The Complete Guide To Live Streaming - Wowza

THE COMPLETE GUIDE TO LIVE STREAMING 2021What Audio Codec Should You Use?LimitationsAAC takes the cake when balancing quality withcompatibility across audio codecs. While open-sourcealternatives like Opus far outperform AAC, they lacksupport across as many platforms and devices.AACMost commonaudio codec.Higher-quality alternativesexist.MP3Also widelysupported.Less advanced than AAC.OpusHighest-qualitylossy audio format.Yet to be widely adopted.VorbisNon-proprietaryalternative to AAC.Less advanced than Opus.SpeexPatent-free speechcodec.Also obsoleted byOpus.Audio Codecs Worth Noting:AACMP3Defined by MPEG-4, this widely supported standardis used by YouTube, Android, iOS, and iTunes. Twoextensions of AAC exist: HE-ACC for low bitrates andAAC-LC for low delay. HE-AAC works best wheneverbandwidth is a concern, while AAC-LC lends itself wellto two-way communication.Nearly every audio-supported digital device in the worldcan play back the MP3 format, making it a viable optionfor live streaming. But because AAC offers superiorcompression, we’d recommend going with that.OpusDeveloped by the Xiph.Org Foundation, Opus provideshigher-quality audio than any other lossy audio format.It’s open-source and royalty-free, but has yet to bewidely adopted.Encoding Best PracticesEncoding best practices go way beyond what codec youselect. You’ll also want to consider frame rate, keyframeinterval, and bitrate.Luckily, a live stream can always be transcoded intoanother format once it reaches the server. This can bedone using a software and your own servers, or in thecloud for professionally managed delivery.In addition to the codecs used, it’s important to examinehow your stream is packaged and which protocols enterthe picture.Page 9 of 23 2022 Wowza Media SystemsTM, LLC. All rights reserved.

THE COMPLETE GUIDE TO LIVE STREAMING 2021Packaging and ProtocolsOnce compressed, video streams must be packagedfor delivery. The distinction between compressionand packaging is subtle but relevant. For the sakeof explanation, let’s picture the process in terms ofresidential garbage removal.We start with the raw video data, which must becompressed down for delivery across the internet. Anencoder allows us to do so by compressing gigabytesinto megabytes. Think of the encoder as a householdtrash compactor and the codecs as the bags ofcompressed trash.In order to actually transport the compressed trash (audioand video codecs) to the dump (viewer), another step isrequired. It’s crucial to place the bag of trash, as well as anyother odds and ends (such as metadata), into a curbsidetrash receptacle. File container formats can be thought ofin terms of these receptacles. They act as a wrapper forall streaming data so that it’s primed for delivery.Finally, the contents of the trash bin are transported tothe dump via an established route. Think of protocols asthe established routes that garbage trucks take.OK. Enough trash talk. Time to define each term for real.What Is a Video Container Format?What Is a Streaming Protocol?Video container formats, also called wrappers, holdall the components of a compressed stream. Thiscould include the audio codec, video codec, closedcaptioning, and any associated metadata such assubtitles or preview images. Common containersinclude .mp4, .mov, .ts, and .wmv.A protocol is a set of rules governing how datatravels from one device to another. For instance, theHypertext Transfer Protocol (HTTP) deals with hypertextdocuments and webpages.Online video delivery uses both streaming protocolsand HTTP-based protocols. Streaming protocols likeReal-Time Messaging Protocol (RTMP) offer fast videodelivery, whereas HTTP-based protocols can helpoptimize the viewing experience.The protocol used can increase streaminglatency by to up to 45 seconds.Page 10 of 23 2022 Wowza Media SystemsTM, LLC. All rights reserved.

THE COMPLETE GUIDE TO LIVE STREAMING 2021Traditional Stateful Streaming ProtocolsAdditionally, fewer players support these protocols thanever before. Many broadcasters choose to transport livestreams to their media server using a stateful protocollike RTMP and then transcode it for multi-devicedelivery.In the early days, traditional protocols such as RTSP(Real-Time Streaming Protocol) and RTMP (Real-TimeMessaging Protocol) were the go-to methods forstreaming video over the internet and playing it backon home devices. These protocols are stateful, whichmeans they require a dedicated streaming server.RTMP and RTSP keep latency at around 5seconds or less.While RTSP and RTMP support lightning-fast videodelivery, they aren’t optimized for great viewingexperiences at scale.HTTP-Based Adaptive Streaming ProtocolsThe industry eventually shifted in favor of HTTPbased technologies. Streams deployed over HTTP arenot technically “streams.” Rather, they’re progressivedownloads sent via regular web servers.HTTP-based protocols are stateless, meaning they canbe delivered using a regular old web server. That said,they fall on the high end of the latency spectrum.Using adaptive bitrate streaming, HTTP-based protocolsdeliver the best video quality and viewer experiencepossible — no matter the connection, software, ordevice. Some of the most common HTTP-basedprotocols include MPEG-DASH and Apple’s HLS.HTTP-based protocols can cause 10-45seconds in latency.STREAMING LATENCY AND INTERACTIVITY CONTINUUMCOMMON HTTPLATENCIES TODAYREDUCEDLATENCYLOWLATENCYNEARREAL-TIMEOne-way streams of liveevents to large audiences;linear programmingOTT providers; live-streamingnews and sportsUGC live streams; gamestreaming and e-sportsTwo-way webconferencing; telepresence;real-time device control(e.g., PTZ cameras, drones)45 18seconds05seconds01secondsApple HLSHLS TunedLow-Latency HLSMPEG-DASHDASH TunedLow-Latency CMAF for DASHRTMP 01secondsecondWebRTCRTMP TunedWOWZSRTRTSP/RTPPage 11 of 23 2022 Wowza Media SystemsTM, LLC. All rights reserved.

THE COMPLETE GUIDE TO LIVE STREAMING 2021Emerging Protocols for Near-Real-Time DeliveryWith an increasing number of videos beingdelivered live, industry leaders continue to improvestreaming technology. Emerging standards likeWebRTC, SRT, Low-Latency HLS, and low-latencyCMAF for DASH (which is a format rather than aprotocol) support near-real-time delivery — evenover poor connections.LimitationsThese new technology stacks promiseto reduce latency to 3 seconds or less!WebRTCReal-time interactivitywithout a plugin.Only scalable with a videoplatform like Wowza.SRTSmooth playbackwith minimal lag.Playback capabilities are stillbeing developed.Low-LatencyHLSSub-three-seconddelivery at scale.Vendors are adding supportfor this new spec.Low-LatencyCMAFVideo Packaging andProtocols for Every WorkflowMany organizations areprioritizing other technologiesat this time.PROTOCOLSFOR EVERYWORKFLOWDepending on how you set up your streamingworkflow, you’re not limited to one protocolfrom capture to playback. Many broadcasters useRTMP to get from the encoder to server, and thentranscode the stream into an adaptive HTTP-basedformat. The best protocol for your live streamdepends entirely on your use case. Let’s take acloser look at how transcoding works.Injest and TranscodeThe fourth step in a live streaming workflow istranscoding the stream into a variety of differentcodecs, bitrates, resolutions, and file containers. Whilethis step can be skipped, it’s essential to most streamingscenarios.This allows broadcasters to reach almost any device— regardless of the viewer’s connection or hardware.Once transcoding is complete, multiple renditions ofthe original stream depart for delivery.A media server located either on premises or in thecloud ingests the packaged stream, and a powerfulconversion process called transcoding ensues.Page 12 of 23 2022 Wowza Media SystemsTM, LLC. All rights reserved.

THE COMPLETE GUIDE TO LIVE STREAMING 2021Transmuxing, Transcoding, Transizing, TransratingTo optimize the viewing experience across a varietyof devices and connection speeds, broadcasters oftenelect to transmux, transcode, transrate, and transizestreams as they pass through the media server. Transmuxing: Taking the compressed audio andvideo and repackaging it into a different containerformat. This allows delivery across differentprotocols without manipulating the actual file. Thinkof transmuxing like converting a word doc into a pdfand vice versa. Transcoding: An umbrella term for taking acompressed/encoded file and decompressing/decoding it to alter in some way. The manipulatedfile is then recompressed for delivery. Transrating andtransizing are both subcategories of transcoding. Transrating: Changing the bitrate of thedecompressed file to accommodate differentconnection speeds. This can include changingthe frame rate or changing the resolution. Transizing: Resizing the video frame — orresolution — to accommodate differentscreens.Rather than creating one live stream at one bitrate,transcoding allows you to create multiple streams atdifferent bitrates and resolutions. That way, your livestreams can dynamically adapt to fit the screen sizesand internet speeds of all your viewers. This is known asadaptive bitrate (ABR) streaming.Page 13 of 23 2022 Wowza Media SystemsTM, LLC. All rights reserved.

THE COMPLETE GUIDE TO LIVE STREAMING 2021What Is Adaptive Bitrate Streaming?Adaptive bitrate (ABR) streaming involves outputtingmultiple renditions of the original video stream toenable playback on a variety of devices and connectionspeeds. Content distributors use adaptive bitratestreaming to deliver high-quality streams to users withoutstanding bandwidth and processing power, whilealso accommodating those lacking in the speed andpower departments.The result? No buffering or stream interruptions. Plus, asa viewer’s signal strength goes from two bars to three,the stream automatically adjusts to deliver a superiorrendition.How Does Adaptive Bitrate Streaming Work?The first step to adaptive bitrate streaming is creating multiplerenditions of the original stream to provide a variety ofresolution and bitrate options. These transcoded files fall onan encoding ladder. At the top, a high-bitrate, high-framerate, high-resolution stream can be output for viewers with themost high-tech setups. At the bottom of the ladder, the samevideo in low quality is available for viewers with small screensand poor service.During the process of transcoding, these renditions are brokeninto segments that are 2-10 seconds in length. The video playercan then use whichever rendition is best suited for its display,processing power, and connectivity. If power and connectivitychange mid-stream, the video will automatically switch toanother step on the ladder.With adaptive bitrate streaming, mobile viewers with poorconnections don’t have to wait for the stream to load. And forthose plugged into high-speed internet, a higher-resolutionalternative can play.Page 14 of 23 2022 Wowza Media SystemsTM, LLC. All rights reserved.

THE COMPLETE GUIDE TO LIVE STREAMING 2021Cloud-Hosted vs. On-Premises Streaming PlatformsAdaptive bitrate streaming requires a trusted videotranscoding solution. Some content distributors installa media server software on their own servers — bothon premises and in the could — while those who wantto get up and running quickly without any hassles oftenprefer a managed cloud service.But how do you make the choice between on-premisesand cloud-based transcoding? Let’s take a look.Wowza VideoPage 15 of 23 2022 Wowza Media SystemsTM, LLC. All rights reserved.

THE COMPLETE GUIDE TO LIVE STREAMING 2021DeliveryBack to the viewers. Because we don’t know where they’relocated, there’s still the issue of distance. The farther youraudience is from the media server, the longer it will take todeliver the live stream. This can cause latency and buffering.To resolve the latency inherent to global delivery, manybroadcasters employ a content delivery network (CDN).What Is a CDN?As the name suggests, a CDN is a system of geographicallydistributed servers used to transport media files. Thisremoves the bottleneck of traffic that can result whendelivering streams with a single server, as CDNs only requirea single stream for each rendition of an outbound video.These large networks help truncate the time it takes todeliver video streams from origin to end users. Sharingthe workload across a network of servers also improvesscalability should viewership increase.Benefits of Using a CDN for Live Streaming Scalability: Employing a CDN is the fastest,most reliable way to get your content in front ofnumerous viewers — even with viewership spikes. Quality: Streaming through a CDN allows you toachieve the highest sound quality and video resolutionpossible, while minimizing buffering and delays. Speed: CDNs use speedy superhighways to delivercontenttovastaudiencesacrosstheglobe. Security: A CDN can help prevent distributed denialof service (DDoS) attacks, which occur when a siteor resource is flooded by multiple, simultaneousattempts to breach it.Reasons Not to Use a CDN Small-scale streaming: If you have a small number ofviewers and/or your geographic scale is limited, youprobably don’t need a CDN. The more elements youintroduce into your live streaming workflow, the moreopportunities for failure — so why do so unless youhave to? Limited budget: We recommend that you compareyour own egress cost to the cost of a CDN, as this canvary based on deployment. There are both paid andfree CDN options available.Page 16 of 23 2022 Wowza Media SystemsTM, LLC. All rights reserved.

THE COMPLETE GUIDE TO LIVE STREAMING 2021Even if you forgo a CDN, other strategies can beemployed to reach a broad audience. Many contentdistributors leverage social media platforms to ensurescalability, speed, and quality without breaking the bank.Simulcasting makes its easy.What Is Simulcasting?Simulcasting is the ability to take one video stream andbroadcast it to multiple destinations at the same time— thereby maximizing your impact. This allows you toreach a broader audience, no matter which platform orservice your viewers prefer.While ‘the more the merrier’ might be an intuitiveapproach, you should only stream to the destinationsthat make sense for your audience. Broadcasting inthe wrong context can result in negative feedback andwasted resources.Live streaming social platforms are everywhere, with bothwide-ranging and niche applications. While Facebookconnects you with the largest general audience, Twitteris a top destinations for news coverage and events.Meanwhile, Twitch is dedicated to gaming. And let’s notforget about YouTube — which has become a searchengine in its own right.It’s also worth noting that the process of simulcastingcan be complex. Multi-destination broadcastingrequires massive amounts of bandwidth and is prone toerrors. That’s why it’s important to start with the righttools.Whether via a CDN, simulcasting, or both, the last stepto consider is your stream’s final destination: playback.Page 17 of 23 2022 Wowza Media SystemsTM, LLC. All rights reserved.

THE COMPLETE GUIDE TO LIVE STREAMING 2021PlaybackThe end-goal of live streaming is playback. And throughthe process of encoding, transcoding, and globallydistributing the video content, your live video streamshould do just that — at high quality, with low latency,and at any scale.Multi-Device DeliveryIf every viewer had a 4K home theater plugged intohigh-speed internet, delivering live streams would beeasy. But that’s not the case.Today’s viewers are out and about. A significant portionof your audience is on mobile devices, relying ondepleted batteries and LTE connections. Other viewersstream content to their laptops using public Wi-Fi, orperhaps to their iPads via mobile hotspots.Different screens and varying internet speeds maketranscoding essential. And with adaptive bitratestreaming, you can deliver the highest-quality streampossible to internet-connected TVs and mobile usersalike.While the bulk of the work is complete at playback, a fewfinal considerations remain: recording, monetization,and security.RecordingLive streams disappear in the blink of an eye. But theydon’t have to.While recorded videos won’t match the immediacy andauthenticity of a live stream, it’s still useful to have thesefiles on hand for later use. That way, you can edit thevideo assets; enable immediate pause, rewind, and fastforward capabilities; and repurpose them for marketingcollateral or internal reference.Sports fans often review game-changing plays duringcable broadcasts, so why not provide your end usersthe same freedom when viewing your live streams?nDVR technology allows users to record a live streamwhile simultaneously playing, pausing, resuming, andrewinding the recorded stream. Content distributorscan also further extend audience reach by transcoding asingle set of recorded source files into multiple formatsfor streaming to any player and device.MonetizationA successful stream is a revenue stream. Regardless ofwhether you’re crowdsourcing content from users viaa mobile live streaming app or producing it yourself,profitability often revolves around the ability to monetizecontent.Whereas surveillance streaming devices like doorbellcameras and service-oriented applications like virtualdoctor visits generate revenue from different meansaltogether, some tactics can be employed across a rangeof industries. Below are the three most straightforwardmodels for converting content into cash.Live streaming monetization comes in many shapes andsizes.Page 18 of 23 2022 Wowza Media SystemsTM, LLC. All rights reserved.

THE COMPLETE GUIDE TO LIVE STREAMING 2021SubscriptionsViewers are moving toward subscription-based contentconsumption due to the quality, lack of interruptions,and ability to take an à la carte approach to contentselection. When an affordable monthly payment meansthe difference between low-brow, ad-riddled fluff andsought-after, commercial-free content — it’s a nobrainer.When using this model, the onus is on the providerto deliver content worthy of the investment. Adaptivebitrate streaming underpins this requirement, allowingcontent distributors to compete with industry giants onthe basis of video quality and user experience.Paywalls help restrict access to subscribed viewers,resulting in a recurring revenue for your business.Services like Netflix and HBO Go have championedsubscription-based monetization.Transactions — Paywalls and Pay-per-View ServicesGone are the days when seeing an event in real timemeant you actually had to be there. Paywalls also enablepay-per-view revenue generation for live sportingevents, concerts, and more.Cord-cutting viewers expect the same on-demandlive options that traditional satellite and cable servicesprovide, which opens up opportunities for live streamingbroadcasts.OBSEnhanced forReal-Time( 500ms)BrowserBasedCapture( 5

The second step in any live streaming workflow is video encoding. After capturing the video with your camera(s) of choice — be it a production-quality setup, IP camera, or your end-users' mobile devices — live video data must be digitized for efficient transportation across the internet. Video encoding is essential to live streaming,