Abstract:
In a method of improving perceived loudness and sharpness of a reconstructed speech signal delimited by a predetermined bandwidth, performing the steps of providing (S10) the speech signal, and separating (S20) the provided signal into at least a first and a second signal portion. Subsequently, adapting (S30) the first signal portion to emphasize at least a predetermined frequency or frequency interval within the first bandwidth portion. Finally, reconstructing (S40) the second signal portion based on at least the first signal portion, and combining (S50) the adapted first signal portion and the reconstructed second signal portion to provide a reconstructed speech signal with an overall improved perceived loudness and sharpness.
Abstract:
Method and decoder for processing of audio signals. The method and decoder relate to deriving a processed vector {circumflex over (d)} by applying a post-filter directly on a vector d comprising quantized MDCT domain coefficients of a time segment of an audio signal. The post-filter is configured to have a transfer function H which is a compressed version of the envelope of the vector d. A signal waveform is reconstructed by performing an inverse MDCT transform on the processed vector {circumflex over (d)}.
Abstract:
Estimation of a high band extension of a low band audio signal includes the following steps: extracting (S1) a set of features of the low band audio signal; mapping (S2) extracted features to at least one high band parameter with generalized additive modeling; frequency shifting (S3) a copy of the low band audio signal into the high band; controlling (S4) the envelope of the frequency shifted copy of the low band audio signal by said at least one high band parameter.
Abstract:
An apparatus for filling non-coded residual sub-vectors of a transform coded audio signal. The apparatus comprises means for compressing coded residual sub-vectors, means for rejecting compressed residual sub-vectors that do not fulfill a predetermined criterion and means for concatenating the remaining compressed residual sub-vectors to form a first virtual codebook. The apparatus further comprises means for combining pairs of coefficients of the first virtual codebook to form a second virtual codebook, means for filling non-coded residual sub-vectors below a predetermined frequency with coefficients from the first virtual codebook and means for filling non-coded residual sub-vectors above the predetermined frequency with coefficients from the second virtual codebook.
Abstract:
An apparatus for generating a high band extension of a low band excitation signal (eLB) defined by parameters representing a CELP encoded audio signal includes the following elements: upsamplers (20) configured to upsample a low band fixed codebook vector (uFCB) and a low band adaptive codebook vector (uACB) to a predetermined sampling frequency. A frequency shift estimator (22) configured to determine a modulation frequency (&OHgr;) from an estimated measure representing a fundamental frequency (F0) of the audio signal. A modulator (24) configured to modulate the upsampled low band adaptive codebook vector (uACB↑) with the determined modulation frequency to form a frequency shifted adaptive codebook vector. A compression factor estimator (28) configured to estimate a compression factor. A compressor (34) configured to attenuate the frequency shifted adaptive codebook vector and the upsampled fixed codebook vector (uFCB↑) based on the estimated compression factor. A combiner (40) configured to form a high-pass filtered sum of the attenuated frequency shifted adaptive codebook vector and the attenuated up-sampled fixed codebook vector.
Abstract:
Method and decoder for processing of audio signals. The method and decoder relate to deriving a processed vector d by applying a post-filter directly on a vector d comprising quantized MDCT domain coefficients of a time segment of an audio signal. The post-filter is configured to have a transfer function H which is a compressed version of the envelope of the vector d. A signal wave form is reconstructed by performing an inverse MDCT transform on the processed vector d.
Abstract:
Described is an encoder (50) for encoding a parametric spectral representation (f) of auto-regressive coefficients that partially represent an audio signal. The encoder includes a low-frequency encoder (10) configured to quantize elements of a part of the parametric spectral representation that correspond to a low-frequency part of the audio signal. It also includes a high-frequency encoder (12) configured to encode a high-frequency part (f H ) of the parametric spectral representation (f) by weighted averaging based on the quantized elements (f L ) flipped around a quantized mirroring frequency (f m ), which separates the low-frequency part from the high- frequency part, and a frequency grid determined from a frequency grid codebook (24) in a closed-loop search procedure. Described are also a corresponding decoder, corresponding encoding/decoding methods and UEs including such an encoder/decoder.