Adapting Robustness in Video Coding

A system comprising the apparatus of claim any preceding claim, and further comprising a receiving terminal which comprises:

• a receiver for receiving the encoded signal;
• a decoder for decoding the encoded signal to generate a decoded signal for output to a screen, storage device or further terminal;
• and
• a concealment module for applying a concealment algorithm in a frame of the decoded signal having lost data;
• wherein the concealment module is configured to determine at least two different regions having different perceptual significance within each of one or more frames of the video signal, to determine an estimate of concealment quality selectively directed toward at least one region having a higher perceptual significance relative to at least one other region, and based on said estimate of concealment quality to determine whether or not to apply the concealment algorithm.

A computer program product for encoding a video signal comprising a plurality of frames, comprising code embodied on a computer-readable storage medium and configured so as when executed on a processing apparatus to perform operations comprising:

• receiving a video signal comprising a plurality of frames, each comprising a plurality of image portions;
• encoding each of the image portions, to generate an encoded signal;
• in performing said encoding, selecting a respective encoding mode used to encode each of the image portions, based on a process that balances an estimate of distortion for the image portion if encoded using the respective encoding mode against a bitrate that would be incurred by encoding the image portion using the respective encoding mode;
• and
• to perform said selecting, determining at least two different regions having different perceptual significance within each of one or more frames of the video signal, and adapting said process in dependence on which of the regions the image portion being encoded is in.

A computer program product comprising code embodied on a computer-readable storage medium and configured so as when executed on a transmitting terminal to perform operations comprising:

• receiving a video signal comprising a plurality of frames, each comprising a plurality of image portions;
• encoding each of the image portions, to generate an encoded signal;
• in performing said encoding, selecting an encoding mode used to encode each of the image portions respectively, by selecting an encoding mode that optimises a function of encoding mode, the function comprising (i) a part representing an estimate of distortion for the image portion, comprising a measure of source coding distortion and an estimate of potential distortion that would be experienced due to loss, (ii) a part representing a bitrate that would be incurred by encoding the image portion, and (iii) a weighting applied to one of said parts;
• to perform said selecting, determining a perceptual importance map comprising more than two different regions and assigning to each a respective level of perceptual significance from amongst more than two different levels, and adapting the weighting of said function in dependence on the level of perceptual significance assigned to the region of the perceptual importance map that the image portion being encoded is in;
• and
• transmitting the encoded signal to a receiving terminal over a lossy, packet-based network as part of a live packet-based video call.