--- title: "Update an asset track" method: PATCH path: "/video/v1/assets/{ASSET_ID}/tracks/{TRACK_ID}" tags: ["Assets"] --- # Update an asset track `PATCH /video/v1/assets/{ASSET_ID}/tracks/{TRACK_ID}` ## Request - Base URL: `https://api.mux.com` - URL: `https://api.mux.com/video/v1/assets/{ASSET_ID}/tracks/{TRACK_ID}` - Auth: one of: - HTTP basic - HTTP bearer Updates the details of an existing Asset Track with the provided Asset ID and Track ID. ## Path parameters - `ASSET_ID` string, required - `TRACK_ID` string, required ## Request body - UpdateAssetTrackRequest - `language_code` string: The language code of this track. The value must be a valid BCP 47 specification compliant value. For example, en for English or en-US for the US version of English. - `name` string: The name of the track containing a human-readable description. This value must be unique within each group of `text` or `audio` track types. The HLS manifest will associate the `text` or `audio` track with this value. For example, set the value to "English" for subtitles text track with `language_code` as en-US. If this parameter is not included, Mux will auto-populate a value based on the `language_code` value. - `closed_captions` boolean: Indicates the track provides Subtitles for the Deaf or Hard-of-hearing (SDH). - `passthrough` string: Arbitrary user-supplied metadata set for the track either when creating the asset or track. ## Response `200` OK - UpdateAssetTrackResponse - `data` Track, required - `id` string: Unique identifier for the Track - `type` 'video' | 'audio' | 'text': The type of track - `duration` number, double: The duration in seconds of the track media. This parameter is not set for `text` type tracks. This field is optional and may not be set. The top level `duration` field of an asset will always be set. - `max_width` integer: The maximum width in pixels available for the track. Only set for the `video` type track. - `max_height` integer: The maximum height in pixels available for the track. Only set for the `video` type track. - `max_frame_rate` number, double: The maximum frame rate available for the track. Only set for the `video` type track. This field may return `-1` if the frame rate of the input cannot be reliably determined. - `max_channels` integer: The maximum number of audio channels the track supports. Only set for the `audio` type track. - `text_type` 'subtitles' | 'chapters': This parameter is only set for `text` type tracks. - `text_source` 'uploaded' | 'embedded' | 'generated_live' | 'generated_live_final' | 'generated_vod': The source of the text contained in a Track of type `text`. Valid `text_source` values are listed below. * `uploaded`: Tracks uploaded to Mux as caption or subtitle files using the Create Asset Track API. * `embedded`: Tracks extracted from an embedded stream of CEA-608 closed captions. * `generated_vod`: Tracks generated by automatic speech recognition on an on-demand asset. * `generated_live`: Tracks generated by automatic speech recognition on a live stream configured with `generated_subtitles`. If an Asset has both `generated_live` and `generated_live_final` tracks that are `ready`, then only the `generated_live_final` track will be included during playback. * `generated_live_final`: Tracks generated by automatic speech recognition on a live stream using `generated_subtitles`. The accuracy, timing, and formatting of these subtitles is improved compared to the corresponding `generated_live` tracks. However, `generated_live_final` tracks will not be available in `ready` status until the live stream ends. If an Asset has both `generated_live` and `generated_live_final` tracks that are `ready`, then only the `generated_live_final` track will be included during playback. - `language_code` string: The language code value represents [BCP 47](https://tools.ietf.org/html/bcp47) specification compliant value, or 'auto'. For example, `en` for English or `en-US` for the US version of English. This parameter is only set for `text` and `audio` track types. During automatic language detection for generated subtitles, this value will be set to `auto` until the language is determined. - `name` string: The name of the track containing a human-readable description. The HLS manifest will associate a subtitle `text` or `audio` track with this value. For example, the value should be "English" for a subtitle text track for the `language_code` value of `en-US`. This parameter is only set for `text` and `audio` track types. - `closed_captions` boolean: Indicates the track provides Subtitles for the Deaf or Hard-of-hearing (SDH). This parameter is only set tracks where `type` is `text` and `text_type` is `subtitles`. - `passthrough` string: Arbitrary user-supplied metadata set for the track either when creating the asset or track. This parameter is only set for `text` type tracks. Max 255 characters. - `status` 'preparing' | 'ready' | 'errored' | 'deleted' | 'skipped': The status of the track. `skipped` means the track was not created because the asset doesn't support it, for example generated subtitles on an asset with no audio. - `primary` boolean: For an audio track, indicates that this is the primary audio track, ingested from the main input for this asset. The primary audio track cannot be deleted. - `auto_language_confidence` number, double: The confidence value (0-1) of the determined language. This value only is available when automatic language detection is utilized in generated subtitles. ## Changes - **2026-11-04** `f55c89fc911c`: 1 warning - added the new `skipped` enum value to the `data/status` response property for the response status `200` - **2026-10-02** `395805a20280`: 1 warning - added the new `chapters` enum value to the `data/text_type` response property for the response status `200` - **2026-08-12** `5b4b3133f27d`: 1 warning - removed the optional property `data/max_channel_layout` from the response with the `200` status - **2026-04-16** `5d0fe920dfba`: 1 info - endpoint added [Operation history](https://skmtc.dev/muxinc/apis/mux-api/changes/video/v1/assets/:ASSET_ID/tracks/:TRACK_ID/patch.md) --- [API](https://skmtc.dev/muxinc/apis/mux-api.md) - [All operations](https://skmtc.dev/muxinc/apis/mux-api/llms.txt) - [OpenAPI document](https://skmtc.dev/muxinc/apis/mux-api/revisions/75b4251a1d96?raw)