Closed Captions guidance for Lecture Capture (Replay)

Contents

1. Introduction to Automatic Speech Recognition (ASR) captions
2. Video guide: Captions in Panopto
3. Enabling ASR captions for a folder
4. Importing ASR captions for a session
5. Editing captions
6. Exporting captions
7. Captions in MP4 files
8. Third-party captioning services

Introduction to Automatic Speech Recognition (ASR) captions

Closed Captions (akin to subtitles) are available for Panopto sessions. Panopto features an excellent Automatic Speech Recognition (ASR) engine, upgraded and greatly improved in March 2020, that automatically analyses the speech within a session, converts it to text and presents this as captions to the viewer underneath the player, as well as on the left-hand side within the Captions tab (Fig. 1).

Selecting a caption on the left-hand side will cause the playhead to jump the relevant section of the session. Viewers can adjust the style of the captions by clicking on the ellipsis in the bottom-right underneath the player.

Fig. 1. Closed captions can be displayed underneath the Panopto player by the viewer clicking the CC button. Captions are also displayed as a timed transcript within the Captions tab on the left-hand side.

Accuracy of the ASR captions is dependent on audio quality, clarity of speech, and subject matter. Below are some tips for improving the accuracy and usefulness of captions.

• Stay within microphone range
• Don't stand too close to any speakers (to avoid audio echo)
• Speak clearly at a normal, steady pace
• Describe visual information

Video guide: Captions in Panopto

Click the small, white arrow at the bottom-centre of the video to view chapters (click chapter heading to jump to that section of the video)

Enabling ASR captions for a folder

NB. Newly created folders will have automatic machine captions enabled by default

ASR captions can be enabled on a per-folder basis within the Folder Settings > Settings tab by selecting "Automatic Machine Captions" in the dropdown menu with the Captions settings (Fig. 2). This setting is applied as default for any folder created from 1st August 2020.

Fig. 2. Enabling automatic captions within the Panopto folder settings.

Importing ASR captions for a session

Captions can also be imported on a per-session basis within the Panopto web editor via the Captions tab, click Import Captions > Import Automatic Captions (Fig. 3).

Fig. 3. Within the Captions tab, click Import captions > Import automatic captions to generate ASR captions for this session.

Editing captions

Captions can be manually edited within the Panopto web editor by clicking on the vertical ellipsis icon > Edit (Fig. 4). Remember to hit the Apply button at the top of the page to save changes.

Fig. 4. Click on the vertical ellipsis > Edit to modify the caption text. You can also delete unwanted captions.

Exporting captions

Captions can be exported from Panopto as an SRT file - a standard, open-source, plain-text format widely used for video subtitles, and compatible with media players such as VLC Player (https://www.videolan.org/) as well as video distribution platforms such as YouTube. Only users with Creator access for the Panopto session may export the SRT caption file. To export captions, visit the session Settings > Captions tab, click on the small triangle next to "Default" to reveal the download links (Fig. 5). If you have already modified the captions or edited the session using the Panopto web editor, you will have the choice of downloading either the raw (unedited) caption file, or the edited caption file (which will contain your modifications and timings will match the edited Panopto session). You can also remove all captions by clicking "Delete Captions".

Fig. 5. The Captions tab of the Session Settings provides the ability to delete, download and upload the captions file.

The downloaded file will have the extension .ASHX. Simply change this to .SRT, then open the file using any text editor e.g. NotePad (Windows) or TextEdit (macOS) to make further modifications. The SRT file can also be re-uploaded into Panopto. First you will need to delete the existing captions using the "Delete captions" link on the page shown in Fig. 4. If you downloaded the edited caption file, when re-uploading remember to check the box indicating "Captions are based on the edited session", otherwise timings may be incorrect. This workflow is useful if you prefer to edit the captions outside of the Panopto web editor (Fig. 6).

Fig. 6. The plain-text captions file can be easily edited using any text editing software.

Captions in MP4 files

Captions are also embedded within MP4 files exported from Panopto, and these can be displayed or hidden depending on the viewer's preference (Fig. 7). The ability to export MP4 files for offline viewing is another useful accessibility feature of Panopto, and guidance on exporting MP4 files can be found here.

Fig. 7. Captions are embedded within MP4 files exported from Panopto. These captions can be enabled when viewing the MP4 files using VLC Player (shown) and other media players.

Third-party captioning services

As an alternative to the free ASR captioning functionality, captioning by a human is also available via integration with third-party professional captioning services. Accuracy is typically very high (98%+), though as with ASR captioning, it is dependent on audio quality, clarity and subject matter. The cost is typically £180 per hour of captioned content with a five-day turnaround. Please contact the Replay team via replay@it.ox.ac.uk for further information.