Here’s how to fix write permissions for DaVinci Resolve.
Oh snap
To fix this, just open a terminal and run:
chmod -R 766 /your/problem/drive/or/directory
What’s Going On?
On linux, security is brilliantly built in. By default, files and folders that you create have a set level of permissions (defined by the umask command). Typically, the default is the user (you) have permission to read and write files that you own, as well as search directories you own. All others have read-only access to your files and directories.
Knowing this, other applications (aka Resolve) do not have permission by default to write to hard drives, folders, or files that you (the user) own. So how do we change this?
chmod
To change permissions of a single file or a whole directory, use the chmod command. chmod gives you the ability to change permissions using short, 3-digit number formats. These are known as octal numbers.
Octal Number
Permissions
File Listing
7
read, write, and execute
rwx
6
read and write
rw-
5
read and execute
r-x
4
read only
r–
3
write and execute
-wx
2
write only
-w-
1
execute only
–x
0
none
—
So in the chmod command, you use the above table to define permissions for the file user/owner, members of the file group, and other people, in that order. The -R flag used in the code above, simply makes the command recursive, applying to every single file and folder inside the directory you apply the command to.
Examples
Readable by owner only: chmod 400 examplefile.txt
Allow the owner and group to read, write, and execute, and anyone else to read and write: chmod 776 examplefile.txt
Also, there’s an awesome tool for those of you, like me, who can’t keep all those chmod codes straight!
After this post made it to Twitter, @rohit_bmd made a great point- check Davinci Resolve > Preferences and under the Media Storage tab, you’ll see a list of drives on your system. Make sure you have read/write privileges on the drive at the very top of that list, because that’s where Resolve will be storing all your cache files. Here’s the the tab:
If you’re new to Resolve on Linux, feel free to check out my other posts.
If you’re like me, you’ve been on a quest to find the best video editing software that you can run on your Ubuntu Linux PC build. If you’ve been in the video world for any amount of time, you’ll probably know that Resolve 15 is arguably one of the most robust tools in the industry. Here’s my experience on running DaVinci Resolve 15 on Ubuntu 18.04
After the initial install, everything seemed to have went fine, but when I clicked the new icon in my application tray… nothing happened. After a few more clicks, I uninstalled it and went on with my life. A few months later, DaVinci Resolve came up in conversation when talking about postproduction solutions for Linux. So I decided to give it another shot. Same issue.
Unfortunately, in Linux_Installation_Instructions.PDF there is literally nothing telling you that you should install dependencies. I ended up finding the required dependencies somewhere online.
After that simple line in the terminal, Resolve fired right up in Ubuntu 18.04 On to the next hurdle: limited file type imports.
Convert footage using FFMPEG.
Only some file types work with Davinci Resolve 15. The ones I’ve tested that work are:
Apple ProRes (.mov)
Motion JPEG (.mov)
If you can afford the space, I’d choose Apple ProRes before anything else. Unfortunately I haven’t found a way to specify 4:2:2, 4:4:4, or HQ preferences. It’s just ProRes, and from the looks of it, it’s the highest quality possible. You may be able to change this with the -q value. Still testing this.
In my 10+ years as a video editing professional, I have never used the motion jpeg codec. However, after running a few tests, playback in Resolve 15 is flawless, and the file size is the same, if not slightly smaller than the original file. My original test file was a Panasonic .MTS file clip at 1.7GB. After the transcode to motion jpeg, the result was 1.6GB, and played perfectly inside Resolve.
The further I tested this transcode setting in ffmpeg, this reduced the file size just a little bit. The biggest clips were originally 4.3GB and the resulting files were hanging out around 2.3GB-2.7GB.
The only way to truly test if this is a viable alternative to Adobe CC on Mac or Windows is to actually test it on a live project with a real deadline. This may have been unwise, but I found it to be thoroughly worth it. I tried the above ffmpeg commands, only to realize after exporting that the resulting transcodes were sub-par. Pixelated garbage in, pixelated garbage out. So this time I hit up Handbrake. This one got me. Handbrake is essentially ffmpeg under the hood, but it doesn’t offer all the options that the command line does. So my exports out of Handbrake looked great, but there was no audio supported. On Ubuntu, Davinci Resolve only supports PCM audio, and that’s the one thing you can’t kick out of Handbrake (at least from the options I have).
New Plan
The original exports from my ffmpeg commands above looked like garbage, but the audio (pcm_s24le) was supported and sounded fine. So I ended up exporting Mpeg4 video out of Handbrake with no audio. I synced those clips up with the existing PCM audio in Resolve, and everything looked and sounded awesome. Next objective, getting an H.264/AAC file out of the free version of Resolve.
Instead, I exported 20-30 minute bits of my 3 hour long timeline as Quicktime MOV files with MPEG4 codecs. They looked and sounded great, but were a touch big on the file size. Next. I just dropped them in order into Shotcut, and encoded the whole thing as H.264/ACC. Done. So for future reference, it probably wouldn’t hurt to just encode everything as Quicktime ProRes PCM, do my work in Resolve, then export QT ProRes PCM as an intermediate, then concatenate in Shotcut or Kdenlive. Kind of a wonky workaround for now, until I can afford the full version.
Notes about the free version of Resolve 15
The editing capabilities of the free version are quite nice, but they clamp down your options when it comes to exporting. First cheap shot: they don’t support H.264 encoding on export for Ubuntu. And at the time of this writing, DNxHD and DNxHR both cause Resolve to crash upon export. So without H.264 and DNxHD/HR… your export options become extremely limited. This is especially true if you have a long (3 hour) timeline that you need to deliver to a client. So is there a workaround? Fortunately there is one, but it requires a bit of hard drive space, extra time, and some FFMPEG knowledge. First, trying kicking out your timeline with these goofy settings:
I thought a Kakadu was a bird…
Here’s the gigantic and disheartening list of features that they hold back from the free version. Also, here’s another magic setting that seems even smaller than Kakadu:
Project Complete
I eventually exported the video in about 10 different sections, using MPEG4 encoded Quicktime MOV files. Decent quality, and decent file size. I ended up assembling all those color graded and sound-edited files in Shotcut and rendering the H.264 MP4 that I was looking to deliver in the first place. A super wonky workflow, but in hindsight, I think it will be worth picking up a copy of Lightworks for my edit work Resolve Studio for my color work, and cutting audio in Resolve’s Fairlight, or if Fairlight absolutely cannot handle the task at hand, I can always grab a copy of Ardour. Those softwares paired with Blender, Kritia, Inkscape, and GIMP, I don’t think there’s anything I’d be missing from Adobe CC that these platforms can’t provide.
