Looking for clarification on FS700 slow-mo compression

B

binba

Active member
I've been reading around, looking to understand exactly how the FS700 records in slow-mo mode. We know it records to a temporary onboard cache/buffer and then dumps it to the cards.


  1. What are the specs for the recording in the buffer? Uncompressed? RAW? Subsampling? Bit depth? Since it holds 1,920 frames (80 seconds) of 1080p, that's up to 10GB of memory. Possible, but I'm looking for clarification or confirmation.
  2. I read that you could play out the buffer over HD-SDI at a normal video rate "as you write to the card". How does it exactly work, and can someone confirm?

So a best case scenario would be pristine uncompressed 4:2:2 8bit video to your external recorder of choice, via HD-SDI, or even full 4K RAW to the Sony unit when the upgrade comes out. The worst case scenario would be like the A77 DSLR, where all those frames get crunched into the same 28Mbps AVCHD rate.

Just looking to understand where we'd stand between those two ends. Maybe no one has authoritative answers yet (not even Sony), but it's worth having the questions out there.
 
I think you misread it. There's no way to tap into the buffer. The buffer will automatically writer to the memory card as soon as you stop the recording or the buffer fills up. You can simply play back a recorded footage to an external recorder but obviously there's no image quality benefit doing so.

If it's anything like FS100, which I'm fully expecting, the max bitrate will be 24Mbps overcranked for S&Q mode recording.
 
While the buffer writes to the memory card, you can watch your footy in slowmo on the screen.
During this time, the same signal is on the SDI/HDMI out and can be recorded.
Can't say if this SDI signal is already compressed though.
But if you think about it, at that speed it is unlikely, that the material in the buffer is compressed,
Cause memory is cheaper than computing power. So - out of my a.. I would say it's at least 4:2:2.
I should get an other 700 for more testing soon - than I check it out.

Frank
 
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