Abstract: A method for providing equitable media streaming between an HTTP server and a number of receivers via shared network. The streaming data is processed to split the data across a number of sub-streams. Each sub-stream contains non-contiguous data. A receiver requesting the streaming media establishes a number of TCP sessions, one for each sub-stream and the received sub-stream data is reassembled at the receiver so that the streaming media can be presented.

Abstract: A client device receives streamed encoded content data, such as encoded video data, which has been encoded at a constant perceptual quality. Several different versions of the content are available to be streamed to the device, at different perceptual quality levels. In order to decide which quality level to request from a content server at intervals the device calculates the delivery rates that would be required for each level of quality. The calculation of the delivery levels is made in dependence on whether the actual delivery rate that has been received so far is greater than or less than a constant bit rate delivery schedule that decreases monotonically but which guarantees to deliver the encoded data in a timely manner such that no buffer underflow and interruption of reproduction takes place.

Abstract: One or more network based video servers is/are connected to one or more video receivers over a shared network. Pieces of video content are each encoded at a number of constant quality levels and stored on one or more of the network based servers. Responsive to requests from a receiver, video content is selected on a server and delivered over the shared network to the receiver. The system selects the quality level of the stream to deliver based on characteristics of the video stream currently being delivered, and the number of bits already buffered at the video receiver and the available network throughput. The aim is to select the video quality being delivered according to the available network throughput to maximize quality while ensuring that video data is delivered over the network in time to be decoded and displayed without interruption. Certain exemplary embodiments make that selection in advance.

Abstract: A client device receives streamed encoded content data, such as encoded video data, which has been encoded at a constant perceptual quality. Several different versions of the content are available to be streamed to the device, at different perceptual quality levels. In order to decide which quality level to request from a content server at intervals the device calculates the delivery rates that would be required for each level of quality. The delivery rates are calculated in dependence on so-called critical points, which are points at which a piecewise constant bit rate delivery schedule is just equal to the decoding schedule.

Abstract: The network contains one or more network based video servers connected to one or more video receivers over a shared network. Multiple pieces of video content are each encoded at a number of constant quality levels and stored on one or more of the network based servers. In response to requests from a receiver, video content is selected on a server and delivered over the shared network to the receiver. The system selects the quality level of the stream to deliver based on characteristics of the video stream currently being delivered, and the number of bits already buffered at the video receiver and the available network throughput. The aim is to select the video quality being delivered according to the available network throughput so as maximise the quality while ensuring that all video data is delivered over the network in time for it to be decoded and displayed without interruption.

Abstract: Embodiments of the present invention provide a compact representation of a cumulative bit curve formed from piece-wise straight line approximations between upper and lower bounds about an actual cumulative bit curve (CBC). In one embodiment the lower bounds are found by applying a constraint such that if a delivery rate was to be calculated using the count at the lower bound it would result in a delivery rate which was greater than the delivery rate that would be calculated using the actual CBC data by a particular amount, for example 10%. The actual CBC data is then used as an upper bound. As a result, the approximated CBC will lie for each GoP between the actual CBC value and the lower bound, with the result that one can be certain that any data rate that is calculated using the approximation will be at least as high as a data rate that is calculated using the actual CBC data.

Abstract: Methods and apparatus for video coding are disclosed, particularly for use in relation to video compression. Many commercially available video encoders support constant bit-rate encoding but not constant quality encoding. Aspects of the present invention are concerned with methods and apparatus for video coding, the methods involving the determination of bit-rates at which a constant bit-rate encoder may be operated such that segments of video can be chosen from files encoded at the bit-rates so-determined in order to produce an output bitstream in which the quality is nearly constant. Bit-stream segments may be chosen from a low bit-rate bitstream for easy-to-compress scenes, and from a high bit-rate bitstream for hard-to-compress scenes.

Abstract: Embodiments of the present invention provide a compact representation of a cumulative bit curve formed from piece-wise straight line approximations between upper and lower bounds about an actual cumulative bit curve (CBC). In one embodiment the lower bounds are found by applying a constraint such that if a delivery rate was to be calculated using the count at the lower bound it would result in a delivery rate which was greater than the delivery rate that would be calculated using the actual CBC data by a particular amount, for example 10%. The actual CBC data is then used as an upper bound. As a result, the approximated CBC will lie for each GoP between the actual CBC value and the lower bound, with the result that one can be certain that any data rate that is calculated using the approximation will be at least as high as a data rate that is calculated using the actual CBC data.

Abstract: A client device receives streamed encoded content data, such as encoded video data, which has been encoded at a constant perceptual quality. Several different versions of the content are available to be streamed to the device, at different perceptual quality levels. In order to decide which quality level to request from a content server at intervals the device calculates the delivery rates that would be required for each level of quality. The delivery rates are calculated in dependence on so-called critical points, which are points at which a piecewise constant bit rate delivery schedule is just equal to the decoding schedule.

Abstract: A client device receives streamed encoded content data, such as encoded video data, which has been encoded at a constant perceptual quality. Several different versions of the content are available to be streamed to the device, at different perceptual quality levels. In order to decide which quality level to request from a content server at intervals the device calculates the delivery rates that would be required for each level of quality. The calculation of the delivery levels is made in dependence on whether the actual delivery rate that has been received so far is greater than or less than a constant bit rate delivery schedule that decreases monotonically but which guarantees to deliver the encoded data in a timely manner such that no buffer underflow and interruption of reproduction takes place.

Abstract: Methods and apparatus for video coding are disclosed, particularly for use in relation to video compression. Many commercially available video encoders support constant bit-rate encoding but not constant quality encoding. Aspects of the present invention are concerned with methods and apparatus for video coding, the methods involving the determination of bit-rates at which a constant bit-rate encoder may be operated such that segments of video can be chosen from files encoded at the bit-rates so-determined in order to produce an output bitstream in which the quality is nearly constant. Bit-stream segments may be chosen from a low bit-rate bitstream for easy-to-compress scenes, and from a high bit-rate bitstream for hard-to-compress scenes.

Abstract: A method for providing equitable media streaming between an HTTP server and a number of receivers via shared network. The streaming data is processed to split the data across a number of sub-streams. Each sub-stream contains non-contiguous data. A receiver requesting the streaming media establishes a number of TCP sessions, one for each sub-stream and the received sub-stream data is reassembled at the receiver so that the streaming media can be presented.

Abstract: The network contains one or more network based video servers connected to one or more video receivers over a shared network. Multiple pieces of video content are each encoded at a number of constant quality levels and stored on one or more of the network based servers. In response to requests from a receiver, video content is selected on a server and delivered over the shared network to the receiver. The system selects the quality level of the stream to deliver based on characteristics of the video stream currently being delivered, and the number of bits already buffered at the video receiver and the available network throughput. The aim is to select the video quality being delivered according to the available network throughput so as maximise the quality while ensuring that all video data is delivered over the network in time for it to be decoded and displayed without interruption. The invention proposes a method for making that selection in advance.

Abstract: The network contains one or more network based video servers connected to one or more video receivers over a shared network. Multiple pieces of video content are each encoded at a number of constant quality levels and stored on one or more of the network based servers. In response to requests from a receiver, video content is selected on a server and delivered over the shared network to the receiver. The system selects the quality level of the stream to deliver based on characteristics of the video stream currently being delivered, and the number of bits already buffered at the video receiver and the available network throughput. The aim is to select the video quality being delivered according to the available network throughput so as maximise the quality while ensuring that all video data is delivered over the network in time for it to be decoded and displayed without interruption.

Abstract: A data streaming system and method typically use a server arranged to stream one of a plurality of encoded data streams to a client. Each of the plurality of data streams may be an independent representation of a common data source encoded at a different resolution to the other of the plurality of data streams. The server can include a transmitter and a first buffer. The transmitter can be arranged to transmit data packets of the encoded data stream to the client via the first buffer. The transmitter can be arranged to monitor the content of the first buffer and switch to transmit another of the plurality of data streams in the event that predetermined criteria are detected from the first buffer.

Abstract: A sequence to be encoded is divided into a plurality of temporal portions or chunks. The sequence is then analysed to determine for each chunk, in accordance with a plurality of encoding quality settings, data establishing the relationship between the quality settings and (i) a quality metric for the portion and (ii) the number of bits generated by encoding the portion at that quality setting. Given a target quality, a target bit rate is then set (or vice versa); then one chooses a set of quality settings, one per chunk, that tends to minimise a combined quality cost for the sequence within the constraint that transmission of encoded video at the target bit rate via transmitting and receiving buffers of specified size and initial receiver buffer fullness shall not cause underflow nor overflow.

Abstract: A video signal is coded using predictive coding. The degree of quantisation that is applied is varied as a function of measures of predictive power, the idea being that a picture that is useful as a predictor for other pictures is worth coding well. These measures are formed in a pre-analysis of the pictures to obtain, for each macroblock analysed, a measure that depends on its similarity to a region for which it is a potential predictor. Preferably these measures are cumulative.

Abstract: A layered coder includes a lower resolution predictive encoder (102) and a higher resolution encoder (402) providing coded low and high resolution signals at lines (110) and (218) respectively. The prediction error of the lower resolution predictive encoder (102) is provided as a prediction error estimate to the higher resolution encoder (402), the prediction error estimate being subtracted from the prediction error generated in the higher resolution predictive encoder (402) by the subtractor (210). This difference from the subtractor (404) is coded by the coder (212) whose output is made available on the line (218). The prediction error estimate from the up sampler (130) is added to the output from the decoder (220) by an adder (406) in order to complete the predictive loop of the higher resolution predictive encoder (402). The prediction error estimate can also be subtracted from the prediction error of the higher resolution predictive encoder in the transform domain.

Abstract: A transcoder for the conversion of video signals between a first and a second coding scheme employing motion compensation comprises a decoder (28) for decoding a received data stream encoded according to a first coding scheme and an encoder (30) for encoding a data stream from the decoder into a data stream according to a second coding scheme. The decoder (28) extracts motion vectors from the received data stream and passes them (42) to the data stream of the encoder, so avoiding the recalculation of the motion vectors. Drift compensation means (52-64; 70-78) may be provided to compensate for any resulting drift after a picture frame.