S/PDIF Misconception

PowerDVD 5 control panelA couple of nights ago I installed CyberLink’s new PowerDVD 5 Deluxe. Good stuff — with some worthwhile improvements over version 4.0, particularly software DTS decoding (this was previously an optional extra). But I couldn’t work out this ’24/96 LPCM Direct Output’ feature, so I went to its support page and wrote:

In FAQ ID number 1366 it states “(25) 24/96 LPCM Direct Output, supports 24bit/96kHz LPCM audio output with more crisp and clear sound. To enable this feature, users should have a sound card that also supports 24bit/96kHz audio output.” I am using a Terratec DMX6fire 24/96 sound card with the latest drivers, but when playing a 24/96 Chesky DVD (which does not have prohibition on 96kHz output), the signal is downsampled to 48kHz. How do you enable 96kHz S/PDIF output?

Much to my surprise, I got an email this afternoon pointing me to a response, which said:

SPDIF cannot support 96/24 SPDIF output since it is the limitation of SPDIF itself.Please switch to analog output (ie 2-speaker or headphone output interface in PowerDVD) to have 96K output.

But, actually, that’s not quite right. As I responded:

Thanks for the quick response!You wrote: “SPDIF cannot support 96/24 SPDIF output since it is the limitation of SPDIF itself.”

That is correct as far as the original design of S/PDIF was concerned (it was limited to 44.1 or 48kHz and 16 bits), but S/PDIF now defacto supports AC3, DTS and higher LPCM standards. In particular, the Terratec DMX6fire 24/96 *does* ouput 24/96 on the S/PDIF, and it will *accept* 24/96 on its S/PDIF inputs. Furthermore, my Marantz SR18 home theatre receiver (and, indeed, most receivers these days) will accept a 24/96 LPCM signal on its S/PDIF input. Many good DVD players will output 24/96 LPCM S/PDIF (most Sony, Panasonic, Pioneer, Yamaha, Denon, Onkyo DVD players, for example). So it would be nice if PowerDVD would likewise support this output on S/PDIF, instead of downsampling it to 48kHz.

The reason, incidentally, is for those of us who prefer the sound of external equipments’ D/A converters.

UPDATE (Tuesday, 12 August 2003, 12:27 pm)CyberLink replies:

We just delivered your suggestion to our product team. We will take this into consideration for further design. Be free for further suggestions. Thank you.

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