Generating Captions for Videos

Video Cloud Studio provides the ability to generate video captions for newly uploaded or existing videos. After the caption files are generated, they are automatically configured as part of the video's text tracks properties. Brightcove recommends using the caption editor for accuracy. Processing time to generate the captions will vary but it generally takes about 1.5x the length of the video to generate captions for a video.

In order to generate captions, the following are required:

• The videos must have been transcoded using a Context Aware or Dynamic Delivery ingest profile
• The minimum length of a video to generate auto captions is:
  • 5 seconds, if the language is specified
  • 15 seconds, if the language is auto-detected
• The maximum length of a video that can be auto-captioned is 4 hours

Video Cloud uses the follow process to determine the source that will be used to generate the captions.

• If the video has default audio track, that will be used as the captions source file (supported by default in the Media module)
• If the video has no default audio track but a master/mezzanine file exists, that will be used as the source file (supported by default in the Media module)
• If the video has no default audio track or master/mezzanine files, but audio tracks are specified in the Dynamic Ingest call, the specified audio track will be used (not yet supported in the Media module)
• If the video has no default audio track, no master/mezzanine files, and no audio track is specified, captions cannot be generated

If you are using a third-party to generate caption files, see Adding Captions to Videos using the Media Module for information on how to associate caption files with videos.

Generating captions when uploading videos

The Upload module provides an option to generate caption files when videos are uploaded. To generate a caption file during upload, follow these steps.

1. Open the Upload module.
2. Enable the Auto captioning option, the Automatic captioning settings dialog will open.

   

3. Select the Language to generate the captions in or select auto-detect to generate captions in the language spoken in the video. If a Language is not selected, the video language is auto-detected. Selecting a language will improve the caption file generation time and may improve overall accuracy.
4. Enter a Label. The label is typically set to the language used in the video. The label will be displayed in the CC dropdown in the video player and will be used by viewers to select the captions to be displayed.
5. Click Done.

Generating captions for an existing video

The Media module provides the option to generate caption files for existing videos in your account. To generate a caption file for an existing video, follow these steps.

1. Open the Media module.
2. Click the link for the video you want to edit to open the video properties.
3. Locate the Tracks tab and over the Text Tracks section click + Add
4. Select the Auto caption option.
5. Select the Language to generate the captions in. If a Language is not selected, the video language is auto-detected. Selecting a language will improve the caption file generation time and may improve overall accuracy.You can select the Status as Draft or Published.
6. The Label will be automatically generated, but you can also edit it. The label is typically set to the language used in the video. The label will be displayed in the CC dropdown in the video player and will be used by viewers to select the captions to be displayed.
7. Select the Status. The status determines if the captions will be public or remain as a draft.

   

8. Click Add.

The caption generation process will begin. When complete, a message will be displayed.



After the captions are generated, Brightcove recommends using the caption editor.

Generating captions for multiple videos

The Media module also provides the option to generate caption files for multiple videos at once. A maximum of 100 videos can be captioned at once. To generate a caption files for multiple videos, follow these steps.

1. Open the Media module.
2. Select the check box next to the videos you want to generate captions for.
3. Click More > Auto caption.

Editing caption files

After the caption files are generated, they are automatically configured as part of the video's text tracks properties. Chances are the caption generation process will not be perfect and you may need to edit product names, titles and punctuation. Brightcove recommends reviewing the generated captions.

1. At the top of the page, select the Tracks tab.
2. Locate the Text Tracks section. Click on and select the Edit track option

   

3. Edit the caption text as needed. Tab out of the field to save the changes.
4. Clicking Save draft will set the caption status to Draft and the captions will not be displayed. Clicking Publish will set the caption status to Published and the captions will be displayed.

Editing caption details

The Media module provides the option to edit caption details. To edit caption details, follow these steps.

1. At the top of the page, select the Tracks tab.
2. Locate the Text Tracks section. Click on and select the Edit track details option

   

3. Edit the caption details as needed.
4. Click Save.

Downloading caption files

The Media module provides the ability to download caption files. To download a caption file, follow these steps.

1. Open the Media module.
2. Click the link for the video you want to edit.
3. At the top of the page, select the Tracks tab.
4. Locate the Text Tracks section and click and select the Download option.

   

The caption file is a formatted WEBVTT file and can be edited using any text editor.

Deleting caption files

The Media module provides the option to delete caption details. To delete caption details, follow these steps.

1. At the top of the page, select the Tracks tab.
2. Locate the Text Tracks section. Click on and select the Delete option

   

Supported languages

Currently, auto captions are limited to the following languages.