Abstract:
An encoder for encoding an audio signal, wherein the encoder is configured to: generate a plurality of signal components, wherein each of the plurality of signal components has an associated scaling factor and bit allocation value; select at least one of the plurality of signal components, wherein the selection is dependent on the bit allocation value associated with the at least one of the plurality of signal components and a bit allocation threshold value; and apply to the at least one of the plurality of signal components selected a further scaling factor and a further bit allocation value.
Abstract:
A multistage quantizing method and apparatus are provided. The multistage quantizing method comprises the steps: obtaining a reference codebook based on a preceding stage codebook, obtaining a current stage codebook based on the reference codebook and a zoom factor, and quantizing the input vector utilizing the current stage codebook.
Abstract:
Codebook indices for a scalable speech and audio codec may be efficiently encoded based on anticipated probability distributions for such codebook indices. A residual signal from a Code Excited Linear Prediction (CELP)-based encoding layer may be obtained, where the residual signal is a difference between an original audio signal and a reconstructed version of the original audio signal. The residual signal may be transformed at a Discrete Cosine Transform (DCT)-type transform layer to obtain a corresponding transform spectrum. The transform spectrum is divided into a plurality of spectral bands, where each spectral band having a plurality of spectral lines. A plurality of different codebooks are then selected for encoding the spectral bands, where each codebook is associated with a codebook index. A plurality of codebook indices associated with the selected codebooks are then encoded together to obtain a descriptor code that more compactly represents the codebook indices.
Abstract:
An encoder comprises a processor (301) which divides an input audio signal into a plurality of frames. A first encoder unit (303) generates, for each frame, first encoding data and a residual signal and a second encoder unit (305) encodes the residual signal to generate second encoding data. A combine processor (307) generates output encoded data comprising at least the first encoding data and the second encoding data. At least one of the first encoder unit (303) and the second encoder unit (305) employs a gradual frame transition extending into a neighboring frame. The encoder includes a processor (313) which determines a time interval of each frame corresponding to the gradual frame transition and a processor (311) for delaying the inclusion in the output encoded data of at least some second encoding data for the time interval to a subsequent frame. A complementary decoder is also provided. The invention may provide improved framing and reduced delay for cascaded coder/decoder arrangements.
Abstract:
L'invention concerne un procédé de dissimulation d'erreur de transmission dans un signal numérique découpé en une pluralité de trames successives associées à des intervalles temporels différents dans lequel, à la réception, le signal est susceptible de comporter des trames effacées et des trames valides et pour remplacer au moins la première trame effacée (N) après une trame valide, on effectue au moins deux étapes, une première étape (El) de préparation ne produisant aucun échantillon manquant et comportant au moins une analyse d'un signal décodé valide et une deuxième étape (E2) de dissimulation produisant les échantillons manquants du signal correspondant à la dite trame effacée. La première étape et la deuxième étape sont exécutées dans des intervalles temporels différents. L'invention se rapporte également à un dispositif de dissimulation mettant en œuvre le procédé selon l'invention ainsi qu'un décodeur comportant un tel dispositif. L'invention permet de distribuer la complexité de la dissimulation d'erreur sur des intervalles temporels différents.
Abstract:
Provided is a method and apparatus for encoding and decoding an enhancement layer to reduce quantization error in a G.711 codec. Exponent indices of additional mantissa information of each sample are calculated based upon exponent information of each sample in a frame. A process of allocating 1 bit to each sample with a current exponent index is repeated, the exponent index starting from the maximum value while decreasing by 1 at every repetition until the total number of bits allocated to the samples is equal to the total number of available bits in the frame. And the most significant bits, as many as the number of bits allocated to each sample, are extracted from the additional mantissa information of each sample in the frame.
Abstract:
L'invention concerne le traitement d'un signal qui a été codé en compression (COD) selon un type de codage prédéterminé, appliquant une opération de quantification (Q), puis décodé (DEC), de sorte qu'un bruit de quantification est présent dans le signal décodé (S*). Le traitement de signal de l'invention applique une réduction du bruit de quantification (TBQ) au signal décodé (S*), préférentiellement comme suit : on obtient d'abord des informations (INF) sur le type de codage en compression; on choisit un modèle de réduction du bruit de quantification adapté à ces informations en estimant le bruit de quantification (BQ) qu'a pu générer le codage; et on applique au signal décodé (S*) un traitement de réduction du bruit de quantification (FIL) selon le modèle choisi.
Abstract:
An audio encoder for encoding an audio signal includes an impulse extractor (10) for extracting an impulse-like portion from the audio signal. This impulse-like portion is encoded and forwarded to an output interface (22). Furthermore, the audio encoder includes a signal encoder (16) which encodes a residual signal derived from the original audio signal so that the impulse-like portion is reduced or eliminated in the residual audio signal. The output interface (22) forwards both, the encoded signals, i.e., the encoded impulse signal (12) and the encoded residual signal (20) for transmission or storage. On the decoder-side, both signal portions are separately decoded and then combined to obtain a decoded audio signal.