How to edit a text track in the Azure portal

Article
02/14/2023

Warning

Azure Media Services will be retired June 30th, 2024. For more information, see the AMS Retirement Guide.

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

Navigate to the Media Services account you want to work with.
Select Assets from the menu. The Assets screen will appear.
The tracks in the asset will be listed in the Tracks list.

Edit the track

There are two ways to edit the track. You can either edit the track in the Azure portal or download the track and edit it locally.

Warning

Be careful that you don't edit the timestamps!

Edit the track in the Azure portal

Select Edit captions next to the track you want to edit. The Captions editing screen will appear.
Edit the file.
Select Save.

Download and edit the track

Select the vertical ellipsis next to the text track you want to work with. NOTE: Live transcription text tracks are usually named auto-generated-best_4800.vtt.
Select Download. Save the file locally.
Open the file in your favorite text edit.
Edit the text or correct anything that live transcription didn't capture.
Save the edited file.

Upload captions

Once the job is completed, the resulting files from the encoder will be in the output asset. You will use this asset going forward.

Navigate to the output asset used to hold the results of encoding.
Select Add text track.
Enter a name in the Name field. For example, for an English text track enter English.
Select Upload new radio button. Alternatively, if you have already created or uploaded a VTT file, you can select the Use existing radio button and select the track.
Enter the text to be displayed in the player in the Display name field.
Select either Visible radio button to ensure that the track will be displayed in the player client.
Select the HLS settings checkboxes to set the track as the default track and/or set forced. For English, set it as the default track.
Select the Accessibility characteristics checkboxes to identify what accessibility guideline the text track is used for.
Select I agree and upload to upload the text track.

View the caption streams in the manifest

View the manifest to see the track changes in the manifest file.

You should already be on the output asset screen.
Select the storage container link. The storage container name starts with the "asset-" prefix. The storage container screen will appear.
Select the .ism file from the file list. The blob screen will appear.
Select Edit.
Look for the following XML above the </switch> element, changing the VTT file names to the ones you've uploaded.

    <textstream src="sample.cmft" systemBitrate="52" systemLanguage="en-us">
        <param name="systemLanguage" value="en-us" valuetype="data" />
        <param name="outputFlag" value="3" valuetype="data" />
        <param name="systemBitrate" value="52" valuetype="data" />
        <param name="transcriptsrc" value="en-us.vtt" valuetype="data" />
        <param name="textIsDefault" value="TRUE" valuetype="data" />
        <param name="textHlsCharacteristic" value="public.accessibility.transcribes-spoken-dialog" valuetype="data" />
        <param name="trackID" value="1" valuetype="data" />
        <param name="trackName" value="subt_en-us" valuetype="data" />
        <param name="textDisplayName" value="English" valuetype="data" />
        <param name="armId" value="English" valuetype="data" />
    </textstream>
    <textstream src="es-es.cmft" systemBitrate="50333" systemLanguage="">
        <param name="systemLanguage" value="" valuetype="data" />
        <param name="outputFlag" value="3" valuetype="data" />
        <param name="systemBitrate" value="0" valuetype="data" />
        <param name="transcriptsrc" value="es-es.vtt" valuetype="data" />
        <param name="textHlsCharacteristic" value="public.accessibility.transcribes-spoken-dialog" valuetype="data" />
        <param name="trackID" value="1" valuetype="data" />
        <param name="trackName" value="subt" valuetype="data" />
        <param name="textDisplayName" value="Español" valuetype="data" />
        <param name="armId" value="Spanish" valuetype="data" />
    </textstream>

Get help and support

You can contact Media Services with questions or follow our updates by one of the following methods:

Q & A
Stack Overflow. Tag questions with azure-media-services.
@MSFTAzureMedia or use @AzureSupport to request support.
Open a support ticket through the Azure portal.

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