Audio Visual Design Guidelines

Define the Scope

2 views November 22, 2018 aetm 0

Ingest Method and Combined Sources

Define the video, audio, and data source requirements for input to the recording system:

AV SourcesDescriptionAV System Design Requirements
Fixed Ingest SourcesVideo and audio source is permanent and consistentVideo and audio signals may be connected directly to lecture capture appliance (hardware) and/or computer with recording software
Switchable Ingest SourcesVideo and audio sources may be any one selected from available sources. May have the ability to switch sources during recording sessionVideo: AV switcher, matrix switcher, Audio: Mixer, Audio Digital Signal Processor (DSP)
Fixed Combined Ingest SourcesVideo sources may be combined (PiP) and audio sources may be mixed as video is encodedVideo: AV PiP or windowing processor

Audio: Mixer, Audio Digital Signal Processor (DSP)

Distributed Recording (Multi-Camera Recording)Multiple video and audio sources may be recorded as a single session / stream. Viewers may switch between sources during playbackVideo and audio signals may be connected directly to multi-input lecture capture appliance (hardware) and/or uploaded to video content management system (software)
Annotation – Video OverlayVideo content may be recorded with a digital annotation overlayVideo: Annotation video processor with HID input from touchscreen or keyboard/mouse

 

Content Management and Distribution

Define the method of managing and distributing recorded video content:

Content Management MethodDescriptionVideo Content Management Requirements
User-ManagedEncoded video file and session data is saved to onboard storage, SD card, or USB storage. May be saved direct to lecture capture appliance or user’s computerDistributed freely by USB storage media, email, shared drive, or cloud-based storage service
On-premises Video Content Management ServerEncoded video file and session data may be uploaded to a centralised on-premises video content management systemWeb browser-based video content management and delivery platform.

Server software installed to on-premises computer hardware

Cloud-based Content Delivery Network (CDN)Encoded video file and session data may be uploaded to a third-party cloud-based CDN platform (ie YouTube, Vimeo, et al)Web browser-based video content management and delivery platform.

Server software accessed via cloud-based computer hardware

Live-Streaming – One-to-ManyEncoded video is streamed and recorded in real-time to a third-party CDN. The CDN manages distribution of the live-stream to audiences connected via the internet.

Live-streams may be saved as a video file for viewing after the fact

Web browser-based, video content management and delivery platform with support for live-streaming.

Server software accessed via cloud-based computer hardware

Webinar – Many-to-ManyEncoded video of instructor content is streamed and recorded in real-time to a third-party CDN. A group of connected users may view the instructor content, and interact in real-time. Connected users may interact with the group through chat, camera, voice, and/or file-sharing.

Webinars may be saved as a video file for viewing after the fact

Webinar content delivery platform facilitating instructor-led seminars over the internet and the capability for viewers to interact and engage with the group.

Server software accessed via cloud-based computer hardware

Data – Comment SectionsUsers may comment on the videoWeb browser-based video content management and delivery platform with support for comment sections
Data – Live Comments (Superchat)Users may discuss or comment on a live-streamed video in real-time providing more context for their commentsWeb browser-based, video content management and delivery platform with support for live-streaming and live-commenting

 

Viewing and Streaming

Define the method of viewing and streaming video content:

Viewing MethodDescriptionViewing Requirements
Lecture Capture AppliancePlayback of encoded video file and session data through lecture capture applianceAV system for presentation of lecture capture appliance output
Video Playback Application – FilesystemPlayback of encoded video file and session data video by opening the content in a video playback application installed on the end-user PC or mobile deviceVideo playback application installed on end-user PC or mobile device
Video Content Management and Delivery System – Web Browser-basedPlayback of encoded video file and session data through web browser-based video delivery platform.

Content delivery server may be on-premises or cloud-based

PC or mobile device running a compatible web browser application (ie Chrome, Safari, Firefox, et al)

Recorded Content Creation Rate

Calculate the estimated creation rate of recorded content as follows:

    • Given N is number of rooms featuring lecture capture
    • Given H is amount of average hours of recorded content per day per room
    • Given R is the estimated total amount of recorded content per day
    • R = N x H

 

  • Example: If there were 5 rooms with lecture capture capability creating an average of 3 hours of video content per day, the organisation estimates that a total of 15 hours of video content will be added to its content library per day.

 

Data Retention Policy

Determine the length of time the recorded content may be available for viewing before it is archived or permanently deleted.

Quality Requirements

Define the quality requirements for encoded video recorded content:

  • Video codec
  • Image resolution
  • Frame rate
  • Colour bitrate
  • Video compression:
    • Data rate (Kbps, or Mbps)
  • Audio quality:
    • Option to remove audio track
    • Mono, stereo, or multi-channel
    • Uncompressed (WAV, PCM, AIFF)
    • Compressed (MP3, AAC)
    • Bitrate
    • Samplerate

The higher the quality of encoded video, the more storage space required per second of recorded content. An organisation’s decisions when determining the quality requirements for lecture capture should take into account any ICT architecture limitations (disk storage and data traffic transmission capacity).

Encoded Video File Size Calculations

Calculate encoded video file sizes by the following:

    • Given D is the encoded video data rate in Mbps
    • Given M is the encoded video length in minutes
    • Given F is the file size of video content in GB
    • F = D x M x 0.0075

 

  • Example: A 3-hour of video encoded at 7.35Mbps will be 9.92GB

 

The calculation may be inverted to conform to ICT architecture limitations.

Calculate total minutes of recorded content by the following:

    • M = F / (D x 0.0075)

 

  • Example: If the total disk space available is 2TB, and the data rate is 7.35Mbps then a total of 36,281 minutes (604 hours) of content may be stored.

 

Calculate optimum data rate by the following:

    • D = F / (M x 0.0075)

 

  • Example: If the total disk space available is 2TB, and 1,000 hours of content must be stored, then the optimum data rate is 4.44Mbps

 

 

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