4 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.

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.

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.