Method of encoding a signal into a bit stream

• US 20060149801A1
• Filed: 06/28/2004
• Published: 07/06/2006
• Est. Priority Date: 06/30/2003
• Status: Abandoned Application

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Kirenko, Ihor
• Application Number:
  US10/562,358
• Publication Number:
  US 20060149801A1
• Time in Patent Office: Days
• US Class Current: 708/200
• CPC Class Codes: G06T 9/005 Statistical coding, e.g. Huffman, run length coding

Abstract

The invention relates to a method of encoding an input signal into an output bit stream (BS). Said method comprises steps of applying (1) a transformation to a block of values (BV) in order to get a transformed block (T), scanning (2) the coefficients (C₁-C₁) of a transformed block (TB) according to a coefficient scanning order, splitting (3) a scanned coefficient (C_i) into K groups of bits (C_i,1-C_i,K) such that at least a group of bits comprise at least 2 bits and such that said scanned coefficient (C_i) is the concatenation of the K groups of bits, entropy coding (4) a kth group of bits (C_i,k) using entropy codes into a kth entropy coded group of bits (EC_i,k) and forming (5) a block bit stream (BBS) from the K entropy coded groups of bits of the scanned coefficients of the transformed block, said output bit stream (BS) comprising said block bit stream (BBS).

Claims

1. A method of encoding an input signal into an output bit stream (BS), said input signal comprising blocks of values, said method comprising the steps of:

applying (1) 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 being greater than one,

scanning (2) the coefficients (C₁-C_I) of a transformed block (TB) according to a coefficient scanning order,

splitting (3) a scanned coefficient (C_i) into K groups of bits (C_i,1-C_i,K) numbered from 1 to K, such that at least a group of bits comprise at least 2 bits and such that said scanned coefficient (C_i) is the concatenation of the K groups of bits,

entropy coding (4) a k^th group of bits (C_i,k) using entropy codes into a k^th entropy coded group of bits (EC_i,k),

forming (5) a block bit stream (BBS) from the K entropy coded groups of bits of the scanned coefficients of the transformed block, said output bit stream (BS) comprising said block bit stream (BBS).

2. A method of encoding a signal as claimed in claim 1, wherein said entropy codes are Variable Length Codes.

3. A method of encoding a signal as claimed in claim 1, wherein the K entropy coded groups of bits (EC_i,1-EC_i,k) of the scanned coefficient C_i are grouped together to form an entropy coded coefficient (EC_i) and said block bit stream (BBS) comprises a concatenation of said entropy coded coefficients.

4. A method of encoding a signal as claimed in claim 1, wherein said block bit stream (BBS) comprises K entropy coded block layers (EBL₁-EBL_K), a k^th entropy coded block layer (EBL_k) comprising the entropy codes of the k^th groups of bits of the I scanned coefficients of the transformed block (TB).

5. A method of encoding a signal as claimed in claim 4, wherein said output bit stream (BS) comprises K layers (L₁-L_K), a layer (L_k) comprising a concatenation of the k^th entropy coded block layers (EBL_k) corresponding to successively scanned blocks of values of the input signal.

12. A computer program comprising a set of instructions which, when loaded into a processor or a computer, causes the processor or the computer to carry out the method as claimed in claim 1.

13. A signal carrying a program as claimed in claim 12.

6. 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 (EC_i), said entropy coded coefficients comprising entropy coded groups of bits (EC_i,1-EC_i,K), said method comprising steps of:

entropy decoding (12) said entropy coded groups of bits (EC_i,1-EC_i,K) into entropy decoded groups of bits (DC_i,1-DC_i,K),

grouping (13) said entropy decoded groups of bits (DC_i,1-DC_i,K) into a decoded coefficient (DC_i),

inversely scanning (14) said decoded coefficients (DC₁-DC_I) 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.

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

entropy decoding a k^th entropy coded block layer (EBL_k) into a k^th entropy decoded block layer (DBL_k), said k^th entropy decoded block layer comprising k^th decoded groups of bits (DC_i,k),

grouping first to K^th decoded groups of bits, in order to form decoded coefficients (DC_i),

inversely scanning (14) said decoded coefficients (DC₁-DC_I) 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.

8. 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-C_I) of a transformed block (TB) according to a coefficient scanning order, a scanned coefficient (C_i) comprising a number (N) of bits, said number (N) being greater than one,

splitting a scanned coefficient (C_i) into a number (K) groups of bits (C_i,1-C_i,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 (C_i) is the concatenation of the K groups of bits,

encoding said k^th groups of bits into k^th entropy coded groups of bits (EC_i,1-EC_i,K) using entropy codes.

forming a block bit stream (BBS) from the entropy codes, said bit stream (BS) comprising said block bit stream (BBS).

9. 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 (EC_i) comprising a number (K) of entropy coded groups of bits (EC_i,1-EC_i,K), said method comprising steps of:

entropy decoding (30) said entropy-coded groups of bits (EC_i,1-EC_i,K) into entropy decoded groups of bits (DC_i,1-DC_i,K), said entropy decoded groups of bits forming decoded coefficients (DC_i),

grouping (31) first to K^th decoded groups of bits, in order to form decoded coefficients

inversely scanning (32) said decoded coefficients (DC₁-DC_I) 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.

10. A video decoder as claimed in claim 9, wherein said K received entropy coded groups of bits (EC_i,1-EC_i,K) are decoded by K parallel decoding means.

11. 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 (T₁C_i), said video trans-coder comprising means for:

decoding (40) said entropy coded first transformation coefficients into entropy decoded first transformation coefficients (DC_i),

inversely scanning (41) said decoded coefficients (DC₁-DC_I) 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 (C_i), a second transformation coefficient comprising N bits,

splitting (44) said second transformation coefficient (C_i) 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 k^th 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).