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How to handle 'damaged' audio CDs

Discussion in 'Audio' started by tigre, Feb 8, 2004.

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  1. tigre

    tigre Moderator Staff Member

    Feb 18, 2003
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    How to rip copy protected audio CDs ...

    As this is a frequently asked question, I make this thread sticky and sum up information from other threads here. If you have to add something, feel free to do so.

    Basically there are 2 copy protection mechanisms for audio CDs:

    1. Manipulated table of content (TOC)
    Result: Software that uses the TOC to find content on a CD instead of scanning the CD (like native Windows, most software players), can't find the audio tracks or confuses them with data tracks.

    2. Manipulated error detection/recovery information
    Audio CDs contain 2 layers of error detection/recovery data (C1 + C2, comparable to redundant CRC checksums). If a CD is slightly damaged (-> light scratches), the audio data returned by the drive is still perfect as C1+C2 information is used to correct errors. On worse damages the original audio data can't be restored anymore, the drive still 'knows' which samples are wrong and tries to interpolate them to make the errors less audible. Generally standalone CD players are designed to do a better job on this than PC drives. Copy protections that introduce C1/C2 errors resulting in interpolation, intentionally try to do this in a way that standalone players' interpolation makes the errors inaudible, while PC drives fail, resulting in audible clicks/pops.

    How to extract audio from protected CDs:

    There are 2 ways:

    1. Using standalone equipment

    There are several ways depending on the available equimpent:
    - standalone CD player -> standalone recorder
    - standalone CD player -> digital connection -> soundcard -> PC recording/editing software
    - standalone CD player -> analog connection -> souncard -> PC recording/editing software

    2. Using PC equipment

    These are the steps that are important:

    2.0. Shift button
    When inserting a copy protected CD press the shift button to disable autostart. Otherwise you might get software you don't want.

    2.1. The Drive
    There are some combinations of drive and copy protection that will never work, no matter what software you use. Before getting desperate, try different drives and/or ask in formus like this about your drives. Trying different firmware versions *might* help in some cases.

    2.2. How to recognise the audio content on the CD
    To be able to extract audio data, you must use software that works arround the manipulated TOC. There are several possibilities. Remember: With some drives you will just have no luck, so you don't have to try every possibility with each drive. The following software has been reported to help against TOC manipulation:
    - A replacement for Win's native CD file system driver CDFS.VXD
    - AnyDVD
    - CloneCD (next step (ripping) integrated), probably other similar programs
    - Exact Audio Copy (EAC) (ripping integrated), Version 0.95 pre-beta3 and earlier
    - Audiograbber (ripping integrated)
    - Plextools (only with Plextor drives - ripping integrated)
    - Easy CD-DA (ripping integrated) - in some cases this software makes clicks caused by CDS disappear that are there with other software.
    - Nero Burning Rom (Direct copy to CD-R; details here: http://forums.afterdawn.com/thread_view.cfm/83180 )
    - There's a CD manipulation trick reffered to as post-it or marker trick to cover a 2nd session data track on the CD and make it unreadable (see links).

    2.3. The software used to read the audio data (and save them to HDD)
    - If one of the 1st two possibilities works, and the copy protection consists of TOC manipulation only, any audio extraction software can be used.
    - If creating an image with CloneCD (or similar software) worked, an image manipulation software like CDMage can be used to extract the audio from the image.
    - The 3 audio extraction programs mentioned at 2.2. have special options to handle manipulated TOC. With EAC it works like this:
    --- Get Exact audio copy 0.95 prebeta 3 from here: http://www.afterdawn.com/software/audio_software/cd-da_extractors/index2.cfm - in newer versions some TOC manipulation options have been removed.
    --- Install EAC using e.g. this guide: http://users.pandora.be/satcp/cd2mp3-en.htm
    --- EAC -> EAC options -> Tools -> 'Activate beginner mode...' disabled
    --- Action -> TOC alterations -> try different commands, e.g. 'Detect TOC manually', 'Retrieve native TOC'
    --- Trying both - Inserting the CD after EAC is started and vice versa - can help.

    2.4. What to do with CDs with altered error recovery data
    The signs for such a CD are these:
    - Even if following 2.0-2.3 resulted in successfully extracted audio files, these files contain audible errors like clicks, pops or gaps of silence.
    - Extraction is noticably slower than of ordinary CDs, especially in EAC secure mode, C2 activated (if drive supports it)
    To get better results this might help:
    - Lower extraction speed, if not accessible with the extraction software you use, with CDBremse or Nero Drivespeed
    - Try burst mode (EAC)
    - Try different drives
    - Extract with different drives, do a WAV comparison (EAC -> Tools) or a wave substraction using a wave editor. Due to different interpolation algorithms, you'll find positions with interpolated samples by this. Listen closely to these positions, if necessary use a wave editor's click/glitch removal (time consuming).
    - One of the methods using a standalone CD player might give better results.

    Related links:

    http://cd-rw.org/articles/archive/cactusdatashield.cfm (article by cd-rw.org about CDS)
    http://forums.afterdawn.com/thread_view.cfm/27915 (threads about copy protected CDs)
    http://forums.afterdawn.com/thread_view.cfm/34124 (Post-It/Marker trick)
    http://forums.afterdawn.com/thread_view.cfm/60316 (about EAC 0.95pb4 missing TOC features)

    _X_X_X_X_X_[small]AFTERDAWN FORUM RULES: http://forums.afterdawn.com/thread_view.cfm/2487[/small]
    Last edited: May 2, 2004
  2. tigre

    tigre Moderator Staff Member

    Feb 18, 2003
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