|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
68.7.107.85
Data Bits Versus Music BitsThere are some major differences in the reading, recovery, and readout of data bits from data CDs from the way that music bits are read, recovered, and played back over time from music CDs. Jitter and audible distortion are essentially irrelevant when reading, recovering, and reading data bits because jitter is irrelevant to the reading and playback of data bits that only convey symbolic information rather than musical data. There’s Exact Audio Copy that reads musical data repeatedly until it gets it right or almost perfect but there’s no Exact Data Copy because the error correction for pure data is much more robust than the Redbook error correction scheme for music CDs that allows for the interpolation of missing data bits and even muting when too much data is missing for the player’s interpolation algorithms If the increased data capacity of SACDs or DVD Audio had been used to give music discs the same error correction scheme as data CDs then music discs might sound a lot better than the new formats that merely increase the number of bits and up-sample.
George S. Louis, Perfect Polarity Pundit
Follow Ups:
The error correction used by all formats of compact disk is cross interleaved Reed-Solomon code (CIRC). There is no difference between this for an audio cd or for a data cd.What makes a data cd more robust is that the error correction built into the format of the files themselves provides a second layer of correction. The data on an audio cd in and of itself is not formatted in the structure of a computer file with error correction built in.
So, because of the dual layers of correction, data cds have a better chance of retaining their file integrity over audio cds.
But, your claim that jitter and audible distortion are irrelevent when reading a data cd shows your fundamental misunderstanding of how the data is stored, how it is read, how it is corrected, and all of the different ways that jitter can be introduced into the real-time datastream at playback.
HowdyMy favorite reference for Audio CD and CD ROM info is off line ( http://www.ee.washington.edu/conselec/CE/kuhn/cdrom/95x8.htm ) but the extra error correction info isn't in the file structure in CD-ROMs it's a third layer of Reed-Solomon error correction below the file level. In lieu of the link above http://en.wikipedia.org/wiki/CD-ROM has a brief intro.
Never the less I'm in complete agreement with your final paragraph.
Are memory and age inversely proportional, or inverse squared proportional?
"If the increased data capacity of SACDs or DVD Audio had been used to give music discs the same error correction scheme as data CDs then music discs might sound a lot better than the new formats that merely increase the number of bits and up-sample."George:
Audiophiles have been whining about CD's since their inception. They have yet to realize that the problem was not with the format so much, but a learning curve in studios with digital audio workstations, which had nowhere near the processing power of modern DAWs used to make the same Redbook CDs today. So, the industry said "Fine - let's give audiophiles a chance to purchase music that is (in many cases) the same bit-depth and sample rate as that of the master". This resulted in hi-res DVD-V (chesky at 24/96 for example) followed by DVD-A at 24/96 and 24/192, confused by DTS and other multichannel music formats, topped off with SACD and DSD and now headed towards another ill-fated "format war": Blue-Ray vesus HD-DVD.
If a format with higher resolution than Redbook is made from analog master tapes, then GREAT! (If a CD is made from the same analog master, it's theoretically is not as good as a hi-res capture.)The analogy of taking a digital photo of something would apply here - the higher the resolution, the larger print you can make - there truly IS more information there.
If a format with a higher resolution is the same bit-depth and resolution of the DIGITAL master, there may not even be a NEED to up/resample. If a CD is made from a higher res DIGITAL master then we're getting into a different ballpark because now there HAS to be resampling at some point.
So, all this being said, what is it you were trying to convey from that last sentence? I'm not disagreeing with you - I just didn't get the jist of your statement is all.
Personally, I think 24/96 on DVD-V was the best thing since sliced bread, and was "killed-off" only because DVD-V copy protection was cracked... which is the same thing that happened to DVD-A! Everyone thinks that MP3 filesharing is the only form of piracy because that is the popular thing here in North America. But in other countries, there is a BIG demand for black-market discs - literal copies in a jewel or DVD case. Now if THESE guys get their hands on unprotected master quality 24/96 or 24/192 material... what's stopping them from making their own little "record company" that makes profits without having to pay all those annoying artists and recording professionals!!
Now, new formats are coming out because of the massive amounts of data that are required for hi-res VIDEO.
Let's be honest here... SACD sounds pretty damned good, can't be played in a PC at ALL, and the data-stream can only be accessed by people smart enough to do a board-level interception of the stream before it hits the DACs. (And usually these people are engineering level types who are doing this for their own shagrin and are NOT handing these methodologies over to the hacker community. Besides. SACD "hacks" are hardware hacks and not something a "filesharing pirating moron" can download from the internet. Don't assume all pirates are morons though - overseas, blackmarket CDs and DVDs are in great demand and these guys are not only technically saavy but are probably as dangerous as drug dealers...Where there is easy money, there is crime!) Taking the internet out of the equation was a good thing for SACD, but bad for the few who are into PC audio playback. Honestly? If that is what it takes for a GOOD format to survive, then I myself would be inclined to live with it and just get the best "Universal" player I could afford (which is, in my case, a top-end Denon which is "not too shabby" according to many discerning audiophiles around here).
If you are saying that jitter is irrelevant on playback until it's time to convert to analog, then I agree. If you're trying to say something else then I miss your meaning entirely.
HowdyI think he's obliquely saying that perhaps the improvement some hear from hi-res is due to better error correction.
He's wrong. It is true the audio CDs have worse error correction than data CDs. It's too bad that this is the way it is, but it isn't the end of the world since uncorrectable errors aren't that common on Redbook.
I read his post as a lamentation that SACD and DVD-A have the same poor error correction as audio CD, which is less than that of a data CD.Which is wrong. The error correction on the hi-rez disks is an order of magnitude greater than that of the audio CD. Don't know how it compares to a data CD.
HowdyI'm pretty darn sure that SACD and DVD-A both build on DVD tech and hence both have at least as good of error correction as DVD's data. Don't quote me tho :)
I think she has analyzed the file structure on an SA-CD and noted that essentially it's based on UDF but with the TOC deliberately corrupted so that a DVD player or a PC can't read it.But I think the salient point is that on DVD-* and SA-CD, audio/video is treated no different from data - they are stored as files on UDF and the player is supposed to provide enough buffering to stream it to DACs.
This post is made possible by the generous support of people like you and our sponsors: