Methods and apparatus for the encoding of audio and/or video data

Apparatus for selecting an encoding specification for encoding audio and/or video data to be streamed from a sender to a receiver via a network, the apparatus comprising a processor at least configured to:

• in respect of a monitored network in each of a plurality of monitored network conditions, respective monitored network conditions being characterised by different combinations of data-transmission characteristics of at least two different types, obtain a performance measure in respect of each of a plurality of different encoding specifications, the performance measure in respect of the monitored network when in a particular monitored network condition and in respect of a particular encoding specification being obtained by applying a predetermined performance measuring process in respect of audio and/or video data encoded using said encoding specification and streamed via the monitored network when in said monitored network condition;
• in respect of a network over which audio and/or video data is subsequently to be streamed from a sender to a receiver, obtain data-transmission characteristics of said at least two different types in respect of said network and select a corresponding one of said monitored network conditions in dependence on the data-transmission characteristics of said at least two different types obtained in respect of said network over which said data is to be streamed and on the combination of data-transmission characteristics of said at least two different types which characterised the monitored network when in said corresponding monitored network condition;
• and
• select an encoding specification for encoding said data to be streamed, the selection of said encoding specification being made in dependence on the performance measures obtained using said plurality of encoding specifications in respect of said monitored network when in said selected corresponding monitored network condition.