Technical options

Recording vs. live broadcasting vs. conferencing


In the media industries such as radio, television, film and music, most broadcasts use recorded content so there is no inherent difference between recording and broadcasting: the main purpose of recording is to enable subsequent broadcasting. Most people are familiar with this and certain recorded formats are used very widely, so it safe to assume that a majority of members will be able to use material in these formats. Recorded content may be downloaded on demand and therefore is accessible across both space and time. Because viewing is decoupled from the production of content, this form of broadcasting is highly scalable to unlimited numbers of users.

In contrast to this, live broadcasting requires both the content producer and the audience to be present in real time. This inherently limits availability to those who are able to partcipate at that time.  Some live broadcasting technologies require particular hardware and/or software to be installed at the receiving location, and others require a high bandwidth connection, both of which may further limit their accessibility for some users. Live broadcasts may also be recorded, but this does not happen automatically, and content cannot be edited while it is being delivered. However, where content is recorded, editing may still be required subsequently in order to create material suitable for an archive. For these reasons, live broadcasting is less scalable than recorded broadcasting and is likely to be restricted to prestige or critical events where timeliness in the delivery of content is of high importance. It may also be linked with the use of high quality equipment, such as the Tricaster system in the BCS Davidson Building, and professional services for content mixing, editing, etc. with higher associated costs.

When live broadcasting is combined with a real time feedback from participants, it is referred to as conferencing. There are many different technologies which enable some form of conferencing, including telephone conferencing, video call software (e.g.  Skype, Apple Facetime), online meeting/webinar software (e.g. Adobe Connect, AnyMeeting, Cisco Webex, Cirix Gotomeeting, Google+ Hangout), and massively multiplayer role playing games (e.g. Second Life). Simple forms of conferencing may be achieved by combining live broadcasting with a near-real-time feedback channel such as Twitter.

Some conferencing technologies require particular hardware or software to be installed at the receiving location, whilst others are browser based and usable on a wide range of devices. Some products include a recording option while others do not, and some allow the recording to be downloaded for subsequent editing. (See the Report of the recording & Broadcasting WG for more information.) In general, conferencing technologies are less scalable than broadcasting technologies, often with a limit of 16 active users, and are therefore more suitable for events such as committee meetings. However, Google+ is unique is providing an option to stream the output from an online meeting via YouTube, providing almost unlimited scalability

Best practice favours options which maximise accessibility and minimise costs. The unique and free capabilities of Google+ coupled with YouTube make this an excellent choice for BCS member groups who want to offer live broadcasts. Where broadcasts are not required, consider recording software as an alternative.

Having decided which of these options to pursue, a group should then select an appropriate software package before choosing a particular hardware configuration. Choice of software sets the overall boundaries of what you can achieve, affects overall cost levels, and has a much greater influence on success or failure than choice of hardware. Many hardware elements such as microphones, cameras, or external storage can be substituted for equivalents or upgraded to more capable devices without changing software or the overall architecture of the solution. Most of the skills that you will need to learn are likely to be software-related and it's ineffective to acquire these skills unless they will be deployed over a significant period. Therefore, choice of software should be treated as a long term decision.

Best practice is therefore to choose recording, live broadcasting or conferencing software before selecting hardware.

The Role of Standards

In the current state of BCS practice, few standards for the format of various types of content or enabling software have been established and there is no intent to impose particular standards. However, it is likely that de facto standards will emerge from experience and the Best Practices Committee will encourage wide dissemination of these standards. The obvious benefits of adopted standards are that content becomes more widely accessible, members can develop interchangeable skills based on those standards, and the BCS can achieve its goals at lower cost than via alternatives.

Industry practice has already created de facto recording standards for some important types of content which BCS groups may use:

  • Documents

Working documents, speaker slides, etc. should be distributed in PDF format to exploit the ubiquitous use of Adobe Reader. Typical file sizes are 50 - 100 kbytes for a one page document, 100 - 150 kilobytes for a one page presentation, hence order of 1megabyte for typical documents and short presentations.

  • Images

Photographic images such as portraits, technical illustrations, etc. should be distributed in JPEG format to exploit the widespread use of photographic capture, processing and printing. Typical file sizes are order of 100 kilobytes for a low resolution passport sized photo, 1 megabyte for a larger high resolution image.

  • Audio recordings

Audio recordings including speech and music should be distributed in the MP3 format used by music players, mobile phones, and PCs which download content from online music stores. Typical file sizes are order of 10 megabytes for a one hour medium quality mono speech recording. Stereophonic recordings and music will require larger file sizes.

  • Video recordings

Multimedia recordings which normally include both video and audio material are widely used on the Internet. However, there are competing format standards with no dominant standard as yet. MPEG4 (also known as MP4, H.264) was developed in 1998 as a successor to MP3 and earlier standards, and is used in the media industries as well as for Internet streaming. The Apple Quicktime player uses this standard. However, MPEG4 is based on patented technologies which require licencing and this has limited its adoption. Around 2002, Ogg was launched as an open source multimedia format free of patent licencing and has subsequently been adopted for both commercial and non-commercial uses, including video games. WebM is a more recent format launched in 2010, derived from Ogg and supported by Google, Adobe and others including several browser makers. Adobe has announced that its Flash player will be updated to support the WebM format. Typical file sizes are order of 100 megabytes for a half hour medium resolution video (including speaker, slides and audio track).


The capability to play video content within an HTML5 script is browser dependent and differs between Windows PCs, Mac PCs, and smartphones. Several browsers can also host plugins which play content that the browser cannot play natively. However, there is no obvious way to determine whether a given user has installed a particular plugin. The relationship between popular standards and browsers without plugins  is documented in the following table [derived from W3C].

Video format browser support
Format IE Firefox Opera Chrome Safari
MPGE4 9.0+ No No 5.0+ 5.0+
Ogg No 3.5+ 10.5+ 5.0+ No
WebM No 4.0+ 10.6+ 6.0+ No

These relationships are likely to change as more of the HTML5 draft standard is implemented in later versions of these browsers. Alternatively, the use of hosting site such as YouTube ca avoid the standards problems since it converts all uploaded videos to MP4 format and implements support for playing in most popular browsers.

Current best practice is therefore to distribute video/multimedia content in MPEG4 format or use a web hosting site such as YouTube. Typical file sizes are 100 megabytes for a 20 minute video recording, and 1 gigabyte for longer or higher quality recordings.