Intra-frame vs Long GOP recording externally

[Nick Mirro]

Hi. I'm using a Canon XF605 recording to a Ninja Inferno in pro-res.

I'd like to shoot 60 fps in 4K to enable smooth slo-mo. That is only possible if I select long GOP vs intra-frame. Connecting a recorder does not change this.

Is it moot when recording pro-res? I am confused since Canon's HDMI output isn't raw or normally compressed.

[Nick Mirro]

I had a feeling it was too technical. Canon isn't at all clear about what ends up coming out of the HDMI port. I'll try posting on the Canon forum.

[Doug Jensen]

Is the HDMI output 10-bit or 8-bit? That is the thing you need to find out.
If it is 8-bit then the Ninja will never be able to match what you can record internally on the camera.

If it is 10-bit, then you could record 10-bit ProRes @ 60 fps on the Ninja -- even though the camera would only allow you to record a Long-GOP codec internally at 4K 60p. One has nothing to do with the other. The camera only sends a signal to the recorder -- it has no control over WHAT you record once the signal exits the camera and reaches the recorder.

Regardless of the answers to those questions, I suggest that you put the Ninja on the shelf and just record internally on the camera. What's your problem with Long-GOP? Canon's specs imply it is 10-bit, so you won't be able to get better picture quality from the NInja. ProRes is not a better codec than modern AVC codecs. I suggest you do some side-by-side tests and I bet you can't see any difference whatsoever. Why over-complicate things with an external recorder? Keep the camera a simple and easier to operate. Dump the Ninja.

[Nick Mirro]

Thank you for helping!

Output is 10-bit. I edit complex multicamera shoots in Davinci. So I need pro-res to speed up editing. I'm not considering visual quality, just the editing benefit of the intermediate codec (no decompression needed).

From your response, there is no impact by setting the 605 to Long-GOP. I take that to mean individual uncompressed (signal?) frames are sent to the HDMI regardless of the setting.

The 7" monitor also provides a huge benefit. I shoot mostly outdoors in the sun and record macro and telephoto (wildlife). So a large, bright, clear monitor is essential.

[Nick Mirro]

One last thing for anyone interested...

XF605 does not send slow motion (30/120 in this example) to a recorder. The "shooting" framerate is not recognized.

So, the only workaroud is to record to the SD card 1080P 422 10 bit Long GOP. Then transcode in editor to an editing codec. I assume the Long GOP artifact is present but minimal at 1080p.

The camera cannot shoot at a native 120fps framerate. So no way to record normally and then reset it to 30 in post.