Not strictly true for all cases.

Just as a point of interest, my digital audio workstation (ProTools) has facilities to change the sample rate and create a new file. If I set it to the highest quality setting (they call it "tweak-head"!), it takes several HOURS of number crunching to convert about 45 minutes of stereo music from say 48k to 44.1k. And this is on a fast computer. Kind of makes me wonder about the performance of sample rate converters that do it 'on the fly'....

ProTools... is that the Mac audio editing software?

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Matthew J. Hill
matt@idsi.net

Bosso: you've said again, that PCM is an IN only format... in my earlier post I was asking why you believe this to be so.

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Matthew J. Hill
matt@idsi.net

Yes. It comes in various configurations, with and without external hardware. My system has a couple racks of external I/Os and sync units, but you can download a software only version of the editing program for FREE (!) at www.digidesign.com. It's called "ProTools Free" and provides 8 tracks, and outputs in stereo through the Mac's internal sound facilities. It's under 'downloads' and is available for Macs and PCs. ProTools is the de facto standard in the music recording and motion picture industries.

[This message has been edited by soundhound (edited October 29, 2002).]

I was thinking more of the conversions that don't inherently discard or truncate information, like converting to a deeper bit depth.

Most non trivial conversions of course have the potential to degrade information, but good engineering can help a lot in most cases. Shuffling bits around IS what I do, and it is possible to do a lot without discarding info, and it's possible to implement most operations poorly too.

[QUOTE]Originally posted by Matthew Hill:
[B]Bosso: you've said again, that PCM is an IN only format... in my earlier post I was asking why you believe this to be so.
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matthew: if you're looking for some sort of technical paper from me...sorry...i'm the wrong guy to ask that.

i only looked at the available evidence and common sense. you can upconvert or downconvert a pcm format to another pcm format. it isn't changed to a new scheme, only higher or lower bit and/or sampling rates of pcm format. at some point, as you go up in resolution, you gain less and less as you trade loss by processing...this is according to the people who invented it.

that aside, suppose you archive in pcm and another format comes along. how would you convert pcm to whatever the new format is?

more importantly, as evidence, the sony engineers say once in pcm, stuck in pcm and the dvd-a camp doesn't deny it when they do. in fact, i find zero info on the subject of pcm archiving/ conversion to a future format except this telling statement in a dvd-a promo paper under 'archiving':

"with so many professional digital formats, there's no knowing for sure which ones will be around and playable in 10 or 15 years. it may be safest to prepare, mix and copy to tried and true analog tape with dolby sr for long term archiving and storage regardless of which digital format was used in the original recording."

on the other side, sony says that dsd rivals 30 ips 1/2" tape and is the preferred archiving method as it can be converted later to any digital format.

i believe, short of better dacs being the rule rather than the exception, we are hearing pcm at it's best in it's current 24/192 state. we haven't heard dsd yet at all and won't until the receivers/prepros come out that can process it. the industry engineers, producers and musicians who have heard it are unanimous, that i've read/talked to.

also, sacd is backward compatable. the cd layer of a hybrid disc will play on a boombox. this is important to retailers who won't have to double stock.

i'm not an engineer and...well, let's just say i have a vested interest in predicting the winner. i ask, i read, i reason. any dvd-a proponents are welcome to chime in.

Well I don't think it's at all that cut and dried. Here is an interesting quote:


http://www.digital-recordings.com/publ/pubrec.html

There are lots of great articles on this site BTW.

EDIT:

Keep in mind, Sony and Sony Marketing have a lot of reasons to boost this technology, not all based on merit. Memory Stick, Beta, and other Sony technologies are examples of Sony's very strong NIH attitude. Sometimes they are better, sometimes just different to be different.

[This message has been edited by charlie (edited October 30, 2002).]

I think Sony produces some great products, but one of the things that irks me most about the company is that NIH attitude you're talking about. I almost hope that Memory Stick, Mini Disk, SACD, etc. fails miserably just so that they start to learn a lesson from all of it. Apparently Beta wasn't enough lesson for them.

Of course, I don't REALLY hope that SACD fails just because it's from Sony. Or Mink Disk & friends. Some of the Sony technologies are actually kind of nice. But others (Memory Stick, in particular) just seem pointless as they don't add anything to the industry.

I think that DVD/A is "neater" technologically, and of course, being a PCM based format will make things easier to integrate with the rest of the system, when we finally get digital interconnects.

I also don't see any reason why it should be harder to convert from PCM to DSD than from DSD to PCM. It all just seems like math to me.

DSD just seems to me to be... needlessly "different" from what's already working well in the market. Now, SACD, as a format is a useful evolution beyond CD, but I think they could have done just as well with PCM in that format.

Also, remember that SACD *can* be backwards compatible with ordinary CD players, but is not necessarily so (the extra layer need not be there). Additionally, DVD-A *can* be backwards compatible with DVD-V players, but is not necessarily so.

I don't see any large technical advantages to one format over the other in this "war", although I think DVD-A's use of PCM and its use of the DVD encoding at the data layer (SACD is an all-new format at the data layer) provide advantages in cost and system integration.

Of course, in the end, I think that it's going to come down to software. I also think that both will probably live on side-by-side for quite some time. This isn't going to be decided soon because, unlike Beta/VHS, it doesn't have to be.

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Matthew J. Hill
matt@idsi.net