Impress freezes on any video

Summary: I’m using LibreOffice Impress (5.2.6.2) on Windows 10 to create and run shows with lots of photos and a few videos. Now suddenly a presentation that worked fine two weeks ago freezes when a slide containing a video is displayed. I’m sure this isn’t a LibreOffice code problem per se, because the same presentation works fine on another computer (also Win10, same version of LO). What can I try?

Details:
Here’s what happens. I open a presentation that contains one or more video slides. As soon as a slide containing a video appears on the screen (Slide Pane, Normal View, Slide Sorter, or Presentation mode), Impress freezes completely. None of the menu items responds, nor do any of the tools, nor does the X. I have to use Task Manager to shut it down. But until a video slide appears, everything is fine. That is, if the video slide is far enough down that it doesn’t show in the Slide Pane, I can display slides and move around. But as soon as the video slide appears in the Slide Pane, the whole system freezes. Similarly, if the first video slide is far enough down that its thumbnail doesn’t show in the Slide Sorter, everything is fine, but if it is within the first group of slides, then all of the previous slides display in the sorter and then the system freezes. Finally, if I create a new presentation, everything is fine until I insert a video (any of my videos), and then the system freezes.
If it’s relevant, I create my videos with VideoPad, storing them as .avi files with H264 video compression and MP3 sound compression.
The problem appears on my Dell desktop, running LO 5.2.2.2 and 5.2.6.2 under Windows 10 Pro (10.0.14393). Everything works fine on my Lenovo laptop running LO 5.2.2.2 under Windows 10 Home (10.0.14393).

What have I tried:
Initially I saw this under LO 5.2.2.2 on the desktop, so I upgraded to 5.2.6.2. No change.
I uninstalled LO and reinstalled. No change.
I used IoBit Uninstaller to do a “deep uninstall” and then reinstalled. No change.

Again, the presentations that fail on the desktop work fine on the laptop, and presentations that worked fine on the desktop a couple of weeks ago now fail on the desktop.

I can imagine that there is some sort of system service that Impress uses to display videos (or thumbnails from videos) and that that’s what is failing. But I don’t know how to verify or fix that.

It appears these type of issues may be related to codecs and file format.
When codecs are missing from the viewer’s system this may cause the lock-ups.
So many people have issues with this I would like to find a definitive answer.
Would it be possible to make this presentation available for testing?

Also have you tested playing the videos in Windows Media Player on both systems?

The videos play fine in Windows Media Player (and in every other app I have that can play videos).
I have uploaded a simple (small) example presentation to Dropbox. Here’s the link: https://www.dropbox.com/pri/get/Public/Meadow%20Bunting.odp?_subject_uid=15169740&w=AAC99hhmg9B_jwnkwxhAlx4c9g5QTnPwG93j5r40xQyeyw
The file consists of 5 preliminary text slides and one video slide.
I hope you can find a clue here.

Cannot get to the file. Wants me to Login.

I asked about WMP because it would use the system codecs. So if one was missing is would not play.

Other players such as VLC have their own codecs included, so they will play anything even if your system does not have the codecs installed.

Try this link: Dropbox - Public - Simplify your life
I don’t use Dropbox often so I don’t know what I’m doing, but I think this one will work.

Nope, wrong again. This should be the link to the actual presentation: Dropbox - File Deleted

OK. Got it.
Let you know what I find.

Tested on 5.3.1.2, 5.2.6.2, and 5.4.x daily master - all work fine.
Looked at the media encoding - a few odd things (e.g. variable framerate, High L3).
Have you tried other more lowest-common-denominator encoding?
Have you tried a test like you sent me with different format and encoding (e.g. MP4, WMV).
Re-read your post above a few times.
Odd that it only happens on one machine.
I assume your clean re-install included deleting the user profile.

Thanks for the suggestion about deleting the user profile. I wasn’t aware of that, so I did the re-install again with the profile gone. Unfortunately, that didn’t change the bad behavior.
I have not tried other video encodings because, after all, the exact same presentations that now fail worked correctly in the recent past. If you think it might provide some insight, I’ll try some of that.

Now we’re getting somewhere. I converted the video to .wmv (two different resolutions, fixed and variable framerate) and inserted each of those into a presentation, and they’re all fine. (No other video formats seem to be supported.) So what would make .avi fail and .wmv work?

Generally, never use variable frame rate. Always use fixed frame rate.
Not sure yet which format and codec combinations will work.
Not documented at all, or very old and out of date.
LO is using what is available/supported in operating system.
So Linux, Mac, and Windows all support different format/codec combos.
And different levels may or may not be supported (e.g. High profile level 3).
Apple went with a lowest common denominator for a long time (Main L1).

And no CABAC or it would not play at all.
They have higher levels supported now.
But that type of restriction is what may be the issue here.
For example your files may have worked with a Main or Baseline profile.
Dunno. No documentation.
Have to do some testing. Format-by-format. Codec-by-codec.
And see what works and what does not.
Regardless, it should not crash on what it does not support.

Thanks so much for the suggestions. Now I can store new video files to make LO work.
Just one more question: I notice that I got a Windows update (W10 v1607) last week. Is it plausible that something in that update affected LO’s handling of .avi files (or the particular format/level of .avi file that I happened to choose)?

“Regardless, it should not crash on what it does not support.” That’s a very good point. Should I submit this on Bugzilla, or does the uncertainty about my system’s quirks make that not worthwhile?

More info. AVI video files fail if I use the H264 compression, but they work with MPEG4 or “Microsoft Video 1” compression. (Those are the VideoPad encoder option names. I don’t understand the significance.) So from what I can see, the problem is in H264 on my desktop, but I don’t know why it happened or if/how I can fix it. And if the same thing affects my laptop at some point, that’s a disaster for me, because all of my existing presentations become unusable and un-editable.

That is what I suspected. H.264 in an AVI container is somewhat unusual.
So it appears that Win10 does not support that particular format/codec combo.
It is hard for me to test this because I have so many encoding apps installed that I cannot see what the OS will not play natively.
H.264 support was added in Win7, but I suspect that was only in an MP4 container.
Try an MP4 with x264/AVC video and AAC audio.
Bet that will work on Windows 7-10, and Linux (?), and Mac (for sure).

I’m sure you’re right, but that still leaves the question of why those videos (H.264 in AVI) worked on my Win10 computer three weeks ago but not now. I’ve dealt with the immediate problem, but I dread having to go through lots of old presentations replacing the videos.

For the record, I downloaded and installed a “Codec pack” (Media Player Codec Pack v4.4.3), hoping that that would fix my problem by replacing whatever was failing to run H.264 AVI videos in Impress. It didn’t.

Here is what finally worked for me. Based on some hints that I found on www.codecguide.com, I downloaded Codec Tweak Tool 6.1.8 from www.videohelp.com. I installed and ran it, then clicked the DirectShow Filters button under Configuration. On the Filter Configuration screen, I clicked the ffdshow video decoder (x86) button, and found that the H.264/AVC format’s decoder was “disabled.” I selected the “libavcodec” instead, then clicked Apply and OK. After exiting from the Codec Tweak Tool, I restarted the computer and loaded one of my freezing presentations into Impress. Success! The slides containing avi videos now display with no problem in Normal View, Slide Pane, Slide Sorter, and Presentation.
I have no idea how the original problem happened, but I’m very happy to have it working again.
(Note: one tidbit of information that helped confirm I was on the right track is that LibreOffice uses DirectShow to display videos on Windows. So that was the piece that was failing for me, and that’s where I could concentrate my efforts.)

I am pretty sure Windows 10 is not using the free open source libavcodec library as its AVC decoder.
So I am guessing that something you installed messed-up the codec connections.
Codec packages, encoding tools, media burners, media players, all install codecs.
Glad to hear you got it sorted-out.