Split gain shape vector coding

1. A method for supporting split gain shape vector encoding performed by a media encoder, where the encoding of each vector segment is subjected to a constraint related to a maximum number of bits, B MAX , allowed for encoding a vector segment, the method comprising:

for a target vector x:

determining an initial number, Np —init , of segments for the target vector x;

determining an average number of bits per segment, B AVG , based on a vector bit budget and Np —init ; and

determining a final number of segments to be used in the gain shape vector encoding based on energies of the Np —init segments and a difference between B MAX and B AVG ,

thereby enabling an efficient allocation of the bits of the bit budget over the target vector.

2. The method according to claim 1 , wherein the determining of a final number of segments comprises:

increasing the number of segments, as compared to the initial number, for the target vector x, when a relation between the energies of the Np —init segments and the difference between B MAX and B AVG fulfills a criterion.

3. The method according to claim 2 , further comprising:

indicating the increase of the number of segments to a media decoder.

4. The method according to claim 1 , wherein the determining of a final number of segments comprises:

increasing the number of segments, as compared to the initial number, for the target vector x, when a maximum deviation, of a target vector segment energy, from an average per-segment energy value, E AVG , for the target vector x is larger than a threshold based on the difference between B MAX and B AVG .

5. The method according to claim 1 , further comprising:

indicating the final number of segments to a media decoder.

6. The method according to claim 1 , wherein the determining of B AVG and of a final number of segments is only performed when at least one additional condition is met.

7. The method according to claim 1 , wherein the determining of B AVG and of a final number of segments is performed when the vector bit budget is above a threshold for additional splits and/or when a bitrate per sample is above a given limit.

8. The method according to claim 1 , wherein the determining of B AVG and of a final number of segments is performed when the initial number of segments is below a threshold.

9. A non-transit computer readable medium having instructions stored therein which, when executed on at least one processor, causes the at least one processor to perform the method according to claim 1 .

10. A method for supporting split gain shape vector decoding performed by a media decoder, where a representation of each vector segment of a gain shape vector x is subjected to a constraint related to a maximum number of bits, B MAX , allowed for encoding a vector segment, the method comprising:

determining an initial number of segments, for a vector x q to be reconstructed;

receiving an indication, from a media encoder, of whether an increased number of segments is applied for the vector x q , or not, and

determining a final number of segments for the decoding of the vector x q based on the received indication.

11. The method according to claim 10 , further comprising:

decoding the vector x q based on the final number of segments.

12. The method according to claim 10 , wherein the receiving of the indication is only performed when one or more additional conditions are met.

13. The method according to claim 12 , where an additional condition is that the vector bit budget is above a threshold for additional splits.

14. The method according to claim 12 where an additional condition is that the initial number of splits is below a threshold and/or that a bitrate per sample is above a given limit.

15. A non-transitory, computer readable medium having instructions stored therein which, when executed on at least one processor, causes the at least one processor to perform the method according to claim 10 .

16. A media encoder, operable to perform split gain shape vector encoding, where the encoding of each vector segment is subjected to a constraint related to a maximum number of bits, B MAX , allowed for encoding a vector segment, the media encoder being configured to:

for a target vector x:

determine an initial number, Np —init , of segments for the target vector x;

determine an average number of bits per segment, B AVG , based on a vector bit budget and Np —init ; and

determine a final number of segments to be used in the gain shape vector encoding based on energies of the Np —init segments and a difference between B MAX and B AVG ,

thereby enabling an efficient allocation of the bits of the bit budget over the target vector.

17. The media encoder according to claim 16 , being configured to, in order to determine the final number of segments:

in response to determining that a relation between the energies of the Np —init segments and the difference between B MAX and B AVG fulfills a criterion:

increase the number of segments, as compared to the initial number, for the target vector x, for the gain shape vector encoding.

18. The media encoder according to claim 17 , being further configured to:

indicate the increase of the number of segments to a media decoder.

19. The media encoder according to claim 16 , being configured to, in order to determine the final number of segments:

increase the number of segments, as compared to the initial number, for the target vector x, when a maximum deviation, of a target vector segment energy, from an average per-segment energy value, E AVG , for the target vector x is larger than a threshold based on the difference between B MAX and B AVG .

20. The media encoder according to claim 16 , being further configured to:

indicate the final number of segments to a media decoder.

21. The media encoder according to claim 16 , being further configured to determine B AVG and a final number of segments only when at least one additional condition is met.

22. The media encoder according to claim 16 , being configured to determine B AVG and a final number of segments when the vector bit budget is above a threshold for additional splits and/or when a bitrate per sample is above a given limit.

23. The media encoder according to claim 16 , being configured to determine B AVG and a final number of segments when the initial number of segments is below a threshold.

24. A wireless device comprising a media encoder according to claims 16 .

25. A media decoder operable to perform gain shape vector decoding, where a representation of each vector segment of a gain shape vector x is subjected to a constraint related to a maximum number of bits, B MAX , allowed for encoding a vector segment; the media decoder being configured to:

determine an initial number of segments, Np —init , for a vector x q to be reconstructed;

receive an indication, from a media encoder, of whether an increased number of segments is applied for the vector x q ; and

determine a final number of segments for the decoding of the vector x q based on the received indication.

26. The media decoder according to claim 25 , being further configured to: decode the vector x q based on the final number of segments.

27. The media decoder according to claim 25 , being further configured to receive the indication only when one or more additional conditions are met.

28. The media decoder according to claim 27 , where an additional condition is that the vector bit budget is above a threshold for additional splits.

29. The media decoder according to claim 27 , where an additional condition is that the initial number of splits is below a threshold and/or that a bitrate per sample is above a given limit.

30. A wireless device comprising a media decoder according to claim 25 .