A study is presented for the use of multiresolution analysis-based onset detection in the complex domain. It shows that using variable time-resolution across frequency bands generates sharper detection functions for higher bands and more accurate detection functions for lower bands. The resulting method improves the localisation of onsets on fixed-resolution schemes, by favouring the increased time precision of higher subbands during the combination of results.

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Digital audio effects are typically implemented on 16 or 24 bit signals sampled at 44.1 kHz. Yet high quality audio is often encoded in a one-bit, highly oversampled format, such as DSD. Processing of a bitstream, and the application of audio effects on a bitstream, requires special care and modification of existing methods. However, it has strong advantages due to the high quality phase information and the elimination of multiple decimators and interpolators in the recording and playback process. We present several methods by which audio effects can be applied directly on a bitstream. We also discuss the modifications that need to be made to existing methods for them to be properly applied to DSD audio. Methods are presented through the use of block diagrams, and results are reported. Keywords: Sigma Delta Modulation, SACD, DSD, Digital Audio Effects, Bitstream Signal Processing

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