EOS R HDMI to SDI to Odyssey

[Steel]

I recently picked up a C500 and Odyssey 7q. Icing on the cake would have been if it was the 7q+ so I could get 10 bit 4:2:2 out of my EOS R to boot.
I searched the forum a bit and it seems years ago people were trying to get 1080p60 out of the original Sony a7s to the Odyssey 7q via HDMI to SDI.
Anyone know if I can get the R's 10 bit 4:2:2 into the Odyssey via a 4k HDMI to SDI converter?
Thanks!

[davedv]

Yes, this is technically possible, but it is not simple due to the fact that the Odyssey 7Q only has 3G SDI ports. The Odyssey 7Q+ actually included hardware changes to both the HDMI input and the SDI inputs, which were upgraded to 6G SDI receivers which is necessary to support 4k 30 over a single SDI cable.

Without a 6G SDI port on the Odyssey 7Q, you have to use two of the 3G SDI inputs in a dual-link SDI configuration. Which means that something like the basic Blackmagic HDMI to SDI 6G converter (for $145) will not be sufficient for this as it only outputs single-link 6G SDI signal. You could, however, take the 6G SDI output from the converter and send it through a Blackmagic SDI Multiplex 4K converter ($495) to convert from single-link 6G SDI to dual-link 3G SDI.

Another option is to use a different HDMI to SDI converter like the AJA HA5-4K ($595) which is capable of outputting dual-link 3G SDI directly. So neither of these options is particularly inexpensive.

[Steel]

Thanks, davedv.
But the Odyssey will record a 4K stream up to 30p via a single SDI able, so shouldn't it be able to take a 4K HDMI to SDI-converted signal, too? Is there any reason a 6G input (or dual 3G inputs) would be necessary?
But yeah, those are pretty expensive options for something that I'd just like to play around with.

[davedv]

For a single-chip, bayer pattern sensor (as used by most modern cinema cameras), RAW video takes up less space than de-bayered baseband video that would typically be sent over an SDI or HDMI cable. This is because RAW image data from a bayer pattern sensor only has one value per pixel, and the de-bayering process converts this into three separate RGB color values for each pixel. So uncompressed, RGB (or 4:4:4) baseband video actually requires 3 times the bandwidth of RAW video at the same bit depth.

Standard uncompressed 1080p30 HD video can be sent over an HD-SDI link with a video bandwidth of 1.5 Gbps in 10-bit format with 4:2:2 subsampling. 4K video has four times as many pixels as 1080p HD, so this requires 6 Gbps of bandwidth to send 2160p30 at 10-bit 4:2:2. And if you want to send 2160p30 full RGB or 4:4:4 video, the bandwidth requirements are actually 1.5x higher or 9 Gbps. But RAW video at the same resolution only has 1/3 as many values and as a result, it will fit within a 3 Gbps link.

This is why a camera like the Canon C500 can send 4K 30fps RAW over a single 3G SDI port, but can't do the same for standard RGB or 4:2:2 baseband video. And converting a 4K 30fps HDMI video signal in 10-bit 4:2:2 format to SDI, requires a 6G SDI port to output over a single cable.

[Steel]

Whoops! Sorry for the late reply, davedv. Interesting stuff! That's something I didn't know about debayered video - or at least hadn't really put two and two together and thought it through. I guess that puts an end to my 'easy SDI-to-HDMI EOS R 4K conversion' idea!