another 3840*1536 5d3 video, and a question for the devs...

[70MM13]

This was shot in the forest, and I know from experience that it would have stopped suddenly if i was using the 3.X "x5" modes.

I'm wondering if the uhd 1:1 mode is more reliable because of the better data balancing between the two cards?

I find it to be almost equal data written to the SD and CF cards.

I'm really liking the look I'm getting in this resolution, including the DOF!

https://youtu.be/aPTMbGr1g-I

[names_are_hard]

I don't think the different modes change the way the card spanning code works.  It just alternates writes to the cards as fast as possible.  If you get about the same amount written to each card it suggests they're about the same speed.

[70MM13]

The speeds are only similar in this mode. In every other mode the majority of the data goes to the CF card.
I wonder if it is related to the extra horizontal resolution somehow providing more time for each scanline,  if that's somehow applicable?
Just a thought...

[names_are_hard]

There's no reason for it that's obvious to me.  Different modes will change cpu required for capture, which will change what's left over for writing, but I don't see a particular reason why that would change the balance of writes to cards.  Maybe if CF or SD routines were of differing cost.

In any case, it's not deliberate.  It would be possible to have a different scheduling algorithm for writes to try and balance the write load, rather than letting the faster card perform faster - but I don't see any reason why that would change the reliability of any mode.  Intuitively you'd expect it would make things worse; you're limiting the write speed of the faster card to that of the slower.

I suspect the real concern here is why some modes are less reliable.  That's a fair question, and worth investigating.  Better logging when things go wrong would seem a sensible first step.

[Jonneh]

In my hands I get fairly similar CF:SD write ratios of around 1.2:1 for both 3.8K and 3.5K modes (1536 and 1730 vertical, respectively). The 5.7K anamorphic mode, on the other hand, is wildly unbalanced, at something like 2.5:1.

With a fast CF card and SD overclocking, the sum of the max speeds when not card spanning (something like 90 and 80 MB/s) is well over the maximum combined speed when card spanning (approx. 140 MB/s), so perhaps that'd mean there'd be room for balancing the write load without reducing the total data rate?

Either way, it's true that some modes are more reliable than others in a way that doesn't seem to depend only on the required data rate. I always assumed it was due to different resolutions differentially affecting the compressibility of the image depending on the type of scene (some modes seem fine until faced with highly detailed high key regions whereas others are closer to the edge but seem less fazed by such areas), but this is pure speculation.