Although the server maintains all the recording information, and has interfaces to allow recording, playback, and editing, this functionality is often not enough. For extended use of the data it is beneficial to provide tools for analysis of the media streams held in the server, and tools for post-processing the media streams in order to modify them
These tools are different for each kind of processing and each kind of media.
With audio, for example, the tools envisaged are (i) for an analysis to graphically present the temporal aspects of the audio for each user in a conference, and (ii) for an analysis to determine the percentage of audio sent by each user in a conference. The analysis data can be used to delete audio from some users in a recording.
With video, for example, it is envisaged that the media streams are post-processed to generate more intra frames than exist in the original stream. Having the extra intra frames enables playback from arbitrary places in the stream. With analogue video a new whole frame is sent to the display every 25th of a second. Due to the way H.261 digital video is compressed using intra frames and inter frames, whole new frames are rarely (if ever) sent to the display. These intra and inter frames are the differences from the previous image. A whole frame is reconstructed from the differences of the image contained in the intra and inter frames.
For shared workspace the post-processing can reconstruct workspace objects from the stream of sub-objects contained in packets.
This list is not exhaustive, but is meant to give a flavour of the kind of processing required.
Next: Clients Up: Recording Previous: Editing Jon CROWCROFT