Abstract: A method of identifying a network condition between a pair of network devices, wherein one of the devices comprises a jitter buffer for storing packets received via a network, the method comprising: monitoring a measure of delay in receiving media packets over the network; monitoring a size of the jitter buffer; and identifying a network condition in dependence on a change in the measure of delay and a variation in the size of the jitter buffer.

Abstract: A media encoder for encoding a stream of media data blocks is provided having an encoder pipeline comprising a sequence of processing modules for processing a stream of media data blocks, and a pipeline configurator configured effect a switch in the encoder pipeline from one or more first encode parameters to one or more second encode parameters. The first processing module of the pipeline can be configured to associate a trigger value with at least a first media data block processed at the first processing module in accordance with second encode parameters, the trigger value passing to subsequent modules so as to cause those modules to adopt the second encode parameters.

Abstract: A method of identifying a network condition between a pair of network devices, wherein one of the devices comprises a jitter buffer for storing packets received via a network, the method comprising: monitoring a measure of delay in receiving media packets over the network; monitoring a size of the jitter buffer; and identifying a network condition in dependence on a change in the measure of delay and a variation in the size of the jitter buffer.

Abstract: A media encoder for encoding a stream of media data blocks has an encoder pipeline including a sequence of processing modules for processing a stream of media data blocks, and a pipeline configurator configured effect a switch in the encoder pipeline from one or more first encode parameters to one or more second encode parameters. The first processing module of the pipeline can be configured to associate a trigger value with at least a first media data block processed at the first processing module in accordance with second encode parameters, the trigger value passing to subsequent modules so as to cause those modules to adopt the second encode parameters.

Abstract: A method of transmitting data in a media stream in accordance with a media streaming protocol includes generating data of a first type associated with a first type identifier in accordance with the protocol, encapsulating the generated data in a data structure defined by the protocol, the data structure including a type identifier field for specifying a type of data contained within the data structure, setting the type identifier field to a second type identifier different than the first type identifier, forming a packet comprising the first data structure, and transmitting the packet in the media stream.

Abstract: A data processing system for calibrating a media codec comprising a sequence of time-stamped frames and comprising: an encoder subsystem configured to perform encoding in accordance with one or more encode parameters; a decoder subsystem; and a calibration system comprising: a data store for storing an encoded media stream; and a calibration monitor configured to, on the media codec entering a calibration mode, cause: the decoder subsystem to decode the encoded media stream so as to generate a decoded media stream; the encoder subsystem to re-encode said decoded media stream; and the re-encoded media stream to pass back into the decoder subsystem; the calibration monitor being configured to, through variation of the encode parameters of the encoder subsystem, identify maximal encode parameters corresponding to the greatest steady-state demand on the media codec that permits decoding of the sequence of time-stamped frames at a rate in accordance with their associated timestamps.

Abstract: A media encoder for encoding a stream of media data blocks has an encoder pipeline including a sequence of processing modules for processing a stream of media data blocks, and a pipeline configurator configured effect a switch in the encoder pipeline from one or more first encode parameters to one or more second encode parameters. The first processing module of the pipeline can be configured to associate a trigger value with at least a first media data block processed at the first processing module in accordance with second encode parameters, the trigger value passing to subsequent modules so as to cause those modules to adopt the second encode parameters.

Abstract: A media encoder for encoding a stream of media data blocks has an encoder pipeline including a sequence of processing modules for processing a stream of media data blocks, and a pipeline configurator configured to effect a switch in the encoder pipeline from one or more first encode parameters to one or more second encode parameters. The first processing module of the pipeline can be configured to associate a trigger value with at least a first media data block processed at the first processing module in accordance with second encode parameters, the trigger value passing to subsequent modules so as to cause those modules to adopt the second encode parameters.

Abstract: A method of transmitting data in a media stream in accordance with a media streaming protocol includes generating data of a first type associated with a first type identifier in accordance with the protocol, encapsulating the generated data in a data structure defined by the protocol, the data structure including a type identifier field for specifying a type of data contained within the data structure, setting the type identifier field to a second type identifier different than the first type identifier, forming a packet comprising the first data structure, and transmitting the packet in the media stream.

Abstract: A method of transmitting data in a media stream in accordance with a media streaming protocol includes generating data of a first type associated with a first type identifier in accordance with the protocol, encapsulating the generated data in a data structure defined by the protocol, the data structure including a type identifier field for specifying a type of data contained within the data structure, setting the type identifier field to a second type identifier different than the first type identifier, forming a packet comprising the first data structure, and transmitting the packet in the media stream.

Abstract: A method of identifying a network condition between a pair of network devices, wherein one of the devices comprises a processor capable of executing instructions for forming a media stream for transmission over the network, the method comprising: monitoring a measure of delay in receiving media over the network; monitoring a measure of load on the processor; and identifying a network condition in dependence on a change in the measure of delay and the measure of load on the processor.

Abstract: A method of estimating processor load at a device for transmitting a media stream, the device comprising an encoder and a processor capable of executing instructions for the encoder, the method comprising: encoding a first media frame and a second media frame at the encoder; determining a first time period between a first timestamp associated with the first media frame and a second timestamp associated with the second media frame; determining a second time period between a first completion time representing completion of the encoding of the first media frame and a second completion time representing completion of the encoding of the second media frame; and forming a measure of processor load in dependence on a difference between the first and second time periods.

Abstract: A data processing system for calibrating a media codec comprising a sequence of time-stamped frames and comprising: an encoder subsystem configured to perform encoding in accordance with one or more encode parameters; a decoder subsystem; and a calibration system comprising: a data store for storing an encoded media stream; and a calibration monitor configured to, on the media codec entering a calibration mode, cause: the decoder subsystem to decode the encoded media stream so as to generate a decoded media stream; the encoder subsystem to re-encode said decoded media stream; and the re-encoded media stream to pass back into the decoder subsystem; the calibration monitor being configured to, through variation of the encode parameters of the encoder subsystem, identify maximal encode parameters corresponding to the greatest steady-state demand on the media codec that permits decoding of the sequence of time-stamped frames at a rate in accordance with their associated timestamps.

Abstract: A system for decoding a data stream, comprising: a first decoder configured to decode the data stream at a first rate so as to generate a first stream of frames for playback and arranged to continue generating the first stream despite encountering an error in a particular frame; a second decoder operable to decode the data stream at a second rate so as to generate a second stream of frames; and a controller configured to: detect the error and cause the second decoder to decode the data stream from the particular frame in dependence on error correction data, the second rate being faster than the first rate such that the second stream catches up with the first stream; determine when the second decoder catches up with the first decoder; and cause the second decoder to operate at the first rate so as to generate the second stream for playback.

Abstract: A method of generating a sequence of packets representing a stream of one or more media frames at an encoding system, the method comprising: in dependence on a measure of data loss over a network, determining a level of error correction data required in respect of a stream of media frames in order to substantially satisfy a recovery parameter expressing a target proportion of packets recoverable using error correction data; in dependence on the determined level of error correction data, identifying a target encoding bitrate so as to not exceed a target transmission bitrate over the network; encoding the stream of media frames so as to generate encoded data at the target encoding bitrate; and processing the encoded data and error correction data formed in respect of the stream of media frames so as to generate a sequence of packets at a rate commensurate with the target transmission bitrate.

Abstract: A data processing system for calibrating a media codec comprising a sequence of time-stamped frames and comprising: an encoder subsystem configured to perform encoding in accordance with one or more encode parameters; a decoder subsystem; and a calibration system comprising: a data store for storing an encoded media stream; and a calibration monitor configured to, on the media codec entering a calibration mode, cause: the decoder subsystem to decode the encoded media stream so as to generate a decoded media stream; the encoder subsystem to re-encode said decoded media stream; and the re-encoded media stream to pass back into the decoder subsystem; the calibration monitor being configured to, through variation of the encode parameters of the encoder subsystem, identify maximal encode parameters corresponding to the greatest steady-state demand on the media codec that permits decoding of the sequence of time-stamped frames at a rate in accordance with their associated timestamps.

Abstract: A method of identifying a network condition between a pair of network devices, wherein one of the devices comprises a jitter buffer for storing packets received via a network, the method comprising: monitoring a measure of delay in receiving media packets over the network; monitoring a size of the jitter buffer; and identifying a network condition in dependence on a change in the measure of delay and a variation in the size of the jitter buffer.

Abstract: A frame processor for preparing a stream of video frames for encoding, the frame processor being arranged to receive a video frame having first pixel dimensions representing the number of pixels along each dimension of the video frame, and comprising: a rescaling filter configured to rescale the received video frame such that one or both of the first pixel dimensions are no greater than respective predetermined pixel dimension(s) and the aspect ratio of the received video frame is maintained; and a frame generator configured to: embed the rescaled video frame within an output video frame having the predetermined pixel dimensions; and mark pixels of the output video frame outside the bounds of the rescaled video frame as inactive; the frame processor being arranged to provide the output video frame to a video encoder.

Abstract: A system for decoding a data stream, comprising: a first decoder configured to decode the data stream at a first rate so as to generate a first stream of frames for playback and arranged to continue generating the first stream despite encountering an error in a particular frame; a second decoder operable to decode the data stream at a second rate so as to generate a second stream of frames; and a controller configured to: detect the error and cause the second decoder to decode the data stream from the particular frame in dependence on error correction data, the second rate being faster than the first rate such that the second stream catches up with the first stream; determine when the second decoder catches up with the first decoder; and cause the second decoder to operate at the first rate so as to generate the second stream for playback.

Abstract: An adaptive control system for a media encoder configured to encode a media data stream in accordance with a set of one or more encode parameters, the system comprising: an input queue for receiving a sequence of data portions representing a media stream; and an adaptation controller configured to form an accumulation parameter indicative of an incidence of accumulation events at the input queue, each accumulation event representing the reception of an incoming data portion into the input queue while a previous data portion in the sequence is in the input queue; the adaptation controller being configured to control the encode parameters of the media encoder in dependence on the accumulation parameter.