News Release：Pioneer Develops High Accuracy Sampling Rate Convert Technology for Professional Audio Use

Tokyo, Japan, June 23, 1997 --- Pioneer Electronic Corporation has announced the development of high accuracy Sampling Rate Convert Technology^*1 for professional audio use. With this technology, real time high quality smooth conversion of sampling frequency and quantize bits between various digital media^*2 of different formats, and high quality mastering and use of existing software are possible.

< Background of the Development >

As sampling frequencies of Digital Audio have been widened and its high resolution technology has improved in the past few years, there is high demand for converters of a higher quality than the existing rate converters. But the reality is that when even in up- sampling from 44.1kHz to 48 kHz, which is in high demand, using the current rate converter caused the sound quality to change and resulted in distortion. For this reason, it did not achieve good results in producing software.

Previously, in order to achieve high accuracy conversion, it took a long time to do the calculations by computer. But by utilizing the newly developed "Multi - Stage Polyphase Filter Algorithm"^*3 by using DSP (Digital Signal Processor) of up to 96kHz x 24 bits, real time high accuracy conversion is possible.

In addition, as this technology achieves high accuracy conversion in every conversion rate, it fully utilizes the existing software, making it possible to produce new software in different media formats. (For example, it can be used in producing DVD software which sampling source is 44.1kHz and CD software which is 96kHz.) Also when recorded in 96kHz x 24 bits --- the highest sound quality format possible at present --- it can be easily down converted to any other media^*3 and can be used with the high quality mastering source^*4.

In late June, two CD software titles using this innovative technology (down converted from 96 kHz x 24 bits) will be introduced to the Japanese market.

*1 Sampling Rate Convert Technology

Technology which converts sources digitally recorded in a certain sampling frequency/quantize bit figure to different sources of different sampling frequency/quantize bit figures. (Ex. Convert 96kHz x 24 bit of DVD to 44.1kHz x 16 bits of CD.) Previous attempts to convert from digital to digital, using the existing technology resulted in sound quality discrepancies and noise. In addition,in order to achieve high accuracy conversion, a large amount of computation was necessary and it was difficult to convert in real time.

*2 Format of Main Media

DVD: 96 or 48kHz x 24 or 20 or 16 bits
CD: 44.1kHz x 16 bits
MD: 44.1kHz
PCM Broadcast: 32 or 48kHz

*3 "Multi - Stage Polyphase Filter Algorithm"

Pioneer succeeded in developing the algorithm with a small volume of computing and memory, which best suits digital audio.

*4 Standardization of Master Recording

Previous sampling rate convert results were not sufficient, and when making the master recording, it was sometimes necessary to record in several different formats.

< Main Features >

1 ) High Sampling/High Bit Audio of DVD. High accuracy direct conversion between each input/output format.

Enables world's first direct conversion between the sampling rate (Fs) of 88.2kHz and 96kHz. And high accuracy direct conversion between each input format (Fs 44.1/48/88.2/96kHz, bit length 16 - 24 bits) and output format (Fs 32/44.1/48/88.2/96kHz, bits length 16/20/24 bits) is possible.

2 ) No frequency deviation by the conversion.

By newly developed technology "Multi - Stage Polyphase Filter Algorithm", it is capable of high accuracy and synchronous conversion by keeping the original sound quality at the time of up- conversion with no frequency deviation. As this technology achieved to decrease the memory of computation, high accuracy and real time conversion became possible.

3 ) Very small conversion noise.

(At the time of 24 bits input/output, "Total Harmonic Distortion + Noise = about -143 dB" is achieved.)

By high quality filter computation of "Multi Stage Polyphase Filter Algorithm", conversion noise is significantly reduced.

4 ) No audible aliasing noise occurs.

Usually, in order to decrease computing volume at the time of conversion, it was necessary to reduce the number of taps of convert filters. But by utilizing this technology, achieving flat frequency characteristic and narrow transition band width at the same time without aliasing noise is possible.

5 ) Bit Mapping by character-selectable dither and noise shaper is possible.

Possible to select 3 options of dither (all output rate) and noise shaper (rates except 32 kHz output) each. When one wants to make sound quality change as little as possible and when one wants to cut the bits by maintaining the resolution, it is possible to adjust this according to resolution of the source or the various purposes of the conversion.