Web Analytics

External recording Using Alexa


Oscar Molano
 

Hello
 
We are having a shoot where we need to record the MON OUT signal of an Alexa SXT Camera due to it being fed to Unreal Engine and outputted from there with a live composite into a External Recorder.
 
I notice on the Alexa Webpage that says
 
1x proprietary signal output for EVF-1 viewfinder
4x MON OUT: 1,5G (SMPTE ST292-1)
uncompressed HD video with embedded audio and metadata
 
So the question is, does this uncompressed HD video can be recorded uncompressed or with minimum compression into ordinary external recorders? PIX, Shogun, the like.
 
Also what is the bit depth on this Mon Out signal, Say if I set my recorder to 444 Prores 10 Bit will I get the bit depth and color sampling out of the camera to fill in my external recording? is there any external recorder that can record the LOG signal of the camera as a Log Signal?
 
What would be the best approach you guys can suggest for a shoot like this using a Alexa SXT camera and recording a composite on an external recording?
 
Thanks


Mark Kenfield
 

The Odyssey7Q will let you record both uncompressed DPX or Prores4444 XQ, so that's your best option for getting the highest possible quality external recording. I think most of the others are limited to regular Prores4444 (though some might do XQ as well).

That said, I forget if the SXT can actually output 4:4:4 externally, or if you're limited to 4:2:2 🤔

Cheers,

Mark Kenfield
Cinematographer

0400 044 500


On Fri, 30 Oct 2020 at 14:07, Oscar Molano <oscmol19@...> wrote:
Hello
 
We are having a shoot where we need to record the MON OUT signal of an Alexa SXT Camera due to it being fed to Unreal Engine and outputted from there with a live composite into a External Recorder.
 
I notice on the Alexa Webpage that says
 
1x proprietary signal output for EVF-1 viewfinder
4x MON OUT: 1,5G (SMPTE ST292-1)
uncompressed HD video with embedded audio and metadata
 
So the question is, does this uncompressed HD video can be recorded uncompressed or with minimum compression into ordinary external recorders? PIX, Shogun, the like.
 
Also what is the bit depth on this Mon Out signal, Say if I set my recorder to 444 Prores 10 Bit will I get the bit depth and color sampling out of the camera to fill in my external recording? is there any external recorder that can record the LOG signal of the camera as a Log Signal?
 
What would be the best approach you guys can suggest for a shoot like this using a Alexa SXT camera and recording a composite on an external recording?
 
Thanks


Adrian Jebef
 

Because the SXT doesn’t have a dedicated Rec Out for external recorders like the old Classics do your best bet is to set the camera into HD 16:9 mode and set your outs to clean. There are plenty of recorders on the market that will record uncompressed or compressed codecs. Log or gamma corrected. 422 or 444.

Adrian Jebef
DIT
(626) 840-1260








On Oct 29, 2020, at 8:34 PM, Mark Kenfield <mark@...> wrote:


The Odyssey7Q will let you record both uncompressed DPX or Prores4444 XQ, so that's your best option for getting the highest possible quality external recording. I think most of the others are limited to regular Prores4444 (though some might do XQ as well).

That said, I forget if the SXT can actually output 4:4:4 externally, or if you're limited to 4:2:2 🤔

Cheers,

Mark Kenfield
Cinematographer

0400 044 500


On Fri, 30 Oct 2020 at 14:07, Oscar Molano <oscmol19@...> wrote:
Hello
 
We are having a shoot where we need to record the MON OUT signal of an Alexa SXT Camera due to it being fed to Unreal Engine and outputted from there with a live composite into a External Recorder.
 
I notice on the Alexa Webpage that says
 
1x proprietary signal output for EVF-1 viewfinder
4x MON OUT: 1,5G (SMPTE ST292-1)
uncompressed HD video with embedded audio and metadata
 
So the question is, does this uncompressed HD video can be recorded uncompressed or with minimum compression into ordinary external recorders? PIX, Shogun, the like.
 
Also what is the bit depth on this Mon Out signal, Say if I set my recorder to 444 Prores 10 Bit will I get the bit depth and color sampling out of the camera to fill in my external recording? is there any external recorder that can record the LOG signal of the camera as a Log Signal?
 
What would be the best approach you guys can suggest for a shoot like this using a Alexa SXT camera and recording a composite on an external recording?
 
Thanks


Mitch Gross
 

I believe the Monitor Out from the camera will be limited to HD 16:9 4:2:2 10-bit. You can record this in uncompressed DPX files on the Odyssey7Q+ but I highly doubt you will see any advantage over recording in ProRes 422HQ. That’s available in many recorders. 

If you output in Log-C you can record in Log-C and set the recorder’s live output to either Log-C or to apply a LUT. Modern recorders have a standard Log-C to Rec709 included as an option or you can load a custom LUT. Please note that all recorders and most LUT boxes only output a 17x LUT, so even if they allow you to load a 33x or 64x LUT it will be concatenated to a 17x. For most used this is fine but I point it out in case you’re use with Unreal Engine may have an issue. I believe the IS-Mini will apply un-concatenated LUTs. 

Mitch Gross
New York

On Oct 30, 2020, at 1:30 AM, Adrian Jebef via cml.news <adrianjebef=yahoo.com@...> wrote:

Because the SXT doesn’t have a dedicated Rec Out for external recorders like the old Classics do your best bet is to set the camera into HD 16:9 mode and set your outs to clean. There are plenty of recorders on the market that will record uncompressed or compressed codecs. Log or gamma corrected. 422 or 444.

Adrian Jebef
DIT
(626) 840-1260








On Oct 29, 2020, at 8:34 PM, Mark Kenfield <mark@...> wrote:


The Odyssey7Q will let you record both uncompressed DPX or Prores4444 XQ, so that's your best option for getting the highest possible quality external recording. I think most of the others are limited to regular Prores4444 (though some might do XQ as well).

That said, I forget if the SXT can actually output 4:4:4 externally, or if you're limited to 4:2:2 🤔

Cheers,

Mark Kenfield
Cinematographer

0400 044 500


On Fri, 30 Oct 2020 at 14:07, Oscar Molano <oscmol19@...> wrote:
Hello
 
We are having a shoot where we need to record the MON OUT signal of an Alexa SXT Camera due to it being fed to Unreal Engine and outputted from there with a live composite into a External Recorder.
 
I notice on the Alexa Webpage that says
 
1x proprietary signal output for EVF-1 viewfinder
4x MON OUT: 1,5G (SMPTE ST292-1)
uncompressed HD video with embedded audio and metadata
 
So the question is, does this uncompressed HD video can be recorded uncompressed or with minimum compression into ordinary external recorders? PIX, Shogun, the like.
 
Also what is the bit depth on this Mon Out signal, Say if I set my recorder to 444 Prores 10 Bit will I get the bit depth and color sampling out of the camera to fill in my external recording? is there any external recorder that can record the LOG signal of the camera as a Log Signal?
 
What would be the best approach you guys can suggest for a shoot like this using a Alexa SXT camera and recording a composite on an external recording?
 
Thanks


Bob Kertesz
 

If I read your post correctly, you will be feeding the Alexa Monitor Out to the Unreal Engine, generating a composited image of some sort in the Engine, then you want to record the composited output of the Engine on an external recorder.

Which means it's the output resolution/colorspace/framerate of the Engine that's relevant, not that of the Alexa. The Alexa needs to feed what the Engine wants to see.

I'm not familiar with the Unreal Engine, and their web site is endless flashy marketing with little technical detail (I got bored after about five minutes of trying to find some), but it's likely you can set its output resolution/colorspace/framerate, so you have to decide what that will be and get a recorder to record that.

Unless I misread what you wrote, you will not be recording the Alexa directly at all - it's the foreground input for a downstream composite.

-Bob

Bob Kertesz
BlueScreen LLC
Hollywood, California

Mostly Retired Engineer, Video Controller, and Live Compositor Extraordinaire.

High quality images for almost five decades - whether you've wanted them or not.©

* * * * * * * * * *

On 10/29/2020 12:25:16 PM, Oscar Molano wrote:
Hello
 
We are having a shoot where we need to record the MON OUT signal of an Alexa SXT Camera due to it being fed to Unreal Engine and outputted from there with a live composite into a External Recorder.
 
I notice on the Alexa Webpage that says
 
1x proprietary signal output for EVF-1 viewfinder
4x MON OUT: 1,5G (SMPTE ST292-1)
uncompressed HD video with embedded audio and metadata
 
So the question is, does this uncompressed HD video can be recorded uncompressed or with minimum compression into ordinary external recorders? PIX, Shogun, the like.
 
Also what is the bit depth on this Mon Out signal, Say if I set my recorder to 444 Prores 10 Bit will I get the bit depth and color sampling out of the camera to fill in my external recording? is there any external recorder that can record the LOG signal of the camera as a Log Signal?
 
What would be the best approach you guys can suggest for a shoot like this using a Alexa SXT camera and recording a composite on an external recording?
 
Thanks



Andy Jarosz
 

You'll need a capture card for the computer running Unreal, Blackmagic Decklinks are the best supported.

Genlock into the camera and the Decklink to ensure frame sync, and then do whatever you need too within Unreal. It's fairly straightforward. Your output will be a BlackMagicMediaOutput blueprint. All details on this here: https://docs.unrealengine.com/en-US/Engine/ProVideoIO/BlackmagicQuickStart/index.html

It doesn't really matter what the camera is outputting as long as it's a supported frame rate and res. You can apply LUTs in Unreal, or you can use postprocessing to match Unreal to the camera. Just depends on what you want to do.

 If you're using Composure within Unreal, you can use the SDI out of the Decklink into whatever recorder you want. As Bob mentioned, this is a different signal and is independent of the camera.  You can also just output the foreground or background elements from Unreal and record the camera feed separately for compositing in post.

-- 
Andy Jarosz
MadlyFX & LOLED Virtual
loledvirtual.com
Andy@...
708.420.2639
Chicago, IL
On 10/30/2020 1:

On 10/29/2020 12:25:16 PM, Oscar Molano wrote:
Hello
 
We are having a shoot where we need to record the MON OUT signal of an Alexa SXT Camera due to it being fed to Unreal Engine and outputted from there with a live composite into a External Recorder.
 
I notice on the Alexa Webpage that says
 
1x proprietary signal output for EVF-1 viewfinder
4x MON OUT: 1,5G (SMPTE ST292-1)
uncompressed HD video with embedded audio and metadata
 


Adrian Jebef
 

Note that the Alexa SXT can only output 16:9 HD. Setting the camera into a different recording mode / resolution (3.4K open gate, 3.2K ProRes, 2K etc) will result in scaling issues as the camera will scale down these other modes to fit into its 1920x1080 video out stream. For a full frame image you’ll want to be in 16:9 HD mode.

Adrian Jebef
DIT
(626) 840-1260





On Oct 30, 2020, at 5:40 PM, Andy Jarosz <andy@...> wrote:

 You'll need a capture card for the computer running Unreal, Blackmagic Decklinks are the best supported.

Genlock into the camera and the Decklink to ensure frame sync, and then do whatever you need too within Unreal. It's fairly straightforward. Your output will be a BlackMagicMediaOutput blueprint. All details on this here: https://docs.unrealengine.com/en-US/Engine/ProVideoIO/BlackmagicQuickStart/index.html

It doesn't really matter what the camera is outputting as long as it's a supported frame rate and res. You can apply LUTs in Unreal, or you can use postprocessing to match Unreal to the camera. Just depends on what you want to do.

 If you're using Composure within Unreal, you can use the SDI out of the Decklink into whatever recorder you want. As Bob mentioned, this is a different signal and is independent of the camera.  You can also just output the foreground or background elements from Unreal and record the camera feed separately for compositing in post.

-- 
Andy Jarosz
MadlyFX & LOLED Virtual
loledvirtual.com
Andy@...
708.420.2639
Chicago, IL
On 10/30/2020 1:
On 10/29/2020 12:25:16 PM, Oscar Molano wrote:
Hello
 
We are having a shoot where we need to record the MON OUT signal of an Alexa SXT Camera due to it being fed to Unreal Engine and outputted from there with a live composite into a External Recorder.
 
I notice on the Alexa Webpage that says
 
1x proprietary signal output for EVF-1 viewfinder
4x MON OUT: 1,5G (SMPTE ST292-1)
uncompressed HD video with embedded audio and metadata
 


Oscar Molano
 

Thank you all for the responses 

It is clear to me now that the most important setting will be what is coming out of UE to our recorder 

Thanks again 

El El vie, 30 de oct. de 2020 a la(s) 8:45 p. m., Adrian Jebef via cml.news <adrianjebef=yahoo.com@...> escribió:
Note that the Alexa SXT can only output 16:9 HD. Setting the camera into a different recording mode / resolution (3.4K open gate, 3.2K ProRes, 2K etc) will result in scaling issues as the camera will scale down these other modes to fit into its 1920x1080 video out stream. For a full frame image you’ll want to be in 16:9 HD mode.

Adrian Jebef
DIT
(626) 840-1260





On Oct 30, 2020, at 5:40 PM, Andy Jarosz <andy@...> wrote:

 You'll need a capture card for the computer running Unreal, Blackmagic Decklinks are the best supported.

Genlock into the camera and the Decklink to ensure frame sync, and then do whatever you need too within Unreal. It's fairly straightforward. Your output will be a BlackMagicMediaOutput blueprint. All details on this here: https://docs.unrealengine.com/en-US/Engine/ProVideoIO/BlackmagicQuickStart/index.html

It doesn't really matter what the camera is outputting as long as it's a supported frame rate and res. You can apply LUTs in Unreal, or you can use postprocessing to match Unreal to the camera. Just depends on what you want to do.

 If you're using Composure within Unreal, you can use the SDI out of the Decklink into whatever recorder you want. As Bob mentioned, this is a different signal and is independent of the camera.  You can also just output the foreground or background elements from Unreal and record the camera feed separately for compositing in post.

-- 
Andy Jarosz
MadlyFX & LOLED Virtual
loledvirtual.com
Andy@...
708.420.2639
Chicago, IL
On 10/30/2020 1:
On 10/29/2020 12:25:16 PM, Oscar Molano wrote:
Hello
 
We are having a shoot where we need to record the MON OUT signal of an Alexa SXT Camera due to it being fed to Unreal Engine and outputted from there with a live composite into a External Recorder.
 
I notice on the Alexa Webpage that says
 
1x proprietary signal output for EVF-1 viewfinder
4x MON OUT: 1,5G (SMPTE ST292-1)
uncompressed HD video with embedded audio and metadata
 

--
Oscar Molano
DIT/Camera Assistant
Bogotá, Colombia