Encoding and decoding of pulse positions of tracks of an audio signal

• US 9,595,263 B2
• Filed: 08/14/2013
• Issued: 03/14/2017
• Est. Priority Date: 02/14/2011
• Status: Active Grant

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Baeckstroem, Tom, Fuchs, Guillaume
• Primary Examiner(s): He, Jialong
• Application Number:
  US13/966,635
• Publication Number:
  US 20130339036A1
• Time in Patent Office: 1,308 Days
• Field of Search: 704/219, 704/500
• US Class Current: 1/1
• CPC Class Codes: G10K 11/16 Methods or devices for protecting against, or for damping, noise or other acoustic waves in general G10K11/36 takes precedence
• CPC Class Codes: G10L 19/00 Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis in musical instruments G10H
• CPC Class Codes: G10L 19/005 Correction of errors induced by the transmission channel, if related to the coding algorithm
• CPC Class Codes: G10L 19/012 Comfort noise or silence coding
• CPC Class Codes: G10L 19/0212 using orthogonal transformation
• CPC Class Codes: G10L 19/022 Blocking, i.e. grouping of samples in time; Choice of analysis windows; Overlap factoring
• CPC Class Codes: G10L 19/025 Detection of transients or attacks for time/frequency resolution switching
• CPC Class Codes: G10L 19/03 Spectral prediction for preventing pre-echo; Temporary noise shaping [TNS], e.g. in MPEG2 or MPEG4
• CPC Class Codes: G10L 19/04 using predictive techniques
• CPC Class Codes: G10L 19/107 Sparse pulse excitation, e.g. by using algebraic codebook
• CPC Class Codes: G10L 19/12 the excitation function being a code excitation, e.g. in code excited linear prediction [CELP] vocoders
• CPC Class Codes: G10L 19/18 Vocoders using multiple modes
• CPC Class Codes: G10L 19/22 Mode decision, i.e. based on audio signal content versus external parameters
• CPC Class Codes: G10L 19/26 Pre-filtering or post-filtering
• CPC Class Codes: G10L 21/0216 characterised by the method used for estimating noise
• CPC Class Codes: G10L 25/06 the extracted parameters being correlation coefficients
• CPC Class Codes: G10L 25/78 Detection of presence or absence of voice signals switching of direction of transmission by voice frequency in two-way loud-speaking telephone systems H04M9/10

Abstract

An apparatus for decoding an encoded audio signal is provided. The apparatus includes a pulse information decoder and a signal decoder. The pulse information decoder is adapted to decode a plurality of pulse positions, wherein each one of the pulse positions indicates a position of one of the pulses of the track, wherein the pulse information decoder is configured to decode the plurality of pulse positions by using a track positions number, a total pulses number, and one state number. The signal decoder is adapted to decode the encoded audio signal by generating a synthesized audio signal using the plurality of pulse positions and a plurality of predictive filter coefficients.

Claims

1. An apparatus for decoding an encoded audio signal, wherein one or more tracks are associated with the encoded audio signal, each one of the tracks comprising a plurality of track positions and a plurality of pulses, wherein the apparatus comprises:

a pulse information decoder for decoding a plurality of pulse positions, wherein each one of the pulse positions is one of the track positions, where one of the pulses is located, and wherein the pulse information decoder is configured to decode the plurality of pulse positions by only using one track position number, one total pulse number and one state number, wherein the track position number indicates a total number of the track positions of at least one of the tracks, and wherein the total pulse number indicates a total number of the pulses of at least one of the tracks; and

a signal decoder for decoding the encoded audio signal by generating a synthesized audio signal using the plurality of pulse positions and a plurality of predictive filter coefficients being associated with the encoded audio signal,

wherein at least one of the pulse information decoder and the signal decoder comprises a hardware implementation,

wherein the pulse information decoder is furthermore adapted to decode a plurality of pulse signs by only using the track position number, the total pulse number and the state number, wherein each one of the pulse signs indicates a sign of one of the plurality of pulses, and

wherein the signal decoder is adapted to decode the encoded audio signal by generating a synthesized audio signal furthermore using the plurality of pulse signs.

2. An apparatus according to claim 1, wherein at least a last track and one or more other tracks are associated with the encoded audio signal, and

wherein the pulse information decoder is adapted to generate a first substrate number and a second substrate number from the state number,

wherein the pulse information decoder is configured to decode a first group of the pulse positions based on the first substrate number, and

wherein the pulse information decoder is configured to decode a second group of the pulse positions based on the second substrate number,

wherein the second group of the pulse positions only comprises pulse positions indicating track positions of the last track, and

wherein the first group of the pulse positions only comprises pulse positions indicating track positions of the one or more other tracks.

3. An apparatus according to claim 2, wherein the pulse information decoder is configured to generate the first substrate number and the second substrate number by dividing the state number by f(p_k, N) to acquire an integer part and a remainder as a division result, wherein the integer part is the first substrate number and wherein the remainder is the second substrate number, wherein p_k indicates for each one of the one or more tracks the number of pulses, and wherein N indicates for each one of the one or more tracks the number of track positions.

4. An apparatus according to claim 1, wherein the pulse information decoder is adapted to conduct a test comparing the state number or an updated state number with a threshold value.

5. An apparatus according to claim 4, wherein the pulse information decoder is adapted to conduct the test by comparing, whether the state number or an updated state number is greater than, greater than or equal to, smaller than, or smaller than or equal to the threshold value, and wherein the pulse information decoder is furthermore adapted to update the state number or an updated state number depending on the result of the test.

6. An apparatus according to claim 5, wherein the pulse information decoder is configured to compare the state number or the updated state number with the threshold value for each track position of one of the plurality of tracks.

7. An apparatus according to claim 1,

wherein the pulse information decoder is configured to divide one of the tracks into a first track partition, comprising at least two track positions of the plurality of track positions and into a second track partition comprising at least two other track positions of the plurality of track positions,

wherein the pulse information decoder is configured to generate a first substrate number and a second substrate number based on the state number,

wherein the pulse information decoder is configured to decode a first group of pulse positions associated with the first track partition based on the first substrate number, and

wherein the pulse information decoder is configured to decode a second group of pulse positions associated with the second track partition based on the second substrate number.

8. An apparatus for encoding an audio signal, comprising:

a signal processor for determining a plurality of predictive filter coefficients being associated with the audio signal, for generating a residual signal based on the audio signal and based on the plurality of predictive filter coefficients; and

a pulse information encoder for encoding a plurality of pulse positions relating to one or more tracks, to encode the audio signal, the one or more tracks being associated with the residual signal, each one of the tracks comprising a plurality of track positions and a plurality of pulses, wherein each one of the pulse positions is one of the track positions, where one of the pulses is located, wherein the pulse information encoder is configured to encode the plurality of pulse positions by generating one state number, such that the pulse positions are decodable only based on the state number, one track position number, and one total pulse number, wherein the track position number indicates a total number of the track positions of at least one of the tracks, and wherein the total pulse number indicates a total number of the pulses of at least one of the tracks,

wherein at least one of the signal processor and the pulse information encoder comprises a hardware implementation,

wherein the pulse information encoder is configured to determine the state number depending on an intermediate sum,

wherein, for each pulse at a track position for each track position of one of the tracks, the pulse information encoder is configured to add an integer value to the intermediate sum, to update the intermediate sum.

9. An apparatus for encoding according to claim 8, wherein the pulse information encoder is adapted to encode a plurality of pulse signs, wherein each one of the pulse signs indicates a sign of one of the plurality of pulses, wherein the pulse information encoder is configured to encode the plurality of pulse signs by generating the state number, such that the pulse signs can be decoded only based on the state number, the track position number indicating a total number of the track positions of at least one of the tracks, and the total pulse number.

10. An apparatus according to claim 8, wherein the pulse information encoder is configured to add the integer value to the intermediate number for each pulse at a track position for each track position of one of the tracks, to acquire the state number, wherein the integer value is defined by f(p, k−

1), wherein p indicates a number of found pulses, wherein k indicates a track position, and wherein f(p, N) indicates the number of possible configurations for a track comprising N track positions and p signed pulses.

11. An apparatus according to claim 8,

wherein the pulse information encoder is configured to divide one of the tracks into a first track partition, comprising at least two track positions of the plurality of track positions, and into a second track partition, comprising at least two other track positions of the plurality of track positions,

wherein the pulse information encoder is configured to encode a first substrate number associated with the first partition,

wherein the pulse information encoder is configured to encode a second substrate number associated with the second partition, and

wherein the pulse information encoder is configured to combine the first substrate number and the second substrate number to acquire the state number.

12. Method for decoding an encoded audio signal, wherein one or more tracks are associated with the encoded audio signal, each one of the tracks comprising a plurality of track positions and a plurality of pulses, wherein the method comprises:

decoding a plurality of pulse positions, wherein each one of the pulse positions is one of the track positions, where one of the pulses is located, and wherein the plurality of pulse positions are decoded by only using one track position number, one total pulse number and one state number, wherein the track position number indicates a total number of the track positions of at least one of the tracks, and wherein the total pulse number indicates a total number of the pulses of at least one of the tracks,

decoding a plurality of pulse signs by only using the track position number, the total pulse number and the state number, wherein each one of the pulse signs indicates a sign of one of the plurality of pulses, and

decoding the encoded audio signal by generating a synthesized audio signal using only the plurality of pulse positions and a plurality of predictive filter coefficients being associated with the encoded audio signal,

wherein decoding the encoded audio signal is conducted by generating a synthesized audio signal furthermore using the plurality of pulse signs.

14. A non-transitory computer readable medium comprising a computer program implementing the method of claim 12 when being executed on a computer or signal processor.

13. Method for encoding an audio signal, comprising:

determining a plurality of predictive filter coefficients being associated with the audio signal, for generating a residual signal based on the audio signal and based on the plurality of predictive filter coefficients; and

encoding a plurality of pulse positions relating to one or more tracks, to encode the audio signal, the one or more tracks being associated with the residual signal, each one of the tracks comprising a plurality of track positions and a plurality of pulses, wherein each one of the pulse positions is one of the track positions, where one of the pulses is located, wherein the plurality of pulse positions are encoded by generating one state number, such that the pulse positions can be decoded only based on the state number, one track position number, and one total pulse number, wherein the track position number indicates a total number of the track positions of at least one of the tracks, and wherein the total pulse number indicates a total number of the pulses of at least one of the tracks,

wherein determining the state number depending on an intermediate sum,

wherein, for each pulse at a track position for each track position of one of the tracks, an integer value is added to the intermediate sum, to update the intermediate sum.

15. A non-transitory computer readable medium comprising a computer program implementing the method of claim 13 when being executed on a computer or signal processor.