FS7: Is FS7 XAVC-L 4K 8 or 10 bit and 422 or 420?

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skimmel

Well-known member
I know that XAVC-L is 10-bit 422 in HD, but I can't seem to figure out what it is in 4K/UHD. Is it also 10-bit, 422? I thought I read somewhere that it may not be.

Thanks.
 
Thanks Ned. This is interesting and I'm wondering how many people know this. I certainly didn't until just now.

The reason I was curious about this is that I recently used the FS7 as a C-camera (it was my first use of the camera for a real concert and I wasn't taking any chances). I used XAVC L to save card space. As I was grading, (I shot in SLOG-3) I was having some problems as the footage seemed a little thin. Now, for all I know I might not have been able to tell the difference from 10-bit 422, but I will certainly use XAVC I for my next important shoot.
 
You correctly point out that XAVC-L 1080 is 4:2:2 and 10 bit. Sorry you got bitten by that XAVC-L UHD dirty little secret.

Ned
 
Oh well, live and learn. Hopefully others will see this so they are aware too in case they didn't know already.
 
I haven't taken my camera out of XAVC-I since I got it. Of course I don't do concerts but the XAVC-I codec is pretty efficient.
 
I shot some test footage in XAVC-L 35mb just for kicks. It doesn't look bad, save for some mosquito noise in high contrast edges. Properties say it's 10-bit 422. Going to reshoot more footage with the 50mb version and compare.

XAVC-I for concerts? Hope you have a lot of XQD cards and someone to change them every 13 minutes! I note that in 4K 60fps, 64GB gives 13 minutes record time. We need XQD cards in the terabyte range!
 
At first I was a little bit disappointed to see UHD in XAVC-L to be only 8 bit 420, but when I started to use the camera I realized my clients doesn't want anything more than 1080 for long formats. So the XAVC-L 50mb/s is perfect to provide long recording with good quality without having to large files.
 
I find uhd/4k xavc-L the worst one from all the fs7 codec options.
Yea, it's 4k and reasonably small sizes but with 4:2:0 8bit it's weak and very heavy on computer power needs in editing.

Donny 123 said:
does the FS7 shoot 35 mbps..? in 10 bit 422.. ?
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Yes, in FHD and xavc-L.
 
basspig said:
I shot some test footage in XAVC-L 35mb just for kicks. It doesn't look bad, save for some mosquito noise in high contrast edges. Properties say it's 10-bit 422.
Click to expand...


XAVC-L 35Mbps is only HD and all the XAVC-L HD formats are 10-bit, so the properties are correct. It is only the XAVC-L UHD formats that are 8-bit.
 
1080p 50Mbps XAVC-L is a really robust codec. I can still recover some stuff in post and its great on storage. I shoot with 4x 64 GB cards and can shoot 143 mins x 4 cards which is an insane amount of time.
 
We've largely stayed in XAVC-I for our shooting (when we aren't going out to our O7Q), however, we have used XAVC-L HD for an interview project.

The important thing to remember is that the XAVC-L codec will break if there is a lot of detail moving from frame to frame. If the shot is relatively static (like an interview) it should look very good.

While I'd love to stay in XAVC-I all the time (for simplicity), when you are talking about 20-25 hours of interview material the disk space savings of XAVC-L is significant.
 
ChristopherA said:
The important thing to remember is that the XAVC-L codec will break if there is a lot of detail moving from frame to frame. If the shot is relatively static (like an interview) it should look very good.
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Are you referring at XAVC-L 35Mbps, do you think that at 100mbit (4k) as implemented in FS5 will break the same?
 
Danilo Del Tufo said:
Are you referring at XAVC-L 35Mbps, do you think that at 100mbit (4k) as implemented in FS5 will break the same?
Click to expand...

Because of the way Long-GOP compresses it's media, this with happen with any Long-GOP format. Obviously a higher data rate will mitigate this somewhat, but it's still a limitation of the format. Given what I've seen from the 4k XAVC-L on my FS7, I would not expect much from the 4k in the FS5.

On the FS7 in 4k XAVC-L, we see all the artifacts that you'd expect from Long-GOP footage, plus the 8bit footage leads to some serious banding issues. As a result, we've judged the 4k XAVC-L on the FS7 to be unusable for serious work.
 
ChristopherA said:
As a result, we've judged the 4k XAVC-L on the FS7 to be unusable for serious work.
Click to expand...
I've read somewhere about the codec that there's a VBR 2 Pass encoding in. Do you think it's possible to mitigate artifacts via 2 pass encoding? There's also the option on FS5 to AVCHD format if I remember exactly, is it better? Thanks
 
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The difference between a 1 and 2 pass encoding can be substantial. That being said, I don't know if it's possible to do a 2 pass encode during an initial record. Assuming it is possible, I wouldn't expect them to do anything dramatically different with the Long-GOP recording between the FS5 and FS7.

In my experience AVCHD is an inferior codec to XAVC.
 
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