Method and device for coding audio data based on vector quantisation
First Claim
1. A method for encoding audio data, comprising:
- providing an audio input vector to be encoded;
preselecting a group of code vectors of an spherical codebook comprising a number of code vectors;
determining a respective partial distortion measurement associated with the code vectors in the preselected group of code vectors;
excluding a number of the code vectors in the preselected group of code vectors, wherein the excluding is based on a value of the determined partial distortion measurement;
as a result of the preselecting and excluding, defining a reduced group of code vectors relative to the number of code vectors comprising the spherical codebook;
searching in the reduced group of code vectors to find a code vector having a sufficiently low quantisation error with respect to the input vector to mask quantization noise; and
encoding the input vector with the code vector found in the searching of the reduced group of code vectors.
2 Assignments
0 Petitions
Accused Products
Abstract
A wideband audio coding concept is presented that provides good audio quality at bit rates below 3 bits per sample with an algorithmic delay of less than 10 ms. The concept is based on the principle of Linear Predictive Coding (LPC) in an analysis-by-synthesis framework. A spherical codebook is used for quantisation at bit rates which are higher in comparison to low bit rate speech coding for improved performance for audio signals. For superior audio quality, noise shaping is employed to mask the coding noise. In order to reduce the computational complexity of the encoder, the analysis-by synthesis framework has been adapted for the spherical codebook to enable a very efficient excitation vector search procedure. Furthermore, auxiliary information gathered in advance is employed to reduce a computational encoding and decoding complexity at run time significantly. This auxiliary information can be considered as the SCELP codebook. Due to the consideration of the characteristics of the apple-peeling-code construction principle, this codebook can be stored very efficiently in a read-only-memory.
121 Citations
20 Claims
-
1. A method for encoding audio data, comprising:
-
providing an audio input vector to be encoded; preselecting a group of code vectors of an spherical codebook comprising a number of code vectors; determining a respective partial distortion measurement associated with the code vectors in the preselected group of code vectors; excluding a number of the code vectors in the preselected group of code vectors, wherein the excluding is based on a value of the determined partial distortion measurement; as a result of the preselecting and excluding, defining a reduced group of code vectors relative to the number of code vectors comprising the spherical codebook; searching in the reduced group of code vectors to find a code vector having a sufficiently low quantisation error with respect to the input vector to mask quantization noise; and encoding the input vector with the code vector found in the searching of the reduced group of code vectors. - View Dependent Claims (2, 3)
-
-
4. A method for encoding audio data, comprising:
-
providing an audio input vector to be encoded; preselecting a group of code vectors of a codebook; and encoding the input vector with a code vector of the group of code vectors having a lowest quantisation error within the group of preselected code vectors with respect to the input vector, wherein the code vectors are obtained by a apple-peeling-method, wherein each code vector is represented as a branch of a code tree linked with a table of trigonometric function values, wherein the code tree and the table are stored in a memory so that each code vector used for encoding the audio data is reconstructable based on the code tree and the table. - View Dependent Claims (5, 6, 7)
-
-
8. A method to communicate audio data, comprising:
-
generating the audio data in a first audio device; encoding the audio data in the first audio device by; providing an audio input vector to be encoded, preselecting a group of code vectors of an spherical codebook comprising a number of code vectors, determining a respective partial distortion measurement associated with the code vectors in the preselected group of code vectors; excluding a number of the code vectors in the preselected group of code vectors, wherein the excluding is based on a value of the determined partial distortion measurement; as a result of the preselecting and excluding, forming a reduced group of code vectors relative to the number of code vectors of the spherical codebook; searching in the reduced group of code vectors to find a code vector having a sufficiently low quantisation error with respect to the input vector to mask quantization noise; encoding the input vector with the code vector found in the searching of the reduced group of code vectors; transmitting the encoded audio data from the first audio device to a second audio device; and decoding the encoded audio data in the second audio device. - View Dependent Claims (9)
-
-
10. A method to communicate audio data, comprising:
-
generating the audio data in a first audio device; encoding the audio data in the first audio device by; providing an audio input vector to be encoded, preselecting a group of code vectors of a codebook, and encoding the input vector with a code vector of the group of code vectors having a lowest quantisation error within the group of preselected code vectors with respect to the input vector; transmitting the encoded audio data from the first audio device to a second audio device; and decoding the encoded audio data in the second audio device, wherein an index unambiguously representing a code vector is assigned to the code vector selected for encoding, wherein the index is transmitted from the first audio device to the second audio device and the second audio device uses a code tree and table for reconstructing the code vector and decodes the transmitted data with a reconstructed code vector, wherein the code vectors are obtained by a apple-peeling-method, wherein each code vector is represented as a branch of the code tree linked with a table of trigonometric function values, wherein the code tree and the table are stored in a memory so that each code vector used for encoding the audio data is reconstructable based on the code tree and the table.
-
-
11. A device for encoding audio data, comprising:
-
an audio vector device to provide an audio input vector to be encoded; a preselecting device to preselect a group of code vectors of an spherical codebook comprising a number of code vectors by selecting code vectors received from the audio vector device, the preselecting device configured to determine a respective partial distortion measurement associated with the code vectors in the preselected group of code vectors; a code vector excluding-device configured to exclude a number of the code vectors in the preselected group of code vectors based on a value of the determined partial distortion measurement, wherein the preselecting device and excluding-device are configured to define a reduced group of code vectors relative to the number of code vectors of the spherical codebook; a code vector searching-device configured to search in the reduced group of code vectors to find a code vector having a sufficiently low quantisation error with respect to the input vector to mask quantization noise; and an encoding device configured to encode the input vector found by the code vector searching-device in the reduced group of code vectors. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
-
-
20. A device for encoding audio data, comprising:
-
an audio vector device to provide an audio input vector to be encoded; a preselecting device to preselect a group of code vectors of a codebook by selecting code vectors received from the audio vector device; and an encoding device connected to the preselecting device for encoding the input vector from the audio vector device with a code vector of the group of code vectors having the lowest quantisation error within the group of preselected code vectors with respect to the input vector, wherein the code vectors of the codebook for the preselecting device are given by an apple-peeling-method, wherein each code vector is represented as a branch of a code tree linked with a table of trigonometric function values, wherein the code tree and the table are stored in a memory so that each code vector used for encoding the audio data is reconstructable on the basis of the code tree and the table.
-
Specification