[vorbis] HDCD

[Giuliano Pochini]

On 29-Jan-2003 Michel Donais wrote:
>> 
>> Would it be possible to extract the information into a 24-bit 96kHz file
>> to retain the same quality from the HDCD format?
>>
>
> Well... Yes. It would be easy to do so, if you happened to know how the
> format is made... but with the DMCA, I wouldn't even try to do so.

Well, so 24b/96KHz may be unable to carry the information of an HDCD,
since we know almost nothing about it.

> The idea behind HDCD is to remove a bit, which is not a big deal
> (1/32768th of quality loss... Yeehaa)

No, when you remove 1 bit and you use it for other purpose, you
add 6dB of noise (full-range) to non-HDCD enabled players.

> ... and add a lot of hinting to
> gain a few KHz of resolution. It alleviates frequency shifting due to
> quantization, and that is the main concern on high-end systems for the
> CD format.

Again, what do you really know about HDCD ? 1bit per sample is a 11Kbps
stream. IMO there is just too few space to add all that fantastic sound
quality and resolution comparable to 20bit audio blah blah blah they
claim to achieve. That stream can be used to drive the digital filter
to do some undocumented things.

> I mean, even with 1 bit resolution, you could theoretically have a very
> good and recognizable sound track (my portable CD player used to use
> such bitstream conversion)... for example, it's how Sony SACD works.

Yes, but the sampling frequancy is 2.8MHz.

> And the resulting A-to-D
> conversion of the HDCD chip is of such high level that even audiophiles
> without the HDCD player can benefit from its conversion.

:-/

> Of course, when you have a Krell HDCD player and can have the luxury of
> having the small blue led light up, it's even better, and by a margin
> ^_^  . Less clanky sounds, especially at higher frequencies (violins are
> remarkable with HDCD, as compared to the strident ordinary CDs).

Yes, the out-of-band data can properly drive the filters.

<p>Bye.

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