摘要:
The present invention provides a new method and an apparatus for spectral envelope encoding. The invention teaches how to perform and signal compactly a time/frequency mapping of the envelope representation, and further, encode the spectral envelope data efficiently using adaptive time/frequency directional coding. The method is applicable to both natural audio coding and speech coding systems and is especially suited for coders using SBR [WO 98/57436] or other high frequency reconstruction methods.
摘要:
The present proposes new methods and an apparatus for enhancement of source coding systems utilising high frequency reconstruction (HFR). It addresses the problem of insufficient noise contents in a reconstructed highband, by Adaptive Noise-floor Addition. It also introduces new methods for enhanced performance by means of limiting unwanted noise, interpolation and smoothing of envelope adjustment amplification factors. The present invention is applicable to both speech coding and natural audio coding systems.
摘要:
The present invention relates to digital audio coding systems that employ high freuqency reconstruction (HFR) methods. It teaches how to improve the overall perforamcne of such systems, by means of an adaptation over time of the crossover frequency between the lowband coded by a core codec, and the highband coded by an HFR system. Different methods of establishing the instantaneous optimum choice of crossover frequency are introduced.
摘要:
The present invention proposes a new method and a new apparatus for enhancement of audio source coding systems utilising high frequency reconstruction (HFR). It utilises adaptive filtering to reduce artifacts due to different tonal characteristics in different frequency ranges of an audio signal upon which HFR is performed. The present invention is applicable to both speech coding and natural audio coding systems.
摘要:
The method involves filtering a low band signal through the analysis part of a digital filter bank and obtaining a set of subband signals. A number of the subband signals are patched from consecutive channels of the filter bank to consecutive channels in the synthesis part of a digital filter bank. Each of the subband signals is patched from a channel with frequency index k to a channel with frequency index j not equal to k. The patched subband signals are adjusted in accordance to a desired spectral envelope. The adjusted subband signals are filtered through the synthesis part of a digital filter bank. An envelope adjusted and frequency translated or folded signal is obtained. An Independent claim is included for an apparatus for enhancement of source coding systems using high-frequency reconstruction techniques.
摘要:
For generating a parametric representation of a multi-channel signal especially suitable for low-bit rate applications, only the location of the maximum of the sound energy within a replay setup is encoded and transmitted using direction parameter information. For multi-channel reconstruction (54), the energy distribution of the output channels identified by the direction parameter information is controlled (57) by the direction parameter information, while the energy distribution in the remaining ambience channels (59) is not controlled by the direction parameter information.
摘要:
The method involves filtering a low band signal through the analysis part of a digital filter bank and obtaining a set of subband signals. A number of the subband signals are patched from consecutive channels of the filter bank to consecutive channels in the synthesis part of a digital filter bank. Each of the subband signals is patched from a channel with frequency index k to a channel with frequency index j not equal to k. The patched subband signals are adjusted in accordance to a desired spectral envelope. The adjusted subband signals are filtered through the synthesis part of a digital filter bank. An envelope adjusted and frequency translated or folded signal is obtained. An Independent claim is included for an apparatus for enhancement of source coding systems using high-frequency reconstruction techniques.
摘要:
The present invention relates to a new method for enhancement of source coding systems using high-frequency reconstruction. The invention teaches that tonal signals can be classified as either pulse-train-like or non-pulse-train-like. Relying on this classification, significant improvements on the perceived audio quality can be obtained by adaptive switching of transposers. The invention shows that the so-switched transposers must have fundamental differences in their characteristics.