Digital Rebellion Color Grading Blog Category

ARRI Alexa dailies workflow with DaVinci Resolve 12

Mon, 1 Feb 2016 05:27:44 +0000

I've been working on a feature film shot on the ARRI Alexa and Alexa Mini and had to come up with a workflow for syncing and rendering out dailies. DaVinci Resolve 12 proved useful because all of the prep work could be done in one application all at once, with the added bonus of being able to roundtrip again after picture lock.

Step 1: Offloading

I used our very own Auto Transfer tool to offload the memory cards to two hard drives at once with checksum authentication to ensure the copies were identical to the source files. The media files were then backed up to LTO tape at the end of the day.

Step 2: Organize and sync clips

In Resolve 12, create a new project, then go to File > Project Settings and switch off Use local version for new clips in timeline from the Color page. This will be important later on.

Then bring the video and audio files into your Media Pool and organize them in whatever manner makes sense to you. I chose to create bins for each scene (be careful what names you choose for the bins).

On this particular movie no audio was shot in-camera so the only way to automatically sync audio and video is by timecode. Select the video and audio files in your bin, right-click and choose Auto-sync Audio Based on Timecode.

In theory this is all you should need to do to get perfect sync, but in practice timecode can drift or it may be set incorrectly (or not at all) in the camera or sound recorder.

An additional reason for splitting things into bins is because if you are shooting time-of-day timecode, you may have multiple clips with the same timecode that could confuse Resolve and cause it to sync clips up to audio from a different scene.

In the event that the audio is not synced correctly, open the video in the viewer, scrub to the exact frame that the slate hits on and write down the timecode for that frame. Then open up the audio file and stop it on the exact frame that you hear the clap of the slate (in a lot of cases this will be an obvious short spike in the waveform towards the beginning of the file). Then right-click the audio file in the Media Pool and select Clip Attributes. In the Timecode pane, enter the timecode from the video you noted down earlier. Then repeat the earlier step of selecting the video and audio files, right-clicking and choosing Auto-sync Audio Based On Timecode again.

(If you can't hear the slate, go to the Audio pane of Clip Attributes and make sure your extra audio channels aren't muted.)

This will modify the timecode of the audio file so it can then be matched up automatically. You may be wondering why automatic matching is so important when you could just manually sync clips in a sequence. There is an important reason for this that will be clear later on.

Now select all the video clips then right-click and select Create Timeline Using Selected Clips.

Step 3: Grading

Open the timeline then switch to the Color tab and grade the clips as you normally would.

Step 4: Render

In the Deliver tab, choose the Individual source clips option under Render timeline as and Use source filename under Save as. This will export each clip in the sequence as an individual movie file with the sameÂ filename as its original source file - this is important to make it easy to reconnect back to the high-res source files later. Because these are offline clips we're rendering as ProRes Proxy to keep file sizes small but keeping the resolution the same as the source files.

This is why it was necessary to auto-sync the clips in the earlier step. I could find no way to manually sync audio clips and then link the audio back to the original source file. That synchronization will only exist in the sequence itself and is ignored if you choose the Individual Source Clips option.

Mark in and out points on the timeline at the bottom of the Deliver page to make sure it's going to render out all of the clips, then click Add to Queue. It's easiest to queue up lots of sequences and render them all out in one go.

Step 5: Edit

Import the rendered proxy files into the NLE of your choice and edit.

Step 6: Roundtripping back to Resolve

After editorial, export an XML from your NLE and reimport back into your Resolve project.Â (With Avid you need to export an AAF and things become a bit more complicated but this is covered in the user manual.)

On the Load XML dialog, deselect Automatically import clips into media pool (because they already exist in the media pool) and deselect Use color information if you edited in FCPX. Then click Ok.

Resolve should present you with a timeline from your NLE, however often things will not translate fully and need to be fixed. A great way to do this is to render out the full sequence from your NLE and then navigate to it in the media pool's browser. Right-click the file and select Add as Offline Reference Clip. Then right-click the timeline in the media pool window and select Timelines > Link Offline Reference Clip and choose the clip you just added.

Switch to the Edit pane and click the icon that looks like a filmstrip underneath the left-hand viewer. Choose Offline and Resolve will show the file you rendered from your NLE. You can then scrub through or play your timeline and it will show the reference clip alongside the corresponding frame of your timeline so you can compare them.

If any clips are offline you can right-click the timeline in the browser and select Timelines > Reconform from Bin(s), then select the bins with your source media. If the clips still won't reconnect, select the relevant clip in the media pool then right-click the offline clip in the timeline and choose Force Conform with Selected Media Pool Clip.

(At this point you may want to media-manage the timeline onto another drive to save disk space but I opted not to.)

Now go to the Color tab. If you don't see the grades you did previously, select all of the clips (you may need to click the Clips button at the top to see them) then right-click and choose Use Remote Grades (you may need to right-click again and choose Update All Thumbnails to see the changes).

Because you switched off local grades by default at the start of the project your grades were remote, which means they will stick across different timelines and if you adjust the grade of a clip, any other copies of it on your timeline (and throughout the project) will also be updated. In some cases this may not be desired, so you can right-click and choose Copy Remote Grades to Local so that your changes only apply to that specific instance of the clip.

Step 7: Sending back to the NLE

After grading you'll probably need to send it back to your NLE again for titling and syncing with the finished audio. You can do this one of two ways: export each clip individually like in Step 4 and then reconnect in your NLE (media managing before doing so will help a lot) or render out a single QuickTime file of the entire timeline. If you don't expect many editorial changes at this point the latter is simpler, which is what I opted for.

Special characters in DaVinci Resolve bin names cause contents to disappear

Tue, 1 Sep 2015 20:10:28 +0000

There's a bug in the DaVinci Resolve 12 beta that can cause the contents of a bin to disappear if certain characters are used in the bin name. What makes it particularly concerningÂ is that there is no indication that anything is amiss until the project is loaded again, so it is easy to lose hours of work this way.

And because the bug only occurs when aÂ project is reloaded, you cannot load up an autosave to get the clips back either.

Here's how to reproduce it:

1. Create a new bin with a forward slash in the name, e.g. "1 / 2".

2. Drag some clipsÂ into it.

3. Save the project and close Resolve.

4. Reopen Resolve. TheÂ bin will now be called "1" (everything after the forward slash is omitted) and will be completely empty.

It's worth noting that theÂ clips and sequences do not appear to actually be removed, justÂ hidden. You can verify this by attempting to create a new sequence with the same name as one that disappeared, only to be told that a sequence of that name already exists.

I have not however been able to come up with a strategy for unhiding the bin contents again - renaming the bin back to the old name did not restore the clips. If anyone can come up with a way of doing this I'd be very interested to hear it.

Fixing offline files in media managed XML

Tue, 21 Apr 2015 03:54:25 +0000

When you media manage a project in Final Cut Pro 7 and then export to XML for importing into a third-party application like Davinci Resolve*, you may get an error message from that application saying it cannot reconnect to the files.

The reason for this is that when FCP 7 creates a new media file (which it does if it trims unused content) it gets created without a .mov extension which can confuse other applications into thinking it is not a media file.

Here's how to fix it:

1. Use a batch renaming tool to find and replace -v with -v.mov (note the dash at the beginning) for the files in your media managed folder.

2. Open up the XML file in a text editor like TextWrangler and find and replace

-v</pathurl>

with -v.mov</pathurl>
.

3. Save the XML file then try the import again.

* The "ignore file extensions" option in Davinci Resolve is supposed to prevent issues like this but this problem still occurs when that box is checked.

Fixing missing database errors in DaVinci Resolve

Mon, 28 Apr 2014 16:09:35 +0000

Upon launching DaVinci Resolve you may see the following error:

"Resolve did not locate a compatible or upgradable database."

Clicking past it shows an empty project view.

There are several possible causes including database corruption but a common one is caused by your PostgreSQL database being too large. This can cause PostgreSQL to request more shared memory than is allowed by OS X or Linux.

To determine the exact error on OS X, you can launch the Start Server app in your /Applications/PostgreSQL folder. If it fails to launch it will show an error message after about a minute or so. On Ubuntu the equivalent command would be sudo service postgresql start.

The error may not have the exact wording shown above but will be labeled "could not created shared memory segment".

There are two ways to fix this problem - either permanently or temporarily until your next reboot. I'd recommend trying the temporary option first because if something goes wrong you can just restart to fix it.

Temporary Fix

1. Enter the following command into the Terminal located in /Applications/Utilities:

sudo sysctl -w kern.sysv.shmmax=41943040

You'll need to enter your admin password after typing this.

2. Launch the Start Server app or type sudo service postgresql start on Ubuntu. If all went well, it should not report an error and Resolve should be able to see the database when you relaunch it.

3. If you still get an error, try the command again with a higher value then repeat Step 2. The memory limit is specified in bytes so multiply the number of megabytes by 1024 twice. PostgreSQL documentation recommends you use 1/4 of the available memory for this, although I was able to get it working with much less.

Permanent Fix

1. Back up the file /etc/sysctl.conf.

2. Use the following command to edit the file:

sudo nano /etc/sysctl.conf

3. Add the following line (or edit it if it already exists):

kern.sysv.shmmax=41943040

4. Press Ctrl + O to save the file, then reboot.

5. Resolve should now be able to see the database. If it can't, try increasing the memory limit further and reboot.

If you get into problems and your system refuses to boot, either boot into safe mode or use target disk mode to copy the backup file and then reboot.

Possible solution to Color 1.0.3 XDCAM issues

Sun, 14 Dec 2008 09:26:08 +0000

As reported earlier, the new Color 1.0.3 patch cannot seem to recognize XDCAM footage, reporting it as offline. Matt Bucy on the Apple discussions board seems to have come up with a potential fix though. It would appear that the problem is with the XDCAM codec that Sony's capture utility uses, and the problem goes away if you re-encode the video with Apple's flavor of the codec.

Matt recommends going to File > Media Manager and selecting Copy referenced media. You could also export to a QuickTime or put the files through Compressor (the latter being the least recommended option due to recompression taking place).

Let me know how well this works for you. Hopefully Apple will fix this soon.

Color 1.0.3 reportedly breaking XDCAM footage

Thu, 11 Dec 2008 09:22:04 +0000

A large number of Color 1.0.3 users are reporting that the latest version breaks XDCAM footage. Apparently their XDCAM media is listed as being offline, with no way to reconnect it. The symptoms vary - some report that 30p XDCAM works fine, others report that no XDCAM works at all. Some are saying it is an issue with 1080p clips only and that 720p is fine.

Currently no-one has managed to come up with a workaround and the only suggested course of action at this stage is to uninstall Color and reinstall version 1.0.2. As far as I'm aware, that is still available from Apple's site. If you experience problems with round-tripping from FCP you will need to uninstall the entire Studio, reinstall from the disc and then ask on some forums for the old FCP 6.0.4 update (included in Pro Applications 2008-02 I believe) because, frustratingly, Apple only posts the very latest updates on their site.

This is why it is recommended to not update in the middle of a project and to read up on the patch in some forums before updating. And to be on the safe side, clone your hard disk before you update as well. We can only hope that Apple fixes this issue soon (don't hold your breath) and in the meantime, all those experiencing issues should notify Apple so they are made aware that it is affecting a large number of their users.

Update 12/14/08: See the fix here.

Apple releases 8800 GT for old Mac Pros

Thu, 17 Apr 2008 05:54:30 +0000

Early Mac Pro users can now use Apple's NVIDIA GeForce 8800 GT Upgrade Kit to add the latest graphics card to their machine.

However, before you rush off to find your credit card, I would advise holding off for a while until Apple fixes the performance issues with an updated driver (these are normally included in operating system updates but sometimes are offered separately).

And if you're planning to use it with Color, you're better off with the original ATI Radeon X1900 XT as the NVIDIA card supports fewer working bit-depths.

But if you're a gamer, you're grand.

How to run Color below its minimum requirements

Thu, 10 Apr 2008 07:17:47 +0000

Color has some pretty stringent requirements. This tip will tell you how to run Color when you do not meet the minimum system requirements. Why would you want to do this? Well, maybe you have a slow machine and just want to grade a couple of simple shots or perhaps you would like to learn how to use the software before buying a new machine. Whatever the reason, here's how to do it.

Note that Apple doesn't set minimum requirements for the sake of it, and you may experience strange behavior from this tip. I wouldn't advise this for production use.

When you launch Color, it will tell you specifically what is wrong with your configuration. In this case, it is less than 128 MB of VRAM (graphics card memory).

1. Go to Applications, ctrl-click on Color and select Show Package Contents.

2. Browse to Contents/Resources.

3. Double-click minsys.plist to open it up in Property List Editor. Alternatively, you can open it in TextEdit. You might want to save a backup of this file before you change anything.

4. You will see several self-explanatory options here such as minimum QuickTime version and minimum system memory. Go to AELMinimumVRAM and change it from 128 to something lower. As I am running it on a system with 64 MB of VRAM, I will change it to 64. Just set it to something lower-than or equal-to what you currently have.

5. Save the file and open Color.

If your screen resolution is set too low, the Color interface will be tiny and unfortunately this is a side-effect of hacking the system requirements. Obviously they are there for a reason.

This tip applies to all programs in Final Cut Studio, not just Color.

Update: Our System Toolkit utility now automates this task. Just select the application name and tick Low Minimum Requirements.

Matrox MXO now runs on Leopard

Thu, 27 Dec 2007 22:02:21 +0000

Matrox has just released a patch for its MXO HD monitoring system. The patch offers "Mac OS X v10.5 (Leopard) support, Apple Color v1.0.2 support, Adobe Premiere Pro CS3 v3.1.1 support and genlock timing offset controls."

The Matrox MXO is a box that you connect between your graphics card and an Apple Cinema Display that allows you to perform accurate high definition monitoring for under $2000. This is a great product for indies, as monitoring solutions normally start at about $8000-9000, and the Matrox MXO is definitely comparable with these higher-priced solutions. The best experience will always be on a CRT monitor but this is a close second for a fraction of the price.

Visit Matrox's MXO support page to download the patch. Note that you will need to be a registered user on their site in order to do so.

[via Broadcast Engineering]

Red Giant releases Magic Bullet Looks

Wed, 17 Oct 2007 17:49:42 +0000

Red Giant Software has just released Magic Bullet Looks, the latest edition to the Magic Bullet family of color correction tools.

What makes Magic Bullet Looks different from other tools is its interface. It doesn't deal with Primary Ins and Secondaries, it follows a very logical model of a camera, starting with the lens, going through the body and coming out at the end.

The genius behind this is Stu Maschwitz, who writes on his blog:

"When you drag tools out from the drawer, an image of a camera appears. Some tools, such as lens filters like Diffusion and Gradient, only operate in one category of the camera. Others, like Exposure, work anywhere in the chain. The camera diagram reminds you that you're building a simulation of how light travels through a camera and is modified by film stocks and post-processes such as Bleach Bypass (neg or print), custom film stocks, and color correction."

As if that wasn't enough, it also offers over 100 look presets for simulating various film stocks and effects. If you've used Magic Bullet Editors, you know how useful these are.

Pricing is $399 or $99 if you already own Magic Bullet Editors or Magic Bullet Suite. If you purchased Magic Bullet Editors on or after April 11th 2007, you can claim a free upgrade here.

ProLost: The Film Industry is Broken

Sat, 8 Sep 2007 16:03:42 +0000

Stu Maschwitz has a great post over at ProLost about the need for a universal color grading format for sharing data between applications. Kind of like an EDL for color.

He makes a great point and it would be a great asset to the industry but sometimes standardization isn't good. What if the worst package on the market is the one creating the standard, locking out the advantages of its competitors? And with a rigid standard in place, how much room will there be for future innovation?

I don't think any one company should set a standard. It should be the result of a consortium of all the companies (or at least the largest ones) or else an independent third party.

Maybe a standard format isn't the way to go, but Stu is right in saying that something is needed.