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 Assessment: Actual-Time Streaming at Scale for Wowza Streaming Cloud
June 25, 2022

Assessment: Actual-Time Streaming at Scale for Wowza Streaming Cloud

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Tim Siglin is a product reviewer for streaming options and the founding father of Assist Me Stream Analysis Basis


Wowza provides characteristic that merges advantages of legacy and newer supply options

Wowza contacted me just lately to overview a brand new characteristic of Wowza Streaming Cloud that permits real-time streaming at scale. I’ve had the prospect to have a look at a number of real-time options over the previous 25 years, each in my position as product reviewer for a lot of magazines and on-line newsletters (together with Streaming Media journal) and extra just lately because the founding government director of the trade’s first charity-based analysis agency, the 501(c)3 Assist Me Stream Analysis Basis, so I used to be delighted to place Wowza’s resolution by its paces.

Readers of this overview have invariably felt the ache factors of interactive video over the previous 18 months: inconsistent supply of content material that’s meant to be very low latency, unpredictable viewers measurement, and an general lack of interactivity that plagues conventional streaming.


Why Did Streaming Swap to HTTP?

One of many important causes that almost all of right this moment’s streaming has important latency is that it’s been purpose-built to take action. A couple of decade in the past, give or take, the trade determined to interchange conventional streaming server software program with generic HTTP-based internet server software program.

There have been 4 important advantages to taking this HTTP strategy:

  • Extra generic, much less sturdy {hardware} may very well be used for HTTP supply
  • HTTP visitors was already open on most networks (no have to open particular streaming solely ports)
  • On-demand content material may very well be cached nearer to giant pockets of finish customers
  • Potential to scale at ranges that streaming servers (each {hardware} and software program) have been unable to realize at anyplace close to an inexpensive price.

Sadly, all the advantages of HTTP segment-based supply got here on the expense of latency. Latencies elevated considerably to accommodate for desired scale, which labored fantastically for on-demand content material supply, and allowed the streaming trade to develop. However these of us who had been round for the reason that inception of streaming — or who, like me, got here from a background in zero-latency video conferencing — knew it was a matter of time earlier than HTTP streaming bumped into the brick wall of low latency wants.

I keep in mind writing an article in 2018 bemoaning the truth that we’re not in a position to get to scale:

“Within the brief run, the trade wants innovation that helps get to scale, at decrease latencies,” I wrote. “Everybody agrees on this. However what we don’t want is one other situation just like the one we’ve confronted over the previous 6 years, the place the expedient scalable resolution (HLS) essentially painted the entire trade right into a nook.”


Interactivity Is the Future. And the Previous. However It Works This Time. 

Skip ahead to early 2020, and the streaming trade didn’t simply want low-latency at scale to thrive, we wanted it to handle the worldwide scale of interactivity that hit with out warning as pandemic lockdowns took impact.

There have been interactive options accessible to satisfy the problem, most notably from the video conferencing trade I’d left within the late Nineteen Nineties to hitch the streaming revolution. But, whereas they have been interactive, they didn’t actually scale, as anybody who tried final yr to do Zoom webinars above 100 attendees might attest. This lack of scale at low latencies was primarily because of a mixed lack of innovation in conventional video conferencing and the inherent limitations of scaling interactive video, each of which required specialised and expensive servers to get to scale. In different phrases, the identical points that moved the streaming trade in the direction of HTTP-based supply within the first place.

Anybody that’s tried to make use of these video conferencing or internet conferencing options will rapidly discover, to their chagrin, that low latency at scale is a relative time period. For these in the course of the 2020 lockdowns trying to host all-hands conferences or webinars, the primary 100 individuals might be a part of with full entry to polling, chat, Q&A and different options, however the remaining attendees have been relegated to watching on non-interactive platforms like YouTube or with latencies starting from 5 to forty-five seconds.

To say many options accessible on the outset of the pandemic yielded poor person expertise could be an understatement. For customers to actually work together with others and expertise the stream “in actual time” requires glass-to-glass supply of nicely below a second — and that features all of the steps within the supply chain, from the encoding time on the presenter’s digicam to the decoding and playback on the screens of tons of, hundreds, and even tens of millions of viewers.


Why Dwell HTTP Streaming Isn’t Quick Sufficient

Anybody who has tried to make use of rising low-latency options similar to Low-Latency HLS (LL-HLS) realizes that HTTP-based supply nonetheless faces a higher than one-second barrier; these modified HTTP options nonetheless run within the 2-3 second vary based mostly on our testing right here at Assist Me Stream Analysis Basis.


WebRTC to the Rescue?

So we have been curious, when Wowza approached Assist Me Stream a couple of overview of their Actual-Time Streaming at Scale within the Wowza Streaming Cloud, whether or not we’d face related latencies, or an absence of scale, or each.

Our fundamental discovering are that, with a couple of pre-release quirks that Wowza is trying into, the Actual-Time Streaming at Scale resolution works as marketed.

We have been in a position to efficiently view a single printed stream at latencies that averages about 400 milliseconds (ms) throughout all kinds of gadgets, utilizing solely a browser-based writer and browser-based viewer.

Whereas we didn’t check to the dimensions of one million viewers that Wowza advertises, we did check on three several types of networks, utilizing a number of gadgets accessing the identical stay low-latency stream throughout not less than two totally different networks — usually WiFi to a cable modem in addition to a mobile information community — and two totally different browsers (cell and desktop variations of Chrome and Safari) every time we carried out a check.

And to verify the low-latency providing didn’t want any further functions, which many low-latency options require, we examined each publishing and playback strictly in a browser-native setting, with out the help of a any specialised plugins or downloaded writer or participant app. The truth that every thing labored in a browser was in itself spectacular.

Latencies have been additionally low sufficient, even throughout each LAN and mobile networks, that we discovered the audio “suggestions loop” candy spot that solely comes with analog sound programs or low-latency digital audio broadcasts. One space of curiosity was the truth that, whereas we skilled some video latency shifting (the place browser playback within the background would possibly slowly lose synch with browser playback within the foreground), the audio latency all the time remained constant sufficient to generate this audio suggestions loop.

Past our preliminary browser-based assessments, we have been additionally in a position to broadcast through WebRTC from a personalized model of OBS (the well-known open-source video mixer resolution) that’s been modified to make use of WebRTC because the output. On this occasion, latencies averaged round 600ms.

Lastly, Wowza presents RTMP, a legacy low-latency know-how, because the publishing engine for its Actual-Time Streaming at Scale characteristic.

RTMP is nearly as previous because the underlying protocols that energy WebRTC, similar to RTSP and SIP, however comes with the good thing about being a TCP-based transport protocol — in distinction to legacy UDP transport, which isn’t carried out on as many routers as TCP — that’s withstood the check of time from the early days of the streaming trade.

If the final paragraph has you considering “every thing previous is new once more” you’re not alone, as a result of we’re not solely utilizing RTMP fairly a bit longer after its preliminary required server has been deprecated (assume Flash Media Server), however the streaming trade is discovering new makes use of for RTMP. A kind of is RTMP’s potential to generate low-latency encodes that may now be scaled by options like Wowza’s that the unique RTMP streaming servers have been incapable of performing.

The draw back of RTMP and its TCP-based streaming is that there’s about a further half-second of latency added on common to the publishing aspect, which implies a mean of about one second of latency. Based on Wowza’s Barry Owen, who’s the corporate’s vice chairman of options engineering, the power to make use of RTMP at scale with out requiring a specialised participant could be very engaging to a lot of its potential clients.


Workflow: Actual-Time Streaming at Scale for Wowza Streaming Cloud


“It’s value noting that up to now all the clients in our pipeline have RTMP workflows they want to use,” mentioned Owen. “None have expressed an curiosity in broadcasting from the browser, so whereas a few of these clients are candidates for the WebRTC model of OBS, all are at the moment utilizing both {hardware} or different software program RTMP encoders of their workflows.”

It’s a legitimate level, however it additionally exhibits simply how entrenched RTMP continues to be within the streaming trade. Even those that have achieved at-scale stay HTTP supply usually begin with an RTMP stream, which is then both transrated, transmuxed (or each) earlier than being segmented into HLS or DASH fragments for supply 10-30 seconds later.

RTMP’s continued reputation additionally exhibits how WebRTC could discover extra traction on the supply aspect — as a method to actually ship low-latency at scale, even when that scale is round a second of latency — relatively than on utilizing WebRTC on the ingest aspect.

In our assessments of OBS for WebRTC, we discovered constant latency throughout networks, together with consistency of playback on the identical LAN that OBS was broadcasting from. Apparently, our mobile information playback check exhibited barely decrease latencies than the playback through a WiFi entry level connected to a cable modem. However the distinction seemed to be lower than 250 ms between all of the gadgets on every community, that means general latency from publish glass to playback glass fell between 400–650 ms when utilizing the OBS WebRTC ingest.

For patrons desirous to implement the Actual-Time Streaming at Scale characteristic in Wowza Cloud, the corporate is at the moment providing Skilled Companies help to take playback integration from pilot undertaking to manufacturing scale.

At present, too, the one method to name the service is through the Wowza Cloud API.

“A buyer can name a Wowza Cloud API name to provision a stream,” mentioned Owen, noting that UI entry is pending. “The API name returns you a stream key, a publish token, and an non-compulsory RTMP URL.”

A typical API name would possibly return one thing like this


    "real_time_stream": {
        "id": "2kbkl5yp",
        "identify": "TSTestRealTimeStream",
        "stream_name": "<>",
        "token": "<>",
        "rtmp_url": "<>",
        "state": "lively",
        "created_at": "2021-09-13T22:18:52.000Z",
        "updated_at": "2021-09-13T22:18:52.000Z"


Subsequent Steps

So what quirks did we discover, and the way are they being addressed?

As a result of we examined the pre-release model of Wowza’s real-time streaming writer, which permits WebRTC streaming to Wowza’s Cloud instantly from a browser, we labored carefully with Wowza to determine and handle any main points. 

Over the course of the ten days of testing, we examined three variations of the writer, utilizing each Apple’s Safari (model 15.0 construct 17612.1.28.5) and Google Chrome (model 93.0.4577.82) on a MacBook Air utilizing the Large Sur macOS working system.

One spectacular discovering to notice is that a number of gamers (one every on a number of gadgets) used on intermittent networks (similar to a WiFi sign that’s exhibiting intermittent connectivity points) all maintained viewing synchronization between gamers. This was true even when the latencies elevated above the 600 ms vary, that means all gamers have been equally delayed.


Testing anomaly Standing Notes
Built-in laptop computer digicam and microphone on MacBook Air wouldn’t connect with writer. Resolved Wowza up to date writer safety settings to accommodate Apple’s latest Safari browser settings.
Latency shifting, when browser window with writer is in background. Leads to longer-than-average latencies. Ongoing Chrome reveals lowest latency shifting, whereas Safari latency might exceed 2.0 seconds; subsequent writer variations lowered Safari latency shift to ~1.5 seconds
Viewer rely inconsistencies in writer. Ongoing If a broadcast stream abruptly ends and is restarted, viewer counts don’t precisely replicate those that have been already viewing the stream. Wowza says this can be addressed in an upcoming model of the SDK.
Gamers stay “stay” even after a stream ends. Ongoing For many who use a everlasting or hard-coded stream key in writer, any participant left open after a broadcast stream ends will have the ability to view the subsequent stream as soon as it begins to publish. Wowza is addressing this challenge, noting “the best situation might be to ship a sign from the platform when the writer stops for a sure time period that the gamers can see as an occasion and reset the stream.”
Auto-view Ongoing Chrome mechanically begins viewing when URL is entered, however Safari viewing inconsistently requires clicking the “play” button on the backside of the browser window. This very nicely may very well be a Safari model mismatch, however Wowza is trying into the problem because it seems throughout all three variations of writer we examined
Hand-off between networks Ongoing Viewing content material on one community (e.g., Wi-Fi) then switching to a different community (e.g., LTE mobile) leads to playback persevering with for about 5 seconds, with a portion of the stay printed stream enjoying again on the brand new community, however then viewing freezes and browser viewer must be refreshed. Wowza is exploring this challenge.


There’s one different observe from our testing: Wowza is utilizing a model of OBS for WebRTC that not solely permits clients who have already got RTMP workflows to make use of OBS as typical, but additionally to discover the choice of utilizing the lower-latency WebRTC on the publishing aspect.

The model of OBS that Wowza is utilizing works fairly nicely. There’s just one challenge we encountered: an NDI error dialog field continues to seem on the launch of OBS, even when an NDI driver shouldn’t be current. Wowza is addressing, however it seems to be based mostly on a difficulty throughout the Github OBS distribution that Wowza is at the moment utilizing, as that model on Github is a bit lengthy within the tooth.



So what’s our backside line? Except the testing anomalies famous above, the Actual-Time Streaming at Scale characteristic within the Wowza Streaming Cloud works nicely, and seems preferrred for the one-to-many or few-to-many low-latency publishing wants of public sale homes, sportsbooks, interactive training, and different key low-latency markets.

Wowza additionally plans to supply a software program improvement equipment (SDK) that can enable clients to customise each the writer and, extra importantly, the participant, to raised combine each into their workflow. If an RTMP workflow is already in place, the SDK would solely be required for customizing the participant to suit into current functions.


Get Began With Actual-Time Streaming at Scale

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Further Assets:

  • Asserting: Actual-Time Streaming at Scale for Wowza Streaming Cloud
  • Exploring Low-Latency Know-how Choices Throughout Wowza’s Product Portfolio
  • 2021 Video Streaming Latency Report

About Tim Siglin

Tim Siglin, who has over 20 years of streaming media design and consulting expertise, and a further 10 years in video conferencing and media manufacturing, has written for Streaming Media journal and different publications for 23 years. He has an… View extra

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