Auto-generation of Captions for Teams Video Messages

In September 2022, Microsoft announced the ability to send video messages in Teams chat. Released in November 2022, the feature allows users to send video clips up to one minute long to participants in Teams private or group chats, if the Teams messaging policy assigned to their accounts allows video messages.

Sometimes it’s hard to listen to video messages and understand fully what the sender says. Microsoft addresses that problem in an update to add support for auto-generated captions that can be read by message recipients with the sound turned on or off. The availability of captions makes it possible to read a video message in a crowded space where you don’t want to turn the device volume up to hear the audio.

According to message center notification MC534735 (last updated March 31, 2023), users in targeted release tenants have started to receive the feature while deployment to standard release tenants will start in mid-April and complete by the end of the month.

Microsoft doesn’t say what languages are available for video message transcripts. Given that meeting transcription is available in 34 languages, I imagine that the same applies.

Caption Auto-Generation

It’s likely that the same process that generates live captions for Teams meetings is employed to generate the captions for video clips. Generation occurs when the sender sends the video message. At that point, Teams uploads the video file to an online repository where the captions are generated.

Figure 1 shows a video messages with captions displayed (enabled with the CC or closed captioning button). Recipients can play video messages in line within the chat or can expand to full screen, which uses what appears to be a version of the Stream video player with minimal playback options (quality, speed, forward/back 10 seconds, turn audio off, etc.).

Caption Transcript File

Captions form the basis for transcript generation in Teams meetings and for other videos stored in Stream. Each caption is text generated for a timecoded part of a video or audio file. Only the sender of the video message can download the transcript (Figure 2).

The result is a file called MicrosoftTeams-transcript.vtt. VTT or WebVTT is a Video Text Tracks file and is a common format used for video subtitling. You can use a text editor like Notepad to open and view the contents of a VTT file like the one shown below.

WEBVTT

00:00:00.340 --> 00:00:03.539

The review for the Office 365 for IT

00:00:03.540 --> 00:00:07.359

Pros 2024 Edition

00:00:07.360 --> 00:00:10.799

will take place on the 27th of April

00:00:10.800 --> 00:00:12.210

and I hope you can be there

Downloading a Video Message

Speaking of downloads, Teams doesn’t offer users the option to download a video clip. It’s possible to do this, but only by using developer tools. In summary:

• Press F12 to open developer tools in the browser.
• Select the Network tab.
• Open the chat where the video message is and play it.
• In the Name section of developer tools, look for 0 (zero) and then look at the Headers tab. You should find a Request URL there that points to the location where Teams fetches the video from (Figure 3). Copy this value to Notepad or your favorite text editor.
• In the editor, select the /dash_video_orginal/videoSegment/0 part of the URL and replace it with /video
• The result should be a URL like https://eu-prod.asyncgw.teams.microsoft.com/v1/objects/0-neu-d1-c4457fef4c67a75fe3c0732e0aceb538/views/video.
• Paste this into a browser tab to download the video message (MP4 file).

Video Messages and Compliance

When I wrote about Teams video messages in September 2022, I pointed out that it’s difficult for compliance investigators to find information in video messages. I had hoped that the advent of transcripts for video messages would close the compliance gap and make it easier to find video messages based on the information captured in the transcript. Alas, this is not so. All my attempts to find video messages by inputting transcript contents into content searches failed. That’s a real pity.

Good Upgrade but Compliance is a Real Miss

Adding transcripts to video messages in Teams chat is a nice upgrade. It would be even nicer if Microsoft addressed the compliance issue as the inability to search for video content (now available in the transcripts) is more than enough to stop some organizations using this facility.

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Use Test-Message to Validate Exchange Online Rules Processing Against Email

Announced in Microsoft 365 message center notification MC503297 (26 January 2023, roadmap item 100494), the Exchange Online Test-Message cmdlet is now generally available. The purpose of the cmdlet is very simple: it tests the path of a message through the rules applied by the Exchange Online transport service to reveal what actions those rules take. The intention is to help tenant administrators understand why a rule doesn’t function as expected without having to ask Microsoft support for assistance.

The set of tested rules include:

• Exchange Online transport rules (ETRs, also known as mail flow rules). Up to 300 ETRs can exist in an Exchange Online organization to do anything from automatically copying messages sent to a certain domain to applying disclaimers to outbound messages (here’s an example of using an ETR to apply a special disclaimer for calendar meeting notifications.
• Rules created to enforce actions from Microsoft 365 DLP policies. For example, to stop people sharing confidential information with external recipients.
• Rules created to apply Microsoft Purview retention or sensitivity labels.

Over time, my small tenant has accumulated 25 different transport rules plus a set of DLP policies and some auto-label policies. The permutations and combinations involved in rule processing within the transport service can become very complex indeed. ETRs have a priority order to determine how the transport service runs the rules. A rule can force processing to stop if necessary. DLP policies run after ETRs, and auto-labeling then kicks in if a message is allowed to proceed by ETRs and DLP.

Test-Message Examples

Here’s a simple example of the Test-Message cmdlet in action:

Test-Message -Sender Lotte.Vetler@office365itpros.com -Recipients Flayosc@outlook.com -SendReportTo Jim.Flynn@office365itpros.com -TransportRules -UnifiedDlpRules

This kind of test runs rules against a sample message. It can only check the message sender and recipients, so apart from cycling through all the available rules, it’s not a very extensive test.

A slightly more complicated example uses a test message that I created with Outlook and saved as a message file. Using a test message makes sure that rules run against precisely the kind of traffic that you expect the rule to detect and process. For instance, you might want to include some specific keywords in the message subject or body text, or an attachment of a certain type.

To pass the message to Test-Message, it must first be encoded and stored in a variable, which is then specified in the MessageFileData parameter.

$EncodedText = ([System.IO.File]::ReadAllBytes('c:\temp\TestMessage.msg'))

Test-Message -MessageFileData  $EncodedText -Sender Lotte.Vetler@office365itpros.com -Recipients Flayosc@outlook.com -SendReportTo Jim.Flynn@office365itpros.com -TransportRules -UnifiedDlpRules

Server                                  MessageId
------                                  ---------
PAXPR04MB8095.EURPRD04.PROD.OUTLOOK.COM 626b8a86-c262-4457-911b-641a027989d7@DB9PR04MB8445.eurprd04.prod.outlook.com

The server information reported by the cmdlet is the Exchange Online mailbox server where the transport rules run. Given the massive pool of Exchange Online servers, it’s likely that Test-Message will use a different server each time it runs.

Test-Message Output

The output is in messages delivered to the address specified in the SendReportTo parameter for each type of rule processed by the test. In my case, the test generated three messages (DLP, auto-label, and ETR). Figure 1 shows the results for the ETR test. We can see that a match occurred for the Office 365 Message Encryption for selected external domains rule, which executed two actions to apply rights management protection to the message with custom branding. After executing the two actions, the transport service stopped processing further rules because the rule settings forced an exit.

Steps to Follow for Rule Creation

Nice as it is to have a cmdlet to help test rules processing, it won’t replace the simple rules that experienced administrators follow when setting up new ETRs or DLP policies.

• Know what your rule should do (the actions).
• Know what conditions the rule needs to detect before it runs.
• Know what exceptions (if any) exist.
• Start with a simple rule and build complexity gradually.
• Always ask if your rule is likely to interfere with another rule before enabling it. You might be able to make a small adjustment to an existing rule to do what you want instead of creating a brand-new rule.

The last point is the most important.

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