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Mike Krumlauf

A few questions regarding Film Rec and AVC Intra100

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I've been working with varicams for years but never gotten a clear answer to this. Does Film_Rec gamma in the varicams lie in a different color space than Rec709 or is it a unique version of Rec709 that allows more latitude? I ask because I want to know how I should treat it when I grade.. do I use base LOG Luts or Rec709 Luts? What steps allow me to maintain the extra bits of information? I've done my share of experimenting and its a mixed bag. Rec709 doesnt seem powerful enough yet LOG seems a tad too strong so i always have to dial it down a tad (the lut intensity that is).

 

As for AVC-Intra 100.. the codec seems to really break apart with heaving grading.. I've never run into this issue with 10bit 4:2:2 material.

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Basically all it does is flatten the image out so the mpeg file has greater dynamic range than it would normally. So you would use a LUT to bring it into the color space you're using to grade, whether that's Rec 709, Rec 2020 or DCI-P3, the color space is chosen in the grading program as a "base" and you will grade to that space. I have given up using pre-programmed luts because I've found most of them to not give me the look I'm going for in-camera. 

AVC-Intra 100 is OK for 1080p, but not for anything else. If you're shooting 4k, you really need 400+Mbps as a source and I'm not sure if the Varicam can do that. I think one of the reasons so many people discount it, is because the codec is very limited. There is a software version that can do Pro Res, but I think it's only HQ. 

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7 hours ago, Tyler Purcell said:

Basically all it does is flatten the image out so the mpeg file has greater dynamic range than it would normally. So you would use a LUT to bring it into the color space you're using to grade, whether that's Rec 709, Rec 2020 or DCI-P3, the color space is chosen in the grading program as a "base" and you will grade to that space. I have given up using pre-programmed luts because I've found most of them to not give me the look I'm going for in-camera. 

AVC-Intra 100 is OK for 1080p, but not for anything else. If you're shooting 4k, you really need 400+Mbps as a source and I'm not sure if the Varicam can do that. I think one of the reasons so many people discount it, is because the codec is very limited. There is a software version that can do Pro Res, but I think it's only HQ. 

Thank you so much for the response. I didnt realize DVCPRO HD and AVC-Intra were MPEG files? That doesnt sound right..

 

I guess i should clarify that I'm shooting on the AJ-HPX2700 Varicam.. not the tape varicams or the current 35 models. So in terms of LUTs to bring film rec into an area to grade correctly, which do you prefer? I've noticed placing the "Smooth Step" node in Apple Color does help tremendously. I know Panasonic had LUTs back in the day for the film rec gammas but i doubt those are anywhere to be found in 2019. Are the ARRI Preview LUTs still available?

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More or less, Film Rec is designed to work within Rec.709, sort of like Sony's HyperGamma, though technically Rec.709 describes a color space, not just a display gamma. So I guess it is possible to turn off the Rec.709 color matrix in the camera and yet shoot Film Rec?  Certainly you could turn off the Rec.709 color matrix in the old F900.

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Posted (edited)
1 minute ago, David Mullen ASC said:

More or less, Film Rec is designed to work within Rec.709, sort of like Sony's HyperGamma, though technically Rec.709 describes a color space, not just a display gamma. So I guess it is possible to turn off the Rec.709 color matrix in the camera and yet shoot Film Rec?  Certainly you could turn off the Rec.709 color matrix in the old F900.

Yeah, i remember being able to turn off the matrix in the panavision 900 I had. There are 3 matrix tables in the varicam and from looking at the menu, you can set them to off. So it begs the question. if color matrix is off and im shooting film rec.. what "space" is the camera recording? still within rec709? seems like film rec sits in its own grey area.

Edited by Mike Krumlauf

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2 hours ago, Mike Krumlauf said:

Thank you so much for the response. I didnt realize DVCPRO HD and AVC-Intra were MPEG files? That doesnt sound right..

Yep, AVC is a MPEG 4 format. There are a few variants like Long GOP or iFrame, 8 bit and 10 bit, 4:2:0 or 4:2:2, but it's still MPEG. The only NON-MPEG single file formats are; Pro Res, DNX and JPEG2000, which all use Wavelet compression technology. Even Red Code and Arri Raw are variants of the same tech. Cinema DNG is TIFF compression, but it's still similar. 

DVCPro has nothing to do with AVC funny enough. Panasonic makes you want to think they're similar, but they are not. AVC is just .h264. 

https://en.wikipedia.org/wiki/AVC-Intra

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Ohh the AJ-HPX2700, hehe. Yea, you should have said "ENG Classic Varicam" because I didn't even know the camera had log capabilities. 

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Just as with the F900, turning off the Rec.709 color matrix probably won't create a big difference, some colors might fall differently on the vectorscope, maybe the gamut is slightly bigger in some directions, smaller in others.  Mostly you see a difference in the saturation and shade of certain colors -- red is more orange in Rec.709 than in P3, for example.  I remember I had some odd color clipping artifacts with purple neon on the F900 that went away when I turned off the Rec.709 color matrix so I assume the matrix was increasing the saturation too much in that color.

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can you just use it with an external prores recorder if you need more bitrate for grading? 

you should get a used 1080p/i external recorder for very cheap nowadays including the capture drives and all

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2 minutes ago, aapo lettinen said:

can you just use it with an external prores recorder if you need more bitrate for grading? 

you should get a used 1080p/i external recorder for very cheap nowadays including the capture drives and all

Funny, because I just sold off my AJA KiPro Mini that i'd had since 2014. I have an AJA KonaLHe card in my mac pro and was doing comparisons between the AVC Intra and native pro res out the HD SDI and there is no difference at all. I hate the external recorder route anyway.

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44 minutes ago, Mike Krumlauf said:

Funny, because I just sold off my AJA KiPro Mini that i'd had since 2014. I have an AJA KonaLHe card in my mac pro and was doing comparisons between the AVC Intra and native pro res out the HD SDI and there is no difference at all. I hate the external recorder route anyway.

but you DID see a difference when grading the material?

you should be able to get the external recorder to run on record trigger so that you can easily record to internal at the same time not thinking about it much and only use the external files if you see in grading that they are needed. full hd prores should be able to be recorded on normal HDDs which are very cheap and you could probably just use the hdds once and store them just as is until the grade is done, no need to copy the files anywhere because you are mainly using the internal files unless the prores version is needed for the more  challenging shots. 

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3 hours ago, aapo lettinen said:

but you DID see a difference when grading the material?

you should be able to get the external recorder to run on record trigger so that you can easily record to internal at the same time not thinking about it much and only use the external files if you see in grading that they are needed. full hd prores should be able to be recorded on normal HDDs which are very cheap and you could probably just use the hdds once and store them just as is until the grade is done, no need to copy the files anywhere because you are mainly using the internal files unless the prores version is needed for the more  challenging shots. 

No, no difference. Graded the same. It’s not terrible but you just shouldn’t stack log luts onto the material. 

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...my point is that I saw both leaving the footage untouched and doing heavy grades, no discernible difference from the KiPro and the internal AVC-INTRA100 codec in the HPX2700, so i sold the kipro. the 10bit codec inside the varicam is every bit as good as prores to my eye and given i still cut in final cut 7, final cut ingests the footage from the P2 card as a Prores 422 file.

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FilmRec on the old Varicam is a "knee" adjustment with the knee point set to 10%.  The result is that the gamma curve from zero to 10% is the same as "standard" REC709 gamma 2.2.  Above 10% video level, depending on your "dynamic level" setting, the contrast is lowered with 200% dynamic level being a mild lowering of the contrast, while 500% or on your camera, maybe 600% being the maximum lowering of the contrast.

Unlike a LOG gamma, which is a curve, this knee adjustment is a straight line reduction in contrast.  So, to correct this, do not use a LOG/709 LUT.  Simply increase the contrast by increasing the gain.  To preserve highlights, you would need to create a curve that is mostly straight in the mid tones and round it off to protect the highlights.  The color space is still REC709, just the contrast / gamma curve is different.

Because the gamma compression here is a straight line, and not a LOG curve, this method is more prone to banding in gradients than a log recording.  Therefore it is essential to use 10 bit recording to minimize banding when using FilmRec mode.  When using FilmRec at maximum dynamic level effect, you should get around 12 or 13 stops of dynamic range in your Varicam recorded images.

Lastly, because you are recording a low contrast image in REC709 color space, you may be able to grade in P3 color space and preserve detail in colors beyond the standard REC709 colorspace.  This may require some adjustment of the saturation to correctly fit your image into P3 color space, should you choose to go this route.

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BRUCE!!!!!! 😄 Always my savor with the varicam! Thank you so much for the explanation. You always helped in grey areas when i had my Varicam H.. nice to hear from you again!

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Bruce, i dont know if you are familiar with Apple Color 1.5 software, but, in its Color Node tap, there is an option called "Smooth Step". In its manual this is its definition... "Applies a nonadjustable “s-curve” adjustment to slightly crush the blacks and boost the whites, leaving the black and white points pinned at 0 and 100 percent. Designed to emulate the exposure tendencies of film at the “toe” and “shoulder” of the image. Thisis a similar contrast adjustment to that made by the Film Look node." This process seems to be the perfect "base" for color correcting film rec material.

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These days it's easier to just make a custom curve in the grading software than use a fixed curve from Apple Color.

But, if you love Apple Color, go for it! 🙂 🙂 🙂

 

 

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On 4/18/2019 at 9:30 AM, Bruce Greene said:

These days it's easier to just make a custom curve in the grading software than use a fixed curve from Apple Color.

But, if you love Apple Color, go for it! 🙂 🙂 🙂

 

 

Apple Color is amazing, always loved it. I've found importing the AVC Intra into final cut 7 as "native" improves the quality of the images as well. Bruce, have you used the HPX2700 Varicam? I tend to like it compared to the H model. Its like that kipro is built right into the body :)

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I totally forgot the HPX2700 was a 720p camera. AVC Intra 100 is fine for 720p really, even at 60fps that's not a lot of bandwidth. That's the reason why it works with 10 year old software natively, because it's just not really that tasking. 

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11 minutes ago, Tyler Purcell said:

I totally forgot the HPX2700 was a 720p camera. AVC Intra 100 is fine for 720p really, even at 60fps that's not a lot of bandwidth. That's the reason why it works with 10 year old software natively, because it's just not really that tasking. 

its imager is native 720p yes, it can do internal 1080p as well but i haven't really used it yet.

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5 hours ago, Mike Krumlauf said:

Apple Color is amazing, always loved it. I've found importing the AVC Intra into final cut 7 as "native" improves the quality of the images as well. Bruce, have you used the HPX2700 Varicam? I tend to like it compared to the H model. Its like that kipro is built right into the body 🙂

I would think the KiPro isn't needed with this camera as it has quality digital (non tape) recording built in.  I would use a color correction software such as Resolve to grade the images though 🙂

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1 hour ago, Mike Krumlauf said:

its imager is native 720p yes, it can do internal 1080p as well but i haven't really used it yet.

Yea it will do 30, 25 and 24p as well, but of course the imager is stuck at 1280x720, so since it has a fixed bit rate recording system, might as well stick with the 100mbps 720p signal. 

Now that we've figured out all of this, I still don't understand the original question because the HPX2700 doesn't really record a log file. So you wouldn't be using luts to do anything really. Bruce's explanation on the knee adjustment is a great trick, but it's still a Rec709 color space no matter what you do. Getting detail out of both the highlights and the blacks, is going to be difficult, even if you screw with the camera's internal gamma curve. The dynamic range of the imager is still limited, so where you could get a bit more out of it, I doubt it would be worth the effort.  

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On 4/19/2019 at 4:53 PM, Tyler Purcell said:

Yea it will do 30, 25 and 24p as well, but of course the imager is stuck at 1280x720, so since it has a fixed bit rate recording system, might as well stick with the 100mbps 720p signal. 

Now that we've figured out all of this, I still don't understand the original question because the HPX2700 doesn't really record a log file. So you wouldn't be using luts to do anything really. Bruce's explanation on the knee adjustment is a great trick, but it's still a Rec709 color space no matter what you do. Getting detail out of both the highlights and the blacks, is going to be difficult, even if you screw with the camera's internal gamma curve. The dynamic range of the imager is still limited, so where you could get a bit more out of it, I doubt it would be worth the effort.  

I wouldn't say 12 or 13 stops is limited in anyway. The 2700 is an amazing camera, and to my excitement there is a color workflow that can allow proper use of LOG luts with Film_Rec. I've been doing my experimenting inside resolve lite and i found that converting film rec from rec709 to linear and then to cineon log, the possibility of grading become that much bigger. I'm getting some really beautiful stuff!

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1 hour ago, Mike Krumlauf said:

I wouldn't say 12 or 13 stops is limited in anyway. The 2700 is an amazing camera, and to my excitement there is a color workflow that can allow proper use of LOG luts with Film_Rec. I've been doing my experimenting inside resolve lite and i found that converting film rec from rec709 to linear and then to cineon log, the possibility of grading become that much bigger. I'm getting some really beautiful stuff!

The imager maybe 12 stops, but since the recording system is locked to Rec709, there is no way to get that much dynamic range out of the camera. This is why we have cameras that shoot raw or wider dynamic range codec's with log color space like Pro Res XQ, which has kinda become commonplace. Sadly most of the ENG cameras are at best around 8 stops of latitude, there isn't much you can do about it even with film mode. If I put the 1st gen blackmagic pocket camera beside it, you'd see right away the difference and it's very subtle, but it's details in the highlights that makes the most difference. If you're shooting an exterior and have a sunny day with clouds and you protect the highlights, you'd see details in the clouds that you wouldn't with the ENG camera, this is the same with all the CCD cameras. They just don't quite have the same dynamic range. 

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Posted (edited)
On 4/17/2019 at 11:03 PM, Bruce Greene said:

 When using FilmRec at maximum dynamic level effect, you should get around 12 or 13 stops of dynamic range in your Varicam recorded images.

Lastly, because you are recording a low contrast image in REC709 color space, you may be able to grade in P3 color space and preserve detail in colors beyond the standard REC709 colorspace.  This may require some adjustment of the saturation to correctly fit your image into P3 color space, should you choose to go this route.

I can attest to getting this much information in my recorded images with film rec Bruce. I know you and I have been over the DR of film rec many times. And to your suggestion I did some tests with p3 color and it did exactly what you thought it would. The varicam is really surprising me. Wish I knew all this when working with my H model years ago.

 

i have to agree that now returning to the varicam line, it def has the edge over the f900. 

Edited by Mike Krumlauf

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