Hybrid Events Wiki

Live streaming

From the Hybrid Events Wiki, published by Magnetize ME

Live streaming is the real-time broadcast of event content to remote viewers over the internet. For an event, it is planned around cameras, audio, moderation, captioning and connectivity.[1] Event streams are often one-to-many broadcasts in which presenters lead and the audience mainly watches.[2]

Signal chain

IBM lists five core elements of a stream: a camera or video signal, a microphone or audio signal, capture or conversion, encoding, and an internet connection.[7] Professional cameras and video switchers usually need a capture card or box before encoding software can use their signal, and audio may come from microphones, a PA system or a soundboard routed through a mixer.[7] A hardware or software encoder then sends the stream to a streaming service, commonly over RTMP,[2] and the service delivers it to viewers through a content delivery network.[2][8]

Protocols

RTMP (Real-Time Messaging Protocol), originally developed by Adobe, is an application-level protocol for packetizing audio, video and interactive content over a transport such as TCP.[9] It remains a common way to send a stream to a platform; YouTube, for example, accepts RTMP and recommends its encrypted form, RTMPS.[3]

HLS (HTTP Live Streaming), developed by Apple and documented in RFC 8216, splits media into short segments listed in a playlist, and a master playlist can point to versions of the stream at different bit rates.[4] Players switch between these versions to suit the viewer's connection, and the content can be served from ordinary web servers and content delivery networks.[8] MPEG-DASH, an adaptive streaming standard ratified by ISO in April 2012, works in a similar way over any HTTP server.[5]

SRT (Secure Reliable Transport) is an open-source protocol for secure, low-latency video over unpredictable networks, created by Haivision.[6] It recovers lost packets by retransmission and supports AES encryption.[10]

Bitrate and bandwidth

YouTube publishes these recommended video bitrates for live streams encoded with H.264:[3]

ResolutionFrame rateRecommended bitrate (H.264)AV1/H.265
1080p30 fps14 Mbps10 Mbps
1080p60 fps17 Mbps12 Mbps
720p30 or 60 fps8 Mbps6 Mbps

YouTube also recommends 128 kbps stereo audio and a keyframe every two seconds.[3] IBM advises that the encoder's bitrate should never exceed half of the available upload bandwidth, and suggests at least 4 Mbps of upload for HD streams.[7] Remote participants who join interactively need less: Zoom lists about 3.8 Mbps up and 3.0 Mbps down for 1080p video in meetings and webinars.[11]

Latency

Latency is the delay between the live moment and what viewers see. YouTube's normal-latency setting gives the highest quality and least buffering; low latency gets most viewers under 10 seconds and ultra-low latency under 5 seconds, at the cost of more buffering, because a shorter delay leaves the player less buffer to absorb delivery problems.[12]

Redundancy and recording

To guard against failures, broadcasters can send the same stream to a primary and a backup ingest address at the same time,[13] and keep a local recording as a backup.[14] Platforms can archive a stream for on-demand viewing after the event; YouTube archives streams of under 12 hours automatically.[14] Brown University notes that recorded event streams can be reused afterward, and requires that they contain no confidential data and that speaker permissions be kept on file.[15]

Captions

Live captions can be embedded in the video signal using the CEA-608/708 standards or sent separately from captioning software; for captioned events YouTube recommends a 30- or 60-second broadcast delay so captions stay in sync.[16]

Main article: Event accessibility

References

  1. ^ "Event Industry Glossary". Meeting Professionals International. mpi.org
  2. ^ ^ ^ "What are Microsoft Teams live events?". Microsoft Learn. learn.microsoft.com
  3. ^ ^ ^ ^ ^ "Choose live encoder settings, bitrates, and resolutions". YouTube Help. support.google.com
  4. ^ ^ Pantos, R. (ed.); May, W. (August 2017). "HTTP Live Streaming" (RFC 8216). RFC Editor. datatracker.ietf.org
  5. ^ ^ "About". DASH Industry Forum. dashif.org
  6. ^ ^ "SRT Alliance". SRT Alliance. srtalliance.org
  7. ^ ^ ^ "Basics of Streaming Video Production". IBM Support, June 18, 2026. ibm.com
  8. ^ ^ "HTTP Live Streaming (HLS)". Apple Developer. developer.apple.com
  9. ^ Parmar, H.; Thornburgh, M. (eds.) (December 21, 2012). "Adobe's Real Time Messaging Protocol". Adobe. veovera.org
  10. ^ "Haivision/srt". GitHub. github.com
  11. ^ "Zoom system requirements: Windows, macOS, Linux". Zoom Support. support.zoom.com
  12. ^ "Understand live streaming latency". YouTube Help. support.google.com
  13. ^ "LiveStreams". YouTube Live Streaming API, Google for Developers, updated October 15, 2026. developers.google.com
  14. ^ ^ "Archive live streams". YouTube Help. support.google.com
  15. ^ "Live Streaming". Brown University Office of Information Technology. it.brown.edu
  16. ^ "Live caption requirements". YouTube Help. support.google.com
Categories: Live streaming · Hybrid events · Streaming protocols