Audio Degradation with Digital Copies?

[Teasing the Korean]

We all know how analog copies start to sound after multiple generations of copies. Is anyone aware of any attempts at doing multi-generation digital to digital audio copies to see what happens? I'm just curious.

[Dan Gould]

We all know how analog copies start to sound after multiple generations of copies. Is anyone aware of any attempts at doing multi-generation digital to digital audio copies to see what happens? I'm just curious.

Its said that there is degradation over time (errors build up).

I've yet to hear it, but I imagine that software like Exact Audio Copy, which goes through extensive error-checking, would eliminate this.

[Stefan Wood]

I still have cdrs from burns I made 10 years ago that still sound fine, no skips. On crappy media (generic Circuit City brand).

Edited January 11, 2007 by Stefan Wood

[Ted O'Reilly]

I think the question is not whether your 10 year old copy sound now, or will sound good years from now, but whether or not a copy of a copy of a copy of a copy of a copy of a copy will sound good today....

[Ted O'Reilly]

"your 10 year old copy sound now"

Should read sounds now, of course.

[Jim Alfredson]

Ted, you can use the "edit" button to edit posts.

[Teasing the Korean]

Thanks for the replies, all.

I should clarify exactly what I'm talking about here.

I don't mean clones of clones of clones of CDs through traditional high-speed burning - although I'm interested in how that plays out, too.

What I'm specifically referring to is this:

Play a CD as audio. Burn a real time, digital copy of the resulting audio.

Play the burned copy as audio. Burn a real time, digital copy of the resulting audio from the previous burn...

and so on...

and so on...

and so on...

In theory, there should be no degradation, but we all know it will occur.

Now, with analog audio, it would result in more hiss, less treble, and an overall muddier sound.

I want to know what happens when you make several generations of AUDIO copies using digital sources and recording to digital media.

What will it sound like after 20, 30, 40, or 50 generations.

You dig? (digital) dig?

[Jim Alfredson]

I assume by "audio" you're referring to using the analog outputs of the CD player into the analog inputs of the record.

The key word is analog. Therein lies the problem.

[bolivarblues]

In the strictly digital realm, you're just copying data, and as long as the data is copied correctly, copy 1,000 should sound the same as copy 1, but the rub is that which each successive generation comes the increased possibility of copying errors, which present themselves as clicks and pops, rather than the sort of anomalies typical of the analog realm, such as decreased s/n ratio and the like. Or at least that's my best guess.

I'm not sure what you're talking about when you speak of playing the CD as audio and copying in real-time. As pointed out above, if at any point in the process you're talking about the D/A convertor is introduced, all bets are off. If you're taking a digital copy, which is converted through the D/A convertor to analog for output, then you record the output (which involves the A/D convertor), you've introduced significant loss of quality as early as the second generation.

Edited January 16, 2007 by Frankie Machine

[Chuck Nessa]

You're just copying data, and as long as the data is copied correctly, copy 1,000 should sound the same as copy 1, but the rub is that which each successive generation comes the increased possibility of copying errors, which present themselves as clicks and pops, rather than the sort of anomalies typical of the analog realm, such as decreased s/n ratio and the like. Or at least that's my best guess.

Pretty much what Frankie said. Repeated and expanded errors would be the problem.

[Claude]

I've heard lossless rips of CDs that have been copied through thousands of miles of cables, multiple switches and routers. Some of these downloads were even assembled from a few dozen sources (filesharing). That should be worse than multi-generation digital copies on the same PC. But the result just sounds like the original.

[Jim Alfredson]

I've heard lossless rips of CDs that have been copied through thousands of miles of cables, multiple switches and routers. Some of these downloads were even assembled from a few dozen sources (filesharing). That should be worse than multi-generation digital copies on the same PC. But the result just sounds like the original.

Actually, they shouldn't sound worse at all. On the contrary, all those "avenues" you mention employ parity checks on the packets, so no information is lost due to data errors. Thus, the copy you see is basically a clone.

This explains it rather simplistically.

[Claude]

Thanks Jim. In fact, I was being ironic with my example of music being torn to pieces and transported over long distances. As long as the music stays in the digital domain, with no manipulation (like sample rate conversion) and no data being lost (integrity check), it will sound the same.

When people notice that a CD copy sounds worse than the original, the reason is usually that the original CD was ripped with digital errors, that the copy has been burned with errors, or that the CD player doesn't handle CD-Rs well.