Media Offline problems and fix solutions

There are many reports of Media Offline problems.
I've had the problem as well, mostly since 17.09 beta - and some with 17.0 release.
Clips flash in and out with Media Offline intermittently.
17.0 release is better, but I never had the problem with 15.x - 16.x
I'm fairly certain the issue is the handling of GPU memory and it presents with Media Offline, rather than the typical GPU Memory Full warning.
There is not enough VRAM available to even display the clip thumbnail, or the viewer or the timeline - or all the above.
Even 8GB of VRAM is really not enough for many things in Resolve.
The solution is to reduce the GPU VRAM needed in the project.

When does the problem appear most frequently - at least for me?
1) Lot's of large 4k high bitrate clips on a 4k timeline. (like 20+?)
2) Adding Speed Warp to a 4k clip in a 4k timeline.
3) Trying to work on 5k clips on a 5k timeline.
4) Heavy Noise Reduction on lots of 4k clips on a 4k timeline
5) Lots of Fusion work (even just a small amount of Fusion with Noise Reduction grades etc)

I usually work on 4k clips in an HD 1080p timeline, and then switch to a 4k timeline for export.
Things go much smoother in an HD timeline.
Maybe it will export, maybe it won't.
At least with the GPU Memory Full warning, you know it won't.
With the flakey Media Offline, often you won't know until the export fails 1/2 way through, or the export file has glitches.

The real solution is to get a video card with more VRAM.
Wishful thinking in the current environment.
So it requires some creative workarounds.
Most of them for me when I run into to this problem involve working on small parts of a project at a time, exporting it to something like DNxHR HQ (or SQ)
and then bringing them back into a new project for final export.
Not sure how the new Render in Place feature might help...

Hopefully BlackMagic can at least move this intermittent Media Offline problem into a GPU Memory Full warning to at least save lots of headaches.
Or even optimize the GPU memory handling to be able to do more with less.

Thoughts? Comments? Tips?

So the current example that prompted this post:

10 5min 5k 135mbps .mp4 h.265 clips added to a 4k timeline for 4k export.
Media offline problems galore.
Remove all but 2 of the clips.
Everything works great. Edit the clips for length and content only.
Export those 2 clips as DNxHR SQ and bring them into a new project for grading.
Repeat.
So having 10 5k clips is overloading the GPU VRAM and giving Media Offline because it can't display a clips thumbnail, or it's view on the timeline or the viewer.
And the clips switch for one to another to another that go offline.

I'm also having this problem a lot and it's driving me nuts. I would have expected 11 GB of VRAM to be plenty for 4K but as soon as you start adding things, it starts to break down and get this Media Offline thing. Why does it not say that it's out of VRAM instead?

Easy reproduction:
1) start new 4k project
1) add eight 5k clips to the Media Pool from the Edit page.
(single clip info: 5,760x 2,880 5 min .mp4 h.265 4.76 GiB 136 Mb/s)
(right-click Media Pool viewer, add Media, navigate to folder, shift-click to select the 8 clips, open)
2) Media Offline errors.
Different clips switch back and forth from Media Offline.
Remove just 2 of the clips from the Media Pool, Media Offline problems disappear.

This is after a fresh reboot.
And even happens with a 1080p project.

Logs attached

Media Info:
General
Complete name : D:\2 Insta360\0A 360\0 Video\0B Studio exports\VID_20210305_145252_00_002.mp4
Format : MPEG-4
Format profile : Base Media
Codec ID : isom (isom/iso2/mp41)
File size : 4.76 GiB
Duration : 5 min 1 s
Overall bit rate : 136 Mb/s
Encoded date : UTC 2021-03-05 14:52:43
Tagged date : UTC 2021-03-05 14:52:43
Writing application : Lavf58.13.101

Video
ID : 1
Format : HEVC
Format/Info : High Efficiency Video Coding
Format profile : Main@L6.1@High
Codec ID : hvc1
Codec ID/Info : High Efficiency Video Coding
Duration : 5 min 1 s
Source duration : 5 min 1 s
Bit rate : 136 Mb/s
Width : 5 760 pixels
Height : 2 880 pixels
Display aspect ratio : 2.000
Frame rate mode : Constant
Frame rate : 29.970 (30000/1001) FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Bits/(Pixel*Frame) : 0.273
Stream size : 4.75 GiB (100%)
Source stream size : 4.75 GiB (100%)
Encoded date : UTC 2021-03-05 14:52:43
Tagged date : UTC 2021-03-05 14:52:43
Color range : Limited
Color primaries : BT.601 NTSC
Transfer characteristics : BT.601
Matrix coefficients : BT.601
Codec configuration box : hvcC

Audio
ID : 2
Format : AAC LC
Format/Info : Advanced Audio Codec Low Complexity
Codec ID : mp4a-40-2
Duration : 5 min 1 s
Bit rate mode : Constant
Bit rate : 129 kb/s
Channel(s) : 2 channels
Channel layout : L R
Sampling rate : 48.0 kHz
Frame rate : 46.875 FPS (1024 SPF)
Compression mode : Lossy
Stream size : 4.62 MiB (0%)
Default : Yes
Alternate group : 1
Encoded date : UTC 2021-03-05 14:52:43
Tagged date : UTC 2021-03-05 14:52:43

Sometimes even a few clips gives Media Offline and won't clear up.
Saving the project, then opening a different project, and then opening up the previous project - back to working. (rather than closing Resolve and restarting)
So the project file isn't corrupt, the media files aren't missing - it's apparently a GPU VRAM issue.

Or a driver issue. I’m only seeing this with Nvidia, not with AMD cards of the same VRAM size for the same media.
But it can happen if your drive has been offline and then reconnected (like when going to sleep). In that case you may need to clear your cache.

I have this vague sense that this is caused by failures in hardware decoding rather than any color processing. When color processing runs out of VRAM it usually tells you but I'm unsure about HW decoding.

Or a driver issue. I’m only seeing this with Nvidia, not with AMD cards of the same VRAM size for the same media.
But it can happen if your drive has been offline and then reconnected (like when going to sleep). In that case you may need to clear your cache.

In 30+ years of computer buying, I've never had an AMD card. Waiting to see what might happen with a 3080 Ti. Current 'rumors' are for 12GB VRAM - down from 'rumored' 20GB. The 3090 won't fit in my small case. AMD with 16GB will deserve my first hard look...
Too bad finding anything to buy is near impossible.
Hard drives are internal, and I even changed to time-out to 120 min. No help.
And it happens with a fresh reboot and a new project so I don't believe it's that.
And I have cleared my cache on numerous occasions, no help either.

I have this vague sense that this is caused by failures in hardware decoding rather than any color processing. When color processing runs out of VRAM it usually tells you but I'm unsure about HW decoding.

Possible. But when reducing the number of clips in the project, the problem goes away.
Less clips to handle/display = less VRAM ?

Nice!!
The Media Offline problems I have been experiencing seem to have been resolved.

I updated my Nvidia video drivers to Studio 461.40 from Studio 457.30.
And installed the latest Davinci Resolve Studio 17.1.

Don't know if it was the video drivers or 17.1 - or both.
But glad to a huge improvement, not only in this, but in other small issues I've seen with 17.0.

Sweet and nice work BlackMagic!!