# Enabling overlay ads
<a name="overlay-ads-getting-started-enabling"></a>

MediaTailor support for overlay ads is enabled by default. A specific SCTE-35 ad-marker type in the manifest triggers the insertion of an overlay ad. Because some players might not support client-side rendering of overlay ads, you can disable the feature at the session level.

**To disable overlay-ad support using HLS or DASH playback prefixes:**
+ From the player, initialize a new MediaTailor playback session using a request in one of the following formats, according to your protocol:
  + Example: HLS format

    ```
    GET {{mediatailorURL}}/v1/master/{{hashed-account-id}}/{{origin-id}}/{{asset-id}}?aws.overlayAvails=off
    ```
  + Example: DASH format

    ```
    GET {{mediatailorURL}}/v1/master/{{hashed-account-id}}/{{origin-id}}/{{asset-id}}?aws.overlayAvails=off
    ```

**To disable overlay-ad support using the session-initialization prefix:**
+ On the player, construct a JSON message body for the session initialization request to MediaTailor:
  + To disable ad-overlay support, add an `overlays` object as a top-level key with a value of `off`. The default `overlays` value is `on`.
  + (Optional) Provide any parameters that MediaTailor then passes to the ADS inside an `adsParams` object. These parameters correspond to `[player_params.param]` settings in the ADS template URL of the MediaTailor configuration.

**Example : HLS**  

```
POST master.m3u8
    {
       "adsParams": {
           "deviceType": "ipad"
       },
       "overlayAvails": "off"
    }
```

**Example : DASH**  

```
POST manifest.mpd
    {
        "adsParams": {
           "deviceType": "androidmobile"
       },
       "overlayAvails": "off"
    }
```