# Streaming protocols

The media engine outputs your live stream in multiple protocols to ensure broad device and player compatibility. The following output protocols are supported: **HESP** and **HLS**. Additionally, **WebRTC** can be configured at the distribution level for sub-second real-time delivery.

### HESP — High Efficiency Streaming Protocol

HESP is a next-generation streaming protocol designed for ultra-low latency live delivery. It is the default and recommended output protocol for the Dolby OptiView Live platform.

* **Ultra-low latency** — delivers end-to-end latency in the 1 to 5 seconds range, significantly lower than traditional HLS.
* **Fast channel switching** — viewers experience near-instant startup and channel changes.

### HLS (CMAF) — HTTP Live Streaming

HLS is the industry-standard protocol developed by Apple for delivering live and on-demand content over HTTP. The media engine outputs HLS using modern CMAF (fragmented MP4) segments.

* **Broad compatibility** — supported by virtually all modern browsers, devices and players.
* **Higher latency** — HLS typically delivers latency of 8 seconds or more, compared to 1–5 seconds with HESP.

### HLS (MPEG-TS)

HLS with MPEG-TS segments is an older variant of HLS that uses traditional transport stream segments instead of CMAF.

> **Warning**
>
> Only use HLS MPEG-TS if you are targeting a platform that genuinely does not support CMAF-based HLS — for example, certain legacy set-top boxes or embedded devices. In all other cases, use the standard CMAF HLS output, which offers better performance and broader modern device support.
>
> HLS MPEG-TS does not support all platform features. For example, [DVR](https://docs-preview.optiview.dolby.com/pr-860/theolive/channel/dvr.md), [Nielsen](https://docs-preview.optiview.dolby.com/pr-860/theolive/channel/nielsen.md), and [DRM](https://docs-preview.optiview.dolby.com/pr-860/theolive/media-engine/drm.md) are not available with this output format.

### WebRTC

WebRTC enables sub-second, real-time delivery by connecting a distribution to an [OptiView Real-time streaming](https://docs-preview.optiview.dolby.com/pr-860/millicast/getting-started.md) source. Unlike HESP and HLS — which are configured on the engine — WebRTC is configured per distribution. This allows you to add real-time delivery to specific distributions while keeping standard protocol delivery on others.

* **Sub-second latency** — delivers end-to-end latency under 500 ms, the lowest of all supported protocols.
* **Hybrid delivery** — works alongside HESP and HLS. The player automatically selects the best available protocol based on priority.

See the [WebRTC distribution guide](https://docs-preview.optiview.dolby.com/pr-860/theolive/distribution/webrtc.md) for configuration details and API examples.

## API example

You can configure output protocols via the API using the `outputs` object when [creating](https://docs-preview.optiview.dolby.com/pr-860/theolive/api/create-channel-engine.md) or [updating](https://docs-preview.optiview.dolby.com/pr-860/theolive/api/update-engine.md) an engine.

`POST https://api.theo.live/v2/channels/{channelId}/engines`

```json
{
  "name": "my-engine",
  "region": "europe-west",
  "quality": {
    "abrLadderId": "your-abr-ladder-id"
  },
  "outputs": {
    "hesp": true,
    "hls": true,
    "hlsTs": false
  }
}
```