What Protocol Is Right for Your Workflow: Delivery

April 16, 2021 by
 

Last week’s post looked at picking the right protocol for live streaming ingest. So today, we’re zeroing in on the opposite end of the live streaming workflow: delivery.

A different protocol is often used for ingest and delivery to speed up the journey from camera screen to end-user device — while also optimizing the viewing experience. That’s why content distributors use a media server software or service to convert the live feed from one protocol to another.

Whereas selecting a protocol for first-mile contribution (a.k.a. ingest) revolves around speed and encoder support, several different factors come into play when picking a protocol for last-mile delivery.

These considerations include:

  • Playback support across browsers, devices, and players.
  • Quality of experience, including the ability to deliver adaptive bitrate streaming.
  • Video latency and whether or not interactivity is required.
  • Scalability, or the capacity to broadcast to thousands of viewers concurrently.
  • Broadcast capabilities like ad insertion and digital rights management (DRM).

The most popular protocol used for delivery is Apple HTTP Live Streaming (HLS). In fact, according to our 2019 Video Streaming Latency Report, more than 45% of broadcasters use it.


Which streaming formats are you currently using?

Graph: Streaming Formats in Use Today

And this makes sense. After all, it’s the most supported protocol in the video streaming space. But that doesn’t mean that it’s not worth considering the alternatives.

Let’s take a look at the primary contenders and why you might decide to take a different route.

 

HLS

HLS is an adaptive HTTP-based protocol used for last-mile delivery. By virtue of being both well supported across devices and optimized for adaptive bitrate delivery via a CDN, It’s super scalable. One major pitfall of HLS, though, is latency. When configured per Apple’s recommendations, HLS streams lag roughly 30 seconds behind a live event.

Benefits:

  • Widely supported and super scalable.
  • Ensures high-quality viewing experiences thanks to adaptive bitrate streaming.
  • Broadcast capabilities like ad insertion and captions are all standardized within the spec.
  • Robust content protection features, including digital rights management (DRM).

Limitations:

  • Conventional implementations come with significant latency.
 

Low-Latency HLS

To address the latency challenges surrounding HLS delivery, Apple released Low-Latency HLS in 2019. The proprietary protocol promises to deliver sub-three-second streams globally for playback on popular devices — while also offering backward compatibility to existing clients. Large-scale deployments of Low-Latency HLS are yet to become commonplace, and many streaming vendors are still adding support.

Benefits:

Limitations:

  • As an emerging spec, vendors are still implementing support.
 

MPEG-DASH

MPEG-DASH is HLS’s non-proprietary cousin, offering the same CDN scalability and high-quality playback. It’s also codec-agnostic and vendor-independent. That said, iOS and Apple TV don’t support DASH, making it a tough sell for anyone streaming to Apple devices.

Benefits:

  • Scalable across a CDN.
  • Delivers a high-quality viewing experience with adaptive bitrate streaming.
  • Vendor-independent and codec-agnostic.
  • Broadcast capabilities like ad insertion and captions are standardized within the spec.
  • Robust content protection features, including digital rights management (DRM).

Limitations:

  • Doesn’t play back on as many devices as HLS because Apple doesn’t support it.
  • Also comes with latency when streamed in conventional format.
 

Low-Latency CMAF for DASH

Low-latency CMAF for DASH is another emerging technology for speeding up HTTP-based video delivery. Although it’s still in its infancy, the technology shows promise in delivering superfast video at scale. Support for this protocol will take some time, and Low-Latency HLS will likely be adopted sooner.

Benefits:

  • All the benefits of MPEG-DASH plus low-latency delivery.

Limitations:

  • Doesn’t play back on as many devices as HLS because Apple doesn’t support it.
  • Still an emerging technology that’s yet to be championed by many vendors.
 

WebRTC

Web Real-Time Communication (WebRTC) delivers near-instantaneous streaming to and from any major browser. The technology was designed for video conferencing and thus supports sub-500-millisecond latency. While it’s the speediest protocol out there, scaling to more than 50 concurrent peer connections requires additional resources.

Benefits:

  • Can be used end-to-end for small-scale broadcasts.
  • Low latency and perfect for interactive use cases.
  • Natively supported in all major desktop browsers.

Limitations:

 

Considerations When Selecting a Protocol for Delivery

Wowza supports all of the egress formats detailed above, meaning that it’s ultimately up to you. But we’d suggest asking the following questions to help narrow down your options. 

 

Are you streaming broadcast-quality content to Apple devices?

When delivering streams for native playback on iOS and Apple TV, you’re going to want to go with HLS or Low-Latency HLS.

 

Is real-time interactivity required for your use case?

If you need true interactivity — we’re talking sub-one-second video delivery for scenarios like emergency response and remote monitoring — then WebRTC fits the bill. It’s the fastest technology of the bunch and also can be used from end to end. Low-Latency HLS and low-latency CMAF for DASH are also good options, but full-blown implementations of these emerging technologies haven’t yet been deployed.

 

Do you need to broadcast at scale?

WebRTC simply wasn’t designed with large-scale broadcasting in mind. So, if you’re trying to reach anywhere north of 300 viewers in a cost-effective manner, you’ll want to opt for an HTTP-based protocol like MPEG-DASH or HLS.

 

What about sophisticated content protection?

Likewise, WebRTC lacks DRM capabilities and standard out-of-the-box security measures for broadcasting workflows.

 

When to Go With a Hybrid Workflow

Hybrid workflows, which combine more than one of the delivery protocols above, are very common. For instance, a live auction content distributor might choose to achieve both real-time interactivity and scale by distributing the stream using WebRTC and HLS. The content can then adapt to audiences of varying sizes and participation levels — accounting for active and passive media consumption.

Diagram of a streaming workflow using Wowza to deliver WebRTC streams to active participants and HLS streams to passive participants.
 

Start With Wowza

No matter what type of streaming architecture you’re trying to build, Wowza makes it happen. Our full-service platform can power any workflow with reliability to boot.

 

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About Traci Ruether

As a Colorado-based B2B tech writer, Traci Ruether serves as Wowza's content marketing manager. Her background is in streaming and content delivery. Aside from writing, Traci enjoys cooking, gardening, and spending quality time with her kith and kin. Follow her… View more