Reuse of syntax element indicating vector quantization codebook used in compressing vectors
In general, techniques are described for indicating reuse of a syntax element indicating a vector quantization codebook used in compressing a vector. A device comprising a processor and a memory may perform the techniques. The processor may be configured to obtain a bitstream comprising a vector in a spherical harmonics domain. The bitstream may further comprise an indicator for whether to reuse, from a previous frame, a syntax element indicative of a vector quantization codebook used when compressing the vector. The memory may be configured to store the bitstream.
1. A device for processing a bitstream, the device comprising:
one or more processors configured to obtain the bitstream, the bitstream comprising a compressed version of a spatial component of a sound field, the spatial component of the sound field being represented by a vector in a spherical harmonics domain, wherein a value of a syntax element for a current frame is indicative of a vector quantization codebook used when compressing the vector, the bitstream further comprising an indicator,
the indicator having a particular value indicating the bitstream does not include the value of the syntax element for the current frame and the value of the syntax element for the current frame is equal to a value of the syntax element for a previous frame; and
a memory coupled to the one or more processors, the memory configured to store the bitstream.
2. The device of claim 1 , wherein the one or more processors are further configured to use the vector quantization codebook to reconstruct the vector.
3. The device of claim 1 , wherein the syntax element is a first syntax element and the indicator comprises one or more bits of a value of a second syntax element for the current frame, the value of the second syntax element for the current frame indicating a quantization mode used when compressing the vector.
4. The device of claim 3 , wherein:
the indicator comprises a value of a third syntax element for the current frame and a value of a fourth syntax element for the current frame, and
the value of the third syntax element for the current frame plus the value of the fourth syntax element for the current frame being equal to zero indicates the bitstream does not include the value of the first syntax element for the current frame and the value of the first syntax element for the current frame is equal to the value of the first syntax element for the previous frame.
5. The device of claim 3 , wherein the indicator includes a most significant bit of the value of the second syntax element for the current frame and a second most significant bit of the value of the second syntax element for the current frame.
6. The device of claim 1 , the one or more processors further configured to:
decompose higher-order ambisonic audio data to obtain the vector; and
specify the vector in the bitstream to obtain the bitstream.
7. The device of claim 1 , the one or more processors further configured to:
obtain, from the bitstream, an audio object that corresponds to the vector; and
combine the audio object with the vector to reconstruct higher-order ambisonic (HOA) audio data.
8. The device of claim 1 , wherein:
the one or more processors are configured to render the HOA audio data to output one or more loudspeaker feeds,
the device is coupled to one or more loudspeakers, wherein the one or more loudspeaker feeds drive the one or more loudspeakers.
9. The device of claim 1 , wherein the one or more processors are further configured to:
obtain the value of the syntax element for the current frame from the bitstream when the indicator does not have the particular value.
10. A method for processing a bitstream, the method comprising:
obtaining the bitstream, the bitstream comprising a compressed version of a spatial component of a sound field, the spatial component of the sound field being represented by a vector in a spherical harmonics domain, wherein a value of a syntax element for a current frame is indicative of a vector quantization codebook used when compressing the vector, the bitstream further comprising an indicator,
the indicator having a particular value indicating the bitstream does not include the value of the syntax element for the current frame and the value of the syntax element for the current frame is equal to a value of the syntax element for a previous frame; and
storing the bitstream.
11. The method of claim 10 , further comprising using the vector quantization codebook to reconstruct the vector.
12. The method of claim 10 , wherein the syntax element is a first syntax element and the indicator comprises one or more bits of a value of a second syntax element for the current frame, the value of the second syntax element for the current frame indicating a quantization mode used when compressing the vector.
13. The method of claim 12 , wherein:
the indicator comprises a value of a third syntax element for the current frame and a value of a fourth syntax element for the current frame, and
the value of the third syntax element for the current frame plus the value of the fourth syntax element for the current frame being equal to zero indicates the bitstream does not include the value of the first syntax element for the current frame and the value of the first syntax element for the current frame is equal to the value of the first syntax element for the previous frame.
14. The method of claim 12 , wherein the indicator includes a most significant bit of the value of the second syntax element for the current frame and a second most significant bit of the value of the second syntax element for the current frame.
15. The method of claim 10 , further comprising:
decomposing higher-order ambisonic audio data to obtain the vector; and
specifying the vector in the bitstream to obtain the bitstream.
16. The method of claim 10 , further comprising:
obtaining, from the bitstream, an audio object that corresponds to the vector; and
combining the audio object with the vector to reconstruct higher-order ambisonic audio data.
17. The method of claim 10 , further comprising:
decoding the bitstream to obtain Higher Order Ambisonics (HOA) coefficients; and
rendering the HOA coefficients to output one or more loudspeaker feeds,
a device rendering the HOA coefficients to output the one or more loudspeaker feeds is coupled to one or more loudspeakers, wherein the one or more loudspeaker feeds drive the one or more loudspeakers.
18. The method of claim 10 , further comprising:
obtaining the value of the syntax element for the current frame from the bitstream when the indicator does not have the particular value.
19. A device for processing a bitstream, the device comprising:
means for obtaining the bitstream, the bitstream comprising a compressed version of a spatial component of a sound field, the spatial component of the sound field being represented by a vector in a spherical harmonics domain, wherein a value of a syntax element for a current frame is indicative of a vector quantization codebook used when compressing the vector, the bitstream further comprising an indicator,
the indicator having a particular value indicating the bitstream does not include the value of the syntax element for the current frame and the value of the syntax element for the current frame is equal to a value of the syntax element for a previous frame; and
means for storing the bitstream.
20. The device of claim 19 , further comprising: means for using the vector quantization codebook to reconstruct the vector.
21. The device of claim 19 , wherein the syntax element is a first syntax element and the indicator comprises one or more bits of a value of a second syntax element for the current frame, the value of the second syntax element for the current frame indicating a quantization mode used when compressing the vector.
22. The device of claim 19 , further comprising:
means for decomposing higher-order ambisonic audio data to obtain the vector; and
means for specifying the vector in the bitstream to obtain the bitstream.
23. The device of claim 19 , the device further comprising:
means for obtaining the value of the syntax element for the current frame from the bitstream when the indicator does not have the particular value.
24. A non-transitory computer-readable storage medium having instructions stored thereon that, when executed, configure a device to:
obtain a bitstream, the bitstream comprising a compressed version of a spatial component of a sound field, the spatial component of the sound field being represented by a vector in a spherical harmonics domain, wherein a value of a syntax element for a current frame is indicative of a vector quantization codebook used when compressing the vector, the bitstream further comprising an indicator,
the indicator having a particular value indicating the bitstream does not include the value of the syntax element for the current frame and the value of the syntax element for the current frame is equal to a value of the syntax element for a previous frame; and
store the bitstream.
25. The non-transitory computer-readable storage medium of claim 24 , wherein the instructions, when executed, configure the device to use the vector quantization codebook to reconstruct the vector.
26. The non-transitory computer-readable storage medium of claim 24 , wherein the syntax element is a first syntax element and the indicator comprises one or more bits of a value of a second syntax element for the current frame, the value of the second syntax element for the current frame indicating a quantization mode used when compressing the vector.
27. The non-transitory computer-readable storage medium of claim 24 , wherein the instructions, when executed, cause the device to:
decompose higher-order ambisonic audio data to obtain the vector; and
specify the vector in the bitstream to obtain the bitstream.
28. The non-transitory computer-readable storage medium of claim 24 , wherein the instructions, when executed, cause the device to:
obtain the value of the syntax element for the current frame from the bitstream when the indicator does not have the particular value.