METHOD AND APPARATUS FOR CODING OR DECODING SUBBAND CONFIGURATION DATA FOR SUBBAND GROUPS

• US 20170243592A1
• Filed: 08/19/2015
• Published: 08/24/2017
• Est. Priority Date: 09/02/2014
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby International AB (Dolby Laboratories Incorporated)
• Inventors: KEILER, Florian, KORDON, Sven, KRUEGER, Alexander
• Granted Patent: US 10,102,864 B2
• Time in Patent Office: Days
• CPC Class Codes: G10L 19/002 Dynamic bit allocation for perceptual audio coders G10L19/032
• CPC Class Codes: G10L 19/0204 using subband decomposition

Abstract

For an efficient encoding of subband configuration data the first, penultimate and last subband groups are treated differently than the other subband groups. Further, subband group bandwidth difference values are used in the encoding. The number of subband groups N_SB is coded using a fixed number of bits representing N_SB−1. The bandwidth value B_SB[1] of the first subband group is coded using a unary code representing B_SB[1]−1. No bandwidth value B_SB[g] is coded for the last subband g=N_SB. For subband groups g=2, . . . , N_SB−2 bandwidth difference values ΔB_SB [g]=B_SB [g]−B_SB[g−1] are coded using a unary code, and the bandwidth difference value ΔB_SB[N_SB−1] for subband group g=N_SB−1 is coded using a fixed number of bits.

Claims

1. Method for coding subband configuration data (N_SB, G₁ . . . G_NSB) for subband groups (g) valid for one or more frames of an audio signal, wherein each subband group is equal to one original subband or is a combination of two or more adjacent original subbands, the bandwidth of a following subband group is greater than or equal to the bandwidth of a current subband group, and the number of original subbands (N_FB) is predefined, characterised by:

coding a number of subband groups N_SB with a fixed number of bits (N_b,SB) representing N_SB−

1;

if N_SB>

1, coding for a first subband group g=1 a bandwidth value B_SB[1] with a unary code representing B_SB[1]−

1;

if N_SB=3 in addition to coding said bandwidth value B_SB[1] for said first subband group g=1, coding for subband group g=2 a bandwidth difference value Δ

B_SB[2]=B_SB[2]−

B_SB[1] with a fixed number of bits (N_b,lastDiff);

if N_SB>

3 in addition to coding said bandwidth value B_SB[1] for said first subband group g=1, coding for subband groups g=2, . . . , N_SB−

2 a corresponding number of bandwidth difference values Δ

B_SB[g]=B_SB[g]−

B_SB[g−

1] with a unary code, and coding for subband group g=N_SB−

1 a bandwidth difference value Δ

B_SB[N_SB−

1]=B_SB[N_SB−

1]−

B_SB[N_SB−

2] with a fixed number of bits (N_b,lastDiff),

wherein a bandwidth value for a subband group is expressed as number of adjacent original subbands,

and wherein for subband g=N_SB no corresponding value is included in the coded subband configuration data.

2. Method according to claim 1, wherein a subband configuration data block (s_SBconfig) includes a configuration value (configIdx) that determines whether:

a first predefined combination of number of subband groups and related subband group widths represents said subband configuration data,

or a different second predefined combination of number of subband groups and related subband group widths represents said subband configuration data,

or optionally further predefined combinations of number of subband groups and related subband group widths represents said subband configuration data,

or subband configuration data are coded according to the method of claim 1,

wherein in case N_SB=0 no subband configuration data is generated.

5. Method for decoding coded subband configuration data (s_SBconfig) for subband groups (g) valid for one or more frames of a coded audio signal, which subband configuration data are data which were coded according to claim 1 and which were arranged as a sequence of said coded number of subband groups and said coded bandwidth value for said first subband group and possibly one or more coded bandwidth difference values,

wherein each subband group is equal to one original subband or is a combination of two or more adjacent original subbands, the bandwidth of a following subband group is greater than or equal to the bandwidth of a current subband group, and the number of original subbands N_FB is predefined, characterised by:

determining the number of subband groups N_SB by adding ‘

1’

to a decoded version of the coded number of subband groups;

determining for the first subband group g=1 a bandwidth value B_SB[1] by adding ‘

1’

to a decoded version of the corresponding coded bandwidth value;

if N_SB=3, in addition to determining said bandwidth value B_SB [1] for said first subband group g=1, decoding (73) for subband group g=2 from the coded version of bandwidth difference value Δ

B_SB[2] a bandwidth value B_SB[2]=Δ

B_SB[2] B_SB[1];

if N_SB>

3, in addition to determining said bandwidth value B_SB[1] for said first subband group g=1, decoding for subband groups g=2, . . . , N_SB−

2 from the coded version of bandwidth difference values Δ

B_SB[g] bandwidth values B_SB[g]=Δ

B_SB[g]+B_SB[g−

1], and decoding for subband group g=N_SB−

1 from the coded version of bandwidth difference value Δ

B_SB[N_SB−

1] a bandwidth value B_SB[N_SB−

1]=Δ

B_SB[N_SB−

1]+B_SB[N_SB−

2],

determining the bandwidth value B_SB[N_SB] for subband g=N_SB by subtracting the bandwidths B_SB[1] to B_SB[N_SB−

1] from N_FB,

wherein a bandwidth value for a subband group is expressed as number of adjacent original subbands.

6. Method according to claim 5, wherein a subband configuration data block (s_SBconfig) includes a configuration value (configIdx) that determines whether:

a first predefined combination of number of subband groups and related subband group widths represents said subband configuration data,

or a different second predefined combination of number of subband groups and related subband group widths represents said subband configuration data,

or optionally further predefined combinations of number of subband groups and related subband group widths represents said subband configuration data,

or subband configuration data were coded based on a number of subband groups N_SB with a fixed number of bits (N_b,SB) representing N_SB−

1, where

if N_SB>

1, coding for a first subband group g=1 a bandwidth value B_SB[1] with a unary code representing B_SB[1]−

1;

if N_SB=3, in addition to coding said bandwidth value B_SB[1] for said first subband group g=1, coding for subband group g=2 a bandwidth difference value Δ

B_SB[2]=B_SB[2]−

B_SB[1] with a fixed number of bits (N_b,lastDiff);

if N_SB>

3, in addition to coding said bandwidth value B_SB[1] for said first subband group g=1, coding for subband groups g=2, . . . , N_SB−

2 a corresponding number of bandwidth difference values Δ

B_SB[g]=B_SB[g]−

B_SB[g−

1] with a unary code, and coding for subband group g=N_SB−

1 a bandwidth difference value Δ

B_SB[N_SB−

1]=B_SB[N_SB−

1]−

B_SB[N_SB−

2] with a fixed number of bits (N_b,lastDiff),

wherein a bandwidth value for a subband group is expressed as number of adjacent original subbands,

wherein for subband g=N_SB no corresponding value is included in the coded subband configuration data, and

wherein only in case N_SB≠

0 the method according to claim 5 is carried out.

7. Apparatus for decoding coded subband configuration data (s_SBconfig) for subband groups (g) valid for one or more frames of a coded audio signal, which subband configuration data are data which were coded according to claim 1 and which were arranged as a sequence of said coded number of subband groups and said coded bandwidth value for said first subband group and possibly one or more coded bandwidth difference values,

wherein each subband group is equal to one original subband or is a combination of two or more adjacent original subbands, the bandwidth of a following subband group is greater than or equal to the bandwidth of a current subband group, and the number of original subbands N_FB is predefined, said apparatus including means adapted to:

determining the number of subband groups N_SB by adding ‘

1’

to a decoded version of the coded number of subband groups;

determining for the first subband group g=1 a bandwidth value B_SB[1] by adding ‘

1’

to a decoded version of the corresponding coded bandwidth value;

if N_SB=3, in addition to determining said bandwidth value B_SB[1] for said first subband group g=1, decoding for subband group g=2 from the coded version of bandwidth difference value Δ

B_SB[2] a bandwidth value B_SB[2]=Δ

B_SB[2]+B_SB[1];

if N_SB>

3, in addition to determining said bandwidth value B_SB[1] for said first subband group g=1, decoding for subband groups g=2, . . . , N_SB−

2 from the coded version of bandwidth difference values Δ

B_SB[g] bandwidth values B_SB[g]=Δ

B_SB[g]+B_SB[g−

1], and decoding for subband group g=N_SB−

1 from the coded version of bandwidth difference value Δ

B_SB[N_SB−

1] a bandwidth value B_SB[N_SB−

1]=Δ

B_SB[N_SB−

1]+B_SB[N_SB−

2],

determining the bandwidth value B_SB[N_SB] for subband g=N_SB by subtracting the bandwidths B_SB[1] to B_SB[N_SB−

1] from N_FB, wherein a bandwidth value for a subband group is expressed as number of adjacent original subbands.

8. Apparatus according to claim 7, wherein a subband configuration data block (s_SBconfig) includes a configuration value (configIdx) that determines whether:

a first predefined combination of number of subband groups and related subband group widths represents said subband configuration data,

or a different second predefined combination of number of subband groups and related subband group widths represents said subband configuration data,

or optionally further predefined combinations of number of subband groups and related subband group widths represents said subband configuration data,

or subband configuration data were coded according to the method of claim 1,

wherein only in case N_SB≠

0 the apparatus operates according to claim 7.

9. Digital compressed audio signal that contains subband configuration data encoded according to the method of claim 1.

10. Digital compressed audio signal that contains multiple sets of different subband configuration data encoded according to the method of claim 1.

11. Storage medium that contains or stores, or has recorded on it, a digital compressed audio signal according to claim 9.

12. Computer program product comprising instructions which, when carried out on a computer, perform the method according to claim 1.

3. Apparatus for coding subband configuration data (N_SB, G₁ . . . G_NSB) for subband groups (g) valid for one or more frames of an audio signal, wherein each subband group is equal to one original subband or is a combination of two or more adjacent original subbands, the bandwidth of a following subband group is greater than or equal to the bandwidth of a current subband group, and the number of original subbands (N_FB) is predefined, said apparatus including means adapted to:

coding a number of subband groups N_SB with a fixed number of bits (N_b,SB) representing N_SB−

1;

if N_SB>

1, coding for a first subband group g=1 a bandwidth value B_SB[1] with a unary code representing B_SB[1]−

1;

if N_SB=3, in addition to coding said bandwidth value B_SB[1] for said first subband group g=1, coding for subband group g=2 a bandwidth difference value Δ

B_SB[2]=B_SB[2]−

B_SB[1] with a fixed number of bits (N_b,lastDiff);

if N_SB>

3, in addition to coding said bandwidth value B_SB[1] for said first subband group g=1, coding for subband groups g=2, . . . , N_SB−

2 a corresponding number of bandwidth difference values Δ

B_SB[g]=B_SB[g]−

B_SB[g−

1] with a unary code, and coding for subband group g=N_SB−

1 a bandwidth difference value Δ

B_SB[N_SB−

1]=B_SB[N_SB−

1]−

B_SB[N_SB−

2] with a fixed number of bits (N_b,lastDiff),

wherein a bandwidth value for a subband group is expressed as number of adjacent original subbands,

and wherein for subband g=N_SB no corresponding value is included in the coded subband configuration data.

4. Apparatus according to claim 3, wherein a subband configuration data block (s_SBconfig) includes a configuration value (configIdx) that determines whether:

a first predefined combination of number of subband groups and related subband group widths represents said subband configuration data,

or a different second predefined combination of number of subband groups and related subband group widths represents said subband configuration data,

or optionally further predefined combinations of number of subband groups and related subband group widths represents said subband configuration data,

or subband configuration data are coded based on a number of subband groups N_SB with a fixed number of bits (N_b,SB) representing N_SB−

1, where

if N_SB>

1, coding for a first subband group g=1 a bandwidth value B_SB[1] with a unary code representing B_SB[1]−

1;

if N_SB=3, in addition to coding said bandwidth value B_SB[1] for said first subband group g=1, coding for subband group g=2 a bandwidth difference value Δ

B_SB[2]=B_SB[2]−

B_SB[1] with a fixed number of bits (N_b,lastDiff);

if N_SB>

3, in addition to coding said bandwidth value B_SB[1] for said first subband group g=1, coding for subband groups g=2, . . . , N_SB−

2 a corresponding number of bandwidth difference values Δ

B_SB[g]=B_SB[g]−

B_SB[g−

1] with a unary code, and coding for subband group g=N_SB−

1 a bandwidth difference value Δ

B_SB[N_SB−

1]=B_SB[N_SB−

1]−

B_SB[N_SB−

2] with a fixed number of bits (N_b,lastDiff),

wherein a bandwidth value for a subband group is expressed as number of adjacent original subbands,

wherein for subband g=N_SB no corresponding value is included in the coded subband configuration data, and

wherein in case N_SB=0 no subband configuration data is generated.