[redshifter]

duncan got me thinking about this on another thread. if md is compressed because it is missing music data compared to cd (5:1), then is redbook compressed compared to sacd? i mean, sacd has more musical data, so does that mean now cd should be considered a lossy format?

keep in mind that yes, atrac is sometimes compressed data from redbook pcm. but atrac can also record from live sources, vinyl, linear dvd pcm at 48khz (converted), so it isn't always a compressed version of redbook pcm. the point being atrac is lossy when compared to cd, but is it still lossy when the source is analog?

is "lossy format" a relative term?

 

[Hirsch]

Quote:

Originally posted by redshifter is "lossy format" a relative term?

Not really. Any A to D technology is by definition lossy. Sampling means that some of the original data must be lost. Whether the loss matters or not is another question.

 

[redshifter]

Quote:

Originally posted by Hirsch Not really. Any A to D technology is by definition lossy. Sampling means that some of the original data must be lost. Whether the loss matters or not is another question.

"not really", but then you say it is. if all a/d must lose some data, then the importance is 1) how much is lost and 2) how the loss is compensated for?

is it theoretically possible that sample rates, bit depths, and encoding schemes can ever achieve more or as much resolution as an analog format or source?

i realize the bottom line is how it sounds when it hits your ears, but people throw around terms like "lossy" and "uncompressed" when talking about digital audio, when in fact it is all relative.

 

[zowie]

No, it's not relative.

I think you're confusing data compression - taking x amount of digital data and making it take up less storage space - with the loss of musical information/resolution, which of course happens with all formats, including analogue. The latter is not what the term refers to.

The data compression is "lossy" if data is eliminated in the compression process. It's not lossy if all the data is still there (or completely recoverable), just in less space, e.g., a zip file.

 

[redshifter]

Quote:

Originally posted by zowie No, it's not relative. I think you're confusing data compression - taking x amount of digital data and making it take up less storage space - with the loss of musical information/resolution, which of course happens with all formats, including analogue. The latter is not what the term refers to. The data compression is "lossy" if data is eliminated in the compression process. It's not lossy if all the data is still there (or completely recoverable), just in less space, e.g., a zip file.

so if these formats are compressed in some form, but not lossy, then all the data from the original performance is in the cd, sacd, md, etc., but needs to be decompressed (decoded) correctly to approach the original performance, right?

if you have the same recording from the same analog master tape, and put it on md, redbook cd, sacd, and vinyl you get:
md = small amount of data (considered "lossy" compression?)
cd = medium amount of data
sacd = large amount of data
vinyl = largest amount of information (analog "data")
......relative to the original performance.
so relative to eachother these are all just different levels and implementations of compression, and with the possible excpetion of md no data is eliminated during the compression stage?

 

[zowie]

No.

Data compression does not mean "compressed in some form." The only one of those formats that has data compression is MD.

Relative to each other, they represent different amounts of lost resolution and information from the original performance (not necessarily in your order). But that is not data compression (except for the MD).

With LP, a somewhat imperfect analogy to data compression might be the development in the 50's of ways to space the grooves closer together to get longer playing time on a record.

I think you understand all of the concepts, but are misapplying terms.

 

[Tim D]

Lossy means that the data you encode is not the original data that you decoded. Make an Mp3 of a CD track, convert the Mp3 to a Wav, that Wav is not the same as ripping it directly from the track.

However different formats have different resolution with bit depth and sampling and quantization, etc.

Technically however, any recording format is lossy in the recording process (A->D, A->A). And if you have a crappy source or amp or headphones, than technically even the reconstruction can be considered lossy. But lossy is a term used for digital data compression, and not really applied to either recording or playback in the wholistic sense but only in the encoding/decoding sense. There aren't any microphones or recorders that transcribe the original performance perfectly, and there are no sources, amps, transducers, that would play it back perfectly so lossy/lossless isn't a useful term there as lossless doesn't exist in those domains.

 

[zowie]

Quote:

Originally posted by Tim D There aren't any microphones or recorders that transcribe the original performance perfectly, and there are no sources, amps, transducers, that would play it back perfectly so lossy/lossless isn't a useful term there as lossless doesn't exist in those domains.

Well put.

 

[redshifter]

thanks for the info everyone. i thought thee might be a juicy discourse here but i'm obviously outgunned.

 

[taoster]

Quote:

Originally posted by Tim D But lossy is a term used for digital data compression, and not really applied to either recording or playback in the wholistic sense but only in the encoding/decoding sense.

yep, and it should only be used in a digital sense else it gets rather confusing rather quickly!

 

[markl]

There is far more info on an SACD than on a Redbook CD. Yet, the SACD is also "lossy" in that it still contains less data than the actual master tape. Unless you have the actual master tape to listen to, sems to me, every medium/format is going to be "lossy".

Mark

 

[Nefarion]

When peformers go into the studio they work their ass off and are left with the master tapes. These tapes are the "uncompressed" version of their work. From the master tapes comes redbookcd's, sacd's,..whatever. Master tapes being the highest quality..

So to ask the question "are redbook cd's compressed" .. I answer: Compressed from what?

If you mean compressed from the masters... Yes they are.

MiniDisc is a compressed version of redbook cd's. Physically and statisticly

.

 

[zowie]

Quote:

Originally posted by Nefarion When peformers go into the studio they work their ass off and are left with the master tapes. These tapes are the "uncompressed" version of their work. From the master tapes comes redbookcd's, sacd's,..whatever. Master tapes being the highest quality.. So to ask the question "are redbook cd's compressed" .. I answer: Compressed from what? If you mean compressed from the masters... Yes they are. MiniDisc is a compressed version of redbook cd's. Physically and statisticly .

Please re-read the earlier posts. Loss of quality is not the same thing as compression, and there can be compression with no loss of quality. These terms have specific meanings when used in this context, not whatever you think should make sense.

 

[Nefarion]

I disagree. Compressing is taking away data or transforming it in some form... taking away/transforming data is loss of quality. The idea with audio is to replicate the original recording as best as possible. If you manipulate the original recording (master tapes) to fit into a "smaller box", you have then changed it in some form. Any form of compression = not the same as the original no matter how you look at it. Maybe so close we cant tell the difference, but none the less not the same.

Im not sure exactly how much space the master tapes (data wise) take up.. But im sure it is significantly more than a redbook cd... or an SACD..etc. The data from the master tapes has to be compressed, where a loss of quality will occur, to fit onto a cd. The idea of different formats is to shrink the loss of quality from the compression of the master tapes to as little as possible.

 

[zowie]

Quote:

Originally posted by Nefarion I disagree. Compressing is taking away data or transforming it in some form... taking away/transforming data is loss of quality.

Ever hear of zip files?

Quote:

The data from the master tapes has to be compressed, where a loss of quality will occur, to fit onto a cd.

Obviously false if the master was a 16/44 recording. And that makes no sense at all for analogue recordings.


You're just being silly now.