Creating and editing captions
Custom dictionaries
Our Custom Dictionary functionality biases the speech recognition algorithms used by Amazon Transcribe and Speechmatics towards a predefined set of terms, improving transcription accuracy for content containing:
- Product names
- Technical jargon
- People’s names
- Brand-specific terminology
This is particularly useful when you know the vocabulary that's likely to appear in your video.
Custom dictionaries are language-aware rather than locale-specific, meaning a single dictionary can be reused across regional variants of the same language. For more information, see Language variants.
Creating a custom dictionary
Before using the Custom dictionary feature, you’ll need to create one:
- Open the Custom dictionaries page from the sidebar.
- Click New custom dictionary.
- Give your dictionary a name, select its language and provide a description if needed.
- Click Create & add terms.
- Add your terms. We recommend keeping your dictionary to fewer than 1,000 entries.
- Add terms manually: type them manually or paste them in bulk (from a text editor or spreadsheet)
- Paste list of terms: paste the terms separated by new lines
- Import from CSV: choose or drag and drop a CSV file
- Generate terms from a source: Use AI to extract terms from:
- A URL
- A document of up to 25,000 characters at a time, including PDF, Word and text files
- An existing CaptionHub project that you select
- Free text that you paste
- Click Submit or Update to save the terms to your dictionary.
- If you used Generate terms from a source, review the suggested terms, select the ones you'd like to add and click Add accepted terms.
Note: Large custom dictionaries can reduce transcription quality, although they do not affect transcription latency. If your dictionary contains a large number of entries, CaptionHub will display a warning.
The Sounds like field is optional and can be used when a term's spelling does not clearly indicate its pronunciation. This is particularly useful for names, product names, abbreviations or terms such as Porsche 911 or .NET.
You can also add an optional Note to record any additional information about a term.
CaptionHub will automatically suggest when a pronunciation hint may be helpful. You can also refer to the Custom Dictionary examples for guidance.
Duplicate entries in your custom dictionary will be highlighted. A warning indicator at the top of the page will also show the number of duplicate entries found. Click this indicator to filter the list and display only duplicate entries.
Adding terms directly from the caption editor
You can also add words to a Custom Dictionary while editing your original captions.
- While editing a caption, highlight and right-click the word you want to add.
- Select Add to Custom dictionary.
- Choose the dictionary you want to add the term to and edit the Text and Sounds like fields if required.
- Click Submit.
The selected word will be added to the dictionary immediately and will be available for future transcriptions, allowing you to improve recognition without leaving the editor.
Using a custom dictionary for transcription
After creating your dictionary, you can apply it when generating a new transcription.
- Click Create captions and choose Auto-transcribe.
- If Amazon Transcribe or Speechmatics is selected as your transcription provider, choose the custom dictionary you'd like to use.
- Make sure your preferred transcription provider is enabled under Team settings > Transcription.
- Complete the remaining transcription settings and click Submit.
Language variants
Custom dictionaries automatically work across regional variants of the same language. As long as the base ISO language matches, you only need to maintain a single dictionary.
For example, a dictionary created for English (UK) can also be used with English (US) or English (Global).
This behaviour applies when:
- Auto-transcribing from the Original captions tab
- Using an Automation template
Updating your custom dictionaries
Once you have created a custom dictionary, you can update it at any time. Click the dictionary to open its edit page.
From here, you can:
- Change the dictionary name or description by clicking the pencil icon next to them.
- Change the dictionary language by opening the language dropdown and selecting a new language.
- Add terms manually using the text fields at the top of the page.
- Edit an existing term, pronunciation hint or note by clicking the pencil icon next to it.
- Remove terms by clicking Remove. You can also select multiple terms and click Remove X terms to remove them in bulk.
- Search for terms using the Search terms... field.
- Use the More actions (⋮) menu to
- Mark the dictionary as default
- Paste a list of terms
- Import terms from a CSV file
- Export phrases
- Duplicate the dictionary
- Delete the dictionary
- Use Suggest terms to access the same options available when using Generate terms from a source while creating a new dictionary.
- Use Improve terms to analyse the terms in your dictionary and identify potential improvements, such as adding pronunciation hints, correcting spelling or removing terms that may be ineffective. Once the analysis is complete, review the suggested improvements, accept or reject them as needed and click Apply selected to confirm.
Don't forget to click Update to save any changes to your dictionary.
Managing your custom dictionaries
The Custom dictionaries page lets you manage all dictionaries available to your team.
The page displays:
- Name: The name of the dictionary.
- Terms: The total number of terms it contains.
- Used in projects: The number of projects where the dictionary has been used.
- Language: The language assigned to the dictionary.
- Last updated: The date the dictionary was last modified.
The More actions (⋮) menu provides the following options:
- Edit: Update the dictionary contents, including searching, editing, selecting and bulk deleting terms.
- Mark as default: Automatically apply the dictionary to supported original caption transcriptions created from the Original captions tab or through Automation templates.
- Export phrases: Export all dictionary entries as a CSV file.
- Duplicate: Create a copy of the dictionary, which can be useful when creating a variation.
- Delete: Permanently remove the dictionary.
