7 results about "Modified discrete cosine transform" patented technology

This disclosure provides methods, components, devices and systems for multirate audio mixing. Some aspects more specifically relate to mixing audio streams with different sample rates. In some examples, an audio source device may convert audio streams with different sample rates to the frequency domain using a modified discrete cosine transform (MDCT), and the audio source device may mix the audio streams with different sample rates in the frequency domain. The audio source device may apply a pre-emphasis filter after mixing the audio streams in the frequency domain. An audio stream with a higher sample rate may be down-sampled by dropping frequency bins after converting the audio stream to the frequency domain. Additionally, or alternatively, an audio stream with a lower sample rate may be up-sampled by padding frequency bins of the frequency domain-converted audio stream.

A method and an apparatus for switching between a lossy codec and a lossless codec are provided. The method includes: obtaining a waveform of a previous frame Ti−1, and updating the waveform of the previous frame Ti−1 to an input frame buffer in the lossless codec, where the waveform of the previous frame Ti−1 is encoded by a lossy encoder; performing integer window time domain aliasing cancellation INT winTDAC on a waveform in a lossless encoder buffer to obtain a first transform result, and updating the first transform result to an overlapped buffer in the lossless codec; obtaining a waveform of a current frame Ti, and updating the waveform of the current frame Ti to the input frame buffer; and performing integer modified discrete cosine transform INTMDCT on the waveform in the lossless encoder buffer to obtain a second transform result.

A method, decoder, and program code for controlling a concealment method for a lost audio frame is provided. A first audio frame and a second audio frame of the received audio signal are decoded to obtain modified discrete cosine transform (MDCT) coefficients. Values of a first spectral shape based upon the MDCT coefficients decoded from the first audio frame decoded and values of a second spectral shape based upon MDCT coefficients decoded from the second audio frame decoded are determined, the spectral shapes each comprising a number of sub-bands. The values of the spectral shapes and frame energies of the first audio frame and second audio frame are transformed into representations of FFT based spectral analyses. A transient condition is detected based on the representations of the FFTs. Responsive to detecting the transient condition, the concealment method is modified by selectively adjusting a spectrum magnitude of a substitution frame spectrum.

The application discloses a low-illumination image enhancement method suitable for freight security monitoring scenes. The method first collects low-illumination original image data through a high-definition starlight-level camera, and carries out non-local mean filtering and linear normalization preprocessing; further, an improved discrete cosine transform filter bank is used for frequency domain transformation of the image, a filter bank with direction selectivity is designed based on image frequency characteristics, texture complexity and edge characteristics, so that multi-frequency domain and multi-direction features are extracted, and separation of noise and effective details is realized; subsequently, multi-source image features are adaptively fused through a fusion rule based on contrast weighting; finally, the fused features are input into a specially trained encoder-decoder structure convolutional neural network, and optimization training is carried out by using a multi-component loss function, so that deep enhancement and reconstruction of the image are completed.

An application-specific integrated circuit for accelerated encoding and decoding and a method, which are related to the technical field of Bluetooth mobile communication. The application-specific integrated circuit for accelerated encoding and decoding includes: a hardware accelerator, wherein the hardware accelerator includes a pre-processing and pronation processing module, which performs a pre-processing and pronation processing of data, a discrete Fourier transform module is used for performing a multi-level discrete Fourier transform, in an accelerated low-delay modified discrete cosine transform operation LD-MDCT and / or an accelerated the low-delay inverse modified discrete cosine transform operation LD-IMDCT. The application-specific integrated circuit for accelerated encoding and decoding and a method of the present invention adopts an ASIC application-specific integrated circuit, and adopts multi-level discrete Fourier transforms, so that the complex operations are completed by the ASIC application-specific integrated circuit.

This disclosure provides methods, components, devices and systems for multi-rate audio mixing. Some aspects more specifically relate to mixing audio streams with different sample rates. In some examples, an audio source device may convert audio streams with different sample rates to the frequency domain using a modified discrete cosine transform (MDCT), and the audio source device may mix the audio streams with different sample rates in the frequency domain. The audio source device may apply a pre-emphasis filter after mixing the audio streams in the frequency domain. An audio stream with a higher sample rate may be down-sampled by dropping frequency bins after converting the audio stream to the frequency domain. Additionally, or alternatively, an audio stream with a lower sample rate may be up-sampled by padding frequency bins of the frequency domain-converted audio stream.

The invention provides a method for real-time concealing errors in audio data packets. A Long Short-Term Memory (LSTM) neural network with a plurality of nodes is provided and pre-trained with audio data. A sequence of packets is received, each packet comprising a set of modified discrete cosine transform (MDCT) coefficients associated with a frame comprising time-domain samples of the audio signal. These MDCT coefficient data are applied to the LSTM neural network, and in case it is identified that a received packet is an erroneous packet, an output from the LSTM neural network is used to generate estimated MDCT co-efficients to provide a concealment packet to replace the erroneous packet. Preferably, the MDCT coefficients are normalized prior to applying to the LSTM neural network. This method can be performed in real-time. A low latency can be obtained and still with a high audio quality.