Cinelog - True logspace conversion for DNG and CinemaDNG footage

[TrueIndigo]

"DNxHD 444 is 10bit" - yes, but those are not available in the free "LE editon" codec set are they? I think the 4:4:4 codecs have an "x" after the name to indicate this extra quality, such as "DNxHD 365x" (1920 x 1080 x 25fps) which is 4:4:4 10-bit compared to "DNxHD 185" (1920 x 1080 x 25 fps) which is 4:2:2 10-bit - I don't see the 365x option in the list. Presumably these are only available in the professional codec pack. To be honest, I don't think my material probably needs full colour sampling, and I would welcome any file size reduction I can get with video. I just wondered though if 4:2:2 (which is broadcast quality) may nevertheless result in a colour degradation, mindful of the fact that if you are going to delete your camera files you therefore want these DNxHD files to be best quality they can be.       

"Are you sure you're getting 2k dimension?" - When I check Windows properties the dimensions for the clip are blank (presumably because it's non-standard?), but when I imported the file into Mpeg streamclip as if to export it, the dialogue shows: "2048 x 858 (unscaled)" as the default size of the clip, so I guess it really is that size and not just automatically stretched-to-fit on my 2K Premiere timeline. There are no black bars top/bottom (within 16:9), just the very wide CinemaScope shape.

[Danne]

Found this https://github.com/dahnielson/iola/wiki/Video:-Avid-DNxHD

Seems I can get 10-bit files from my testing right now. How can one compare and decide ProRes or dnxhd in this case?


DNxHD 220x

For highest image quality in a YCrCb-color space for 10-bit sources.

    1920x1080 and 1280x720
    progressive or interlaced
    10-bit 4:2:2 YCbCr
    185 Mbit/s @ 1080p25
    175 Mbit/s @ 1080p24
    90 Mbit/s @ 720p25
    90 Mbit/s @ 720p24

To transcode a file into eg. a 1080p25 10-bit 4:2:2 DNxHD 220x file:

ffmbc -i INPUT_FILE.MOV \
    -vcodec dnxhd -b 185M -pix_fmt yuv422p10le \
    -acodec pcm_s16le \
    DNXHD_FILE.MOV

[Danne]

MLVFS and raw2dng both now use the same matrices that are embedded by the Adobe DNG converter.

Do you mean raw2cdng or have raw2dng v1 been reworked?

[Andy600]

typo - it's raw2cdng

[Danne]

Ok thanks.
 I so wished for dnxhd 444 but seems 10-bit 422 is max on ffmpeg. Gonna check some but stick to ProRes444 meanwhile.

[DeafEyeJedi]

That would be sweeeet!

I believe in you, @Danne!

[emoji119]

[Andy600]

@TrueIndigo - AFAIK the LE pack is the same as the PE but does not have IMX (due to licensing). You should have DNxHD 1:1x in the PE pack if needed (I never use this) plus 444 up to 1080p/i 30fps. I have the LE pack installed and there are 444 options but no 'x' except for 1:1x.

1080p 444 might actually be 365x because 365 relates to bit rate. From memory, DNxHD 444 1080p is around 350Mbps (i.e. close to that number). I'll need to check to be sure.

http://www.avid.com/static/resources/US/documents/dnxhd.pdf DNxHD 444 1080 25p is 367Mbps - and called 365x. It's just a naming issue by the looks of things.

[blainesuque]

Does anyone know how to export our cinelg Log C MAsters to prores4444XQ from AE? i was able to get the option in the codec choices tab, but i get a errror when rendering out 4444xq. Project settings are 32 bit float.  but i am on yosemite 10.10.2 which i dont think should make a problem but maybe?

I get the error Codec COmpression Error

[Andy600]

@blainesuque - I think it's a CC2014 related issue. Try setting the project bit depth to 16bit and make sure to set RGB+alpha (not that you need the alpha channel). If this doesn't work I think it will require Adobe intervention.

[blainesuque]

Thanks! yea i tried that and it still didnt work, i am going to get on the phone with Adobe.

[Andy600]

@blainesuque - Sorry I can't be of more help with this issue but do let us know what (if anything) you discover from Adobe.

[Danne]

Hi! Some progress in dnxhd and ffmpeg. Found a setting for 10-bit 440M! DOn,t know if this is overkill or not. Not really sure if it,s an alternative to ProRes444 from ffmpeg but hope you guys would shed some light here.


Fast
dnxhd1obit-440M
 

ProRes444






*Further progress on this theme will be on the cr2hdr-r thread. Got carried away in dnxhd discussion here, realize this thread is about cinelog.

[bengibb]

Looking at the quick start guide it directs you to load [REC709]_Cinelog-C_to_REC709 in the 3D Video Monitor Lookup Table but I'm only seeing [REC709]_Cinelog-C_to_Cinelog_REC709 in the LUT folders. Was there a name change at some point and the guide is outdated?

[Andy600]

@bengibb - Sorry, that's a typo. It was correct but I since replaced the single [REC709]_Cinelog-C_to_REC709 lut with full range and legal range options (the full range lut is the same as the one in the guide but I'll update it.

You could actually use any of the Cinelog Rec709 luts (except FM or DSLR) when white balancing and/or adjusting exposure as they all have the same white point. The Rec709 Legal and Rec709 Full luts are transfer function only (i.e. no s-curve) so you need to add your own curve before using those. The FM versions transform to Alexa Film Matrix RGB primaries (close to re709 but with some hue rotation to warmer tones and it's more colorful) and the DSLR versions are looks based on Picture Styles. 

[bengibb]

Thanks Andy, loving what I'm getting so far. In your opinion what's the max someone should be pushing exposure in their WB/EXP adjustments to the Cinelog intermediary file?

[Andy600]

@bengibb - Good to hear!

WB should always be corrected to neutral while the image is still raw but there is a lot of headroom for adjustment later (especially if you rendered ProRes 444 intermediates).

I can't say exactly how much exposure correction is safe because it depends entirely on how you exposed the image when shooting. I've pushed/pulled exposure by +/-2 stops and it holds up fine so could probably take more - but if you constantly need to adjust by more that 2 stops you should look at your exposure practices.

I mainly shoot ETTR for raw shots but allow specular highlights to clip a little for better SNR. I don't use ETTR for low light / HDR scenes (i.e. night shots in a city) as most of the important information would be pushed towards the noise floor. In those situations I always expose for the main subject.

[kontrakatze]

Hi,
you said, that you were going to add input luts for the gopro protune. Is this still true? I would be very interested in this, because I very often use my gopro for action-shots.

Regards

[bengibb]

Not a ton of info to go on but I'd be interested to hear what you thoughts are on Resolve 12 now that details are coming out Andy, specifically the Color Managed Timelines.

https://www.youtube.com/watch?v=yMsLQDS0YeU

[QuickHitRecord]

Yes, at the end he talks about "genuine mathematical transforms"... similar to Cinelog? What new opportunities might this bring when used in conjunction with Cinelog? I know that there is no way of knowing how accurate these are without working with the program, but I'd be curious to hear what Andy thinks.

[Andy600]

@kontrakatze - Yes, Protune, Cinestyle, ProLost, MarvelsCine, ACES 1.0 (cc, cg, proxy etc) and other colorspaces are coming in the next update. The transfer functions are fairly simple but it takes a little time and some tricky matrix math when it comes to finding the colorspace of baked profiles - but it's nearly ready and looking good

@bengibb & @QuickHitRecord - Without having R12 to play with, my best guess would be that the new per-clip colorspace inputs are based on ACES 1.0 (using IDTs) but work in Resolve's YRGB workspace. We do the same thing with OCIO in our ACR version of Cinelog-C. It will not affect a Cinelog workflow as Cinelog is mainly about getting raw images into a defined colorspace for transcoding but it will help multi-cam timelines come together quicker. If you transform Cinelog-C to one of the supported colorspace input presets you should get good results - it basically means you can use the same Resolve output transform (rec709, rec202 etc) for any footage, regardless of it's colorspace - sound familiar? 

When Peter Chamberlain talks about "genuine mathematical transforms" he simply means that the internal transformations in Resolve are using the actual formulae and chromaticity (RGB) of each colorspace (and possibly additional color correction matrices) - this is what we also do. We work with the exact same math then bake the transforms into high precision 1D+3D shaper luts. Luts have inherent rounding errors but the precision of Cinelog-C luts is so high that you will not get visible artifacts. We're working on a GPU accelerated OFX plugin solution too

To sum up, it's a useful addition to Resolve and will work great with Cinelog-C but the new shot match function will probably be more useful to end users.

[Andy600]

Just reading the R12 specs and these 2 stand out as potentially useful tools IF they are not meta locked specifically to BM cams

• Ability to view and change ISO for Blackmagic Camera RAW clips
• Black Sun Highlight Correction for Blackmagic Camera clips

this is useful

• Canon still camera RAW format CR2

Remote rendering also sounds awesome if you have more than one system available

and DNxHR in a Quicktime wrapper is supported 

[bengibb]

Pretty sure you've always been able to adjust ISO on non-BM RAW files ex: r3d.

[Andy600]

@bengibb - You can adjust gain but not override meta before debayering. .r3d has a lot more options. I'm puzzled why there is still no raw white balance helper function, especially in the lite version. It's a relatively easy thing to implement. Cinema DNG specs assume the image is shot with correct white balance but in my experience this is rarely the case.

[KelvinK]

Andy, was curious... If you add BMDFilm>Cinelog-C>Cinelog C to Arri>and then FilmConvert AlexaC - footage looks so "reddish" and dark that require alot of color correction (gamma, gain and reducing red channel). Why is that? I never had RAW from Alexxa, but what I saw in tests, applying FC on real Arri footage looks pretty good from start.

[Andy600]

@KelvinK - That's a little unusual. Can you send me a DNG so I can check the meta and let me know which version of FC you are using (and the settings you chose) and which version of Resolve. If your footage is correctly white balanced you shouldn't get a significant colorcast and if the image is dark you'll need to add some exposure correction (this is normal). The Cinelog-C luts transform the colorspace but the primaries depend entirely on the embedded color matrices in the DNG. I'll need to see the problem to tell you exactly what is happening.