Latest post Fri, Dec 1 2017 12:12 PM by nigelad. 11 replies.
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  • Sat, Aug 29 2015 9:30 AM

    • S.Clements
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    Unique Embedded Amira LUT not supported by Avid to After Effects to Avid workflow?

    Hi,

         I am editing a film shot on Arri Amira.  The original files are UHD 3840 × 2160 ProRes 4444 Quicktimes.  When I brought them into Avid via AMA, they had an embedded LUT on them.  The color transformations in the source settings were: levels scaling (video levels to full range) and Rec 709.AML (embedded).  

         I needed to stabilise the shots and required After Effects' Warp Stabiliser, as Avid's stabiliser didn't give me enough control. So, I exported an AAF of my sequence and went import > pro import into After Effects.  The quicktimes that came up in After Effects had no color transformations applied and appeared milky.  I went ahead and did the VFX work.

         When the shots were done, I rendered them out as ProRes 4444 files that I planned to edit back into the timeline in Avid. When I ama linked to them, they came in milky, with no LUT.  I opened the source settings and added "levels scaling (video levels to full range)" and "ARRI ALEXA LOG C to Rec 709" color transformations.  

         Now, it sort of looks the same as the original shots, but is ever-so-slightly different.  Is this the best I can do?  I couldn't figure out any way of grabbing the embedded Rec 709.AML  LUT that the DOP put on the original footage.  All I could do was apply the "ARRI ALEXA LOG C to Rec 709" LUT that was on my system.

    Avid Media Composer 8.3.1 Macbook Pro (Retina, 15-inch, Mid 2014) 2.8 GHz Intel Core i7, 16GB Ram Mac, OS 10.10.2 [view my complete system specs]
  • Mon, Aug 31 2015 2:45 PM In reply to

    Re: Unique Embedded Amira LUT not supported by Avid to After Effects to Avid workflow?

    Not sure about adding the LUT, but couldn't you have sent a QT to AE with the LUT baked in?  Or would that have screwed you up down the road?

    Symphony v8.8 | OS 10.11.6 • Nitris DX • 12-core MacPro (Mid 2012) • 36 GB RAM • Facilis Terrablock 24EX [view my complete system specs]

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  • Mon, Aug 31 2015 7:30 PM In reply to

    Re: Unique Embedded Amira LUT not supported by Avid to After Effects to Avid workflow?

    Perhaps try the Amira Color tool to extract the embedded LUT as a .cube and use that when reapplying the LUT after the roundtrip. ARRI generates different LUTs based on ASA of the shot if you’ve ever played with their online LUT generator. MC have have a general LogC to 709 LUT that does not quite match up.  Amira Color Tool: http://www.arri.com/camera/amira/workflow/amira_workflow/looks_metadata/amira_color_tool/ Arri online LUT generator: http://www.arri.com/camera/alexa/tools/lut_generator/
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  • Tue, Sep 1 2015 7:22 AM In reply to

    • S.Clements
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    Re: Unique Embedded Amira LUT not supported by Avid to After Effects to Avid workflow?

    Thanks, guys.  Kevin, I didn't want to export a quicktime out of Avid to then import into After Effects - I wanted to send the original file.  However, while the original quicktimes would ama link to Avid with the embedded LUT, they would not do so in After Effects.  Job, I will try to extract the embedded LUT with the tool you mentioned.

    Avid Media Composer 8.3.1 Macbook Pro (Retina, 15-inch, Mid 2014) 2.8 GHz Intel Core i7, 16GB Ram Mac, OS 10.10.2 [view my complete system specs]
  • Tue, May 16 2017 8:00 PM In reply to

    • nigelad
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    Re: Unique Embedded Amira LUT not supported by Avid to After Effects to Avid workflow?

    Apologies for reviving an old thread, but.......

    I'm used to seeing Amira LogC Prores footage with "ARRI ALEXA LOG C to Rec 709" automatically applied by avid MC when I link the files.

    Recently I've been seeing some footage with the "levels scaling (video levels to full range)" and Rec 709.AML (embedded) automaticlaly applied. I believe this is because the DOP has set the Amira monitoring to show Rec 709.

    However it's not consistent. Often a card will contain a mixture of these two 'LUTS'. 

    They look pretty similar, and I'm wondering which is the best one to use.

    Thanks for any info 

    Nigel

    ISIS 5500, with Interplay Production bundle, mainly MC 8.6.1 & PT 12.5.1 on Mac OS X.11.3 with BM Mini-Monitors and AJA T-taps. Running on 2013 Mac... [view my complete system specs]

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  • Wed, May 17 2017 10:52 PM In reply to

    • S.Clements
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    Re: Unique Embedded Amira LUT not supported by Avid to After Effects to Avid workflow?

    Hi, nigelad.  Sorry, I don't have an answer for you.  My only suggestion is to ask the DOP or DIT what their workflow is.  You should haven't to guess what their plan for the footage is.

    Avid Media Composer 8.3.1 Macbook Pro (Retina, 15-inch, Mid 2014) 2.8 GHz Intel Core i7, 16GB Ram Mac, OS 10.10.2 [view my complete system specs]
  • Mon, Sep 11 2017 4:39 PM In reply to

    Re: Unique Embedded Amira LUT not supported by Avid to After Effects to Avid workflow?

    nigelad:
    Recently I've been seeing some footage with the "levels scaling (video levels to full range)" and Rec 709.AML (embedded) automaticlaly applied.

    All Arri generated Prores, 422 and 444 is Video/Studio Swing, so that seems wrong.

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  • Mon, Sep 11 2017 7:10 PM In reply to

    Re: Unique Embedded Amira LUT not supported by Avid to After Effects to Avid workflow?

    I've seen this and it seems to end up with the same result as removing both color adapters.

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  • Thu, Nov 30 2017 9:41 AM In reply to

    • nigelad
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    Re: Unique Embedded Amira LUT not supported by Avid to After Effects to Avid workflow?

    Still grappling with this as we find some clips have the levels scaling [video levels to full levels], followed by the ARRI_Rec_709.aml LUT,  while others link without the LUT ,and so MC applies it's own ARRI ALEXA LogC to Rec709.

     

    In response to Pat:

    If you remove the levels scaling [video levels to full levels], followed by the ARRI_Rec_709.aml LUT, what you get is a logC flat image with blacks well above 16 in MC Y waveform scope.

    With both applied you gets blacks at 16 in MC YWaveform scope, and a crisp image. Reversing the order of the two conversions you get blacks at 0 and an image with crushed blacks.

     

    In response to David: The initial scale to full levels is necessary for the logC image, before applying the Rec 709 LUT which scales back to legal levels as well as adding a gamma curve and increasing saturation.

     

    Now I just need to discover why MC randomly recognises - or doesn't recognise - the ARRI_Rec_709.aml, even on clips recorded at the same time on the same card.

    So far I've found that putting the .aml file in the root of the card folder, and linking to the card folder seems to consistently apply it to all clips.

    Nigel

    ISIS 5500, with Interplay Production bundle, mainly MC 8.6.1 & PT 12.5.1 on Mac OS X.11.3 with BM Mini-Monitors and AJA T-taps. Running on 2013 Mac... [view my complete system specs]

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  • Thu, Nov 30 2017 12:33 PM In reply to

    • nigelad
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    Re: Unique Embedded Amira LUT not supported by Avid to After Effects to Avid workflow?

    Case solved!

    MC is erratic at reading ARRI camera looks when you link to individual files. If it doesn't see a camera look, MC applies it's own ARRI ALEXA LogC to Rec709, which is old and gives poor results.

    To avoid this ensure you always link to the root folder contianing the mov clips. It will then apply the look used in camera for EVF and SDI monitoring. By default this is ARRI_Rec_709.aml. MC also applies a levels scaling to full range on the LogC prior to applying the look.

    The end result is a Rec709 complaint file with video levels and gamma curve applied for contrast.

    I'm posting this in case it's of use to others in the future.

    ISIS 5500, with Interplay Production bundle, mainly MC 8.6.1 & PT 12.5.1 on Mac OS X.11.3 with BM Mini-Monitors and AJA T-taps. Running on 2013 Mac... [view my complete system specs]

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  • Thu, Nov 30 2017 1:56 PM In reply to

    Re: Unique Embedded Amira LUT not supported by Avid to After Effects to Avid workflow?

    nigelad:
    In response to David: The initial scale to full levels is necessary for the logC image, before applying the Rec 709 LUT which scales back to legal levels as well as adding a gamma curve and increasing saturation.

    From Arri:

     


    Legal and Extended Range

    An image encoded in 10 bit legal range has a code value range from 64 to 940 (876 code values), and a 10 bit extended range signal has a code value range from 4 to 1019 (1015 code values). Contrary to popular belief, extended range encoding does not provide a higher dynamic range, not does legal range encoding limit the dynamic range that can be captured. It is only the quantization (the number of lightness steps between the darkest and brightest image parts) that is increased by a marginal amount (about 0.2 bits).

    The concept of legal/extended range can be applied to data in 8, 10, or 12 bit. All ProRes/DNxHD materials generated by the ALEXA camera are in legal range, meaning that the minimum values are encoded by the number 64 (in 10 bit) or 256 (in 12 bit). The maximum value is 940, or 3760, respectively.

    All known systems, however, will automatically rescale the data to the more customary value range in computer graphics, which goes from zero to the maximum value allowed by the number of bits used in the system (e.g. 255, 1023, or 4095). FCP will display values outside the legal range (“superblack” and “superwhite”) but as soon as you apply a RGB filter layer, those values are clipped. This handling is the reason why the ALEXA camera does not allow recording extended range in ProRes.

    -I would think the Arri LUT will take the source levels and convert to 709 without additional adjustment if the material is always legal ArriLogC?

    David

     

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  • Fri, Dec 1 2017 12:12 PM In reply to

    • nigelad
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    Re: Unique Embedded Amira LUT not supported by Avid to After Effects to Avid workflow?

    Hi David

    My tests suggest otherwise. Try them yourself to see if you get different results.

    The Arrri quote is absolutely right if you record using the Rec.709 settings, but doesn't mention logC, which is designed to be manipulated in full range in Resolve, Baselight etc.

    My tests showed that with logC ProRes it's necessary to scale to full range BEFORE the Rec709 look to achieve blacks at 64 on a 10-bit scale. Scaling after the LUT predictably shows black levels as 0, and no scaling at all produces blacks around 128.

    As Arri says, all systems treat anything encoded with ProRes [even 4444] as video levels, and editing programmes like MC work in video levels.

    So the best I can suggest is that MC automatically applies the scaling to remap the LogC values, because this is what the LUT requires as input.  The ARRI_Rec_709.aml LUT [or look] then scales this to legal, adding a gamma curve and some saturation.

    regards

    Nigel

    ISIS 5500, with Interplay Production bundle, mainly MC 8.6.1 & PT 12.5.1 on Mac OS X.11.3 with BM Mini-Monitors and AJA T-taps. Running on 2013 Mac... [view my complete system specs]

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