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Formats2 min read

LESSON 128

Live streaming setups

Camera to encoder to platform, live.

IN THIS LESSON

  1. What live streaming is
  2. The chain
  3. Several cameras
  4. Practice: a reliable small stream

What live streaming is

Live streaming sends video or audio over the internet in real time or close to it, which is what separates it from video on demand. It covers games, sport, concerts, news, talks and personal broadcasts, on services such as YouTube, Twitch, Facebook Live and others. A chat beside the stream lets viewers talk to the broadcaster and each other, which is a large part of the appeal. Brands use it as an inexpensive way to reach an audience, because one well-planned stream can replace an event that would otherwise need a venue.

The chain

A stream passes through a chain of parts. Cameras and microphones feed a switcher or a computer, where sources are mixed and graphics added. An encoder, hardware or software, compresses the programme, usually with H.264 or a newer codec, and sends it to the platform. A long-standing protocol for that upload is the Real-Time Messaging Protocol, RTMP, first developed by Macromedia and later Adobe; plain RTMP runs over TCP on port 1935 by default, and RTMPS adds TLS encryption. The platform then re-encodes and delivers to viewers.

Several cameras

With more than one camera, the sources must stay in time with each other so the switcher can cut cleanly between them. In broadcast facilities this is done with genlock, which locks every source to one reference signal; it is used for fast multi-camera events such as sport. In small setups, a hardware switcher that accepts several HDMI or SDI inputs often handles timing itself. Multi-camera streams are directed live, like television, so the director must call shots without a second chance.

Practice: a reliable small stream

This is working practice. Use a wired internet connection rather than Wi-Fi, and test the upload speed at the venue; keep the stream bitrate well below it. Prioritise sound: viewers forgive soft pictures but leave over bad audio. Use a dedicated microphone and monitor it on headphones. Do a full private test stream the day before, and a short one an hour before going live. Prepare a holding slide for problems, and record a local copy in case the stream fails.

Try it today

  1. 01Install a free streaming encoder on your computer.
  2. 02Add one camera, one microphone and one title graphic.
  3. 03Run a private test stream for ten minutes.
  4. 04Measure your upload speed and set a bitrate well below it.
  5. 05Watch the test back and note any drops in sound or picture.