Method of encoding a signal into a bit stream

A method of decoding a bit stream (BS) comprising block bit streams into a decoded signal, a block bit stream (BBS) comprising entropy coded coefficients (ECi), said entropy coded coefficients comprising entropy coded groups of bits (ECi,1-ECi,K), said method comprising steps of:

• entropy decoding (12) said entropy coded groups of bits (ECi,1-ECi,K) into entropy decoded groups of bits (DCi,1-DCi,K),
• grouping (13) said entropy decoded groups of bits (DCi,1-DCi,K) into a decoded coefficient (DCi),
• inversely scanning (14) said decoded coefficients (DC1-DCI) to form a decoded transformed block (DTB),
• applying (15) an inverse transformation to said decoded transformed block (DTB) in order to get a decoded block (DB), said decoded signal comprising decoded blocks.

A method of decoding a plurality of entropy coded block layers (EBL1-EBLK) into a decoded signal, said method comprising steps of:

• entropy decoding a kth entropy coded block layer (EBLk) into a kth entropy decoded block layer (DBLk), said kth entropy decoded block layer comprising kth decoded groups of bits (DCi,k),
• grouping first to Kth decoded groups of bits, in order to form decoded coefficients (DCi),
• inversely scanning (14) said decoded coefficients (DC1-DCI) to form a decoded transformed block (DTB),
• applying an inverse transformation to decoded transformed block (DTB) in order to get a decoded block (DB), said decoded signal comprising decoded blocks.

A video encoder for encoding a sequence of images, said images comprising blocks, said video encoder comprising means for:

• applying a transformation to a block of values (BV) in order to get a transformed block (TB), said transformed block comprising a number (I) of coefficients, said number (I) being greater than one,
• scanning the coefficients (C1-CI) of a transformed block (TB) according to a coefficient scanning order, a scanned coefficient (Ci) comprising a number (N) of bits, said number (N) being greater than one,
• splitting a scanned coefficient (Ci) into a number (K) groups of bits (Ci,1-Ci,K) numbered from 1 to K, said number (K) being greater than one, such that at least a group of bits comprises at least 2 bits and such that said scanned coefficient (Ci) is the concatenation of the K groups of bits,
• encoding said kth groups of bits into kth entropy coded groups of bits (ECi,1-ECi,K) using entropy codes.
• forming a block bit stream (BBS) from the entropy codes, said bit stream (BS) comprising said block bit stream (BBS).

A video decoder for delivering a sequence of decoded images by decoding a bit stream (BS) comprising block bit streams, said block bit stream (BBS) comprising entropy coded coefficients (ECi) comprising a number (K) of entropy coded groups of bits (ECi,1-ECi,K), said method comprising steps of:

• entropy decoding (30) said entropy-coded groups of bits (ECi,1-ECi,K) into entropy decoded groups of bits (DCi,1-DCi,K), said entropy decoded groups of bits forming decoded coefficients (DCi),
• grouping (31) first to Kth decoded groups of bits, in order to form decoded coefficients
• inversely scanning (32) said decoded coefficients (DC1-DCI) to form a decoded transformed block (DTB),
• applying an inverse transformation (33) to said decoded transformed block (DTB) in order to get a decoded block (DB), said decoded image comprising said decoded block.

A video trans-coder for trans-coding a first bit stream (BS1) into a second bit stream (BS2), said first bit stream (BS1) comprising first block bit streams, a first block bit stream (BBS1) comprising entropy coded first transformation coefficients (T1Ci), said video trans-coder comprising means for:

• decoding (40) said entropy coded first transformation coefficients into entropy decoded first transformation coefficients (DCi),
• inversely scanning (41) said decoded coefficients (DC1-DCI) to form a decoded transformed block (DTB′),
• applying (42) an inverse first transformation to the entropy decoded first transformation coefficients in order to get a decoded block (DB″),
• applying (43) a second transformation to said decoded block (DTB) in order to get second transformation coefficients (Ci), a second transformation coefficient comprising N bits,
• splitting (44) said second transformation coefficient (Ci) into K groups of bits numbered from 1 to K, such that at least one group of bits comprises at least 2 bits and such that said second transformation coefficient is obtained by concatenating the K groups of bits,
• entropy coding (45) said kth groups of bits using entropy codes,
• forming said second block bit stream (BBS2) from the entropy codes, said second bit stream (BS2) comprising said second block bit stream (BBS2).