How to make Capture One generate missing previews?
Is there any way to make Capture One generate missing previews? Sometimes it does so automatically when you select a folder, but not always.
I'm aware of the Regenerate Previews option, but generating previews for tens of thousands of images in order to fill out a few hundred missing ones seems like a somewhat inconvenient solution.
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If you are in a a particular folder, you don't have to have Capture One regenerate tens of thousands of previews. Just open the folder, with its 150 (or whatever) images, Select All (Cmd-A), then choose regenerate previews and it will regenerate previews for those 150 only.
Ian
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You're right. Regenerating previews for the entire catalogue only needs to be done one time.
Do you have any idea why previews are generated automatically for some folders but not for others?
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Thomas,
Have the files without previews been imported into the catalogue or are they files that have been created elsewhere and added to a folder that is already known to the catalogue database?
A session will automatically generate previews, etc., for any new folder that is opened within it and check for previously unidentified images within a folder when it is opened.
Catalogues, as far as I know will only check when commanded to do so via the Import or Synchronise features. I'm not sure if "Locate" goes as far as looking for any editable file or simply attempts to find previously known files that were not found at the known "address" in the database. It looks to me like Locate is only interested in already known files - which is what I would expect.
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They're photos that are already in the catalogue, imported into the catalogue a long time ago. For some reason they don't all have previews; I assume because Capture One didn't finish generating previews before it was shut down after the photos in question were imported. My impression is that in most cases Capture One starts generating previews automatically, if any are missing, when a folder with is selected, but with some folders it doesn't.
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Interesting Thomas.
I don't use catalogue enough to have experience of anything going missing (at least nothing that I might recognise!)
If previews are identified by the program as missing but are regenerated automatically in some cases but not others one wonders whether the problem may be that the database finds the preview file "exists" by reference to the catalog database internal data but the file in question is either corrupt or does not exist.
In other words the check for a possible need for generation only goes as far as "do we think we have created a preview previously" rather than the extended " and does it still exist?"
Nevertheless, even if one adopted that policy for decisions related to preloading memory one might have expected some further checking and regeneration (where necessary) if the file was selected for browsing and editing.
I could also envisage a situation with some very old files uploaded in much earlier versions where there could be a mismatch with original preview files/edit instruction settings and current processing engines but I would imagine that is something that would be trapped and a generic message provided. However, that seems unlikely in this instance.
It's relatively easy to check the file system for preview files in a session but not something I have looked into for a catalog.
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It may very well be an issue of preview files appearing to Capture One to exist but not actually existing.
I just noticed that there's also an issue of thumbnails not being generated. Inside my current catalogue, in the Previews folder, there are 55,296 sets of .cof and .cop files, but in the Thumbnails folder there are only 16,985 .cot files. So it seems that currently 38,311 thumbnails are missing. I wonder if thumbnails are only generated when files are viewed in Capture One.
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Do you have any idea why previews are generated automatically for some folders but not for others?
In my experience, the generating of previews has often been a bit erratic, from time to time. For instance, mostly as you import images it starts generating previews while the import is going on. But very occasionally it just won't, and waits until they have all been imported. It's been like that for years (though I don't think I've seen it yet with 23.)
Perhaps "quirky" is the appropriate word!
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I just quickly checked a session and there I would expect to find the same number of cot files as cos (and cof) files.
I see 172 cot and 169 cop.
These have been edits in 3 different "versions" so I have 3 separate folders of cos files. Two have 169 files, One has 173 files but that includes 4 comask files.
The extra thumbnails seem to be duplicates. One file (by file name) with 1 duplicate, another with additional duplicates and the final "extra" one, i.e. added later than the original set in the folder, is a thumbnail for a dng version of a file that also has a cos file and cop and cof files.
So nothing that represents anything like the scale of numbers of files differences you can see.
There may be a logical explanation but I would not like to speculate about it on the basis of what we have seen.
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@Ian
Yes, definitely quirky.@SFA
In order to check thumbnail generation I did some scrolling through the catalogue in grid view, and the number of .cot files in the Thumbnails folder has now increased by thousands. So it seems that rather than being generated along with preview files, thumbnails are generated when images are actually displayed in the browser in Capture One. In a session with a smaller number of images I assume you're more likely to having viewed all these images, and consequently they should all have thumbnails.0 -
Thomas,
Normally all of my thumbnails are created during the import process as we all expect.
In a session, if one opens a folder of images that have already been imported to a C1 session somewhere before the readily available cot and cop files, plus any edits would be used.
If one copies some images to a folder and excludes the previous C1 folder of Settings and cache the session will see the new (to the session) files and create the required workfiles as if they were being imported - but with any of the additional processing that is available during import.
So yes, in a catalog it seems that any images that manage to sneak into a folder that is then presented to the catalog without an import activity (does that require a Synch process to make the recognition happen?) would then fill in any "missing" (to C1's understanding at the time) cot, cop and cof files, etc.
That's good to know, even if a little obscure in its potential use for most people using catalogs, or so I would suspect.
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@SFA
In my case, most of the images in my current catalogue were imported into the catalogue when importing a previous Capture One catalogue, so all previews and thumbnails would have had to be generated from scratch. It would be useful if there was a way to complete this process if it hadn't finished.
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Thomas,
I work mostly with sessions some small, some with up to 6 or 7000 files across several folders.
On a very few occasions, I recall having some glitches that left import batches still processing Previews or, more often, Thumbnails. As I recall on re-opening the Session the processing would resume for the incomplete images. However, the session concept tends to promote the idea of "finding" and image and preparing what will be required to edit it and that might not be the same for Catalogs. The anticipation that a catalog might have tens of thousands of images rather than thousands of images may have resulted in a different philosophy.
I'm speculating, of course.
Out of interest did you run a verification against the catalog before re-running the thumbnail creation? If so, did it report anything?
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@SFA
I've verified the catalogue, and there are no issues with it. Also, it's a relatively new catalogue (in connection with the issues I have with Capture One becoming unresponsive constantly, I've created new catalogues a number of times to make sure that these issues weren't caused by undetected problems with the catalogue).
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That's interesting Thomas.
I suppose, in theory, that cache "convenience" files, such as previews and thumbnails, are not significant to the validation of the catalog's completeness since they can easily be regenerated if required. But only if the core structure is in place and appears to be unbroken.
It occurs to me that random unresponsiveness might be a symptom of some actions prompting C1 to load some thumbnails and previews into memory ready for editing only to find they do not exist. At which point it seems likely that it may start a preview/thumbnail regeneration process.
If that happens with a Session it would usually be for a single folder and so probably for a relatively small number of images. So any perceived unresponsiveness might be for a rather short period. For a catalog, it could be much longer, especially if the catalog size is large and the work requires a lot of loading and unloading in working memory. Obviously, I am speculating. I don't have a large enough catalog to consider testing that theory.
Does the creation of a new catalog from an existing catalog involve just creating a copy of the catalog with a new name or is it more like export/import from an old catalog to a new one involving regeneration of everything one would normally find in the C1 Cache folder? If so I would imagine that could take some time.
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@SFA
When I've created a new catalogue, I've created an empty catalogue and imported the old catalogue into the new one. This does indeed take quite a long time. And it hasn't solved any of the issues with unresponsiveness.
Regarding unresponsiveness (here's a description), I doubt it has anything to do with thumbnails and previews. If it had, I assume Capture One support known about it – and since I first contacted them about the issue five months go, they haven't as much as offered a suggestion as to what could be causing it. Also, you shouldn't think that unresponsiveness when switching between tooltabs would relate to thumbnails and previews, but of course you never know.
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Thomas,
Having re-read most of the other thread you linked - notably the constant appearance of the DxO advice in the logs despite your clearance activity, I started to wonder if the might be something going in a config file somewhere. user config files in Windows but as I recall they are plists in Mac speak.
In Windows, the files hold all sorts of user-related settings values in a "last used" state. What is recorded can be retained for quite a long period and, potentially, carried forward across updates. So the contents offer a source for unexpected data, although it may require the addition of some form of file corruption (not enough to crash the use of the file) to throw up the errors you see so frequently.
Just a random suggestion. Probably of no help but I have found in the past that sometimes odd ideas spark new thoughts that can lead to something useful being discovered. Especially if everyone seems to be completely in the dark after a wide and extensive diagnosis.
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@SFA
I've looked practically everywhere on the hard drive but couldn't find anything related to DxO. Capture One preference files didn't contain anything either. And according to support, it's unrelated. So I assume it's a false lead. Also, I've sent off everything I could think of to support, and they haven't come up with anything yet, not as much as a suggestion what try in order to solve the issue. I assume if one of the files I've sent them was corrupted, they would have known.
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I finally heard from support.
There is no way of making Capture One generate missing previews other than regenerating previews for the entire catalogue.
As for thumbnails, there's no other way of making Capture One generate thumbnail than to scroll slowly through the catalogue, which of course isn't a useful solution if you have a large catalogue.
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Presumably if one accessed the file in some way - like scrolling through the catalog but is there a different option one could discover? - the previews and thumbnails for all images discovered would be created if they were missing?
So a "create on need" option - if only one knows what one needs and that it is there to be discovered...
I suppose the theory is that a valid catalog should not have such problems but, if it does, then the whole catalog may be suspect. Therefore a regeneration of the whole thing might make sense and take no longer than checking for anomalies and fixing them. Hmm.
Regenerate preview might typically be used only on a change of default screen resolution, in which case a consistent starting size for the Preview resolution might be desirable. Well, maybe.
I think sessions are more flexible in that regard, though I would need to check. In any event they are likely to involve fewer files so the overhead of regeneration would be much lower.
Whatever, it seems frustrating in your situation Thomas.
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I made a quick test just to make sure that the same would happen with a new catalogue:
* created a new catalogue
* imported a folder containing 365 image files
* let Capture One finish generating previewsStatus:
15 thumbnails (.cot files)
365 previews (.cop files)After slowly scrolling through the catalogue, the number of thumbnails had increased to 365.
. . .
I've made a request for an option to generate missing previews and thumbnails – here.
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You can Regenerate the Previews (and thumbnails) by selecting the files and system folders.
What I noticed though is that when the computer is locked, it stops generating them. Therefore if you have a large batch e.g. when importing a large number of photos or if you move them around, then it might well be that the generation of the previews is not finished and you end up with the missing thumbnails and previews. C1 picks up the generation when you unlock/login again. But if you by then have taken your catalog offline (when referenced), then the previews/thumbnails are missing in the overview. This is what I observed.
I opened a feature request that thumbnail/preview generation continues to run in the background also in Windows locked mode. https://support.captureone.com/hc/en-us/community/posts/11044778601629-Generate-previews-thumbnails-in-background-while-OS-user-is-locked
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