Online video – Technical considerations

Progressive download, live streaming or download?

Progressive download

  • Most video files available on the web today are suited to progressive download, where a video file commences playback as soon as it begins to download.
  • It is a useful way for low- and medium-quality video to be quickly previewed.

Live streaming

  • Real-time events are generally best suited to live streaming (broadcasting the proceedings of enquiries or live announcements, for example).
  • Agencies may also find that there is a demand for higher-quality versions of live-streamed video to be made available in downloadable forms.
  • Additional accessibility considerations are applicable to live streaming video.

Download

  • Downloadable video requires the entire video file to be saved to a user’s computer before playback can commence, usually via dedicated video playback software.
  • This is a delivery mechanism generally suited to high-quality video, and is a useful fallback mechanism for users who may not have the required browser capabilities for live streaming or progressive download.

Providing video content online should be subject to specialist technical considerations that may not apply to the bulk of your textual content.

Codecs and formats

  • Developers may choose to provide the same audio / video content in multiple formats, at varying quality levels, to ensure maximum playability across target audiences and target devices.
  • Mature video platforms are typically able to ingest a single video/audio file, and transcode it to several target formats, as defined by the web developer.
  • Typical target file formats are listed below. Inclusion does not imply endorsement:

Video

Audio

Subtitles / Captions

Plugins, downloads and native support

Flash coverage

Flash-based video players remain the dominant form of video delivery. However, customised work-arounds are usually required to fully address accessibility issues, and several emerging devices and platforms are reducing their support for Flash.

Table 1 – Flash Version Coverage (Source: australia.gov.au Web Statistics – Q1 2010)
Flash Version %Usage
10.0+ 82.5
9.0+ 10.4
8.0+ 0.47
7.0+ 0.16
6.0+ 0.53
(Not set) 5.8

HTML5 coverage

The HTML5 and tags are increasingly being supported by commonly-used browsers, even though the HTML5 specification is still in draft mode. Playback is usually handled by the browser’s native interface, but can be overwritten with custom players.

Table 2 – HTML5 video-capable browser coverage (Source: australia.gov.au Web Statistics – Q1 2010)
Browser H.264 Ogg/Theora %usuage
Internet Explorer (All Versions) No No 56.5
Safari (3.1+) Yes No 6.1
Firefox (3.5+) No Yes 15.47
Chrome (3.0+) Yes Yes 4.9
Opera (10.5+) No Yes 0.2

External HTML5 Video resources:

Testing

In addition to an agency’s standard browser test suite, video playback should also be tested against both the presence and absence of recent versions of any target client-side technologies or plugins.

Reporting

Web developers should aim to ensure that video reporting capabilities are integrated with existing web site reporting and analytics tools.

Subjects:

Last Reviewed: 2010-08-31

 

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