Abstract: A method for estimating a bit rate and the distortion of at least one compressed image using at least one wavelet transform operation delivering at least one sub-band b containing coefficients, said sub-band being subdivided into at least one packet of coefficients associated with a compression quality layer, said packet also including a packet header and being transmitted through a propagation channel, said method including estimating a distortion Dbc linked to a compression of the coefficients of said packet, estimating a distortion D?bc linked to a corruption or loss of said packet, estimating a compression bit rate Lb, estimating a sensitivity {tilde over (D)}bc of said packet according to Dbc and D?bc and the bit rate Lb, and estimating a distortion of said image linked to a decompression of said packet based on {tilde over (D)}bc.

Abstract: A method is provided for adapting the throughput of a video stream comprising a plurality N of compressed images with a plurality of spatial resolutions and/or a plurality of quality layers, the images being compressed separately from one another.

Abstract: A method for protecting multimedia data encoded by the H.264 standard, the data being encapsulated in a structure of the network abstraction layer or NAL type, characterized in that the user inserts at least one redundancy NAL containing the error-correcting code used for transmitting the data.

Abstract: A method is provided for adapting the throughput of a video stream comprising a plurality N of compressed images with a plurality of spatial resolutions and/or a plurality of quality layers, the images being compressed separately from one another.

Abstract: A method allowing operating parameters, such as the compression ratio and/or the protection ratio for a multimedia data transmission channel to be determined, wherein it includes at least one step during which several values of sensitivity are determined for pairs of values fixed source bit-rate, desired compression ratio, a step where the different values obtained for an operating point of the fixed channel are compared with one another, and a step where the optimum sensitivity value is selected, the sensitivity value being defined taking the desired source bit-rate and the compression ratio into account.

Abstract: Procedure and device for shaping frames of a video sequence or group of pictures GOP using a mixing table adapted for arranging the frames of the highest importance regularly while leaving intervals between them, filling the intervals with frames of lesser importance, and coding the new sequence thus obtained.

Abstract: A method for estimating a bit rate and the distortion of at least one compressed image using at least one wavelet transform operation delivering at least one sub-band b containing coefficients, said sub-band being subdivided into at least one packet of coefficients associated with a compression quality layer, said packet also including a packet header and being transmitted through a propagation channel, said method including estimating a distortion Dbc linked to a compression of the coefficients of said packet, estimating a distortion D?bc linked to a corruption or loss of said packet, estimating a compression bit rate Lb, estimating a sensitivity {tilde over (D)}bc of said packet according to Dbc and D?bc and the bit rate Lb, and estimating a distortion of said image linked to a decompression of said packet based on {tilde over (D)}bc.

Abstract: A method for encrypting data exchanged between an encoder and a decoder in a video system is disclosed. A set of bits which, when encoded, do not have any influence upon the decoding stage, are determined during the encoding stage. At least one part or all of the bits selected in stage 1 is/are encoded prior to transmission to the decoding stage. The bit selection stage determines the parts of the flow of bits that only modify the contexts of the decoding process in an insignificant manner in the sense that the modification due to encryption does cause desynchronization or does not lead to non-compatible bit flows with regard to encoding contexts and visual impact. The present invention is used with H.264 encoders/decoders.

Abstract: A method allowing operating parameters, such as the compression ratio and/or the protection ratio for a multimedia data transmission channel to be determined, wherein it includes at least one step during which several values of sensitivity are determined for pairs of values fixed source bit-rate, desired compression ratio, a step where the different values obtained for an operating point of the fixed channel are compared with one another, and a step where the optimum sensitivity value is selected, the sensitivity value being defined taking the desired source bit-rate and the compression ratio into account.

Abstract: A method for protecting multimedia data encoded by the H.264 standard, the data being encapsulated in a structure of the network abstraction layer or NAL type, characterized in that the user inserts at least one redundancy NAL containing the error-correcting code used for transmitting the data.

Abstract: Procedure and device for shaping frames of a video sequence or group of pictures GOP using a mixing table adapted for arranging the frames of the highest importance regularly while leaving intervals between them, filling the intervals with frames of lesser importance, and coding the new sequence thus obtained.

Abstract: A method for encrypting data exchanged between an encoder and a decoder in a video system is disclosed. A set of bits which, when encoded, do not have any influence upon the decoding stage, are determined during the encoding stage. At least one part or all of the bits selected in stage 1 is/are encoded prior to transmission to the decoding stage. The bit selection stage determines the parts of the flow of bits that only modify the contexts of the decoding process in an insignificant manner in the sense that the modification due to encryption does cause desynchronization or does not lead to non-compatible bit flows with regard to encoding contexts and visual impact. The present invention is used with H.264 encoders/decoders.