How to edit a text track in the Azure portal

When your live event has used live transcription to create a VTT or TTML file for use with captions and transcripts for the captured video, it's likely that the live transcription will need some editing. You may also want to deliver the text in multiple languages and allow your viewers to choose which to use in the player. This article covers how to edit the source VTT file in the Azure portal.

Find and edit the track

List asset tracks in the portal

1. Navigate to the Media Services account you want to work with.
2. Select Assets from the menu. The Assets screen will appear.
3. Select the Storage link for the asset you want to work with. The asset storage container screen will appear with a list of all the folders and track files for the asset.

Download and edit the track

1. Select the vertical ellipses next to the text track you want to work with. Live transcription text tracks are usually named auto-generated-best_4800.vtt.
2. Select Download. Save the file locally.
3. Open the file in your favorite text edit.
4. Reminder: Be careful with the timestamps.
5. Edit the text and correct anything that live transcription didn't capture properly.
6. Check for complete sentences and grammar.
7. Save the edited file with either the same name if you plan to overwrite the source file, or with a different name if not.

Upload the edited file

You can either upload a file with a different file name or you can overwrite the existing file.

1. Select Upload. The upload screen will appear.
2. Select file icon to select the file you want to upload. If the file already exists in the asset, you'll get a warning message.
3. If you want to overwrite the file, select the Overwrite checkbox.
4. Select Upload. The file will begin uploading.

You can upload additional files in the same way you uploaded the edited file.

Edit the .ism file to use the track

1. Navigate to the storage container associated with the asset.
2. Select the .ism file. The file screen will appear.
3. Select edit to view and edit the .ism file.
4. Add the following XML to the .ism file.
5. Set the systemLanguage parameter to the language designator for the language. For example, "en-us" for United States English or "ja-JP" for Japanese.
6. Set the trackID to a number.
7. Set the trackName to the language for the track.
8. Set the outputFlag parameter to:
   1. 3 to tell the client player to display the track.
   2. 2 to tell the client player that the track should be hidden.

The example below sets the text track to visible.

<textstream src="english.vtt" systemBitrate="0">
    <param name="textDisplayName" value="English" valuetype="data" />
    <param name="outputFlag" value="2" valuetype="data" />
    <param name="armId" value="english.vtt" valuetype="data" />
</textstream>