.

[RRRoger]

Thanks for posting this. Maybe someone has a definitive way of finding out whether this is true 4:2:2 or not.

 

What are your impressions of this camera for video?

Open the file with MediaInfo

[SimonBlu]

Hi guys! 

 

I have a D5200, and love it for video.

My question: does the HDMI output send signal when you are in live mode,

and not recording? This would mean I could use a Hyperdeck (or other) to

shoot continuously! 

 

This would be... awesome!

 

Thanks in advance, 

 

Simon

[Jamie_Dale]

Getting back to the D5200 NTSC issue, has anyone found a way around this for PAL users? Are we stuck with having to convert from 59.94 or 29.97 to 50 or 25 in order to use the HDMI video?

 

Here are my finding's so far: http://www.jdale.net/nikon-d5200-hdmi-problems/

 

[crontbeck]

On 2/26/2013 at 3:31 PM, jgharding said:

 A few clarification are needed are.

 

Uncompressed does by no mean RGB and full resolution. Uncompressed is a codec with raw data and without lossless compression (zip or similar), think a regular text file, a .bmp, or a .wav. An uncompressed video codec can be YUV 4:2:2. If you are using an uncompressed codec, you can recode it millions of times without ever losing any information for the source.

 

Like I wrote in a previous post, 4:2:0 is not a and half resolution blue channel, and a quarter resolution red channel. Both chroma channels - which neither are blue or red - have the same sampling : a quarter of resolution.

 

Lossless and lossy compression are terms that describe whether or not, in the compression of a file, all original data can be recovered when the file is uncompressed. Lossless compression reduces a file's size with no loss of quality. This seemingly magical method of reducing file sizes can be applied to both image and audio files. While JPEGs and MP3s use lossy compression, newer compression algorithms, such as JPEG 2000 and Apple Lossless compression, can be used to create lossless compressed files. The PNG format is supposed to be a lossless format, but when you save an image as a PNG file, you are asked to choose a compression level.

[BTM_Pix]

Saw this thread come back up and thought the new post was going to be that someone had devised a hack to get RAW out of the HDMI port or something.

Alas, its just the return of the over helpful spambot.

[IronFilm]

Forum's captcha probably needs to be upgraded.