HDSDI OUT is 420

[Bill Ravens]

Originally Posted by Mark David Williams

Bill HDSDI is 420? Thats the title of this thread? I'd like to know for sure whether it is or not and so far nothing shown proves anything? Or am I getting somehing wrong here?

...............sigh.........................

[Mark David Williams]

Originally Posted by Steven Thomas

???

You're joking right?

I'm sorry if you feel I am joking about whether the live feed of the HDSDI OUT although I'm not sure why this could be seen as a joke.

I can't see a difference between Jim Arthurs pics? I have been told however that in panning there would be a difference and all I ask is evidence to show this

[Piotr Wozniacki]

Originally Posted by Mark David Williams

I can't see a difference between Jim Arthurs pics? I have been told however that in panning there would be a difference and all I ask is evidence to show this

Now Mark, no offence meant - but what equipment are you watching Jim's pics on? The difference is striking!

Ever since I equipped my editing work-post with the 50" HDTV plasma, hanging above my computer monitor - I can watch virtually every pixel of the gorgeous EX1's output.

But since the better is the good's enemy, I am looking forward to use the NanoFlash for an even better HD experience. This is why the 4:2:0 vs 4:2:2 debate is so important to me.

However, even with the difference in Jim's comparison being evident, you're right we still haven't arrived at a 100% certain conclusion. Mike of Converget Design has promised his engineer would provide us with some, but we're still waiting.

Let's assume now that - as Bob suggests - the SDI signal goes through some processing, and "what is coming out the SDI port is from 4:2:0 processed video that's been resampled into 4:2:2". But even then the processing is doing its thing very well!

Add to it no macroblocking or mosquito noise (due to much more relaxed compression), and the nanoFlash is still a worthy upgrade. Now, if it turns out that the SDI output is a "true" 4:2:2 - the better for us! Especially for those, whose ego feels better when all specs are the best possible, also on paper - especially when it comes to spending more money...

Oh, and one more thing: we have witnessed many instances of pure incompetence from Sony "reps"; on the other hand what higher-rank Sony's officers like Mr. Martinez were saying, always proved to be right so far; why not believe in what he said this time?

[Mark David Williams]

Hi Piotr

Thanks But Im still puzzled? Ive downloaded the image and zoomed in? By zooming in surely I am compensating although maybe I'm missing something here again? Im starting to wonder if there really isnt a true 422 and even whether a faster bit rate is making much discernable difference? At least this is the picture Im seeing at the moment.. I fully expect though to be able to see a difference being demonstrated and am eager for that. But certainly at this moment in time I wouldnt take a gamble there even was one certainly not on what Ive seen so far.

[Greg Boston]

Originally Posted by Thomas Smet

Look at the thin horizontal line in the upper left of the images. In the 4:2:0 version the line is clearly much thicker. This is because 4:2:0 can never have objects a pixel thin since it really works in blocks that are 2x2 pixels in size. So a thin line will will be twice as thick in the chroma channels in a 4:2:0 image.

If the video was chroma smoother or up sampled you would still end up having blocks of color that are bigger then the pixels on the luma channel. A chroma up sampler doesn't remove extra pixels, it just blurs the chroma channels only or fills in the missing chunks.

On the 4:2:2 version of the image the chroma line is clearly much thinner or what we would expect how it should look compared to the luma channel. Therefore I don't think it was up sampled at all but a true 4:2:2 output from the camera. If it was up sampled that thin line would be much thicker.

Nice work, Thomas. Looking at the images side by side, one can see better edge definition throughout the frame. That helps pull cleaner keys of course, but as Bill alluded to, the lack of mpeg compression on the HDSDI output will also have a positive effect on image quality. Bottom line to this whole discussion is that the HDSDI is going to give you the most 'pristine' image you can get from the camera when captured live.

[Mark David Williams]

Piotr

I zoomed in 400x on the line in the left hand corner and this is the image I'm getting. I think its obvious which is which so obviously the HDSDI Output is giving better quality is this the difference your seeing?

You'll need to download it and zoom in

[Piotr Wozniacki]

Mark, there is no need to look that deep into these pictures - just take a look at the foreground red areas, and specifically compare:

- macro-blocking inside them
- edge definition between them, and the neighbouring whites
- the thin horizontal line (of red on white background)

I hope you can see it now :)

[Mark David Williams]

No sorry cant see a difference on this screen. However I have to now agree there is quite a difference Obviously not one I can apreciate on my limited resolution. But I really should invest in a decent HD monitor. I'd be interested in seeing more tests done still and am now interested much more in the Nanoflash. I know its cheap compared to whats gone before. Just wish it was a bit cheaper still!

[Bill Ravens]

Originally Posted by Greg Boston

Looking at the images side by side, one can see better edge definition throughout the frame. That helps pull cleaner keys of course, but as Bill alluded to, the lack of mpeg compression on the HDSDI output will also have a positive effect on image quality.

Let's not forget that, while the HD-SDI output is "uncompressed", when it gets recorded by (nano)Flash, it's being mpeg compressed. Just not as much as in the native EX1 scenario.

[Piotr Wozniacki]

Originally Posted by Bill Ravens

Let's not forget that, while the HD-SDI output is "uncompressed", when it gets recorded by (nano)Flash, it's being mpeg compressed. Just not as much as in the native EX1 scenario.

Exactly - and, while before the 420 vs 422 hype started, I was aiming at the 50Mbps, 422 format as my "sweet" nanoFlash setting (with direct HD422 MXF support in Vegas), I'm afraid that with more goodies coming from relaxed compression than colour sampling, we might need the 100Mbps to really get what we're after... With the I-frame only, 160Mbps for "special purposes" only.

As to the uncompressed (only available on the bigger XDR box), I personally think I don't need it - with all the storage requirements being an overkill, considering my real editing scenarios.

[Greg Boston]

Originally Posted by Bill Ravens

Let's not forget that, while the HD-SDI output is "uncompressed", when it gets recorded by (nano)Flash, it's being mpeg compressed. Just not as much as in the native EX1 scenario.

Sorry Bill, I wasn't clear. I was actually referring to the uncompressed samples captured directly to a Blackmagic or Kona card when I made that statement, though I understand you were referring to the lesser compression that will be offered via Nanoflash. In either case, the macroblocking will be minimized.

-gb-

[Steven Thomas]

Originally Posted by Greg Boston

Nice work, Thomas. Looking at the images side by side, one can see better edge definition throughout the frame. That helps pull cleaner keys of course

Yes, that image alone easliy shows 4:2:0 vs 4:2:2 difference.

[Mike Schell]

Originally Posted by Bob Grant

Perhaps a bit late in this discussion to be pointing this out however I do recall Sony saying the SDI signal is derived from the camera's component outputs. If correct then the signal has been though a chroma smoothing process in the D->A converters.
Avid has long maintained that the best way to capture DV is via component from a VCR so equiped. Clearly the VCR cannot put back that which the DV compression lost so the same result can be achieved in post.
Even if what is coming out the SDI port is from 4:2:0 processed video that's been resampled into 4:2:2 the critical question for keying is how much chroma resolution is available, not the sampling scheme.

Hi Bob-
The live HD-SDI (or HDMI, for that matter) output is derived from an internal video processing chip, which gets it's input from the image sensor A/D converter. The output of the video processing chip is simultaneously fed to the analog encoder (analog component output) and the HD-SDI (or HDMI) driver circuit. So, the HD-SDI/HDMI output has not seen any analog processing except for the original A/D conversion off the CMOS/CCD sensor(s).

Also, just to clarify another point of confusion, HD-SDI is always, always 4:2:2 10-bit, full-raster (1920x1080 or 1280x720). No other formats are permitted. Yes, the video stream may have originated in another format (such as HDV which is 1440x1080 4:2:0 8-bit), but it absolutely has to be scaled, upsampled or appended with 2 lower (zero) bits (to go from 8-bit to 10-bit) accordingly to meet the HD-SDI specifications. There are no exceptions permitted!

[Mike Schell]

Originally Posted by Bill Ravens

Funny that no one brings up motion artifacts, except for the allusions made by Thomas Smet. As far as I'm concerned, the 35Mbps bitrate from the EX1 is more than satisfactory UNTIL the camera starts panning, vertically or horizontally. As Thomas points out, it's in full frame motion(like a pan) where 35 mbps gets overwhelmed by the amount of compression it needs to do. Image blurring, aka motion artifacts become painfully apparent, especially on fine detail. Compression rates on the order of 50-100 mbps effectively reduce the amount of compression by 1/3-2/3rds, and hopefully, the motion artifacts. This has nothing to do, really, with chroma sampling rate or chroma keying. At least, this is my biggest hope for the nanoFlash I've ordered.

Please don't tell me to reduce my pan rate. I know the arguement, it's valid, up to a point. Motion artifacts can occur in other instances where in frame motion is a big part of the image frame.

Hi Bill-
Just wanted to point out that the Sony MPEG2 module used in XDR/nano actually has two hardware CODEC chips for 4:2:2 processing (same chip as used in the EX1/EX3, but two instead of one). I suspect that Sony sends the luminance data to one CODEC and the chrominance data to the second chip. You therefore, should have considerable more processing power to further eliminate motion artifacts.

Many people examined the high-motion airplane footage we played this past week at IBC. No one noticed any blocky or dropped frames whatsoever. We showed some very high-motion scenes with water and smoke. All captured at 50Mbps 4:2:2.

So, the higher bit rate should help, but the additional MPEG2 processing power should also minimize motion artifacts.

[Bill Ravens]

wow! great info. thanx, Mike.