Chapter thumbnails compared to 10 second

[blgentry 51]

I've got Emby set up in my video libraries to create thumbnails at chapter markers.  This mostly works as expected.  But in a few instances, the chapter markers are all at black screens that appear between scenes.  So the thumbnails either show as totally black, or as a barely visible picture of the next frame that's being blended in at the chapter marker.  This makes sense from a DVD/BD authoring perspective.  Put the chapters at the scene transitions.

 

But this makes the thumbnails not very useful for trying to visually identify parts of a show or a movie.  I was considering changing to 10 second thumbnails, but I'm thinking that won't solve my problem.  When I press the interface button to display chapters, I'm still only going to get the thumbnails at are AT the chapter markers right?  I won't get hundreds of thumbnails showing on the timeline.

 

So what are the 10 second thumbnails for?  I guess for some sort of visual fast forwarding support?  Can anyone link me to a picture or video that illustrates what these thumbnails are good for?

 

Next, I've read up on how to change the thumbnail generation setting.  It seems that I have to "refresh metadata" for them to be regenerated.  That will potentially overwrite all of my existing metadata and erase my carefully selected choices.  I'm hoping that I misunderstand the whole process, but I don't think I do.

 

Thanks for any information and help.

Brian.

[Luke 42079]

Quote

So what are the 10 second thumbnails for?  I guess for some sort of visual fast forwarding support?

Correct, yes. I don't know if we have a screenshot handy, but it's just like you can imagine. the more frequent the image interval, the better the visual seeking process will be.

But also the slower your library scans will be, so you have to look at all of that and make the decision about what's best for you.

[blgentry 51]

Since my issue is isolated to just a few video titles, I'm guessing my best path is to edit the individual video files and change the chapter markers to be 10 or 15 seconds forward of their current positions.  Then rescan the library and/or re-run the scheduled task to generate thumbnails.  It's messy and probably not easy to automate.

 

...so maybe I just won't do anything about it.  It's quite minor.  Emby is so good that I'm able to spend effort on tiny little things like this.  All of the bigger issues are solved for me.  Yay!

 

Brian.

[GrimReaper 4740]

For few odd (or a few more) items, you can use community-made plugin, it'll make short work of adjusting those (or creating new):

 

[blgentry 51]

@GrimReaperThanks for the pointer to the plugin.

 

If I decide to pursue this, I'm probably going to need something semi-automated.  I looked around a bit last night and a good bit of my TV collection has this issue.  Babylon 5 is a good example.  Half or more of the chapter thumbnails are black because they are right at a scene transition.

 

To manually correct just this series would be a hours of work.  A lot more than I am willing to do.  So I'm either going to forget about this (maybe), or go figure out how to export the chapter info, run an automated process to add a few seconds to each marker, and then import the changed chapter information.  I'm pretty sure it can be done, but I'm not sure if it's worth my time.

 

Thanks again for the input!

Brian.

[GrimReaper 4740]

Must admit I find that somewhat odd as I've rarely encounter such occurences (though it does happen on rare instances), but one more thought that came to mind: are those problematic chapter markers at exactly 5-minute intervals (meaning Emby created) or they're at various intervals (meaning embedded, Emby is just extracting images at those exact timings), as if file contains embedded chapter markers, those take priority, Emby doesn't interfere there?

[blgentry 51]

These black thumbnails are from embedded chapters that were present in the original source material.  In this example of Babylon 5 S2 E2, they came from DVD.  If you think about it, it's quite natural for the author of the DVD to put chapter markers where scenes begin.  When there's a scene transition, many times the video goes black for a moment to signify the transition.  Attached is an Emby screen shot of this episode, with the chapters at the bottom.

 

I'm not sure if this really matters the more I think about it.  I don't often jump forward in TV episodes.  I normally watch them all the way through.  With movies, I sometimes locate a particular scene and watch it or show it to a friend or something.  With TV shows I don't do that very often.  This mainly came to my attention because when I showed the timeline in Emby I had black frames in almost all of the chapter markers and it looks weird.  I'd still like to fix that for cosmetic purposes if possible.

 

Thanks,

Brian.

[GrimReaper 4740]

16 minutes ago, blgentry said:

These black thumbnails are from embedded chapters that were present in the original source material.  In this example of Babylon 5 S2 E2, they came from DVD.  If you think about it, it's quite natural for the author of the DVD to put chapter markers where scenes begin.  When there's a scene transition, many times the video goes black for a moment to signify the transition.

Yeah, don't quite see mitigation to that other than for Emby core to implement fixed offset for embedded chapter marker images, preferably +x seconds for extraction. 

[rbjtech 5284]

I'm pretty sure the extraction for thumbnails IS offset by a second or so for this very reason.

There was a discussion about it with sw I believe when I was looking at the HDR thumbnail extraction - just need to find it .. haha

@softworkz

A debug log of those chapters extraction and the chapter points may be useful to track this one down.

Edited October 5, 2023 by rbjtech

[blgentry 51]

On 10/5/2023 at 9:41 AM, rbjtech said:

I'm pretty sure the extraction for thumbnails IS offset by a second or so for this very reason.

There was a discussion about it with sw I believe when I was looking at the HDR thumbnail extraction - just need to find it .. haha

@softworkz

A debug log of those chapters extraction and the chapter points may be useful to track this one down.

Let me see if I understand:

 

1.  Thumbnails are supposed to be extracted several seconds after the actual chapter marks.

2.  Something about HDR chapters might apply.  This is from a 480p DVD source so HDR should not be involved.

3.  A log of the thumbnail chapter extraction might have some clues.

 

The thumbnails were done quite some time ago.  How do I get Emby to do that again so that I can post a log?  

I'm attaching two screen shots.  One of Emby showing S1E1 of Babylon 5 with the chapter thumbnails and times.  The second is from MKVToolNix showing the exact same chapter times.  So I don't think the offset is configured or working.

 

Thanks for the help.

Brian.

[Luke 42079]

Hi, the user interface currently does not have a way for you to regenerate them. You’d have to locate the existing extracted images, delete them, and then run a library scan or the video thumbnails scheduled task.

[Luke 42079]

Has this answered your question?

[blgentry 51]

5 hours ago, Luke said:

Has this answered your question?

Thank you for asking.  My issue is unresolved.  Apparently Emby is supposed to make thumbnail images a few seconds after the chapter markers and that's not happening on my system as evidenced by the screen shots in my last post.  

 

I would like to delete the thumbnails associated with one or more of these and capture a log for you.  However, I'm unable to find instructions on how to locate the thumbnails so I can remove them and then re-run the thumbnails scheduled task.  Based on my poking around, I suspect that the image thumbnails are referenced by a database ID of some sort.  I found an ID in the URL of the TV show episode, but it does not seem to correspond to the large hex numbers in the Emby metadata directory.

 

This issue isn't super important and if it requires lots of effort then I can just drop it for a while.  I'm much more interested in a few other things I've asked about like the Mac server beta for example.

 

Thanks for your help.

Brian.

[rbjtech 5284]

15 minutes ago, blgentry said:

Thank you for asking.  My issue is unresolved.  Apparently Emby is supposed to make thumbnail images a few seconds after the chapter markers and that's not happening on my system as evidenced by the screen shots in my last post.  

 

I would like to delete the thumbnails associated with one or more of these and capture a log for you.  However, I'm unable to find instructions on how to locate the thumbnails so I can remove them and then re-run the thumbnails scheduled task.  Based on my poking around, I suspect that the image thumbnails are referenced by a database ID of some sort.  I found an ID in the URL of the TV show episode, but it does not seem to correspond to the large hex numbers in the Emby metadata directory.

 

This issue isn't super important and if it requires lots of effort then I can just drop it for a while.  I'm much more interested in a few other things I've asked about like the Mac server beta for example.

 

Thanks for your help.

Brian.

If you have set the library to create 10 second thumbnails, set it to save with the media - then as a test, turn on debug logging, right click on an item in the library - and select Refresh metadata.   Opt to Replace All metadata.  

You should see a 'quick-image-series' log get created - this is the log creating the thumbnails.

You should also after a short while see a .BIF file get written next to the media.

After a further item refresh, or wait for the Real Time Monitor to pick it up (or run a scheduled Scan) then the thumbails (at 10 second intervals) should show when playing.   Only the chapters (every 5 mins if no real chapters are available) - will show on the item screen.

If this then works - then you can Refresh the entire library - you do not have to do it one item at a time - but this obviously take a while ...

[blgentry 51]

18 minutes ago, rbjtech said:

If you have set the library to create 10 second thumbnails, set it to save with the media - then as a test, turn on debug logging, right click on an item in the library - and select Refresh metadata.   Opt to Replace All metadata.  

I have mine set to chapter markers.  It's kind of the whole point for me:  So I can arrow up and see the chapters visually while the show is playing.

 

Doesn't replace metadata well.. replace metadata?  That's potentially bad for me as I like my metadata.  In some cases I've spent quite some time curating it and I don't want scraped and replaced from another source.

 

This is why I was trying to delete the thumbnails themselves.  I don't want to replace any real metadata just to regenerate thumbnails.

 

Thanks for trying to help.  I appreciate it.

 

Brian.

[rbjtech 5284]

42 minutes ago, blgentry said:

I have mine set to chapter markers.  It's kind of the whole point for me:  So I can arrow up and see the chapters visually while the show is playing.

 

Doesn't replace metadata well.. replace metadata?  That's potentially bad for me as I like my metadata.  In some cases I've spent quite some time curating it and I don't want scraped and replaced from another source.

 

This is why I was trying to delete the thumbnails themselves.  I don't want to replace any real metadata just to regenerate thumbnails.

 

Thanks for trying to help.  I appreciate it.

 

Brian.

Ah-ha - right, so in that case BIF's will not be generated.   They are only generated for the 10 second option.

'Finding' the metadata(images) used in the chapters is going to be almost impossible, as it will be kept in 'cache' areas.   Even if you did manage to find and remove it - you would still need to Refresh the metadata, but use the 'Missing' option - and it would ,I believe, just regenerate the chapter images - but I've never done this - I've always used the BIF option saved with media as it's way more flexible.

Chapters will show as well if you use the 10 second option btw - they will be identical to what is shown now - but you'll have the images every 10 second inbetween as well - which will only be shown/used on actual playback.    The chapters shown in the item listed, will be identical.

[Luke 42079]

7 hours ago, blgentry said:

Thank you for asking.  My issue is unresolved.  Apparently Emby is supposed to make thumbnail images a few seconds after the chapter markers and that's not happening on my system as evidenced by the screen shots in my last post.  

Hi, this isn't really true. It's based on the timestamp of the chapter marker.

[blgentry 51]

57 minutes ago, Luke said:

Hi, this isn't really true. It's based on the timestamp of the chapter marker.

What does that mean?  Are my images above what you expect?

 

Thanks,

Brian.

[Luke 42079]

1 hour ago, blgentry said:

What does that mean?  Are my images above what you expect?

 

Thanks,

Brian.

It means that if you configure thumbnails to extract at chapter intervals only, then the extraction occurs at the start time of the chapter.

[blgentry 51]

On 10/5/2023 at 9:41 AM, rbjtech said:

I'm pretty sure the extraction for thumbnails IS offset by a second or so for this very reason.

 

I was basing my assertion on this quote.  I guess rbjtech is incorrect.

 

Thanks,

Brian.

[rbjtech 5284]

9 hours ago, blgentry said:

I was basing my assertion on this quote.  I guess rbjtech is incorrect.

 

Thanks,

Brian.

@softworkz@Luke

Maybe this is true for the 10 second thumbnails only - but I'm pretty sure that some work has been done to alter the frames extracted so they are in advance of the actual time - for the very reason the OP has highlighted.    If you extract on the exact time, the chances of you getting a blank screen are very high due to scene transitions - thus pretty useless as a thumbnail.

I very rarely see a blank thumbnail beyond 'Chapter 1' - is this because I use 10 second thumbs (and the chapter points are taken from the BIF file with the offset) - or are the chapter thumbs extracted seperately the same as if I had chosen chapter only ?

@blgentry

As an experiment/test - maybe create a test library, set that library to 10 second extract, copy the media you used in the example - and then see if you see the same chapter markers as you do in the other library where have only chapter extraction set.    I can quickly do this some time today if you are unable - as I'm now curious myself and happy to be corrected if I'm incorrect !

[blgentry 51]

I decided to throw caution to the wind.  On my TV library I set it to create 10 second thumbnails and to store the BIF files next to the media.  Half way through it seems to have locked up the server.  But I got it restarted and tried a few TV shows that had black chapter markers as thumbnails.  So far all of them have good chapter thumbnails now that I can see.  I guess the code is different for the 10 second thumbnails in terms of where it makes the chapter thumbnails.  That's kind of weird, but I'm glad it's now working as I wanted it to.

 

The server is now creating thumbnails for the remainder of my TV library, which is going to take quite some time.  I'll let it run and then report back when it's done everything.  So far, while this is something I didn't think I needed (thumbnails every 10 seconds), it seems to have solved my base issue.

 

Thanks,

Brian.

[rbjtech 5284]

9 hours ago, blgentry said:

I decided to throw caution to the wind.  On my TV library I set it to create 10 second thumbnails and to store the BIF files next to the media.  Half way through it seems to have locked up the server.  But I got it restarted and tried a few TV shows that had black chapter markers as thumbnails.  So far all of them have good chapter thumbnails now that I can see.  I guess the code is different for the 10 second thumbnails in terms of where it makes the chapter thumbnails.  That's kind of weird, but I'm glad it's now working as I wanted it to.

 

The server is now creating thumbnails for the remainder of my TV library, which is going to take quite some time.  I'll let it run and then report back when it's done everything.  So far, while this is something I didn't think I needed (thumbnails every 10 seconds), it seems to have solved my base issue.

 

Thanks,

Brian.

Good news - so I was right then ...? 

[blgentry 51]

4 hours ago, rbjtech said:

Good news - so I was right then ...? 

You are right in that the 10 second thumbnails mostly fixed my black thumbnail chapter images issue.  So thank you.  

 

This is a pretty murky area of Emby.  It's not clear to me why the 10 second thumbnail process produces CHAPTER thumbnails that are not at the same spot as chapter thumbnails only.  I suppose it doesn't matter all that much, but it is quite confusing for someone new to Emby that expects chapter only thumbnails to produce visible images (as opposed to black screen transition images).

 

Thanks again,

Brian.