Pocket 4K to Alexa Conversion

[Sage]

59 minutes ago, majoraxis said:

Also,  is there the concept of having different EC LUT versions that are tuned for high and low dynamic range scenes as well as the standard EC LUT?  Or maybe this does not apply and only one EU daylight LUT is need for any amount of dynamic range in an daylight light scene?

That's right, only one is needed for the entirety of the range. Conversion accuracy is 'exposure independent'; though white balance will affect accuracy. With Exp Comps, it is now possible to dynamically allocate scene range for the 709 display variations in post without affecting core accuracy.

Spell this one out for me - 'So would having a set of EC LUTS for emulation film stock or an ideal sensor response LUT would benefit from having an EC LUT for each target output to do it in a single conversion?'  I couldn't quite follow

[benpicko]

So, perhaps I'm being stupid, but:

I do a lot of work with gels on lights balanced for daylight. If I use the daylight LUTs for these images, will the image look accurate to how an Arri would capture lights using those gels, or will colour accuracy be entirely wrong because I'm not just using unmodified daylight or tungsten lights?

[Mark Romero 2]

Just wanted to chime in and say that it looks really good. Sadly, don't own a GH5 nor a P4K.

[majoraxis]

11 hours ago, Sage said:

Spell this one out for me - 'So would having a set of EC LUTS for emulation film stock or an ideal sensor response LUT would benefit from having an EC LUT for each target output to do it in a single conversion?'  I couldn't quite follow

@Sage My question is if one plans to do further tweaking like color correction, film emulation, reduction for contract and saturation, would it be better to have variations of the EC LUT to accomplish these tweaks because doing it in a single conversion (using just one EC LUT instance) would turn out better than using the EC LUT and following it with more nodes to tweak the look. Thanks!

[Sage]

3 hours ago, majoraxis said:

@Sage My question is if one plans to do further tweaking like color correction, film emulation, reduction for contract and saturation, would it be better to have variations of the EC LUT to accomplish these tweaks because doing it in a single conversion (using just one EC LUT instance) would turn out better than using the EC LUT and following it with more nodes to tweak the look. Thanks!

Oh, I understand now.  EC Gen.4 is at the theoretical limit of smoothness, acting like a pass through of source material. This means that if the source material is of sufficient bit depth (for sparse regions), its like the conversion is transparent. This allows for Pre format stacking to support formats like HLG and Cine-D (which will see a major improvement with Gen4) - two V4 cubes stacked is identical to one summed, unless they are intricate 33x with bad interpolation (AE - bad, Premiere - good, Resolve with tetrahedral - very good). Nodes following thereafter may introduce artifacts of their own (the final space is only as clean as the most problematic link in the chain), but EC as yet doesn't cover creative looks etc. One may use the EC gradient chart to verify that each new grade step is not introducing problems in the wider space.

@Mark Romero 2 Thank you - what camera do you use?

[Mark Romero 2]

8 hours ago, Sage said:

@Mark Romero 2 Thank you - what camera do you use?

Right now, still using Sony a6500.

In a week from now, who knows??? Maybe a7 III, maybe S1, maybe P4K, maybe P6K, maybe X-T3...

Just probably NOT a GH5 nor Z6 nor EOS R (fine cameras that they might be). 

[Zeng]

Amazing job. Wish you could do it for more cameras. I could provide you with samples of most of them side by side with Alexa, and you just do the math. How about it? :).

[Sage]

4 hours ago, Zeng said:

Amazing job. Wish you could do it for more cameras. I could provide you with samples of most of them side by side with Alexa, and you just do the math. How about it? :).

Thank you Zeng; I need the cameras in hand, as the measurement phase is the trickiest, now that Gen4 is figured out. The code is based around a sample system I made that has ~1k samples per slice, with ~40 slices, and the measurement conditions are defined; often it must be redone several times before everything is sorted out with a new camera. I will move with considerably more efficiency to support new cameras, now that Gen 4 is finalized.

[katlis]

@Sage Just checked the GHa thread and noticed you released this P4k version, awesome! I just grabbed a P6k last month and have been excited about this. I know you're still working on that version, but in the meantime I'll test it out on the 6k for fun. From what you've seen using the P4ka on P6k footage, any tips on how to make the most of it or get it as close as it should be in your eyes? 

[Sage]

24 minutes ago, katlis said:

@Sage Just checked the GHa thread and noticed you released this P4k version, awesome! I just grabbed a P6k last month and have been excited about this. I know you're still working on that version, but in the meantime I'll test it out on the 6k for fun. From what you've seen using the P4ka on P6k footage, any tips on how to make the most of it or get it as close as it should be in your eyes? 

I haven't looked at it in-depth yet, but from what I've seen there are subtle differences (i.e. green). Overall, the default color of the 6k is a little nicer. The sensor response as things fall into shadow is a little different. I'll know more soon.

[superporpoise]

I tracked drums at a session at Bear Creek Studio last week and brought along the Pocket 4K to grab a few shots in my downtime. Only the interview shot was actually "lit" but even with mostly shitty lighting and a quick edit I like how this LUT looks. I'm excited to use it more.

 

Here's one more quick edit. I am not an expert at any of this stuff but I'm super please with how quickly I can get pleasing results.

 

I'll also add that up until this point I'd been using the Buttery LUT — which I do like — however this is the first LUT I've used that actually fixes the greens and what a treat that is.

[Sage]

Very nice! I liked the edit flow in the first, and that coffee shot at 0:40 was great

[crevice]

Alex - would I be able to use the pocket 4K version on the URSA mini pro, if I used a color space transform to get to the pocket 4K first. Or does that not make any sense? I’m very eager to see how good URSA mini footage would look with this. 

[Sage]

1 hour ago, crevice said:

Alex - would I be able to use the pocket 4K version on the URSA mini pro, if I used a color space transform to get to the pocket 4K first. Or does that not make any sense? I’m very eager to see how good URSA mini footage would look with this. 

That could be done; granted it wouldn't be tailored to the sensor. I'd like to support it directly, and I think there may be some rental options that would make that feasible.

[crevice]

On 12/9/2019 at 7:21 PM, Sage said:

That could be done; granted it wouldn't be tailored to the sensor. I'd like to support it directly, and I think there may be some rental options that would make that feasible.

That would be great. I can help with footage if you need as well and I'm sure others would also

[austinchimp]

On 12/9/2019 at 11:30 PM, superporpoise said:

I tracked drums at a session at Bear Creek Studio last week and brought along the Pocket 4K to grab a few shots in my downtime. Only the interview shot was actually "lit" but even with mostly shitty lighting and a quick edit I like how this LUT looks. I'm excited to use it more.

 

Here's one more quick edit. I am not an expert at any of this stuff but I'm super please with how quickly I can get pleasing results.

 

I'll also add that up until this point I'd been using the Buttery LUT — which I do like — however this is the first LUT I've used that actually fixes the greens and what a treat that is.

Nice, but one thing I noticed - your uploads are super low quality and blocky. Are you uploading very small files? I'd up your bitrate a lot. Shame to do such nice work and have such a nice camera and upload such poor quality files!

[Sage]

When exporting to YT and Vimeo from Resolve, I've found h.265 to be optimal. There is a slight magenta shift when the video sites re-encode the footage, and I've found it to be slightly less with h.265 (the colors are slightly more accurate). The difference for h.265, to compensate during export, is a node with -3 Tint. H.265 is also a much smaller filesize, which is less heavy on the Vimeo upload quota, and there is no size penalty for higher resolution.

However, I've found the sweet spot for streaming video sites is 2560x1440 (or 2560 pixels wide). The load times are not much worse than 1080p, but the apparent visual quality is much better (because 1080p is very compressed for streaming on these sites). The load times for 4k are much higher, with less of a leap in visual quality. Also, the fluidity of playback for 2560 is smoother than compressed 4k for streaming.

Here are my Resolve settings (horizontal resolution to match aspect ratio):

[superporpoise]

7 hours ago, austinchimp said:

Nice, but one thing I noticed - your uploads are super low quality and blocky. Are you uploading very small files? I'd up your bitrate a lot. Shame to do such nice work and have such a nice camera and upload such poor quality files!

 

3 hours ago, Sage said:

When exporting to YT and Vimeo from Resolve, I've found h.265 to be optimal. There is a slight magenta shift when the video sites re-encode the footage, and I've found it to be slightly less with h.265 (the colors are slightly more accurate). The difference for h.265, to compensate during export, is a node with -3 Tint. H.265 is also a much smaller filesize, which is less heavy on the Vimeo upload quota, and there is no size penalty for higher resolution.

However, I've found the sweet spot for streaming video sites is 2560x1440 (or 2560 pixels wide). The load times are not much worse than 1080p, but the apparent visual quality is much better (because 1080p is very compressed for streaming on these sites). The load times for 4k are much higher, with less of a leap in visual quality. Also, the fluidity of playback for 2560 is smoother than compressed 4k for streaming.

I appreciate the feedback — I'm always down for any tips on how to make my work better. I'll definitely upload higher quality files in the future. I'm coming from the world of social media, where I take for granted that everything looks rough no matter what I do. I also use a Mac/Safari and can't view 4K on YouTube in the first place #cool.

@Sage do you have a recommendation for bitrate for 2560x1440 h.265 for YouTube?

[Sage]

1 hour ago, superporpoise said:

 

@Sage do you have a recommendation for bitrate for 2560x1440 h.265 for YouTube?

It appears there is only the option to set Quality to Auto-Best, or to restrict the upper bitrate (unlike Premiere). I gather that they've looked at the needed bitrate for each quality ranking, and kept the works 'under the hood'

[docmoore]

3 hours ago, superporpoise said:

 

I also use a Mac/Safari and can't view 4K on YouTube in the first place #cool.

Dump Safari in the Mac ... Firefox has better quality and color sense for video ... does not shift the gamma when you view things on the U or V.