GH5 "5K Open Gate" mode for non-anamorphic shooting?

[kye]

I've been reading about the 5K Open Gate mode and wondering if I should be using that instead of normal UHD?

I'm currently shooting the 4K 10-bit 150Mbps mode in HLG (I only have a Sandisk 95MBs UHS-I card so can't shoot 400Mbps).  I understand that the 200Mbps 5K mode will give an increase in resolution, bitrate, and will allow me to re-frame in post, which are all desirable features, but are there any hidden downsides to using this mode?  What hassles or catches are there?

I read that the 5K mode is h265, but is the 4K mode h264, or h265?

[OliKMIA]

Yeah, it's nice. I use it sometime, useful to reframe during interview. Gives you a lot of extra room but you must attach a very sharp lens otherwise you gonna loose resolution (something like the Sigma ART 18-35mm f1.8 will do)

If my memory serves me well, the 5k mode is h265 whereas all the 4k modes are only in h264.
The 5k is 10 bits 420 instead of 10 bits 422 in 4k so it might not be the best option for keying on green screen.

5k is limited to 30p max.

I haven't found much downside except the codec that will put most computers under stress. But I use proxy so it doesn't matter much for me.

[kye]

1 hour ago, OliKMIA said:

Yeah, it's nice. I use it sometime, useful to reframe during interview. Gives you a lot of extra room but you must attach a very sharp lens otherwise you gonna loose resolution (something like the Sigma ART 18-35mm f1.8 will do)

If my memory serves me well, the 5k mode is h265 whereas all the 4k modes are only in h264.
The 5k is 10 bits 420 instead of 10 bits 422 in 4k so it might not be the best option for keying on green screen.

5k is limited to 30p max.

I haven't found much downside except the codec that will put most computers under stress. But I use proxy so it doesn't matter much for me.

Thanks.

I also got the impression that the 5K mode are h265 and the 4K modes are h264.  This is a big deal for me, from what I read h265 gets similar image quality at about heal the bitrate of h264, so going from 150Mbps h264 to 200Mbps h265 is more like the quality of 400Mbps h264.  In terms of the 422 vs 420 it's definitely a down-side, but it's offset by the extra bitrate, codec efficiency, and slightly extra resolution, so it should result in a net gain overall.

I'll have to do some trials with it.

30p limit doesn't phase me, I'm shooting mostly in 25p now unless something is obvious slow-motion material.  Apart from the benefit of HLG, it also helps in low-light.

Once you've cropped and downscaled the image, is the overall "look" the same as the 4K modes?

[anonim]

It seems that 5k (via open gate or  6k in photo mode) has less sharpening as result in processing image, at the same time keeping tiny little bit more details (maybe because of different algorithm used in photo and video mode). It also provide more room for stabilizing and, obviously, for framing. But, being 4:2:0 is less great for grading than 4k. Using HLG, of course, still provides usage of great GHa lut.

[Rinad Amir]

This might sound like dumb question but is there any advantages shooting h265 in anamorphic ? 

Apart from slowing down your pc (iuseproxy) 

[Shirozina]

1 hour ago, Rinad Amir said:

This might sound like dumb question but is there any advantages shooting h265 in anamorphic ? 

Apart from slowing down your pc (iuseproxy) 

The chroma subsampling is 4.2.0 and not 4.2.2 so potentially ( and depending on your subject matter and how you grade) you have less colour information to play with.

[Vision]

1 hour ago, Rinad Amir said:

This might sound like dumb question but is there any advantages shooting h265 in anamorphic ? 

Apart from slowing down your pc (iuseproxy) 

Improved intraframe motion prediction

Video compression relies on predicting motion between frames. When there’s no change in a pixel, a video codec can save space by referencing it, rather than reproducing it. So improved motion prediction means improved file size and compression quality. Alongside the improved compression standards in H.265, we also find major improvements in motion prediction and compensation.

Improved intraframe prediction

Video compression also benefits from analyzing “movement” within individual frames, allowing single frames of video to be compressed more efficiently. This can be achieved by essentially describing pixels with a mathematical function rather than actual pixel values. The function takes up less space than pixel data, shrinking file size. However, the codec must support a sufficiently advanced mathematical function for this technique to be truly useful. H.265’s intraframe prediction function is far more detailed than H.264’s, allowing for 33 directions of motion over H.264’s nine directions.

Parallel processing

H.265 uses tiles and slices which can be decoded independently from the rest of a frame. This means that the decoding process can be split up across multiple parallel process threads, taking advantage of more efficient decoding opportunities on now-standard multi-core processors. With video resolutions getting higher, this kind of improved efficiency is required to decode video at a watchable pace on lower-end hardware.

Higher maximum frame size

The world is getting higher-res, and H.265 supports that. With H.265, video can be encoded at up to 8K UHD or 8192 pixels × 4320 pixels. Currently, only a handful of cameras can even produce 8K video, and very few monitors can display that kind of resolution. But just as HD is today’s standard, we can expect 4K and eventually 8K to rise to similar prominence eventually.

[Towd]

I really like shooting with the 5k "open gate" format on the GH5.  I find it to to be practically indistinguishable to the eye from the 4k 422 mode even when I zoom in and pixel peep a shot.  You can then drop it on a 4k timeline as a center extraction which allows some panning and stabilization possibilities.  This also allows you to deliver in C4k or UHD if you are just out collecting B-Roll that may be used in a variety of projects.  All that said, I find that the vast majority of the time, I'm still delivering 1080p as a final video format.  But the 5k full frame feels the most future proof down the line.  It'll probably upres to 8k pretty well if we're ever delivering that format in 10 years.  GH5 footage is so sharp-- really too sharp!   I've matched it with 5k and 6k Red footage in projects, and find I have to always use a small amount of the defocus filter on it in post so it is not so crisp.  This is with the GH5's sharpness set to the lowest settings.

As far as extreme grading, I typically always shoot V-LOG and run my footage through Neat Video first so the 420 vs 422 has not made much of a difference.  I got into this habit while salvaging 5D mark II footage as it really helps the gradability of 8-bit.

One thing you will notice is that you lose the Ex Tele Converter zoom functionality in 5k, but you can still punch in in post on the image, so the versatility is still there.  Maybe if I was shooting something that I knew was going to be shot entirely with the Ex Tele Converter, I'd just shoot in 4k 422 for the extra chroma sampling, but that's never come up for me.

The one place where I do find the 4k 422 better is in green screen extraction.  The 422 pulls a finer edge.  Where any time I've had to pull a key on 420 footage, I'm left with a 1 pixel outline on my initial matte edge from the chroma sub sampling even after running it through Neat Video.  You can erode the mask to fix the edge, but then you loose fine hair detail, etc.  I have tested the two modes and both are quite usable compared to some old DSLR 420 8 bit footage, but the 422 is marginally nicer.  Obviously an external recorder for green screen footage would be ideal, but in a pinch I've found the 4k 422 recorded internally to give really nice results-- especially for a 2k delivery.  And I don't have or use an external recorder with my GH5.

Obviously, if you are doing an elaborate green screen shoot, use a pro camera with 444 uncompressed color output, but I sometimes just need to shoot a quick element for a composite and the GH5 in 4k 422 works just fine. 

For my needs GH5 is just a great little workhorse to get footage to support a larger production or to generate high quality footage for any quick small budget or personal project.  I love that I can just throw the camera in a bag without external monitors, gimbals, or other crap and shoot high quality footage from such a tiny form factor.  There really is nothing else like it.

[kye]

Thanks @Towd - that's useful.  

I didn't think about the ETC mode being unavailable.  I guess you can just crop in post, although that would be a slight shift in how I work so I'd have to get used to it.  

In terms of being too sharp, I'm curing that with lenses - like many people do.  Although if you're delivering in 1080 I'm not sure how much that really matters, I haven't done much testing to see, and for me it doesn't matter that much for my projects.

I love the combination of small form-factor, image quality, and that it's a workhorse not a diva.  Very few cameras can claim all three.

[OliKMIA]

23 hours ago, kye said:

Thanks.

I also got the impression that the 5K mode are h265 and the 4K modes are h264.  This is a big deal for me, from what I read h265 gets similar image quality at about heal the bitrate of h264, so going from 150Mbps h264 to 200Mbps h265 is more like the quality of 400Mbps h264.  In terms of the 422 vs 420 it's definitely a down-side, but it's offset by the extra bitrate, codec efficiency, and slightly extra resolution, so it should result in a net gain overall.

I'll have to do some trials with it.

30p limit doesn't phase me, I'm shooting mostly in 25p now unless something is obvious slow-motion material.  Apart from the benefit of HLG, it also helps in low-light.

Once you've cropped and downscaled the image, is the overall "look" the same as the 4K modes?

It's true that h.265 at 200mbps should give better results than h.264 at 150mbps (IPB) and 400mbps (All-I) BUT you should compare that to 5k resolution.

• C4K is 8.8mpx (4096x2160 pixels)
• 5K is 18.8mpx (4992 x 3774 pixels)

Basically, a factor 2 between 4k and 5k. Therefore, even though the h.265 codec is said to be 50 to 100% more efficient that h.264, the 5k mode also has twice the amount of data (and the reasoning could go further, saying that C4k is only available in 24p whereas 5k has 30p).
That's the theory at least but no one knows exactly how Panasonic uses the codecs and compression between the two modes.

In the end, I really think that we are splitting hair here. Both modes are good, the GH5 is an amazing camera whether you use it in 4k or 5k. I haven't noticed any difference personally with grading, sharpness and noise.

As for downscale keep in mind that 4k comes from full sensor readout anyway so there shouldn't be a major difference. One downscale is made by the camera, the other one by your NLE.
 

12 hours ago, Towd said:

For my needs GH5 is just a great little workhorse to get footage to support a larger production or to generate high quality footage for any quick small budget or personal project.  I love that I can just throw the camera in a bag without external monitors, gimbals, or other crap and shoot high quality footage from such a tiny form factor.  There really is nothing else like it.

+1, that the main point. The GH5 is a fantastic camera for the price.

[kye]

Thanks @OliKMIA - I hadn't factored in 5K vs 4K, but as you say, it's splitting hairs, and the whole thing is downscaled anyway.  Especially for me considering I don't do green-screen, I deliberately use softer lenses and love the film-look of the output, and I typically just publish 1080p to YT.   I'd trade-off resolution for bit-depth and DR any day of the week.

I guess the whole point of this thread was to understand if there were any hidden down-sides I didn't know about.  Apart from shifting the ETC mode from production to post-production I don't really see any issues for me.

Yay!

[Towd]

3 hours ago, kye said:

In terms of being too sharp, I'm curing that with lenses - like many people do.  Although if you're delivering in 1080 I'm not sure how much that really matters, I haven't done much testing to see, and for me it doesn't matter that much for my projects.

Just as an FYI, I used to shoot Nikon for stills, so my lens collection is primarily old Nikon glass.  Even when delivering at 1080p, I've found I need to defocus my GH5 footage to match the softness of footage coming out of Red cameras.  Once that that sharpness creeps into the image, it seems to hang on even after the downrez.

I think I read a while back that some users like Sage only shoot in 1080p with their GH5 for the more cinematic image.  Being the maximalist that I am, I can't seem to let myself do that when 4k and 5k are available formats.  But yeah, GH5 footage is REALLY sharp compared to other cameras I've matched it to.

[buggz]

Great information in this thread.

Thanks to all!

[tweak]

If you shoot with anamorphic lenses the difference between the 4k and 5k modes is noticeable. I shot a whole short almost entirely on 5k anamorphics with HLG and it was a dream to grade.

[kye]

44 minutes ago, tweak said:

If you shoot with anamorphic lenses the difference between the 4k and 5k modes is noticeable. I shot a whole short almost entirely on 5k anamorphics with HLG and it was a dream to grade.

What was the main difference that you noticed?  Resolution, or something else?

[tweak]

1 hour ago, kye said:

What was the main difference that you noticed?  Resolution, or something else?

Resolution and colour, both seem to look nicer to me even on a 1080p display. I really notice the difference trying to match the two side by side.

[kye]

2 hours ago, tweak said:

Resolution and colour, both seem to look nicer to me even on a 1080p display. I really notice the difference trying to match the two side by side.

Fascinating.  I can feel a camera test coming on

[jase]

A year ago, I did a small comparison between 4k and 6k, see here:

 

[kye]

On 12/17/2017 at 5:30 PM, jase said:

I tried this on my own. The following two shots are taken in 24p 10bit HLG 150mbit and 6k 24p 200mbit. After that I applied some grading with some grain, what I noticed is that the 6k image is indeed a bit less sharp (compare the ear for example), however the amount of detail is still the same - at least to my eyes. Obviously you need to check the files at 100%, otherwise you wont see it. At least I dont.

4k HLG

6k HLG

(quoting @jase comment in the other thread - to see the image full size you have to click through to the other thread)

Thanks, that's very helpful

I can see what you mean about there being an equivalent amount of detail but with less sharpening.   In fact it's quite a difference in sharpening, I didn't realise there was that much of it being applied TBH.

On the whole though, it doesn't seem like there is really much downside to using it.  Looking at individual frames really blows me away, such a great looking image

[tweak]

What's going on there? Looks like some serious BK pollution in that image.