Why Do Some CDs Rip More Slowly than Others?

I’m ripping some CDs today. I got a set of eight CDs by Bill Nelson, The Practice of Everyday Life (Amazon.com, Amazon UK). I’m using a brand new CD/DVD/Blu-Ray drive, the Pioneer BDR-XD05. (Amazon.com, Amazon UK)

The first CD started ripping at about 5x, and ended around 10x. (The first CD drives could read data at 150 kb/sec; this is 1x. Read and write speeds, for CDs, use multiples of that original speed.) Yet yesterday, I was ripping some other CDs, and they started at around 10x, finishing at 24x. Why this difference?

First, you need to know why the read speeds of optical discs changes as the process progresses. Optical discs are read from the center to the outside, and an optical drive spins at a (more or less) fixed rate. So as the laser goes from the center to the outside, the amount of data in one rotation is greater, hence the highest speed you’ll see is the very last track on an album.

But why do some discs read quickly and others slowly? This is a bit of a mystery. The only logical reason is that some discs are harder to read; that somehow, in the manufacturing process, something is done that makes a disc harder to read. Because when a CD rips slowly, you can hear the difference in the speed of the drive. Part of this may be that there are more errors on certain discs. I strongly recommend that you turn on Error Correction in iTunes, or whatever app you use to rip CDs. (Choose iTunes > Preferences, click General, then Import Settings.)

Error correction

While error correction will slow down rips, it does ensure that the rips are better. These aren’t what is known as “accurate rips,” but you’re less likely to have any diginoise – pops or clicks – in CDs you rip with error correction.

In this Bill Nelson set that I ripped, the first two CDs ripped very slowly, then the third ripped at the maximum speed of my drive: around 12x at the beginning, going up to 24x at the end of the CD.

To sum up, there’s no way to find out why certain CDs rip slowly. The best guess is that they were produced in a way that makes them harder to read. You won’t notice then when playing them; the read speed is much slower. But you’ll find a vast difference between ripping speeds if you rip a lot of CDS.

Update: A friend suggested that I left something out. That the complexity of the music affects the ripping speed. That’s not the case, at least not with modern computers. Any computer sold today can compress files at much faster speeds than optical drives can rip. You can do a test. Take a lossless file from a CD, add it to iTunes, then convert it to AAC or MP3. You’ll see that iTunes compresses at 40-100x or more, depending on your processor (as long as you’re not using your CPU intensely for other software).

Here’s an example of iTunes compressing a lossless file to AAC; I had to find one long enough so I could take a screenshot, since it’s so fast:

Screen Shot 2015 01 23 at 2 44 38 PM

34 thoughts on “Why Do Some CDs Rip More Slowly than Others?

  1. I think you’re on the right track when you say the discs are harder to read. I have imported several thousand CDs into iTunes. I believe it has something to do with the current trend of mastering CDs to be “loud”. When you look at them in an audio editor, brickwalled CDs have far less peaks and valleys. I think the encoder has a much easier time since all it sees is a wall of “garbage”. Try importing a recent CD, and then a CD made in the ’80s. I think the difference will be very noticeable.

    • Sorry, that doesn’t make sense. A CD contains a series of 0s and 1s; no matter how loud the music is, it’s still just 0s and 1s. Because it’s louder doesn’t mean it has 2s on it.

      And, if anything, CDs from the 80s have aged a lot, and may be harder to rip.

  2. I think you’re on the right track when you say the discs are harder to read. I have imported several thousand CDs into iTunes. I believe it has something to do with the current trend of mastering CDs to be “loud”. When you look at them in an audio editor, brickwalled CDs have far less peaks and valleys. I think the encoder has a much easier time since all it sees is a wall of “garbage”. Try importing a recent CD, and then a CD made in the ’80s. I think the difference will be very noticeable.

    • Sorry, that doesn’t make sense. A CD contains a series of 0s and 1s; no matter how loud the music is, it’s still just 0s and 1s. Because it’s louder doesn’t mean it has 2s on it.

      And, if anything, CDs from the 80s have aged a lot, and may be harder to rip.

  3. On the subject of Mac Blu-Ray drives, I’m considering the purchase of the MCE Tech one you mention here: http://www.macworld.com/article/2042431/watch-and-rip-blu-ray-movies-on-your-mac.html

    In that article, you describe your thoughts on the bundled software, but don’t really discuss the hardware. Is it of reasonable quality? Solid construction? Reviews of this piece of equipment are almost nonexistent (to the point that, if it weren’t for your article, I might think it was a scam), so I’d appreciate any impressions you recall.

    • It was my editor who added that specific drive; I don’t have it, so I can’t comment. I’m currently using this Pioneer drive, after an older Plextor drive that I had for more than five years died.

  4. On the subject of Mac Blu-Ray drives, I’m considering the purchase of the MCE Tech one you mention here: http://www.macworld.com/article/2042431/watch-and-rip-blu-ray-movies-on-your-mac.html

    In that article, you describe your thoughts on the bundled software, but don’t really discuss the hardware. Is it of reasonable quality? Solid construction? Reviews of this piece of equipment are almost nonexistent (to the point that, if it weren’t for your article, I might think it was a scam), so I’d appreciate any impressions you recall.

    • It was my editor who added that specific drive; I don’t have it, so I can’t comment. I’m currently using this Pioneer drive, after an older Plextor drive that I had for more than five years died.

  5. Hm. I smell paid endorsement. It was on your recommendation that I was considering it. Now that I know you *didn’t* recommend it, I’m rethinking my decision.

    Is the Pioneer compatible with iDVD, etc?

    • I don’t think it was a paid endorsement. The drive i was using at the time was fairly old, so my editor suggested mentioning something more tecent. iDVD? No idea, that’s so old now that i dont know if anyone claims to supportt it.

  6. Hm. I smell paid endorsement. It was on your recommendation that I was considering it. Now that I know you *didn’t* recommend it, I’m rethinking my decision.

    Is the Pioneer compatible with iDVD, etc?

    • I don’t think it was a paid endorsement. The drive i was using at the time was fairly old, so my editor suggested mentioning something more tecent. iDVD? No idea, that’s so old now that i dont know if anyone claims to supportt it.

  7. You show importing with AAC Encoder and iTunes Plus. I have Apple Lossless and Automatic. Am I using the wrong settings?

    • No, if you want to rip in lossless, that’s your choice. I don’t; with all the CDs I have, I would run out of disk space too soon.

  8. You show importing with AAC Encoder and iTunes Plus. I have Apple Lossless and Automatic. Am I using the wrong settings?

    • No, if you want to rip in lossless, that’s your choice. I don’t; with all the CDs I have, I would run out of disk space too soon.

  9. I may be off on this, but I believe CDs spin at variable speed depending on the location of the playhead. The 1s & 0s are spaced out consistently, so the CD spins slower as the playhead moves out. Unlike a record player, which goes from outside in, but plays at a constant 33.3 rpm, so at the beginning of the record it’s higher quality because there’s more tracks space being used for the same amount of time. Wikipedia appears to back this up: “equivalent to approximately 500 RPM at the inside of the disc, and approximately 200 RPM at the outside edge” and it’s visibly noticeable on a portable CD player that has a window in the lid.

  10. I may be off on this, but I believe CDs spin at variable speed depending on the location of the playhead. The 1s & 0s are spaced out consistently, so the CD spins slower as the playhead moves out. Unlike a record player, which goes from outside in, but plays at a constant 33.3 rpm, so at the beginning of the record it’s higher quality because there’s more tracks space being used for the same amount of time. Wikipedia appears to back this up: “equivalent to approximately 500 RPM at the inside of the disc, and approximately 200 RPM at the outside edge” and it’s visibly noticeable on a portable CD player that has a window in the lid.

  11. I know, old thread. But I have a little input on the rip speed.
    Commercial discs are stamped and the stampers vary a little from each other.
    Then there is the aluminum reflective backing which varies significantly in thickness.
    Lastly there is the dreaded sound degrading copy right protection.
    Any one of these will cause more compute cycles to compensate for errors.
    More of these problems will likely cause even more slow down.
    So it’s not any one thing so much as a combination of things.

  12. I know, old thread. But I have a little input on the rip speed.
    Commercial discs are stamped and the stampers vary a little from each other.
    Then there is the aluminum reflective backing which varies significantly in thickness.
    Lastly there is the dreaded sound degrading copy right protection.
    Any one of these will cause more compute cycles to compensate for errors.
    More of these problems will likely cause even more slow down.
    So it’s not any one thing so much as a combination of things.

  13. I think the answer to this question is that if there is any inconsistency to the disk (slightly warped or slightly off centered) the laser has to move slightly to track the CD. The more the CD is imperfect, probably the more it has to move and it probably can’t keep up with the high speed. This is also why some CDs vibrate when being ripped.

  14. I think the answer to this question is that if there is any inconsistency to the disk (slightly warped or slightly off centered) the laser has to move slightly to track the CD. The more the CD is imperfect, probably the more it has to move and it probably can’t keep up with the high speed. This is also why some CDs vibrate when being ripped.

  15. Some Compact Disc use copy protection, thus slowing the ripping process by adding unnecessary read errors in the ripping copying process slowing it down significantly.

  16. Some Compact Disc use copy protection, thus slowing the ripping process by adding unnecessary read errors in the ripping copying process slowing it down significantly.

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