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 same  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. (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.

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 concerning 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 a 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 clips into it.

3. Save the project and close Resolve.

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

It's worth noting that the clips and sequences do not appear to actually be removed, just 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.

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>

-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.

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.