November 1, 2021
Eng | Ru

Live broadcasting from the mountains? Easy!


Currently, there is no such problem as live broadcasting in cities with high-speed Internet provided by cellular operators anytime, anywhere. However, as soon as we leave cities for remote areas, we face issues with broadcasting.

Thus, broadcasting professionals face the issue of how to shoot in the absence of high-speed Internet. Now, solutions based on the SRT protocol have come to the rescue.

This article tells the story of Sergey Korneev, an enthusiastic engineer who managed to conduct a technical test of the capabilities of a solution based on the SRT protocol and broadcast from a mountainous area alone, without any help at all.
Live broadcast with SRTMiniServer:
Live broadcast with SRTMiniServer:

Who is Sergey Korneev, and what is the AVStream community about?

Sergey Korneev is the founder of AVStream, an international Russian-speaking community and an educational YouTube channel with the same name dedicated to creating and engineering live broadcasts. In particular, the AVStream YouTube channel is dedicated to vMix, of which Sergey is the popularizer.

AVStream is somewhat unique, even by world standards, since there are no similar communities with such a large number of participants (about four thousand people) from all over the world.

The community was formed at the end of 2016, and it unites enthusiasts, amateurs, and professionals from small, medium and large video production studios from Russia and the CIS, as well as regional TV channels.

Technical challenges

Let's have a look at the key challenges Sergey faced during live broadcasting from the mountains and how he handled all of them.

The first challenge was the complete absence of any communications, including high-speed Internet, which we are used to in urban areas.

It seemed like a satellite Internet could be helpful to Sergey. He used the following equipment:

  • a 0.87-meter satellite dish
  • a Yamal-601 satellite (Ka band).

The power supply was provided by an inverter, as well as all the other equipment in the car.

The second challenge was that even with satellite Internet, the channel wasn’t stable and didn’t meet the data transfer rate requirements for live broadcasts.

The satellite guaranteed only 2.5 Mbps, so it was necessary to ensure maximum video transmission quality within such a small bandwidth. The solution Sergey used was HEVC (High-Efficiency Video Coding). Unlike h264, this codec can give significantly better quality at lower bitrates.

Sergey had previously carried out similar experiments, but they were less successful in terms of implementation. Nevertheless, they allowed him to gain valuable knowledge and understanding of how to succeed.

Thus, based on his experience with previous extreme live broadcasts, Sergey concluded that vMix was not very stable in terms of receiving HEVC streams, and with an unstable connection, streams can lag. As a result, he used SRTMiniServer as a proven solution for receiving SRT which is optimized for complete or temporary loss of communication and is more stable when working with HEVC.

The third challenge was to manage live broadcasting alone, with no help from others: to fully manage stable equipment and software operations during the online broadcast. Sergey successfully solved this task!

What was the solution?

To organize the broadcast, Sergey used a combination of SRTMiniServer and vMix. Both software products were hosted in the cloud.

The procedure is as follows:
  1. Video cameras are connected to an ATEM Mini video mixer via HDMI, then the signal is transferred via an HDMI-to-USB adapter to vMix on a laptop, which then encodes it in SRT.
  2. The SRT stream is sent to a remote cloud server via a satellite modem.
  3. Sergey also used an additional solution, an independent SRT signal from a mobile phone via LarixBroadcaster. He was able to broadcast video even several meters away from the car.
  4. SRTMiniServer receives SRT signals from the broadcast vehicle.
  5. The signal is sent to vMix by converting it to the NDI standard.
  6. In vMix, the signal is processed and combined with other audio and video content, graphic content, and chat. Switching views in vMix is done via the Web interface.
  7. From vMix, the processed video content is broadcast to YouTube.

What is SRTMiniServer for, since an SRT signal can be received directly by vMix?

We asked Sergey this question, and here’s what he said:
Even though vMix was one of the first vendors on the market to integrate SRT support into its video mixer software (they did it even earlier than the super-popular OBS), even at the end of 2021, it is still implemented in software in a very peculiar way. For example, vMix does not distinguish StreamID at all, which is used to delimit and sign SRT streams.

You can specify absolutely any StreamID, and vMix will still read the stream, regardless of whether that StreamID even exists.

Also, SRT stream buffering is implemented in a very peculiar manner in vMix. Experimentally, it was found that, with a lousy Internet connection through an intermittent LTE signal achieved by switching between towers, vMix cut off and stopped the stream. With the same lousy connection, SRTMiniServer continued to show video and sound.

Also, when compared directly under the same conditions, the picture received via SRTMiniServer with poor connection quality has fewer artifacts than if you send the signal directly into vMix.

Furthermore, SRTMIniServer has convenient functions for monitoring the input SRT stream on each channel, as well as automatic and forced reset of the accumulated buffer, not to mention the ability to synchronize SRT streams by time code.
In the end, SRTMiniServer is a highly specialized solution for implementing a single task, which is receiving SRT streams and sending them for further processing. It has specific functions onboard that are not present in any other product.

In particular, there is a function for measuring SRT speed. Thus, before starting a broadcast, you can measure the actual SRT speed and conduct a stream based on the obtained values.

What are the main advantages of the SRT protocol over RTMP?

If you are a professional in the field of live broadcasts, you might wonder why you should choose the SRT protocol instead of the equally popular RTMP for broadcasting high-quality video.

  • The crucial difference between the SRT protocol and RTMP is that SRT allows reliable and secure data transmission (low-latency media files) over communication channels of unstable and unpredictable quality, primarily such as the public Internet.
  • Unlike RTMP, SRT allows you to transmit HEVC content, which was critical in Sergey’s situation.
  • SRT allows you to more flexibly find a compromise between content quality and delivery speed. An engineer can adjust the required latency level.
Read more about the advantages of SRT over RTMP here.

Conclusion

With the SRT protocol, it is possible to easily broadcast high-quality video, even from the mountains!


In this article, we described how Sergey Korneev, founder of the AVStream YouTube and Telegram channel, managed to successfully conduct a technical experiment in which he carried out the first private online broadcast from the mountains all by himself. He used the SRTMiniServer solution in conjunction with vMix.


Sergey’s experience opens up significant opportunities for organizing high-quality video broadcasts, even from the most remote regions, both for amateurs carrying out individual video broadcasts and for small teams that broadcast events online and journalists who cover live events.