Video coding method and device

• US 20060114998A1
• Filed: 11/27/2003
• Published: 06/01/2006
• Est. Priority Date: 12/04/2002
• 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: BARRAU, Eric
• Application Number:
  US10/537,616
• Publication Number:
  US 20060114998A1
• Time in Patent Office: Days
• US Class Current: 375/240.190
• CPC Class Codes: H04N 19/10 using adaptive coding
• CPC Class Codes: H04N 19/114 Adapting the group of pictures [GOP] structure, e.g. number of B-frames between two anchor frames H04N19/107 takes precedence
• CPC Class Codes: H04N 19/13 Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC]
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/615 using motion compensated temporal filtering [MCTF]
• CPC Class Codes: H04N 19/63 using sub-band based transform, e.g. wavelets

Abstract

The invention generally relates to a three-dimensional (3D) video coding method for the compression of a bitstream corresponding to an original video sequence that has been divided into successive groups of N=2ⁿ frames (GOFs), and, more precisely, to a method comprising the following steps: (a) a spatio-temporal analysis step, leading to a spatio-temporal multiresolution decomposition of the current GOF into low and high frequency temporal subbands and itself comprising a motion estimation sub-step, a motion compensated temporal filtering sub-step, performed on each of the 2ⁿ⁻¹ couples of frames of the current GOF, and a spatial analysis sub-step, performed on the subbands resulting from said temporal filtering sub-step; (b) an encoding step, comprising entropy and arithmetic coding sub-steps. According to the invention, when said temporal filtering sub-step comprises (n−1) levels and the final temporal decomposition level that would have led to a single low-frequency subband is omitted, the spatio-temporal analysis and encoding steps are performed according to the following rules: (a) each current input GOF is splitted into two new GOFs with half the original size; (b) in each of these two new GOFs, a complete spatio-temporal multiresolution decomposition with (n−1) levels is performed down to the last low frequency temporal subband; (c) a modified 3D-SPIHT scanning is applied consecutively and independently on these two new GOFs.

Claims

1. A three-dimensional (3D) video coding method for the compression of a bitstream corresponding to an original video sequence that has been divided into successive groups of frames (GOFs) the size of which is N=2ⁿ with n being an integer, these GOFs being themselves subdivided into successive couples of frames (COFs), said coding method comprising the following steps, applied to each successive GOF of the sequence:

a) a spatio-temporal analysis step, performed with a given number of levels at most equal to n and leading to a spatio-temporal multiresolution decomposition of the current GOF into low and high frequency temporal subbands, said step itself comprising;

a motion estimation sub-step;

based on said motion estimation, a motion compensated temporal filtering sub-step, performed on each of the 2<sup>n−

1</sup> COFs of the current GOF;

a spatial analysis sub-step, performed on the subbands resulting from said temporal filtering sub-step;

b) an encoding step, said step itself comprising;

an entropy coding sub-step, performed on said low and high frequency temporal subbands resulting from the spatio-temporal analysis step and on motion vectors obtained by means of said motion estimation step;

an arithmetic coding sub-step, applied to the coded sequence thus obtained and delivering an embedded coded bitstream;

said coding method being further characterized in that, when said temporal filtering sub-step comprises (n−

1) decomposition levels so that the final temporal decomposition level that would have led to a single low-frequency subband is omitted, the spatio-temporal analysis and encoding steps are performed according to the following rules;

(a) each current input GOF is splitted into two new GOFs with half the original size and half the number of COFs, said new GOFs being independent and comprising respectively the 2<sup>n−

1</sup> first frames and the 2<sup>n−

1</sup> last ones of said original input GOF;

(b) in each of these two new GOFs, a complete spatio-temporal multiresolution decomposition with (n−

1) levels is performed down to the last low frequency temporal subband in order to get only one final approximation subband for each of said new GOFs;

(c) a modified 3D-SPIHT scanning is applied consecutively and independently on these two new GOFs, the spatio-temporal orientation trees used by said SPIHT scanning for defining the spatio-temporal relationships inside the hierarchical pyramid of the wavelet coefficients including now half the original number of subbands with respect to a spatio-temporal decomposition as conventionally performed on the original GOF.

2. A video coding device for the implementation of the three-dimensional video coding method according to claim 1, said device comprising:

(a) spatio-temporal analysis means applied to each successive GOF of the sequence with a given number of levels at most equal to n and leading to a spatio-temporal multiresolution decomposition of the current GOF into low and high frequency temporal subbands, said analysis means performing;

a motion estimation sub-step;

based on said motion estimation, a motion compensated temporal filtering sub-step, performed on each of the 2<sup>n−

1</sup> COFs of the current GOF;

a spatial analysis sub-step, performed on the subbands resulting from said temporal filtering sub-step;

b) encoding means, themselves comprising;

entropy coding means, applied to said low and high frequency temporal subbands resulting from the spatio-temporal analysis step and to motion vectors obtained by means of said motion estimation sub-step;

arithmetic coding means, applied to the coded sequence thus obtained and delivering an embedded coded bitstream;

said video coding device being further characterized in that, when said temporal filtering sub-step comprises (n−

1) decomposition levels so that the final temporal decomposition level that would have led to a single low-frequency subband is omitted, the spatio-temporal analysis and encoding means use the following rules;

(a) each current input GOF is splitted into two new GOFs with half the original size and half the number of COFs, said new GOFs being independent and comprising respectively the 2<sup>n−

1</sup> first frames and the 2ⁿ-last ones of said original input GOF;

(b) in each of these two new GOFs, a complete spatio-temporal multiresolution decomposition with (n−

1) levels is performed down to the last low frequency temporal subband in order to get only one final approximation subband for each of said new GOFs;

(c) a modified 3D-SPIHT scanning is applied consecutively and independently on these two new GOFs, the spatio-temporal orientation trees used by said SPIHT scanning for defining the spatio-temporal relationships inside the hierarchical pyramid of the wavelet coefficients including now half the original number of subbands with respect to a spatio-temporal decomposition as conventionally performed on the original GOF.