Synchronising a transmitter and receiver in a CSMA ad-hoc network

A transmitter and receiver in an ad-hoc network synchronise an application event, e.g. Start Of Frame 300 of a video source. The transmitter and receivers of the network share knowledge of some future expected network events, e.g. future medium access events based on carrier sense multiple access (CSMA) backoff values, and the transmitter chooses one of the future network events 322 (T4) as a reference. It transmits synchronization information 321 comprising an index of this chosen event and a time interval 311 related to the time difference between the application event at the transmitter and the reference network event. The receiver computes the time to trigger a corresponding receiver application event 301 from the received information and knowledge of a synchronization delay 330. Accordingly, the synchronisation of diverse applications is managed without disturbance in an unstable network. This generic synchronization protocol is also bandwidth efficient.

Intra video coding in error prone environments

A method of processing data for video encoding comprises: obtaining a current coding entity (e.g., slice segment) of a current video frame to encode, the frame being segmented according to a plurality of coding entities, each coding entity or object comprising plural coding units (CUs, e.g. macro-blocks, MBs), and, for a current coding obtained: determining whether there are neighbouring pixels outside the current coding entity that can be used for generating an outside (external) coding unit predictor for predicting the current (i.e., inside coding entity) coding unit; enabling, based on result of this, use of neighbouring pixels outside the current coding entity, for generating at least one outside predictor; and selecting, using at least one weighting criterion applied to the at least one outside predictor, a predictor from among a default coding unit and the at least one outside coding unit predictor. The method is applied to intra video coding in error prone environments. Weighting ...

Method and device for compression of video data

Method of contending for access to a communication channel and associated communication device

The invention relates to contention for access to a communication medium. A method according to the invention includes, at a first node, steps of generating backoff values of a Collision Avoidance mechanism for a plurality of collaborative nodes, each backoff value being associated with a respective collaborative node; loading at least one hardware backoff counter with the backoff values, each hardware backoff counter being decremented over time until expiry; and upon detecting the expiry of one of the hardware backoff counters, accessing the medium if the backoff value loaded in the hardware backoff counter that has just expired is associated with the first node; otherwise. directly loading the hardware backoff counter that has just expired with the backoff value associated with a collaborative node different from the one with which the backoff value last loaded in that hardware backoff counter is associated.

Video Data Compression & Decompression by Non-Predictively Encding Central / Important Zone(s) and Predictively Encoding Less Important Areas

A bitstream comprising one or more pictures, each divisible into blocks of pixels, is encoded/decoded. A zone of blocks in a picture is chosen (410) (e.g. central area of picture, Region of Interest (RoI) such as a face), these blocks being non-predictively (i.e. spatially) encoded (411). A first and second group of blocks outside the zone are predictively (i.e. temporally) encoded in a first and second scanning direction respectively (412, 413). The direction of scanning is transmitted to the decoder which decodes the first and second groups of blocks in the same directions in which they were encoded using the non-predictively encoded (and thus decoded) blocks in the chosen zone as reference blocks. Prediction encoding/decoding of the blocks of the first and second groups with respect to the chosen zone blocks improves the likelihood that important areas of the picture(s) are coded and decoded without errors. If error propagation occurs due to temporal prediction, it is thereby confined ...

Intra video coding in error prone environments

Method and apparatus for synchronizing the display of video data on two display devices

In a method and a device for synchronizing the display of video data on different display devices, a source device provides the same video data stream to the display devices through a communication network. One of the display devices (first display screen device) is provided with picture acquisition (camera) capabilities. By taking a distant picture of the second device display and comparing it with the local picture being displayed at the same (acquisition) moment or time on the first display, these images may be localized within a sequence. The time drift between the two different displays may be determined, allowing a command to modify a display timer to be provided to the source device or display itself. Precision may be improved by iterating the process with dichotomous delay applied to at least one display. Drift determination using local and distant (other display captured) images may comprise determining distance (in terms of pictures / frames) between points of interest (POI) in ...

Dynamic control of bandwidth allocation for multiple transmission channels based on video data encoding characteristics

A method and device for transmitting video frame data over a communication network comprises: encoding coding units such as slices of at least one video frame into encoded data; obtaining encoding statistics 1110 from the encoded data of first coding units; and creating a plurality of classes 1180 as a function of one item of characteristic information of the obtained statistics. Preferably, the statistics relate to the bitstream size or bitrate of the coding units, and the encoding method may be intra-prediction. Transmission channels for the respective classes are subsequently reserved, each channel having a reserved bandwidth 1130 that depends on a value of the characteristic information for the respective class. Second encoded coding units are assigned to each to one of the classes and transmitted over the reserved channel corresponding to the class to which the coding unit is assigned. The method improves the use of the network bandwidth in case of multi-channel transmission of compressed ...