To settle the record, can the FS100 record 8bit RGB?

T

Tim Lawrence

Member
I've been trying to find information about this for awhile but only recently started emailing, making calls, etc.

I'm trying to find either an external recorder, studio recorder, or even a PCIe card that could capture 8bit RGB off of my FS100.

recently I emailed Cinedeck, and they got back to me almost immediately with this reply

"Hi Tim,

They all support 422 recording because no one supports Sony's proprietary 8bit RGB pixel format, including us, unfortunately.

You could possibly use an AJA 'HDMI to dual link' converter and record dual link 4:4:4 to the RX or EX"

A few days later I called abelcine, and the representitive said that the FS100 only supported 4:2:2 output.

I also called AJA, and the representitive at AJA said because it is the live, uncompressed signal out of the HDMI port, it doesn't have any format be that YUV or RGB, 4:2:2 or 4:4:4 that it was all decided on the recording end.

BHphotovideo's page on the FS100 still states

"Uncompressed 4:2:2 & RGB Output via HDMI" as a feature point

BHPhotovideo here

Sony's page however states

"HDMI Output with Embedded Time code for 4:2:2 Uncompressed digital output. For extra convenience when using external recorders, the NEX-FS100 provides an HDMI Output with Embedded Time code and pull down markers Signal Output al Output."

http://pro.sony.com/bbsc/ssr/product-NEXFS100U/

I've tried contacting Sony directly but I've received no email reply, and when I call their phone line and select "Sony Professional Products" the automated system tells me to go to their website.

Does anyone know for a fact that the FS100 is even capable of a true RGB signal? or would it just be YUV converted to RGB after camera processing.

And if it does, is there ANY product that can capture that RGB signal from HDMI, or losslessly convert it from HDMI to SDI.

every product I've seen from Blackmagic, Atomos, Cinedeck, Cinemartin, AJA. They all only take a 4:2:2 signal.

Let me know if you know otherwise, I'd like to get this settled once and for all, and if it isn't capable, this becomes a matter of false advertising.
 
The FS100 cannot RECORD RGB, no. It can output RGB, but that RGB will be made from its Bayer sensor, so you wouldn't get a "true" 4:4:4 signal anyway -- you'd get an uprezzed signal from the Bayer sensor.
 
Right, poor choice of words on my part. What I meant was can it output a clean RGB signal from it's HDMI port. So if you could in theory output an unprocessed bayer image, is there even any hardware/software out there that you could process that image with outside of the camera?

Also, why would it be up-ressed? why is the picture from the Bayer sensor not true 4:4:4?

I know there is nothing wrong with 8 bit YUV 4:2:2. Hell, even the internal AVCHD codec is brilliant, I'm just curious about what's possible, and curious why it was advertised if there is no way to really get it.

I guess I'm just trying to understand when they say "HDMI can output uncompressed 8 bit RGB" what does that mean, and how can I benefit from it. Is there any device that can capture that. If not, what's the point?
 
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I thought some of Black Magic's higher-end hardware like the Ultrastudio could capture 8 and 10 bit uncompressed RGB? Although from what i understand trying to actually capture that much data quickly puts you up against a throughput brick wall.

As for the FS100 - you're right that details are a little sketchy but I was under the impression it output 8 bit uncompressed 4:2:2 but embedded in a 4:4:4 stream (for whatever reason).

Cheers,
Jeff K
 
Thanks everyone for the replies,

black magic's, as well as other products can capture RGB, but it's exclusively through the SDI ports, never the HDMI ports. Most devices don't even output RGB at 8 bit, because it's seen as more advantageous to have 10 bit 4:2:2 than 8 bit RGB. For awhile I even wondered if you could put out an 8 bit uncompressed RGB signal over HDMI at all, but research has shown that HDMI should be able to handle it, it's just not something you ever see in the industry due to lack of demand and price.

to be clear, there is no such thing as chroma subsampling in RGB. RGB is pretty much never compressed or subsampled. there is YUV 4:2:2 and YUV 4:4:4, but there is no RGB "4:4:4" as it doesn't have subsampling anyways. In practice YUV 4:4:4 and RGB should provide identical, completely lossless images, albeit in different color spaces.

That said, when you say it would have an "embedded 4:4:4 stream" what does that mean? how is that utilized? that's the bottom line I'm trying to get down to, is this something that is usable? and if so, how.
 
According to several sources I came across when the FS100 was released, the HDMI output is 4:4:4, however it only contains the bits from a 4:2:2 8-bit data stream coming from the sensor. I have no idea why it was advantageous to do that but the Sony engineers had their reasons, I guess.

Ultimately though, it simply means that if there ever is a recorder that can capture the uncompressed RGB signal then it's there, ready and waiting. Meanwhile the existing recorders are getting the best signal possible to transcode into whatever their designers choose as a recording format.

I would suggest the final answer is that the signal is there but no, you can't do anything with it in it's 'raw' state.

Although - and I don't have any need for recording RGB so I'll let others do the research - if, as you suggest, there are SDI devices that can record the signal, are there any HDMI to SDI converters that pass the RGB signal straight through?

Cheers
Jeff K
 
Barry_Green said:
The FS100 cannot RECORD RGB, no. It can output RGB, but that RGB will be made from its Bayer sensor, so you wouldn't get a "true" 4:4:4 signal anyway -- you'd get an uprezzed signal from the Bayer sensor.
Click to expand...

That then brings up the question of what is "true" RGB or true 4:4:4? Does any camera output "true" RGB and does any display display it? The simple answer is no. RGB as it is stored in a computer will always differ greatly from the way it is acquired/displayed. Some might say prism cameras are true RGB, some might say C300 is, other might just say any 4k+ Raw debayered and downrez'ed to 1080p. I'm sure some feel that any camera or display does do it, but they are just working with their own personal definition of "true" RGB or 4:4:4. :)

The reality is that RGB means something different in different in various realms, and it may mean something different in image sensors/processing than it does in image storage/encoding/decoding or in displays. The physical components of each are very different even if the conceptual/theoretical components seem similar.
 
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Jeff Kirkland said:
According to several sources I came across when the FS100 was released, the HDMI output is 4:4:4, however it only contains the bits from a 4:2:2 8-bit data stream coming from the sensor. I have no idea why it was advantageous to do that but the Sony engineers had their reasons, I guess.
Click to expand...

Thanks Jeff, if this is true, and there is only 4:2:2 data, there would be no benefit to having anything else, and that would simplify it all. What is odd is that they said it is RGB, you cannot have YUV color data in a RGB color data file, that doesn't really make sense. hmm, can anyone confirm this?
 
nyvz said:
That then brings up the question of what is "true" RGB or true 4:4:4? Does any camera output "true" RGB and does any display display it? The simple answer is NO, and even more so for YUV 4:4:4. RGB as it is stored in a computer will always differ greatly from the way it is acquired/displayed. I'm sure some feel that any camera or display does do it, but they are just working with their own personal definition of "true" RGB or 4:4:4. :)
Click to expand...

I see what you are saying by "true" but I do know that the Sony PMW F3 does record RGB, so there are cameras out there that do this. The reason I said "true" is because a lot of people confuse 4:4:4 YUV (in the YUV color space) with RGB (RGB color space) I was just trying to clarify that point.
 
Tim Lawrence said:
I see what you are saying by "true" but I do know that the Sony PMW F3 does record RGB, so there are cameras out there that do this. The reason I said "true" is because a lot of people confuse 4:4:4 YUV (in the YUV color space) with RGB (RGB color space) I was just trying to clarify that point.
Click to expand...

Yes RGB and YUV are certainly different and worth differentiating, with RGB being perhaps a step closer to most imagers since they mostly use RGB filtration. As Barry said, its also worth nothing that its misleading to say an F3/FS100/whatever records RGB since none of them do the recording in-camera. They can send out a signal that can be externally recorded by another device.
 
very true nyvz, although it's still a capability. From what I've been hearing though, I also posted the topic on dvinfo.net here

RGB question at dvinfo

From what I've been hearing, the FS100 doesn't output an actual RGB signal, but instead upconverts a 4:2:2 signal to RGB for compatibility with monitors. This would explain why no one is using it, it still doesn't make entire sense to me as all CMOS sensors that I know of deal with data in RGB, but I guess if the D to A converters on the sensor are processing the RAW data in 4:2:2 this would make sense. It would take very beefy hardware to process/output RGB data at that resolution.

If this is true though, then the FS100 can't REALLY do RGB at all, where as the F3 can. That would make the advertising on the FS100 VERY misleading, but still a great camera. The ultimate reason I even asked this, was because I was willing to do a little more research or invest a bit more money in a field or studio recorder for RGB so that my footage would be even more future proof.

There is nothing wrong with the FS100's codec, or even capturing 4:2:2. I just didn't want to buy a 4:2:2 recorder, and then the next day find out I could have gotten an RGB recorder instead.

On top of that, if the FS100 wasn't outputting a full information (aka not up-sampled from 4:2:2) RGB file, why have I been hearing so many mixed opinions? Hopefully this will set the record straight.

nyvz said:
Yes RGB and YUV are certainly different and worth differentiating, with RGB being perhaps a step closer to most imagers since they mostly use RGB filtration.
Click to expand...

Yes, sensors capture the raw data in RGB, and the pixels on any CRT, LCD, Plasma, OLED, etc display are all RGB, so it would make sense to stay with the same color space from acquisition to delivery to customers to prevent the most loss you can, it also means you aren't losing any color detail.
 
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"I just didn't want to buy a 4:2:2 recorder, and then the next day find out
I could have gotten an RGB recorder instead."

These were my thoughts exactly
when I started my thread about this, but I could never get a straight answer.

Even when I was at NAB right before I bought my FS100 the reps were all telling
me the camera outputted 8 bit 444 and one rep told me it was 10 bit 422, but as
it turned out no one really knew.

I definitely go with your statement that Sony was very misleading on some of the
advertising of the FS100. Still a great camera though and I do not regret my purchase
one bit.
 
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Tim Lawrence said:
I just didn't want to buy a 4:2:2 recorder, and then the next day find out I could have gotten an RGB recorder instead.
Click to expand...

4:2:2 recorders = YUV, and nothing wrong with that. However, 4:4:4 is a whole new game and are we losing sight of 10 bit over 8 bit? I think I'd prefer 10 bit 4:2:2 over 8 bit 4:4:4. The recorders can do it - but can the camera?
 
The way it seems the camera can't do any ( 10 bit 4:2:2 or 8 bit 4:4:4 or RGB ) I would personally like to always shoot in RGB if possible, but that's just a personal preference.

Think about this, most all consumer monitors and projectors can only display 8 bit color, but EVERY one of them displays RGB. Of course this doesn't matter to most people because nobody distributes or screens an uncompressed RGB file anyways (but you could, maybe for a special event or screening) For me it's more about long term personal archival and getting the most out of my camera.
 
Tim Lawrence said:
Think about this, most all consumer monitors and projectors can only display 8 bit color, but EVERY one of them displays RGB.
Click to expand...

Think about this, everything is 4:2:0 when it goes through the air to your telly, bluray or the internet.

You only "need" 4:4:4 for keying. It won't help anywhere else (well maybe doing color keys in grading). After you've done those and everything is outputted, it's back to 4:2:0.
 
If the FS100 outputs RGB via the HDMI port it would be 8 bit SRGB color space as that is the same color space as YUV encoded REC709 video. RGB represents each color channel individually with no sub sampling. YUV is a sum and difference format with Y carrying a defined percentage of RGB value mix to produce a full resolution monochrome image and the U/V chroma channels carrying inverted signals with different percentage mixes of RGB subtracted from Y to define color values. Chroma is subsampled only in YUV formats. It does not apply to RGB.
Plug the HDMI output of the camera into a computer monitor via HDMI or HDMI to DVI adapter. If you see a normal color image, the camera is putting out 8 bit SRGB. You can check your monitor setup menu to confirm its signal format and color space, but most computer monitors do not decode YUV.
If the camera does output RGB, then it either has a menu item to select YUV or RGB output for the HDMI port, or it uses EDID to detect the format of an attached device and sets the format automatically.
 
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thanks Razz, I'm fairly certain it uses EDID to handshake with whatever device it's plugged into. I'm fairly confident that it can output to a monitor just fine, and thus, logically it would stand via RGB.

The main debate is about, is the camera outputting a truly lossless 8 bit RGB signal (aka, not just upconverting a YUV 4:2:2 signal for RGB compatibility with monitors, but actually the true original superior signal)? and if so, why in no recorder manufacturer making a device that can capture it? Is it just a matter of economics? It would cost more to serve a niche to non existant customer base that wants RGB from HDMI based cameras?

or is it a technical issue, I know a rep from Cinedeck said that the 8 bit RGB format Sony was using was proprietary, and that nobody supported that format. I think I owe it to myself and other members here to keep trying to get ahold of Sony themselves and get a straight answer.
 
An update:

I don't know where I went on the website before that I couldn't find the number, but I found the professional contact number for Sony and gave them a call. I got transferred to the technical department and asked about RGB recording. The serviceman asked I hold, and I was on hold for about 8 minutes. After doing his research he came back and explained that this feature is not available on the FS100 but will be on the FS700. So it's official from Sony's mouth, the FS100 is a 4:2:2 YUV camera only, no RGB.
 
Ya! I figured as much. That should have been the official statement out of Sony's mouth in the first place.
I wonder what the motivation was behind the 444 in the first place.
 
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