Telediffusion De France

Centre National D'etudes Des Telecommunications

Etat Francais

French State, Represented by the Minister of Post, Telecommunications

Philippe Bernard

Marie-Jean Colaitis

A method and device are provided for encoding-decoding an HD digital television signal into a narrow band encoded signal. The HD digital television signal is representative of high definition images sampled at a frequency f1, and the narrow band encoded signal corresponds to a narrow band signal sampled at f2, wherein f2&lt;f1. Narrow band encoding is achieved by horizontal compression by decimation of the image lines of the HD digital television signal so as to bring the number N1 of useful pixels per image line to a value N2=.alpha. of the sampling frequencies, so as to thus form an encoded signal representative of an image line and obtain reduced format high definition images. A narrow band encoded signal representative of digital television signals can thus be broadcast over an HD-MAC NB type channel.

Method and device for encoding-decoding a narrow band high definition

A movement estimation method and system are disclosed for high definition digital television frames. The movement is estimated for a current block Bc of the even fields T.sub.2k, 2r-1 of the uneven frames with which n movement vectors are associated, with the current block Bc of the even fields T.sub.2k, 2r of the even frames there is associated, by relative addressing, a movement vector with respect to s vectors of the preceding frame I.sub.2r-1 surrounding the frame B'c of the current block Bc. The s vectors are chosen by eliminating the vector redundancies among the n vectors. The invention is applicable to broadcasting and transmission of digital television signals by HD-MAC or HD-MAC NB narrow band channel.

Movement estimation method and system for high definition digital

A method and installation are provided for broadcasting high definition television programs, particularly for broadcasting HD-MAC programs on a narrow channel, while reducing degradation of the picture when received by a first generation MAC receiver. The signal obtained by analysis of the source picture is subjected to spatio-temporal subsampling and to non-linear motion compensation filtering, leading to transmitting the points representative of the same source frame over at least two successive transmission frames (t1, t2) and transmitting, at the same time, assistance data defining a motion vector field. To improve the compatible frame delivered by a first generation receiver, the second analysis field corresponding to the same source frame is subjected to time attenuation in the direction of motion. Such attenuation depends on the movement vector and leads to assigning to each point of said parts an intermediate position between its position in the analyzed source frame and its anticipated position in the direction of movement.

High definition television signal processing including subsampling and

For broadcasting an HDTV picture over a transmission channel having a frequency band narrower than that necessary for direct transmission of the HD TV picture, the HDTV source picture is sub-sampled at an analysis image frequency f.sub.o for distributing the spatial data of each HDTV image of the source picture over n successive frames, n being greater than 1. The resulting samples are subjected to temporal energy attenuating filtering in a frequency range around fO/n to obtain a modified signal, which is sent over the transmission channel. Upon reception, the modified signal is subjected to temporal filtering for enhancing energy in the frequency range before subjecting it to decoding for restoring the HDTV picture.

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Cesson Sevigne, France

Philippe Bernard