Abstract:
The invention pertains to a method of decoding a digital audio signal, comprising the steps of decoding (E602) according to an inverse transform decoding of a previous frame of samples of the digital signal, which frame is received and coded according to a transform coding, decoding (E608) according to a predictive decoding of a current frame of samples of the digital signal, which frame is received and coded according to a predictive coding. The predictive decoding of the current frame is a transition predictive decoding which does not use any adaptive dictionary arising from the previous frame and the method furthermore comprises a step of reinitialization (E606) of at least one state of the predictive decoding to a predetermined default value, an add-overlap step (E609) which combines a signal segment synthesized by predictive decoding of the current frame and a signal segment synthesized by inverse transform decoding, corresponding to a stored segment of the decoding of the previous frame. The invention pertains correlatively to a method of coding comprising a reinitialization of at least one state of the predictive coding to a predetermined default value. It pertains to a coder and decoder implementing the respective methods.
Abstract:
The present document relates to audio encoding / decoding. In particular, the present document relates to a method and system for reducing the complexity of a bit allocation process used in the context of audio encoding / decoding. An audio encoder (300) configured to encode an audio signal according to a first audio codec system is described. The audio encoder (300) comprises a transform unit (302) configured to determine a set of spectral coefficients (312) based on the audio signal. Furthermore, the encoder (300) comprises a floating-point encoding unit (304) configured to determine a set of scale factors and a set of scaled values (314), based on the set of spectral coefficients (312); and to encode the set of scale factors to yield a set of encoded scale factors (313). In addition, the encoder (300) comprises a bit allocation and quantization unit (305, 306) configured to determine a total number of available bits for quantizing the set of scaled values (314), based on a first target data-rate and based on the number of bits used for the set of encoded scale factors (313); to determine a first control parameter (315) indicative of an allocation of the total number of available bits for quantizing the scaled values of the set of scaled values (314); and to quantize the set of scaled values (314) in accordance to the first control parameter (315) to yield a set of quantized scaled values (317). Furthermore, the encoder (300) comprises a transcoding simulation unit (320) configured to determine a second control parameter (321) based on the first control parameter (315); wherein the second control parameter (321) enables a transcoder to convert the first bitstream into a second bitstream at a second target data-rate; wherein the second bitstream accords to a second audio codec system different from the first audio codec system; and wherein the first bitstream comprises the second control parameter.
Abstract:
The present document relates to audio encoding / decoding. In particular, the present document relates to a method and system for reducing the complexity of a bit allocation process used in the context of audio encoding / decoding. An audio encoder (300) configured to encode an audio signal according to a first audio codec system is described. The audio encoder (300) comprises a transform unit (302) configured to determine a set of spectral coefficients (312) based on the audio signal. Furthermore, the encoder (300) comprises a floating-point encoding unit (304) configured to determine a set of scale factors and a set of scaled values (314), based on the set of spectral coefficients (312); and to encode the set of scale factors to yield a set of encoded scale factors (313). In addition, the encoder (300) comprises a bit allocation and quantization unit (305, 306) configured to determine a total number of available bits for quantizing the set of scaled values (314), based on a first target data-rate and based on the number of bits used for the set of encoded scale factors (313); to determine a first control parameter (315) indicative of an allocation of the total number of available bits for quantizing the scaled values of the set of scaled values (314); and to quantize the set of scaled values (314) in accordance to the first control parameter (315) to yield a set of quantized scaled values (317). Furthermore, the encoder (300) comprises a transcoding simulation unit (320) configured to determine a second control parameter (321) based on the first control parameter (315); wherein the second control parameter (321) enables a transcoder to convert the first bitstream into a second bitstream at a second target data-rate; wherein the second bitstream accords to a second audio codec system different from the first audio codec system; and wherein the first bitstream comprises the second control parameter.
Abstract:
Methods and apparatuses are disclosed that can combine audio content from two encoded input signals into a new encoded output signal without requiring a decode or re-encode of audio content in either encoded input signal. Encoded data representing audio content and spatial location of audio objects in two different input encoded signals are combined to generate an encoded output signal that has encoded data representing audio objects from both of the input encoded signals.
Abstract:
The present invention provides a novel end-to-end solution for creating, encoding, transmitting, decoding and reproducing spatial audio soundtracks. The provided soundtrack encoding format is compatible with legacy surround- sound encoding formats, so that soundtracks encoded in the new format may be decoded and reproduced on legacy playback equipment with no loss of quality compared to legacy formats.
Abstract:
The present document relates to the design of anti-aliasing and/or anti-imaging filters for resamplers using rational resampling factors. In particular, the present document relates to a method for designing such filters having a reduced number of filter coefficients or an increased perceptual performance, as well as to the filters designed using such method. A method for designing a filter (102) configured to reduce imaging and/or aliasing of an output audio signal (113) at an output sampling rate (fs out ) is described. The output audio signal (113) is a resampled version of an input audio signal (110) at an input sampling rate (fs in ). The ratio of the output sampling rate (fs out ) and the input sampling rate (fs in ) is a rational number N/M. The filter (102) operates at an upsampled sampling rate which equals N times the input sampling rate (fs in ). The method comprises the steps of selecting an allowed deviation of the frequency response (531, 532) of the filter (102) within a stop band of the filter (102) based on a perceptual frequency response indicative of an auditory spectral sensitivity; wherein the allowed deviation indicates a deviation of the frequency response (531, 532) of the filter (102) from a predetermined attenuation within the stop band; and of determining coefficients of the filter (102) such that the frequency response (531, 532) of the filter (102) is fitted to the allowed deviation of the frequency response (531, 532).
Abstract:
A multi-stage recursive sample rate converter ("SRC") typically embodied as digital signal processor provides for an efficient structure for converting digital audio samples at one frequency, such as 48 kHz, to another frequency, such as 44.1 kHz. A parameter codebook comprising memory stores parameters used at a plurality of stages by the SRC. For each stage, a controller coordinates the SRC to use the appropriate set of parameters from the codebook, process an input audio sample stream, and store the intermediate results in a buffer. The controller then causes the intermediate results to be processed again as input to the SRC in a subsequent stage of processing using a different set of parameters. The process is repeated until all stages are completed, and the final results arc the output digital audio data stream at the desired sampling rate.
Abstract:
A method is provided for decoding data streams in a voice communication system. The method includes: receiving two or more data streams having voice data encoded therein; decoding each data stream into a set of speech coding parameters; forming a set of combined speech coding parameters by combining the sets of decoded speech coding parameters, where speech coding parameters of a given type are combined with speech coding parameters of the same type; and inputting the set of combined speech coding parameters into a speech synthesizer.