Relinking Optimized Medias

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Forest Finbow

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Relinking Optimized Medias

PostTue Apr 18, 2017 10:48 am

Hi Folks,

So I've grading with Resolve for a couple of years now but I have recently begun advising people to try out the very neat editing possibilities resolve features. I have also tried that myself on personal projects and have come to the conclusion, like many, that Resolve is indeed a very interesting option in the current NLE competition.

So far, two things have however darkened the horizon:

- Resolve doesn't support OMF export, and while it does feature AAF for protools exports, they don't come with handles so needless to say the sound people are generally very unhappy.
- Optimized medias links are VERY fragile, especially as the project grow in size. They get lost for no real reason (auto-save, save as, crash, unavailable volume upon start etc...) and never come back.

For the first issue I've found several workarounds: Export as a plain AAF will keep the links to original files OR have the timeline make a pitstop in Adobe Premiere to convert it to an OMF. It's not a vanilla Resolve workflow but hey, I paid for both softwares so I'm fine with it.

For the second part, however, it's a little more tricky. I've dug deep into resolve and I think I have a solution, but it is nowhere near trivial. It involves reading from the database, relinking the medias to found optimized medias on disk and then updating that database.

I'm currently writing an app in order to automate those steps and much to my surprise I'm getting close to a functional build (I had to actually learn C++ and cross-platform coding ;-) so it took me a while).

My current version will only work on disk-based databases (ie XML files) but it has been written with SQL databases in mind so the port will be easy when I get there.

I'm now seeking help for debuging and cross-platform testing. I've seen many messages here and elsewhere from people concerned about those OM-links breaking, if you're one of them, or if you wish to help the community, please drop me a message here, in public if possible, this is intended to be a collective workaround to this quite annoying problem.

The app should compile fine on MacOS/Windows/Linux platforms so I can releasing binaries for all of those willing to help.
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Forest Finbow

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Re: Relinking Optimized Medias

PostMon Apr 24, 2017 12:38 pm

Coming again on my road to reconnect lost optimized medias.
I can now confirm I have a proper working solution to relink lost optimized medias.

My first solution will cover the following scenarios :

- You've generated your OM with the OM size optioned to "choose auto" (default) and then decided to change the timeline resolution. Resolve figures the OM is not the proper size anymore and destroys the link but the files are still in your cache folder.

- Your Cache folder is sitting on and external drive, or a network location. For some reason (unpowered drive, Windows drive letter change, or network lag), upon Resolve startup the cache drive was not available and you've saved your project since. OM is gone for good and you have to regenerate it (overwriting files that were actually perfectly fine when the folder came back to life.

- You've been messing with the cache location in the settings after the generation and saved your project. The files are of course not present in the new cache folder. Resolve will figure they are unavailable and will destroy the link. Even if you reset your cache folder to it's original location or move the OM files to that new folder, if the link is broken, it doesn't come back.


What my solution doesn't cover yet is the File->Save as... (and from what I've hear the Auto-save to backup). Indeed upon "Save as" Resolve assigns new unique ids to everything in the project, including the project id itself. The Cache folder will not reflect those changes if the files in there are too large and thus the new project won't have any OM available for footage in the Media pool.
I have an idea however on how I will achieve retrieval of such OM so keep tuned for that.

I know it's not like I'm fixing Resolve or anything big. Those that have encountered that before know that there is a trivial workaround available to all, just regenerate the OM and you're done! But my experience is that the more you actually EDIT with resolve, the more you end up running into those issues. Especially with modern small cameras footages such as the Sony A7s wich feature h.264 with very long GOP and very high profile compression. I've been many times frustrated about OM disappearing and only reading similar complaints on internet without any proper solution offered.
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John Paines

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Re: Relinking Optimized Medias

PostMon Apr 24, 2017 12:50 pm

Forest Finbow wrote:What my solution doesn't cover yet is the File->Save as...


There is a workaround of sorts, if you invert the order of things. Go into the database, make a copy of the project file, then rename it. Now you've got two project files which reference the same cache. Can't swear to its reliability, but it worked the one time I tried.
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Forest Finbow

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Re: Relinking Optimized Medias

PostMon Apr 24, 2017 2:05 pm

Yes, I've read about this before, another bright user here, Eugene Afanasiev, had come up with a similar solution to move your cache folder to another drive or to reconnect a new project to old OM moving around timelines with XMLs.
I have myself experienced the issue at work, learned from that and moved on (just don't Save as with OM). Since I read Eugene Afanasiev, any versioning on my side is always done exporting projects to a backup folder, keeping my project in a single file, never even renaming it...

That's actually the reason why I began on working on the other problem I experienced, and not this one. The thing is, in my case OM seems to disappear no matter how careful you are. I am part of those [poor people] only having a 256Gb SSD to run Resolve, I'm just not going to build my OM on that drive. Regular cache during grading, maybe, but not 40 hours+ of that wonderfully daring new documentary shot on a 4k DSLR. So I have an external drive attached to my computer. It's large but every now and then it seems to fail responding fast enough that resolve considers the OM to be present (not even talking about drive letters changing and so). So I loose OM and have to regenerate it. After the first dozen times that happened (and a lot of googling to try find if there was a solution to avoid hours of regeneration) I started looking deep into it and came up with the idea that since I am not alone, it's probably worth finding a solution :)
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Forest Finbow

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Re: Relinking Optimized Medias

PostMon Apr 24, 2017 6:32 pm

Wait, wait what ?

Davinci Resolve 14 :
...
• Ability to "Rediscover Optimized Media" in the Media Pool
...

Oh well, seems I've been working on this for nothing... Davinci team, you rock, as usual!
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Konrad Eksteen

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Re: Relinking Optimized Medias

PostTue Jan 16, 2018 8:56 pm

After reading this thread as well as an older one dating back to 2015 it still seems that there is no solution to re-linking some OM?

Am I correct in saying that if we want to minimize (not prevent) the risk of losing of OM, "Auto-save" as well as "Save As" must not be used? It's funny because I can "delete OM" from the same project but cannot "re-link".

Didn't change any project settings and saving to internal drive on Win 10.

I have such a love hate relationship with Resolve. Brilliant program but the issues makes life difficult.
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Hector Corcin

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Re: Relinking Optimized Medias

PostThu Jan 24, 2019 12:42 am

2019.... Waiting for a solution to rediscover Optimized Media after a crash and reopening a backup...

No worries... Resolve almost never crashes so it is not very often that you have to rebuild Optimized Media for ours.... :roll:

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