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Transform coding of high quality digital audio at low bit rates-algorithms and implementation

Transformationscode der hochwertigen digitalen Tonsignale für einen Algorithmus mit kleiner Bitrate und die Systemimplementierung


Institute of Electrical and Electronics Engineers -IEEE-:
IEEE International Conference on Communications. ICC '90 including SUPERCOMM Technical Sessions. Conference record. Vol. 3
Piscataway, NJ: IEEE, 1990
International Conference on Communications (ICC) <1990, Atlanta/Ga.>
SUPERCOMM Technical Sessions <1990, Atlanta/Ga.>
Conference Paper
Fraunhofer IIS A ( IIS) ()
Tonsignal; Tonwiedergabetechnik; Digitalsignal; Codierung; Systembeschreibung; adaptives System; Echtzeitbetrieb; Versuchsergebnis; Übertragungsqualität; digitale Signalverarbeitung; Rechnerunterstützung; Signalgenerator; Digitalsignalverarbeitungs-Chip; Frequenzbereich

Low bit rate coding schemes for coding high quality digital audio at bit rates of 64 to 128 kbit/sec per channel are described. LC-ATC (Low-Complexity Adaptive Transform Coding) and OCF (Optimum Coding in the Frequency domain) both use transform coding to get high redundancy removal and high adaptation to the perceptual requirements. OCF uses entropy coding of the spectral values for increased coding efficiency an flexibility of the coder. Real time implementations using DSP32(C) and DSP 56000 digital signal processors are presented for both algorithms. Results using listening tests and Noise-to-Mask-Ratio (NMR) are given: CD-quality can be achieved at 2 bit/sample. At 64 kbit/sec, the quality at 1 5 kHz bandwidth is still higher than todays FM radio.