Track insertion transform for a VOD asset
Perform side-loading of subtitle files or other type of tracks to an existing VOD asset.
Track insertion transforms are created using the transform endpoint in MK.IO API.
Track side-loading is only available for MP4 content and requires a WebVTT file (.vtt) provided as input to the job.
Track insertion preset must use the #MediaKind.TrackInserterPreset value for @data.type attribute.
If the manifest has been played back before inserting a subtitle track, there will be a delay of up to 60s before the manifest will contain the subtitles, due to cache settings.
Configuration parameters
The following table lists the configuration parameters for the VTT side-loading:
Parameter | Description |
---|---|
@odata.type | Only subtitle track addition is supported for now and the following value must be used: #MediaKind.TextTrack |
trackName | The name of the track as it will appear in the manifest.. |
displayName | The display name of the track on a video player. In HLS, this maps to the NAME attribute of EXT-X-MEDIA. |
hlsSettings | The HLS specific setting for the track. The attributes for this object are described in a separate table. |
languageCode | The language code for the track. The value is an RFC5646 language code. |
playerVisibility | When playerVisibilityis set to Visible , the track will be present in the DASH manifest or HLS playlist when requested by a client.When the playerVisibilityis set to Hidden , the track will not be available to the client.The default value is 'Visible'." |
HLS Specific Settings
Parameter | Description |
---|---|
characteristics | The characteristics for the HLS setting. For subtitles, a comma separated string of public.accessibility.transcribes-spoken-dialog , public.accessibility.describes-music-and-sound and public.easy-to-read can be provided. |
default | A boolean indicating whether this track should be marked as a default track in the HLS playlist. If value is 1 , the HLS playlist will contain a DEFAULT=YES attribute. |
forced | A boolean indicating whether this track should be marked as a essential for playback in the HLS playlist. If value is 1 , the HLS playlist will contain a FORCED=YES attribute. |
Transform example
Below is a sample transform that illustrates how to use these parameters.
Once the transform is in place, it can be used to create a job on a given VOD asset.
Add a subtitle track to a VOD asset
Below is a sample transform that will add an English hearing-impaired VTT subtitle track.
curl --request PUT \
--url https://api.io.mediakind.com/api/ams/project_name/transforms/transform_name \
--header 'accept: application/json' \
--header 'content-type: application/json' \
--header 'Authorization: Bearer bearer-token' \
--data '
{
"properties": {
"outputs": [
{
"preset": {
"@odata.type": "#MediaKind.TrackInserterPreset",
"tracks": [
{
"@odata.type": "#MediaKind.TextTrack",
"trackName": "subtitle_en_US",
"displayName": "eng (hearing-impaired)",
"hlsSettings": {
"characteristics": "public.accessibility.describes-music-and-sound"
},
"languageCode": "en-US"
}
]
}
}
]
}
}
'
Updated 1 day ago