A decoding method of digital data having the form of a frame, said data being classified into a plurality of classes (102 i), each class of the plurality of classes (102 i) corresponding to a protection level with respect to errors wherein each class of the plurality of classes (102 i) corresponds to a protection level different to the protection level of the other classes of the plurality of classes (102 i), wherein the digital data have been encoded using an error correction encoding method (100; 300) for encoding so called digital data comprising the following steps: - a first encoding step (110 1; 306 1) for encoding data to be encoded, formed by the data of a first class (102 1), to obtain encoded data; and - implementing the following steps, successively for at least one other class (102 i>1): o mixing (108 i>1; 304 i>1) the data of said other class (102 i>1) with data encoded or to be encoded from a preceding encoding step; and o encoding (110 i>1; 306 i>1) data to be encoded formed by said mixed data, to obtain encoded data and wherein the encoded data have been transmitted over a transmission channel, the decoding method being characterised in that it comprises the following steps: - for one of the classes (102 i), a first decoding step performing the following operations: o decoding (510 i; 410 i) encoded data of said class, o providing at least one so-called extrinsic datum, provided to be used as an a priori datum for at least one decoding of the data of another class; ∘ providing at least one so-called "soft" datum, for assessing the data of the class, - a decoding step for at least one other encoded class, performing the following operations: ∘ decoding the encoded data of said other class, as a function of at least one extrinsic datum provided by at least one other decoding step, used as an a priori datum, ∘ providing at least one extrinsic datum, ∘ providing at least one "soft" datum for assessing said other class, the first decoding step being performed for the latest class that has been encoded, and the following decoding steps being performed for classes considered in the reverse order from that in which they have been encoded. - a first encoding step (110 1; 306 1) for encoding data to be encoded, formed by the data of a first class (102 1), to obtain encoded data; and - implementing the following steps, successively for at least one other class (102 i>1): o mixing (108 i>1; 304 i>1) the data of said other class (102 i>1) with data encoded or to be encoded from a preceding encoding step; and o encoding (110 i>1; 306 i>1) data to be encoded formed by said mixed data, to obtain encoded data and wherein the encoded data have been transmitted over a transmission channel, the decoding method being characterised in that it comprises the following steps: o mixing (108 i>1; 304 i>1) the data of said other class (102 i>1) with data encoded or to be encoded from a preceding encoding step; and o encoding (110 i>1; 306 i>1) data to be encoded formed by said mixed data, to obtain encoded data and wherein the encoded data have been transmitted over a transmission channel, the decoding method being characterised in that it comprises the following steps: - for one of the classes (102 i), a first decoding step performing the following operations: o decoding (510 i; 410 i) encoded data of said class, o providing at least one so-called extrinsic datum, provided to be used as an a priori datum for at least one decoding of the data of another class; ∘ providing at least one so-called "soft" datum, for assessing the data of the class, o decoding (510 i; 410 i) encoded data of said class, o providing at least one so-called extrinsic datum, provided to be used as an a priori datum for at least one decoding of the data of another class; ∘ providing at least one so-called "soft" datum, for assessing the data of the class, - a decoding step for at least one other encoded class, performing the following operations: ∘ decoding the encoded data of said other class, as a function of at least one extrinsic datum provided by at least one other decoding step, used as an a priori datum, ∘ providing at least one extrinsic datum, ∘ providing at least one "soft" datum for assessing said other class, the first decoding step being performed for the latest class that has been encoded, and the following decoding steps being performed for classes considered in the reverse order from that in which they have been encoded. ∘ decoding the encoded data of said other class, as a function of at least one extrinsic datum provided by at least one other decoding step, used as an a priori datum, ∘ providing at least one extrinsic datum, ∘ providing at least one "soft" datum for assessing said other class, the first decoding step being performed for the latest class that has been encoded, and the following decoding steps being performed for classes considered in the reverse order from that in which they have been encoded.