Which Service Is Not A Promise That Can Be Made By The Transport Layer?
Streaming Protocols: Everything You Demand to Know (Update)
Jan 20, 2022
What Is a Protocol?
A protocol is a set of rules governing how data travels from i communicating system to some other. These are layered on top of i some other to form a protocol stack. That way, protocols at each layer can focus on a specific function and cooperate with each other. The lowest layer acts equally a foundation, and each layer above information technology adds complexity.
You've likely heard of an IP accost, which stands for Internet Protocol. This protocol structures how devices using the net communicate. The Internet Protocol sits at the network layer. It's typically overlaid by the Manual Control Protocol (TCP) at the transport layer, besides as the Hypertext Transfer Protocol (HTTP) at the awarding layer.
The seven layers — which include physical, data link, network, transport, session, presentation, and application — were defined past the International Organization for Standardization's (IS0'south) Open Systems Interconnection model, as depicted above.
What Is a Streaming Protocol?
Each fourth dimension yous watch a live stream or video on need, video streaming protocols are used to deliver data over the internet. These tin sit in the application, presentation, and session layers.
Online video delivery uses both streaming protocols and HTTP-based protocols. Streaming protocols like Real-Time Messaging Protocol (RTMP) transport video using dedicated streaming servers, whereas HTTP-based protocols rely on regular spider web servers to optimize the viewing experience and quickly calibration. Finally, emerging HTTP-based technologies like Apple'due south Low-Latency HLS seek to deliver the best of both options by supporting low-latency streaming at calibration.
Table of Contents
- UDP vs. TCP: A Quick Background
- Considerations When Choosing a Video Streaming Protocol
- What Are the Preferred Protocols for Video Streaming?
- Traditional Video Streaming Protocols
- HTTP-Based Adaptive Protocols
- New Technologies
- Conclusion: How to Choose the Best Protocol for Streaming Video
UDP vs. TCP: A Quick Groundwork
User Datagram Protocol (UDP) and Transmission Control Protocol (TCP) are both cadre components of the internet protocol suite, residing in the send layer. The protocols used for streaming sit down on top of these. UDP and TCP differ in terms of quality and speed, and so it'southward worth taking a closer look.
The primary difference between UDP and TCP hinges on the fact that TCP requires a three-style handshake when transporting information. The initiator (client) asks the accepter (server) to kickoff a connection, the accepter responds, and the initiator acknowledges the response and maintains a session between either end. For this reason, TCP is quite reliable and can solve for packet loss and ordering. UDP, on the other paw, starts without requiring any handshake. It transports data regardless of whatsoever bandwidth constrains, making it speedier and riskier. Because UDP doesn't support retransmissions, parcel ordering, or fault-checking, there'due south potential for a network glitch to corrupt the data en route.
Protocols like Secure Reliable Ship (SRT) often use UDP, whereas protocols like HTTP Alive Streaming (HLS) use TCP.
Considerations When Choosing a Streaming Protocol
Selecting the right media streaming protocol starts with defining what you lot're trying to achieve. Latency, playback compatibility, and viewing experience tin all be impacted. What's more, content distributors don't always stick with the same protocol from capture to playback. Many broadcasters use RTMP to get from the encoder to server and and then transcode the stream into an adaptive HTTP-based format.
Keep Up With All the Latest Trends
Subscribe to stay in the know about all things live streaming.
Subscribe Now
What Are the Preferred Protocols for Video Streaming?
Traditional Video Streaming Protocols
- RTMP (Existent-Time Messaging Protocol)
- RTSP (Real-Time Streaming Protocol)/RTP (Existent-Time Transport Protocol)
HTTP-Based Adaptive Protocols
- Apple tree HLS (HTTP Live Streaming)
- Low-Latency HLS
- MPEG-DASH (Moving Picture Expert Group Dynamic Adaptive Streaming over HTTP)
- Depression-Latency CMAF for DASH (Common Media Awarding Format for DASH)
- Microsoft Smooth Streaming
- Adobe HDS (HTTP Dynamic Streaming)
New Technologies
- SRT (Secure Reliable Ship)
- WebRTC (Web Real-Time Communications)
Traditional Video Streaming Protocols
Traditional streaming protocols, such as RTSP and RTMP, back up low-latency streaming. But they aren't natively supported on nearly endpoints (e.thousand., browsers, mobile devices, computers, and televisions). Today, these streaming formats work best for transporting video between and IP camera or encoder and a dedicated media server.
As shown above, RTMP delivers video at roughly the same pace equally a cable broadcast — in just over five seconds. RTSP/RTP is even quicker at around two seconds. Both formats achieve such speed by transmitting the data using a firehose approach rather than requiring local download or caching. But because very few players support RTMP and RTSP, they aren't optimized for great viewing experiences at scale. Many broadcasters cull to transport live streams to the media server using a stateful protocol similar RTMP. From in that location, they can transcode it into an HTTP-based engineering science for multi-device commitment.
Adobe RTMP
Adobe designed the RTMP specification at the dawn of streaming. The protocol could transport audio and video information between a dedicated streaming server and the Adobe Flash Player. Reliable and efficient, this worked great for live streaming. Only open standards and adaptive bitrate streaming eventually edged RTMP out. The writing on the wall came when Adobe announced the expiry of Flash — which officially ended in 2020.
While Wink'south stop-of-life date was overdue, the same cannot exist said for using RTMP for video contribution. RTMP encoders are still a go-to for many content producers, fifty-fifty though the proprietary protocol has fallen out of favor for terminal-mile delivery.
- Video Codecs: H.264, VP8, VP6, Sorenson Spark®, Screen Video v1 & v2
- Audio Codecs: AAC, AAC-LC, HE-AAC+ v1 & v2, MP3, Speex, Opus, Vorbis
- Playback Compatibility: Not widely supported (Wink Player, Adobe AIR, RTMP-uniform players)
- Benefits: Depression-latency and requires no buffering
- Drawbacks: Non optimized for quality of experience or scalability
- Latency: 5 seconds
- Variant Formats: RTMPT (tunneled through HTTP), RTMPE (encrypted), RTMPTE (tunneled and encrypted), RTMPS (encrypted over SSL), RTMFP (travels over UDP instead of TCP)
RTSP/RTP
Like RTMP, RTSP/RTP describes an onetime-schoolhouse applied science used for video contribution. RTSP and RTP are often used interchangeably. But to be articulate: RTSP is a presentation-layer protocol that lets cease users control media servers via pause and play capabilities, whereas RTP is the transport protocol used to move said data.
Android and iOS devices don't have RTSP-compatible players out of the box, making this another protocol that's rarely used for playback. That said, RTSP remains standard in many surveillance and closed-circuit telly (CCTV) architectures. Why? The reason is uncomplicated. RTSP support is still ubiquitous in IP cameras.
- Video Codecs: H.265 (preview), H.264, VP9, VP8
- Sound Codecs: AAC, AAC-LC, HE-AAC+ v1 & v2, MP3, Speex, Opus, Vorbis
- Playback Compatibility: Not widely supported (Quicktime Player and other RTSP/RTP-compliant players, VideoLAN VLC media player, 3Gpp-uniform mobile devices)
- Benefits: Low-latency and supported by most IP cameras
- Drawbacks: No longer used for video delivery to end users
- Latency: 2 seconds
- Variant Formats: The entire stack of RTP, RTCP (Real-Time Control Protocol), and RTSP is often referred to every bit RTSP
Adaptive HTTP-Based Streaming Protocols
Streams deployed over HTTP are not technically "streams." Rather, they're progressive downloads sent via regular web servers. Using adaptive bitrate streaming, HTTP-based protocols deliver the all-time video quality and viewer experience possible — no matter the connection, software, or device. Some of the most common HTTP-based protocols include MPEG-Nuance and Apple'due south HLS.
Apple HLS
Since Apple is a major actor in the earth of internet-connected devices, it follows that Apple'southward HLS protocol rules the digital video landscape. For ane, the protocol supports adaptive bitrate streaming, which is cardinal to viewer feel. More than chiefly, a stream delivered via HLS will play back on the majority of devices — thereby ensuring accessibility to a large audience.
HLS back up was initially limited to iOS devices such equally iPhones and iPads, but native back up has since been added to a wide range of platforms. All Google Chrome browsers, also as Android, Linux, Microsoft, and MacOS devices, can play streams delivered using HLS.
- Video Codecs: H.265, H.264
- Audio Codecs: AAC-LC, HE-AAC+ v1 & v2, xHE-AAC, Apple Lossless, FLAC
- Playback Compatibility: Great (All Google Chrome browsers; Android, Linux, Microsoft, and MacOS devices; several gear up-pinnacle boxes, smart TVs, and other players)
- Benefits: Adaptive bitrate and widely supported
- Drawbacks: Quality of feel is prioritized over low latency
- Latency: vi-30 seconds (lower latency just possible when tuned)
- Variant Formats: Low-Latency HLS (come across below), PHLS (Protected HTTP Alive Streaming)
Depression-Latency HLS
Low-Latency HLS (LL-HLS) is the latest and greatest technology when it comes to depression-latency streaming. The proprietary protocol promises to deliver sub-3-second streams globally. It besides offers backward compatibility to existing clients.
In other words, information technology's designed to deliver the aforementioned simplicity, scalability, and quality as HLS — while significantly shrinking the latency. At Wowza, we telephone call this combination the streaming trifecta.
Even and so, successful deployments of Depression-Latency HLS crave integration from vendors across the video commitment ecosystem. Support is all the same lacking, and large-scale deployments of Low-Latency HLS are few and far between.
- Playback Compatibility: Any players that aren't optimized for Depression-Latency HLS tin can fall dorsum to standard (college-latency) HLS behavior
- HLS-uniform devices include MacOS, Microsoft, Android, and Linux devices; all Google Chrome browsers; several prepare-meridian boxes, smart TVs, and other players
- Benefits: Depression latency, scalability, and high quality… Oh, and did we mention astern compatibility?
- Drawbacks: As an emerging spec, vendors are still implementing back up
- Latency: ii seconds or less
MPEG-DASH
MPEG-DASH is a vendor-independent culling to HLS. Basically, with DASH you get a non-proprietary choice that ensures the same scalability and quality. But because Apple tree tends to prioritize its ain tech stack, support for Nuance plays second fiddle in the slew of Apple devices out there.
- Video Codecs: Codec-doubter
- Audio Codecs: Codec-agnostic
- Playback Compatibility: Expert (All Android devices; most mail service-2012 Samsung, Philips, Panasonic, and Sony TVs; Chrome, Safari, and Firefox browsers)
- Benefits: Vendor-contained, international standard for adaptive bitrate
- Drawbacks: Non supported by iOS or Apple TV
- Latency: 6-30 seconds (lower latency only possible when tuned)
- Variant Formats: MPEG-Nuance CENC (Mutual Encryption)
Depression-Latency CMAF for DASH
Low-latency CMAF for Dash is another emerging technology for speeding up HTTP-based video delivery. Although it'due south nevertheless in its infancy, the technology shows promise delivering superfast video at calibration by using shorter data segments. That said, many vendors have prioritized back up for Low-Latency HLS over that of low-latency CMAF for Nuance.
- Playback Compatibility: Any players that aren't optimized for low-latency CMAF for Nuance can autumn back to standard (higher-latency) Dash behavior
- Benefits: Low latency meets HTTP-based streaming
- Drawbacks: As an emerging spec, vendors are still implementing support
- Latency: 3 seconds or less
Microsoft Smooth Streaming
Microsoft developed Microsoft Smooth Streaming in 2008 for use with Silverlight player applications. It enables adaptive delivery to all Microsoft devices. The protocol can't compete with other HTTP-based formats and is falling out of utilize. In fact, in our 2021 Video Streaming Latency Report, only 5 pct of respondents were using Smooth Streaming.
Which streaming formats are you currently using?
- Video Codecs: H.264, VC-1
- Audio Codecs: AAC, MP3, WMA
- Playback Compatibility: Skillful (Microsoft and iOS devices, Xbox, many smart TVs, Silverlight player-enabled browsers)
- Benefits: Adaptive bitrate and supported past iOS
- Drawbacks: Proprietary technology, doesn't compete with HLS and DASH
- Latency: 6-30 seconds (lower latency simply possible when tuned)
Adobe HDS
HDS was developed for use with Flash Thespian as the first adaptive bitrate protocol. Because Flash is no more, it'due south too slowly dying. Don't believe us? Just take a look at the graph above.
- Video Codecs: H.264, VP6
- Audio Codecs: AAC, MP3
- Playback Compatibility: Non widely supported (Flash Thespian, Adobe AIR)
- Benefits: Adaptive bitrate technology for Flash
- Drawbacks: Proprietary applied science with lacking support
- Latency: half-dozen-30 seconds (lower latency only possible when tuned)
New Technologies
Last but non to the lowest degree, new technologies like WebRTC and SRT promise to change the landscape. Similar to low-latency CMAF for Dash and Apple tree Depression-Latency HLS, these protocols were designed with latency in mind.
SRT
This open-source protocol is recognized as a proven alternative to proprietary ship technologies — helping to evangelize reliable streams, regardless of network quality. It competes directly with RTMP and RTSP as a first-mile solution, just it'due south notwithstanding being adopted as encoders, decoders, and players add support.
From recovering lost packets to preserving timing behavior, SRT was designed to solve the challenges of video contribution and distribution across the public net. And information technology'southward quickly taking the industry by storm. One interactive apply case for which SRT proved instrumental was the 2020 virtual NFL draft. The NFL used this game-changing engineering to connect 600 live feeds for the starting time entirely virtual outcome.
- Video Codecs: Codec-agnostic
- Audio Codecs: Codec-agnostic
- Playback Compatibility: Limited (VLC Media Player, FFPlay, Haivision Play Pro, Haivision Play, Larix Player, Brightcove)
- Benefits: High-quality, depression-latency video over suboptimal networks
- Drawbacks: Not widely supported for video playback
- Latency: iii seconds or less, tunable based on how much latency you want to trade for package loss
WebRTC
As the speediest technology available, WebRTC delivers near-instantaneous voice and video streaming to and from whatever major browser. It tin too be used end-to-end and thus competes with ingest and delivery protocols. The framework was designed for pure chat-based applications, but information technology's now finding its way into more diverse employ cases.
Scalability remains a challenge with WebRTC, though, so y'all'll need to use a solution like Wowza's Real-Fourth dimension Streaming at Calibration feature to overcome this.
- Video Codecs: H.264, VP8, VP9
- Audio Codecs: Opus, iSAC, iLBC
- Playback Compatibility: Chrome, Firefox, and Safari back up WebRTC without any plugin
- Benefits: Super fast and browser-based
- Drawbacks: Designed for video conferencing and not scale
- Latency: Sub-500-millisecond delivery
Conclusion: How to Cull the Best Protocol for Streaming Video
Protocols differ in the following areas:
- Scalability
- Latency
- Quality of experience (adaptive bitrate enabled, etc.)
- Utilize (offset-mile contribution vs. final-mile commitment)
- Playback support
- Proprietary vs. open up source
- Codec requirements
Past prioritizing the to a higher place considerations, it'due south easy to narrow down what's best for you.
RTMP and SRT are great bets for commencement-mile contribution, while both Dash and HLS lead the fashion when information technology comes to playback. Depression-Latency HLS and WebRTC ensure speedier commitment, and so yous'll want to consider them when deploying interactive video environments.
Luckily, Wowza's flexible video platform supports all of these technologies and can be customized to your needs. Simply contact us today to talk to an adept about the best way to architect your streaming workflow.
About Traci Ruether
Which Service Is Not A Promise That Can Be Made By The Transport Layer?,
Source: https://www.wowza.com/blog/streaming-protocols
Posted by: lawsblied1944.blogspot.com
0 Response to "Which Service Is Not A Promise That Can Be Made By The Transport Layer?"
Post a Comment