#115 Videos that are located on separate domain do not load in SEB

[Fernando Oliveira]

Videos that are located on separate domain do not load in SEB.

The "filter" feature (in the network tab) seems like it should do the trick, but it doesn't. Take a look at this screenshot:

https://www.screencast.com/t/w0cd9UCBti

The filter setting allows the video player to show in the quiz, but the video itself will not play.

Are there any additional dependencies?

Thanks,
Fernando

[Damian Büchel]

Please note that SEB 3.x only supports open-source video codecs.

[Fernando Oliveira]

Our videos are all mp4, which I believe are encoded in the H.264 format.

[Damian Büchel]

Exactly, that is a proprietary format.

[Fernando Oliveira]

I may be reading this incorrectly, but says here that H.264 is open source:

https://en.wikipedia.org/wiki/List_of_open-source_codecs
https://en.wikipedia.org/wiki/OpenH264

[Fernando Oliveira]

I replaced the mp4 videos with WebM (and VP8 codec) but still can't get them to work on Mac OS. Is there anything special that needs to get changed on on the SEB config side?

[SEB Support]

I thought you said the videos are playing on Macs?

[Fernando Oliveira]

Yes, MP4 videos play on Mac but not on PC. And WebM play on PC but not on Mac! Tried many different settings but can't get it to work.

[SEB Support]

Unfortunately SEB cannot do anything about that. Do some research about playing videos in browsers, you will see that Safari doesn't support WebM and some browsers don't support MP4. Therefore (as far as I know) web develpers use Javascript players like http://jplayer.org which select the right format for each platform and they provide two formats of every video. Web compatibility is bad, up to today.

[Fernando Oliveira]

Strangely, the videos play on Mac computers but not PC.

[SEB Support]

That's because Apple is providing H.264 codecs in the operating system (macOS and iOS), thus they don't need to be provided by the browser.

[Fernando Oliveira]

Got it. Is there anything I can add to the "Permitted processes" section to allow it to work on Windows OS? Otherwise, any other suggestions for a workaround? Thanks.

[Fernando Oliveira]

Does SEB use the H.264 open source binary module that’s maintained by Cisco? This video provides a good overview: https://vimeo.com/79578794

[SEB Support]

No, SEB cannot use that Cisco H.264 module, because SEB is using the CefSharp framework as browser engine. As you can see in its release notes "Due to licensing issues default builds do not support proprietary codecs like H264/AAC".

We clarified this, it doesn't seem feasible to add the Cisco H.264 module to CefSharp (it would require to completely rebuild it) and licensing at least of the AAC codec (which is used often together with H.264) seems impossible for an open source freeware project like SEB.

The only feasible way how to support MP4 H.264/AAC in future on Windows seems to switch completely to the Microsoft WebView2 (which is also Chromium-based). Unfortunately WebView2 currently lacks some features which SEB requires, so we need to wait until Microsoft adds those missing features.

[Lukas Stampfer]

Dear SEB support,
we are currently having students watch videos from a peertube platform hosted by our university. This appears to work well for most users of windows and mac (as long as windows users have the legacy version 2.4.1). Unfortunately we now have the second but rare case of mac users that are just unable to watch the video. There is a error code saying:

On 29 Apr 2021, Safe Exam Browser tried to establish a connection to tube1.it.tuwien.ac.at on port 443 (https). The request was denied automatically during login.

minimum version of macOS seems to be in order, also I tried uploading the videos in webM format instead of mp4 like before - but still not solving the problem. I am trying now to use MediaCoder to convert to a h.264 format with flac audio codec (in hope this is in fact an open source codec) and will hope this can solve my problem. But as you might see, I am a bit fishing in the dark - any advice on how I could solve this problem or any experiences where this might come from?

[SEB Support]

If this happens only on a few Macs and works on others, then there must be something different on those machines, try to figure out what:

• Are they using the latest SEB version (2.3.2 for macOS, don't use any older, as there have been many issues fixed in the latest) or do those students use another version?
• The error message indicate some network issue. Investigate if they use some third party software which monitors, filters (anti-malware software) or customizes network access. Most of that kind of software manipulates root certificates or some other network behavior and has to be disabled or uninstalled before using SEB (especially if there are indications of network issues)
• Make sure their internet connection is good enough, especially if the errors happen arbitrarily. SEB aborts page loads when single resources cannot be loaded, other web browsers sometimes just ignore that (what wouldn't be a good idea in an exam...)
• The affected Macs might be infected with some malware. We had such cases which actually SEB discovered, because it detected misbehaving processes and tried to terminate them (and displayed an error if that wasn't possible)
• Are the affected students using a different macOS version than all the others?
• Students might try to cheat and using manipulated versions of SEB

[Lukas Stampfer]

Thank you for the fast reply, I forwarded this to maybe be able to locate the problem. As this is quite a large course I don't really have a possiblility to compare what systems students are using, but it seems to be working for most people, as for several hundred students I only have two mentions of SEB not showing the video properly.

But for one student with this problem I do have the system information at hand:
SEB Version 2.3.2.
OS X 10.11.1 El Capitan
Model Name: MacBook
Model Identifier: MacBook5,1
Processor Name: Intel Core 2 Duo
Processor Speed: 2 GHz
Number of Processors: 1
Total Number of Cores: 2
L2 Cache: 3 MB
Memory: 8 GB
Bus Speed: 1,07 GHz
Boot ROM Version: MB51.007D.B03
SMC Version (system): 1.32f8

further internet connection is apparently stable and the videos on the desired platform are accessible with other browsers than SEB

[SEB Support]

Given the relation of several hundred to two it will most likely be some third party tool interfering with SEB. Some students might use Little Snitch or similar network monitoring tools. Some tools might interfere with SEB, but usually that applies only to software which does things not recommended by Apple (replacing root certificates as some anti-malware scanners do for example is a Man-in-the-Middle Attack and I would definitely never use such software).

An idea what students could try first: Start their Mac in Safe Mode, as SEB should probably run but such tools would be disabled:
https://support.apple.com/en-us/HT201262
Safe mode prevents your Mac from loading certain software as it starts up, including login items, system extensions not required by macOS, and fonts not installed by macOS.