Editing

The editing interface will allow the user to make copies of a whole media stream or to select a segment of a media stream in order to create their own personal archives. When editing, the user will be able to create a text description of arbitrary parts of the media to aid playback selection. Further editing tools can be used to combine pre-selected segments of media, from possibly different conferences, into new presentation material. The new presentations could then be used as lecture material, for summaries of work, or for presentations of project work. As these newly created presentations will be independent of one another it allows multiple uses of one recording and thus allow a more flexible use of the whole archive.

A full playback of a video conference can be time consuming and often not what is required. It is envisaged that a set of media editors be designed to enable each media to be made presentable for different uses. This will allow for:

• text annotations to be added at multiple positions in a recording
• the creation of conference summaries
• the elimination of quiet sections
• the creation of lecture material
• the creation of special presentations

The editing functions required are the addition of annotations, the selection of segments, and the ability to do post-processing of the data.

Addition of Annotations

The addition of annotations allows users to add meta-data to a recording. These annotations can take on many forms, such as text, to interface to browsing and selection tools; HTML data or URLs, to interface with the World Wide Web; content classification data, to interface to search engines; start of video frame or start of speech burst markers, to interface to special player; and so on. The addition of text descriptions allows users to specify what is contained in different sections of a recording. These descriptions can be presented via the playback tool, and allow the user to play from a specified point. Figure 9.4 show a stream with three added text annotations.

  

Figure 9.4: Having multiple text descriptions for a media

Segment Selection

The editing process allows segments of a recording to be selected and saved for later use. These segments are independent of the original recording and can be manipulated freely for other uses. Some related techniques to the one suggested here are described by Hampapur in [#!hampa!#]. Figure 9.5 shows that some segments that have been selected from the original media stream. One selection has three small segments, whilst the other has one larger segment. This results in three instances of media for the one recording; the original media, the 3 small segments, and the larger segment. Each can be used independently of the others.

  

Figure 9.5: Selecting segments from a recording

For each type of media, and for each different format for that media, a different segment selection editor may be required. For example:

• For H.261 video, when using or an editor could select on Macro Block (MB) or Group Of Block (GOB) boundaries closest to the selection made by the user.

• For audio, the selection boundary could be on either each audio sample or on each talkspurt

• For shared workspace applications, such as the whiteboard, an editor may not be useful if selections were done on a time-slice basis. Both video and audio are continuous media whereas the whiteboard is a non-continuous media, such that selecting data from a time period would give a random set of objects. Selection would only be useful on an object-by- object basis and therefore some kind of post-processing is required.

When using stream synchronisation, the segments of the media should be synchronised such that when one media segment is selected an equivalent part of some associate media is also selected. Figure 9.6 shows that the user is able to select segments (shown in grey) of video and audio which are equivalent with respect to the synchronisation information stored by the server.

  

Figure 9.6: The synchronisation of 3 segments of audio and video