Low time-delay transform coder, decoder, and encoder/decoder for high-quality audio
US5222189A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 26, 1990 |
| Grant date | Jun 22, 1993 |
| Priority date | — |
| Expiry date | Sep 26, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B1/665
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A low bit-rate (192 kBits per second) transform encoder/decoder system (44.1 kHz or 48 kHz sampling rate) for high-quality music applications employs short time-domain sample blocks (128 samples/block) so that the system signal propagation delay is short enough for real-time aural feedback to a human operator. Carefully designed pairs of analysis/synthesis windows are used to achieve sufficient transform frequency selectivity despite the use of short sample blocks. A synthesis window in the decoder has characteristics such that the product of its response and that of an analysis window in the encoder produces a composite response which sums to unity for two adjacent overlapped sample blocks. Adjacent time-domain signal samples blocks are overlapped and added to cancel the effects of the analysis and synthesis windows. A technique is provided for deriving suitable analysis/synthesis window pairs. In the encoder, a discrete transform having a function equivalent to the alternate application of a modified Discrete Cosine Transform and a modified Discrete Sine Transform according to the Time Domain Aliasing Cancellation technique or, alternatively, a Discrete Fourier Transform is used …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.