Investigation Procedure to Obtain Perception Limits of Filter Related Sonic Degradations in Digital Audio Source Encoding
PCM source encoding techniques require mandatorily sophisticated low-pass filters for anti-aliasing and anti-imaging purposes. Currently applied low-pass filters introduce sonic degradations like group delay distortion, passband ripple and ringing. In order to investigate the perceptual limits of these effects, a test method was developed by the use of digital filter techniques with the advantage that each parameter influence becomes separated. According to this method, subjective tests are already performed using high quality PCM-recorded music passages, the results of which will aim at optimal codec design. The test procedure and preliminary results are discussed. A reasonable hardware design concept on a proposed PCM-codec, including optimized digital low-pass filters, will be outlined.
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