Streaming Protocols for Live Broadcasting: Everything You Need to Know [2022 Update]

 

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. 

Streaming platforms 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 broadcasting, there is a lot of technology that works behind the scenes. A streaming protocol is a technology that makes streaming live video possible.

Today, we’re going to talk about five of the most prominent live streaming protocols used by professional broadcasters today. Before we get into the specific streaming protocols, we are going to talk about what exactly a video protocol is. We’ll also compare some similar technologies that are related to live streaming, including codecs and video streaming formats.

You will learn all about streaming protocols, including what is the best streaming protocol for your specific application.

Table of Contents

• The Basics of Streaming Protocols 
• Live Streaming Protocol vs. Codec
• Streaming Protocols vs. Video Streaming Formats
• 5 Common Video Streaming Protocols
• Conclusion

The Basics of Streaming Protocols

A streaming protocol, also known as a broadcast protocol, is a standardized method of delivering different types of media (usually video or audio) over the internet.

Essentially, a video 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 a few major media streaming protocols in widespread use, which we’ll look at in detail in a moment. The five most common protocols include:

1. HTTP Live Streaming (HLS)
2. Real-Time Messaging Protocol (RTMP)
3. Secure Reliable Transport (SRT)
4. Dynamic Adaptive Streaming over HTTP (MPEG-DASH)
5. Microsoft Smooth Streaming (MSS)

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

Live 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 video protocol. However, a live streaming protocol is different from a video 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. That is where a codec comes into play. 

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. This process is what happens when a video codec is used. A video codec is essentially streaming method tool. 

Streaming Protocols vs. Video Streaming Formats

Another source of potential confusion is the video streaming 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, and so forth.

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.

5 Common Streaming Protocols

Different video streaming protocols are used for different use cases. Certain streaming protocols are better suited for some streaming setups and others. The best protocol for live streaming depends on the situation. 

There are five common streaming protocols that professional broadcasters should be familiar with, including HLS, RTMP, SRT, MSS, and MPEG-DASH. Let’s take some time to explore some of the background and technical requirements for the most popular protocols.

1. HTTP Live Streaming (HLS)

HLS streaming is an alternative protocol developed by Apple. HLS stands for HTTP Live Streaming, and today it 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)

If you want to connect with viewers who use Apple devices, HLS streaming is one of the best protocols for live streaming.

2. Real-Time Messaging Protocol (RTMP)

Real-Time Messaging Protocol (RTMP) is a protocol that was previously used to deliver videos to the Adobe Flash player. Since Flash is dead, RTMP has limited playback support. However, RTMP is now used for ingestion from the encoder to the online video platform.

RTMP ingest allows users to tap into the support of low-cost RTMP encoders. Much of the online video streaming industry, including leading streaming software and OVPs, is still compatible with RTMP ingest.

When paired with HLS delivery, RTMP ingest produces a low-latency stream.

Video Codecs Supported:

• H.264 
• MP4 
• x264

Audio Codecs Supported:

• AAC-LC
• AAC

Transport/Package Format:

The transport/package format for RTMP is unavailable.

Playback Support:

• Flash Player
• Adobe AIR
• RTMP-compatible players

Segment Duration:

• The segment duration for RTMP is unavailable.

If you need a stream with low latency, where there is a minimal delay in the processing of the data, RTMP ingest is one of the best video streaming standards to use.

3. Secure Reliable Transport (SRT)

Secure Reliable Transport (SRT) is a relatively new streaming protocol from Haivision, a leading player in the online streaming space. SRT is an open-source protocol that is likely the future of live streaming. This video streaming protocol is known for its security, reliability, and low latency streaming.

SRT is still quite futuristic because there are still some compatibility limitations with this protocol. The protocol itself is open-source and highly compatible, but other streaming hardware and software have yet to develop to support this protocol.

Haivision has created the SRT Alliance, which is a group of companies in the technology and telecommunications industry that are dedicated to bringing SRT up in the live streaming space. Currently, the best way to access SRT is by using technology that is founded by or backed by any of the SRT Alliance members.

Video Codecs Supported:

• SRT is media and content agnostic, so it supports all video codecs.

Audio Codecs Supported:

• SRT is media and content agnostic, so it supports all audio codecs.

Transport/Package Format:

• SRT is media and content agnostic, so it supports all transport and package formats.

Playback Support:

• Haivision does not specify playback support for SRT.

Segment Duration:

• Haivision does not specify segment duration for SRT.

If you want to be on the cutting edge of video streaming protocols, you may want to consider adapting SRT.

4. Microsoft Smooth Streaming (MSS)

Smooth Streaming (MSS) is a streaming protocol that Microsoft developed in 2008 to meet early needs for adaptive bitrate streaming. This video streaming protocol is known to be for being cost-effective, reduced buffering, and offering optimized performance.

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

If you are looking for the best streaming protocol for Windows devices, be sure to consider MSS.

5. Dynamic Adaptive Streaming over HTTP (MPEG-DASH)

The last protocol in our review is MPEG-DASH. This is one of the newest streaming protocols, and it is beginning to see broader adoption.

Dynamic Adaptive Streaming over HTTP (DASH) which is also known as MPEG-DASH, 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

Not all viewers have the same internet connection, which means that when trying to connect with a large audience, you need to stream your video at different resolutions, which is possible with adaptive bitrate protocol, which MPEG-DASH supports. MPEG-DASH is the best streaming protocol for providing your viewers with a video that meets their needs.

Conclusion

The world of live streaming can be quite confusing, especially for new broadcasters. 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 reviewed the basic functionality of five of the most popular video streaming protocols, including MPEG-DASH, RTMP, SRT, HLS, and MSS.

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. The best protocol for live streaming depends on your needs and the needs of your audience.

We believe that HLS is currently the best protocol for most video streaming 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. We believe HLS and HDS are currently the best streaming protocols for reaching the widest audience with the highest quality video.

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 14-day free trial to test out the Dacast online video platform for yourself?

Get started for free

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

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