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

Low-bit-rate coding schemes for coding high-quality digital audio at bit rates of 64 to 128 kbit/s 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 and flexibility of the coder. Real-time implementations using the DSP32(C) and DSP 56000 digital signal processors are presented for both algorithms. Results using listening tests and noise-to-mask ratio are given: CE quality can be achieved at 2 bit/sample. At 64 kbit/s, the quality at 15 kHz bandwidth is still higher than today´s FM radio