Sony A7s - no S-Log2 from HDMI Out

S

skimmel

Well-known member
I thought this is important as a new thread for anyone with an A7s:

I had rented an A7s a while ago and it seemed like s-log wasn't being outputted from the HDMI when I recorded 1080p on a PIX240i. I chalked it up to not knowing what I was doing at the time. However, it seems like this is, indeed the case, as has been confirmed by numerous people including Dan Keaton at Convergent Design.

No one is sure if this is a firmware problem or not.

Anyway, just beware.
 
So, the issue is that s-log on an external recorder has more contrast than on the internal recording. As I've said, Convergent Design has confirmed this with an external monitor and feels it's not the recorder. Same thing with Blad and Blackmagic recorders. Perhaps it's a settings issue -- for those in who it is working, what settings are you using?

Here's the quote and link:


http://www.dvinfo.net/forum/digital...ew-sony-a7s-shoot-4k-video-9.html#post1861302

Dear Friends,

This issue can be easily shown without a video recorder.

Just connect an A7s (set to S-Log 2) to any HDMI television.

The image will not look like normal S-Log 2, it will not be "flat", there will be more contrast.

This is not a recorder issue.

Personally, I believe that this is not an attempt to cripple this camera.

Of course, we would like Sony to allow regular S-Log 2 to be output the HDMI port, when S-Log 2 is enabled in the menu.

Respectfully,
__________________
Dan Keaton
Augusta Georgia
 
We were shooting it as B cam to Ninja and it matched up so visually perfectly with the F3 Log recorded on KiPro mini I never thought it was off. But I'm not much of a scope / pixel peep / over scrutinize guy. It looked great. That was my bottom line.
 
Correct. I noticed that initially as well. However it matches the internal xavc SLOG when you change the output levels to 16-235 in your NLE.
 
roro20 said:
Correct. I noticed that initially as well. However it matches the internal xavc SLOG when you change the output levels to 16-235 in your NLE.
Click to expand...

Thanks. I use Edius Pro but not sure how to set output levels to 16-235 in that program. I'll try to figure it out.
 
Here, macgregor provided proof that it works and that any issues you may have are related to either your recorder (the pix ones seem to be particularly problematic) or your workflow (wrong settings clipping the highlights, etc).
 
Mad Marvin said:
So, Levels in After Effects will suffice, setting it to 16-235 input?
Click to expand...

No. That will clip it even more. Set it to 16-235 output.

(edit: actually, to whatever its translation to 32-bit is, because superwhites are not available in After Effects in 8-bit comps, at least on CS5) (in Premiere, 16-235 output works great with my 5N footage, which is also full range and wrongly imported)
 
There's a similar thread i posted too with a comparison.

Depending on workflow usually the Slog2 signal from the XAVC comes in as video range (16-235) with elevated blacks. The ProRes version of the Slog out of the HDMI is full range (0-255) therefore the blacks are lowered and there are superbrights. If you offset and gain the HDMI output you can pretty much match the internal Slog2.

This appears to be more of a workflow issue.

It does beg the question whether there is more fidelity in the HDMI output because of this?

However at the very top end i do think there's a tiny bit of difference. the Slog2 XAVC appears to have some highlight reconstruction whereas the HDMI signal does not. This could be something to do with the way XAVC stores it's YUV.

But it's pretty much the same signal, just different clamping points

cheers
Paul
 
Really, check out macgregor's excellent test here. With his recorder and workflow, there's no difference (except for the fact that ProRes preserves the original noise, whereas XAVC-S muds it a little).
 
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