Streaming Protocols for Live Broadcasting: Everything You Need to Know in 2020

Did you know that 80% of people would rather watch a live stream than read a blog post? Additionally, the typical viewer watches a live stream for at least twice as long as they stick with a standard video. 

Live streaming solutions are increasingly popular as live video content becomes a preferred type of media. It is engaging, fresh, personal, and easy to access. 

When it comes to live streaming, there is a lot of technology that works behind the scenes. A streaming protocol is a technology that makes live streams possible. 

Some professional broadcasters require more control over their streaming protocols. This greater need is often solved by using a professional online video platform that is designed with the viewers’ experience in mind.

Today, we’re going to talk about four of the most prominent streaming protocols used by professional broadcasters today. Before we get into the specific protocols, we are going to talk about what exactly a video streaming protocol is and compare two similar technologies that are essential to live streaming.

Table of Contents

• The Basics of Video Streaming Protocols 
• Streaming Protocol vs. Codec
• Streaming Protocol vs. Transport Format
• 4 Common Streaming Protocols
  • MPEG-DASH
  • Apple HTTP Live Streaming (HLS)
  • Microsoft Smooth Streaming
  • Adobe HTTP Dynamic Flash Streaming (HDS)
• Conclusion

The Basics of Video Streaming Protocols

So what is a streaming protocol? A streaming protocol is a standardized method of delivering multimedia (usually video or audio) over the internet.

Essentially, a streaming protocol sends “chunks” of content from one device to another. It also defines the method for “reassembling” these chunks into playable content on the other end.

That points toward one important aspect of streaming protocols: both the output device and the viewer have to support the protocol in order for it to work. 

For example, if you’re sending a stream in MPEG-DASH, but the video player on the device to which you’re streaming doesn’t support MPEG-DASH, your stream won’t work.

For this reason, standardization is important. There are currently four major video streaming protocols in widespread use, which we’ll look at in detail in a moment. The four common protocols include MPEG-DASH, HTTP Live Streaming (HLS), Smooth Streaming, and HDS.

Before we dive into the specific protocols, let’s clear up some potential confusion in the realm of streaming protocol and codecs.

Streaming Protocol vs. Codec

“Codec” is a word that comes up often in the world of live streaming, and at first glance, the definition seems similar to that of a protocol. However, a streaming protocol is different from a codec. 

Codec stands for “coder/decoder.” It is a tool for making video files smaller. RAW video files are made up of many still images played quickly in sequence (typically at 30 frames per second). Now, imagine thirty photos that are two megapixels each. That’s a lot of storage space.

The solution for saving space is compression, which uses mathematical algorithms to discard data that isn’t very important. For example, if a corner of the video is black, and remains black for a few seconds, you can toss the individual pixel data and just include a reference instead.

Once the file has arrived at its destination, it is then decompressed so that the video can play as normal. This process happens in real-time when it comes to live streaming.

Streaming Protocol vs. Transport Format

Another source of potential confusion is the transport format. This refers to the “container” or “package” that’s used for video transmission. A container format usually contains compressed video, compressed audio, and metadata such as subtitles, timing info, etc.

This data is transmitted via a streaming protocol. The transport format defines how the content is stored within the individual chunks of data as they are streamed. Common transport formats or containers for streaming video include MP4 (fragments) and MPEG-TS.

4 Common Streaming Protocols

There are four common streaming protocols that any professional broadcaster should be familiar with.   

Today, we are going to cover MPEG-DASH, HLS, MSS, and HDS. 

1. MPEG-DASH

First up on our review is MPEG-DASH. This is one of the newest streaming protocols, and it is beginning to see broader adoption.

MPEG-DASH, like the other protocols that we will discuss, uses standard HTTP web servers. This reduces the cost and technical difficulty of implementation when compared to legacy methods of streaming like RTP.

MPEG-DASH is also an adaptive bitrate (ABR) protocol. This means it will automatically detect changes in the internet connection speed of the viewer and serve the best available quality video at any given time. ABR streaming reduces buffering and enhances the viewers’ experience. 

It is also important to note that MPEG-DASH is an open standard that isn’t controlled by any one company.

Video Codecs Supported:

• H.264 (the most common codec)
• H.265 / HEVC (the next-generation successor)
• WebM
• VP9/10
• Any other codec (MPEG-DASH is codec agnostic)

Audio Codecs Supported:

• AAC
• MP3
• Any other codec (MPEG-DASH is codec agnostic)

Transport/Package Format:

• MP4 fragments
• MPEG-2 TS

Playback Support:

• Native support on Android devices
• Plays back on most Samsung, LG, Philips, Panasonic, and Sony TVs made after 2012
• Works on Chromecast
• Supported on YouTube and Netflix
• Not natively supported via HTML5, but players can be implemented via Javascript and Media Source Extensions

Segment Duration:

• Variable

2. Apple HTTP Live Streaming (HLS)

HLS streaming protocol is an alternative protocol developed by Apple. Today, HLS is the most widely used streaming protocol on the internet.

HLS is an adaptive bitrate protocol and also uses HTTP servers. This protocol is an evolving specification, as Apple adds features regularly.

HLS is one of the protocols that Dacast uses.

Video Codecs Supported:

• H.264
• H.265 / HEVC 

Audio Codecs Supported:

• AAC
• MP3

Transport/Package Format:

• MPEG-2 TS

Playback Support:

• iOS and macOS devices
• Safari, Chrome, Firefox, and Edge web browsers
• Many set-top boxes, such as Roku
• Many online video players, such as JW Player and the Dacast all-device video player

Segment Duration:

• 10 seconds (can be manually reduced as part of reducing latency)

3. Microsoft Smooth Streaming

Smooth Streaming is a streaming protocol that Microsoft developed in 2008 to meet early needs for adaptive bitrate streaming.

Deploying Smooth Streaming requires Silverlight, Microsoft’s proprietary developer plugin framework. One strength of Smooth Streaming is support for PlayReady DRM to thwart piracy.

Video Codecs Supported:

• H.264
• VC-1

Audio Codecs Supported:

• AAC
• WMA

Transport/Package Format:

• MP4 fragments

Playback Support:

• Browsers with the Silverlight plugin
• Xbox
• Windows Phone
• iOS devices
• Windows computers
• Many Smart TVs

Segment Duration:

• 2-4 seconds

4. Adobe HTTP Dynamic Flash Streaming (HDS)

The final streaming protocol we’ll look at here is Adobe’s adaptive bitrate-based protocol: HTTP Dynamic Flash Streaming (HDS).

HDS evolved from RTMP—Adobe’s original standard for streaming Flash video—which is often still used for stream ingest. 

HDS comes with some major advantages over its predecessor. These include the adaptive bitrate feature, as well as the ability to cache content on browsers and CDNs to reduce the load on servers.

One drawback is that HDS requires Flash, and so it doesn’t work on iOS devices. Despite this downfall, it is still widely used because it delivers some of the lowest latency in the industry. 

The Dacast OVP uses HDS for viewers with Flash players for this reason. Our platform also pushes HLS video streams to those who don’t support HDS.

Video Codecs Supported:

• VP6
• H.264

Audio codecs supported:

• MP3
• AAC

Transport/Package Format:

• MP4 fragments

Playback Support:

• Any device with Flash player installed
• Adobe AIR applications

Segment Duration:

• 2-4 seconds

Conclusion

The world of live streaming can be a very confusing place. Becoming an expert requires knowledge of not just streaming protocol but also codecs, container formats, CDNs, video workflows, and much more, and we are here to help. 

In this article, we’ve gone over the basic functionality of four of the most popular streaming formats: MPEG-DASH, HDS, HLS, and Microsoft Smooth Streaming. 

Each streaming protocol comes with pros and cons. Which protocol you use will depend on who you are trying to reach and which devices they use.

We believe that HLS is currently a good baseline for most use-cases. It remains the most popular streaming protocol for good reason. That’s why it, along with HDS, is our default protocol here at Dacast. 

Technology is always evolving, and we’ll surely be using different methods in the future. For regular tips and updates on live streaming, please join our LinkedIn group.

Not yet a Dacast customer but interested to learn more? Our unified streaming solution includes secure video upload, lots of customizable features, and even China video hosting for VOD. Take advantage of our 30-day free trial to test out the Dacast platform for yourself

We know that the world of live streaming can be a very confusing place. Becoming an expert requires knowledge of not just streaming protocol but also codecs, container formats, CDNs, video workflows, and much more. That’s why we’re here to help. Articles like these aim to give you a good grounding in the technology of live streaming so that you can worry less about these complexities and more about producing successful streams.

Not yet a Dacast customer but interested to learn more? Our streaming solutions include secure video upload, live streaming, and on demand content hosting. Why not take advantage of our 30-day free trial to test out the Dacast platform for yourself?

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Thanks for reading and, as always, good luck with your broadcasting!