Abstract:
An apparatus (100) calculates a number (102) of spectral envelopes (104) to be derived by a spectral band replication (SBR) encoder, wherein the SBR encoder is adapted to encode an audio signal (105) using a plurality of sample values within a predetermined number of subsequent time portions (110) in an SBR frame extending from an initial time (t0) to a final time (tn), the predetermined number of subsequent time portions (110) being arranged in a time sequence given by the audio signal (105). The apparatus (100) comprises a decision value calculator (120) for determining a decision value (125), the decision value (125) measuring a deviation in spectral energy distributions of a pair of neighboring time portions. The apparatus (100) further comprises a detector (130) for detecting a violation (135) of a threshold by the decision value (125) and a processor (140) for determining a first envelope border (145) between the pair of neighboring time portions when the violation (135) of the threshold is detected. The apparatus (100) further comprises a processor (150) for determining a second envelope border (155) between a different pair of neighboring time portions or at the initial time (t0) or at the final time (tn) for an envelope having the first envelope border (145) based on the violation (135) of the threshold for the other pair or based on a temporal position of the pair or the different pair in the SBR frame. The apparatus (100) further comprises a number processor (160) for establishing the number (102) of spectral envelopes (104) having the first envelope border (145) and the second envelope border (155).
Abstract:
An apparatus for processing an audio signal is provided. The apparatus comprises a configurable first audio signal processor (110) for processing the audio signal (s 0 ) in accordance with different configuration settings (conf) to obtain a processed audio signal (s 1 ), wherein the apparatus is adapted so that different configuration settings (conf) result in different sampling rates (sr 1 ) of the processed audio signal (s 1 ). The apparatus furthermore comprises n analysis filter bank (120) having a first number (c 1 ) of analysis filter bank channels, a synthesis filter bank (130) having a second number (c 2 ) of synthesis filter bank channels, a second audio processor (140) being adapted to receive and process an audio signal (s 2 ) having a predetermined sampling rate (sr 2 ), and a controller (150) for controlling the first number (c 1 ) of analysis filter bank channels or the second number (c 2 ) of synthesis filter bank channels in accordance with a configuration setting (conf).
Abstract:
In a method for encoding a symbol it is determined whether the symbol can be encoded by a codeword of a first code- book. In case this is true, the appropriate codeword for the symbol is selected from the first codebook. Otherwise, a codeword is selected from the first codebook indicating that the symbol cannot be encoded by a codeword of the first codebook and the symbol is split into a plurality of first sub-symbols and for at least one of the first sub- symbols a codeword is selected from a second codebook. Also a corresponding method for decoding is described.
Abstract:
An apparatus (100) calculates a number (102) of spectral envelopes (104) to be derived by a spectral band replication (SBR) encoder, wherein the SBR encoder is adapted to encode an audio signal (105) using a plurality of sample values within a predetermined number of subsequent time portions (110) in an SBR frame extending from an initial time (t0) to a final time (tn), the predetermined number of subsequent time portions (110) being arranged in a time sequence given by the audio signal (105). The apparatus (100) comprises a decision value calculator (120) for determining a decision value (125), the decision value (125) measuring a deviation in spectral energy distributions of a pair of neighboring time portions. The apparatus (100) further comprises a detector (130) for detecting a violation (135) of a threshold by the decision value (125) and a processor (140) for determining a first envelope border (145) between the pair of neighboring time portions when the violation (135) of the threshold is detected. The apparatus (100) further comprises a processor (150) for determining a second envelope border (155) between a different pair of neighboring time portions or at the initial time (t0) or at the final time (tn) for an envelope having the first envelope border (145) based on the violation (135) of the threshold for the other pair or based on a temporal position of the pair or the different pair in the SBR frame. The apparatus (100) further comprises a number processor (160) for establishing the number (102) of spectral envelopes (104) having the first envelope border (145) and the second envelope border (155).
Abstract:
Das Transientenproblem kann ausreichend adressiert und dafür eine weitere Verzögerung auf Seiten der Decodierung reduziert werden, wenn eine neue SBR-Frame-Klasse verwendet wird, bei der die Framegrenzen (902a, 902b) nicht verschoben werden, d. h. die Rastergrenzen immer noch mit den Framegrenzen (902a, 902b) synchronisiert sind, aber bei der ferner eine Transientenpositionsangabe (T) als Syntaxelement verwendet wird, um codierer- bzw. decodiererseitig innerhalb der Frames dieser neuen Frameklasse zur Bestimmung der Rastergrenzen innerhalb dieser Frames verwendet zu werden.
Abstract:
An apparatus for decoding (100) an encoded audio signal (102). A first decoder (110a) decodes a first portion (104a) in accordance with a first decoding algorithm for a first time portion of the encoded signal (102) to obtain a first decoded signal (114a). A second decoder (110b) decodes a second portion (104b) in accordance with a second decoding algorithm for a second time portion of the encoded signal (102) to obtain a second decoded signal (114b). A BWE module (130) has a controllable crossover frequency (fx) and is configured for performing a bandwidth extension algorithm using the first decoded signal (114a) and BWE parameters (106) for the first portion (104a), and for performing a bandwidth extension algorithm using the second decoded signal (114b) and the bandwidth extension parameters (106) for the second portion (104b). A controller (140) controls the crossover frequency (fx) for the BWE module (130) in accordance with a coding mode information (108).
Abstract:
An apparatus (100) for generating bandwidth extension output data (102) for an audio signal (105) comprises a noise floor measurer (110), a signal energy characterizer (120) and a processor (130). The audio signal (105) comprises components in a first frequency band (105a) and components in a second frequency band (105b), the bandwidth extension output data (102) are adapted to control a synthesis of the components in the second frequency band (105b). The noise floor measurer (110) measures noise floor data (115) of the second frequency band (105b) for a time portion (T) of the audio signal (105). The signal energy characterizer (120) derives energy distribution data (125), the energy distribution data (125) characterizing an energy distribution in a spectrum of the time portion (T) of the audio signal (105). The processor (130) combines the noise floor data (115) and the energy distribution data (125) to obtain the bandwidth extension output data (102).