X70 HDMI output RGB or YUV?

[Mike Buckhout]

I am waiting for my X70 to arrive and am also looking into getting an external recorder for capturing uncompressed video for greenscreen compositing work. The Blackmagic Hyperdeck Shuttle will do this, but some people seem to have trouble recording via HDMI if the output from their camera/source is in the RGB color space as the Shuttle requires YUV. https://forums.creativecow.net/thread/124/882374

The issue may be moot as I could just switch to an SDI connector since the X70 and the Shuttle both have that (although the Shuttle uses a smaller 1.0/2.3 DIN style connection), but still I have not been able to find out what color space the X70 uses on the HDMI video output. The X70 manual says nothing about it.

[Mark Watson]

I have recorded to the Shuttle from the FDR-AX100 HDMI jack. I don't believe the AX100 outputs uncompressed on the HDMI port; manual didn't give the specs and I called Sony and they said they weren't giving that info out. I don't know what's been published on the X70 HDMI specs. Does it say somewhere that it outputs uncompressed?

Mark

[Mike Buckhout]

The fact that you have been able to record without having any problem with your video being a green image indicates that the color space is not an issue on your camera, which is good to know.

Here is what the X70 manual says about the HDMI output:

Originally Posted by X70 operations manual, page 75

"HDMI (High-Definition Multimedia Interface) is an interface for transferring uncompressed digital audio and video signals between a TV and a connected device. By connecting a cable from the camcorder’s HDMI OUT jack to your TV, you can enjoy high image quality video and digital audio."

So I suppose there could secretly be some compression from the X70 output, but I have no idea why that would be the case, and it would be counter to everything I have come to understand about the reasons for including HDMI and SDI outputs on video cameras. There are settings for what resolution, timecode and other overlays you want to output via HDMI, so I am pretty sure this is all just a live uncompressed video signal.

[Terence Morris]

I have a related (probably less technical) question. I'm about to order the PXW-X70 and was thinking of getting the the Atmos Samurai Blade as an external recorder. My assumption was that I could capture externally, via the SDI at 10-bit 4:2:2, Apple ProRes - as this is what Atmos advertises it does (and this is what I want, not "raw"). I guess this is where my knowledge is limited and this thread made me question my understanding of the chain of events. Principally, does the camera determine the final compression or is it the recorder? In other words, would the X70 put out a raw signal (which I assume to mean no compression, 10 bit, 4:4:4) and the recorder then compress it to 4:2:2 ProRes? Or, is the X70 actually incompatible with the Samurai, since it only puts out a raw signal and the Samurai expects to see 4:2:2 ProRes. You can see my level of confusion, but I hope this is clear at least. Thanks for any guidance guys.

[Mark Watson]

There are others on here that can answer this better than I can but here's my understanding about it.
First, I think raw is where the camera is outputting the image data in an unprocessed format so that things like ISO settings on the camera are not "baked in". It gives a user the ability to adjust the final ISO in post production editing. To be able to do this, the data output from the camera would seemingly need to be very much larger than the processed, non-raw, type of output we normally see.

On the other hand, compression is all about getting the image data reduced in size. To output the full, uncompressed image data would require very high-speed electronics in the camera as well as the recording media, which drives the price upward. Many users don't need/want to deal with all that data in their work flow, so before it gets written to the memory card/tape, the data is ran through a compression process to shrink it down to a more manageable size, while trying to retain image quality. Different compression schemes exist, and some give higher image quality than others. I think SD DV format (tape) is about a 5:1 compression and HDV is about 15:1.

As far as using an external recorder... Recorders cannot record everything and anything a camera puts out on HDMI or SDI. Recorders are limited to whatever recording specifications they are manufactured with, so you have to shop for the recorder carefully to get the one that will do what you need. If a camera can output uncompressed video, for example, and you want to capture that uncompressed video, than you are limited to only those recorders which can actually do that, and the BMD Hyperdeck Shuttle 2 is one of them. Same goes for a camera with 4K output, need a 4K capable recorder. Now, I beleive, the HDMI output has some handshaking going on between the camera and the external device. So, even though an HDMI output on a certain camera might be able to output uncompressed video, if you connect a recorder or other device (monitor screen) that cannot accept uncompressed, the recorder's capability is provided to the camera during the handshaking and then the camera adjusts that HDMI output to what the recorder/monitor can accept. I admit I'm a little fuzzy on all this, but it sums up my understanding as of today.

Mark

[Christopher Young]

Originally Posted by Terence Morris

My assumption was that I could capture externally, via the SDI at 10-bit 4:2:2, Apple ProRes - as this is what Atmos advertises it does

Your assumption is correct. The SDI out is quoted as '3G/HD/SD SMPTE 424M/292M/259M standards.'
this means it will support up to 1080p up to 2.97 Gbit/s, so up to 50 / 60p. The Samurai Blade of course will not record 50 / 60p. I use one on a regular basis. If you want any flavour of 50 /60i that's fine but you will be restricted to 25 / 30 in progressive modes.

The HDMI is specified as 'Type A.' Only guessing here but as the camera is mooted for a UHD 3840 x 2160 (TV 4K) upgrade next year I would think that the HDMI standard could be v2.0 which came out Sept 2013. This HDMI standard is the current TV UHD 4K standard. People call it 4K but in reality 4K is digital film standard of 4096 not 3840, 3840 being the UHD TV standard. If the X70 does support HDMI v2.0 then I think you may even see UHD external recording on something like the Atomos Shogun which would be nice. I have ordered an X70 as I was pretty impressed with its performance.

If you go to the following DVInfo posts there is a good discussion going on there plus there are are links to some X70 footage and downloadable MP4s if you are interested.

http://www.dvinfo.net/forum/sony-pxw...-ax100-23.html

Chris Young
CYV Productions
Sydney

[Terence Morris]

Mark, Christopher: Fantastic feedback, and so what I love about this site. Information that spans between technical expert and self-taught amateur is often difficult to dig up. With professional equipment, manufacturers just assume you understand all the technical details. At the "prosumer" level, information is often completely missing or so dumbed down as to be meaningless.

Thank you both for amending my knowledge gaps. I think I have a pretty reasonable conception of the signal processing chain now and plan to get the Samurai at some point.

Chris - I was very curious to view the X70 MXF clips you posted on the other thread. As I understand it, I think I will need to convert them in Catalyst Browse to some flavour of ProRes before I can play or import them to FCPX - is that correct?

Thanks again.

[Christopher Young]

Deleted

Chris Young
CYV Productions
Sydney

[Christopher Young]

If you are on Mac I would say ProRes if you are on PC I would select File / Transcode / XAVC and this will then convert the file to XAVC Intra 1920 x 1080 50p. This is the XAVC-Intra CBG format which supports the UHD 1920 x 1080 TV specification. Not the 2K 2048 XAVC-Intra VBR specs.

Catalyst is very slow though. Not helped by converting only one file at a time. I'm doing batch converts at a colleagues facility where they have TotalCode from MainConcept. It rattles through them. All the encode / decode XAVC codecs in Catalyst are from MainConcept.

Emails from SCS (Sony Creative) have told us that Catalyst is being worked on for speed improvements, batch conversion and file stitching for AVCHD files that span the 2GB boundry. They also told us that work on the XAVC-L decode / encode plugin for most NLEs is under way.

Chris Young
CYV Productions
Sydney

[Terence Morris]

Chris: Yes, I'm on a Mac, so will go the the ProRes route. This is just a look-see exercise, so speed is not an issue. I can see how having no batch conversion could be a nightmare for a real project. Thanks for the insider info: It's good to know that Sony is working on the software, especially NLE import. You would have thought this stuff would already be in place in time for the codec!

[Terence Morris]

I can browse and play the MXF files in Catalyst Browse but not transcode (Macbook pro circa 2010, NVIDIA, 8BG, GeForce 320M, Mavericks). I also get the "cannot use GPU for open CL" message. The files don't even display in the transcode window that pops up. I'm just assuming my system is too decrepit. Planning a big hardware upgrade soon (amazingly this system copes pretty well with PMW-200 footage, with a few tea breaks thrown in). Anyway, good enough viewing these clips in Catalyst for now.

[Christopher Young]

Hmm! Not sure what the Mac issue could be. Sorry can't be much help as all PC based here.

Chris Young
CYV Productions
Sydney