CD audio vs. WAV/AIFF - problem extractiong audio - Long post

Discussion in 'Pro Audio' started by Tom Jancauskas, Sep 6, 2005.

  1. Hi all

    Bear with me. This is a long post...

    I had something very interesting happen today. I had a last minute call from
    a new client needing help with a compilation product for release.

    This person gets permission from old bands from the 60's and re-releases
    them in short replicated runs for collectors.

    He gets the songs from many different sources: people and formats. As he
    says he doen't get the original masters, but audio CD's. Most of the time
    they are ready for release. Sometimes he has to add a few bonus tracks to
    the product so a new CD master has to be created.

    Anyway, accordinng to him, any copy of the CD's that are made from his
    masters don't sound the same to him as his main discs that the songs were
    taken from. He says he hears a loss of detail and air around the recording
    in the copies.

    The master he was sent is what he wants and sounds good to him but,
    according to him, any copies made of this disc sound wrong. He says both
    the direct copy as well as an audio extraction sound different to him and
    can pick out the different versions.

    So, I had him bring over the discs that he had. He had the original audio
    CD-R master, extracted AIFF files saved on a CD-ROM, as well as the bonus
    tracks that need to be added the the final product in AIFF format.

    I proceeded to extract the audio using Samplitude Pro 8.2 CD extractor. I
    made him a CD and he sat there with headphones and switched CD's back &
    forth in the player & said the copy doesn't sound the same.

    Then I imported the AIFF files into the timeline and lined them up with the
    extraction files to A/B them. There was a SLIGHT difference - yes, the AIFF
    sounded "better" than the extraction - but my GOD he was being picky! My
    monitoring and room are good so I know what I can trust hearing here.

    Anyway, I made him an audio CD of the AIFF files and he compared all 3 disks
    - the original, the extracted copy, and the AIFF disc. He compared again and
    said all 3 sounded different!!

    What he is trying to do is eliminate the change he is getting while trying
    to copy the disc so it sounds like the master.

    I am suspect of the original files as he didn't do the transfer, and doesn't
    know what was used to do the transfer, and how the files were treated before
    he got them. He did say someone had done some noise reduction especially on
    the vinyl transfers.

    I did see that the waveform of all of the files was VERY flat, giving me the
    impression that the files were heavily compressed or normalized. Started
    life as an mp3 maybe?

    The actual audio level was quite low though - strange.

    Anyway, anybody have any ideas on what might be going on?

    Thanks!
     
    Tom Jancauskas, Sep 6, 2005
    #1
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  2. Tom Jancauskas

    Geoff@work Guest

    What drive is being used for the extraction ? You are sure they are being
    ripped, not recorded from analogue or SPDIF, or course.... How do other
    rippers work - EAC, etc.

    How is he comparing the files - presumably all thru the same DA/CD player.
    What is different - different media ? (= different error rate and different
    degrees of error correction.) The CD copies will of course be one 'write
    and read' cycle older that the master, with accumulated errors in both
    directions, but I've never managed to hear a difference, except of flawed
    media.

    Being more devious, how about getting two files, one a copy of the other ,
    label them differently and see if he hears a difference in those.

    And if they may have once been MP3's what 'detail and air' anyway ?

    geoff
     
    Geoff@work, Sep 6, 2005
    #2
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  3. His AIFF files were extracted using an iMac internal drive using Peak. My
    extraction was using a Lite-on 5232 IDE drive through a digital data
    connection from the reader to the hard drive. I didn't get a chance to try
    EAC.

    He was fighting me all the way in trying to figure this out. He wanted help,
    but didn't want to hear what I thought some of the problems might be, as
    well as the cures.

    The CD comparisons were through the same DA/CD player.

    He IS using different media than what the master was recorded on. I tried to
    bring this to his attention, but he had his mind made up that he was going
    to use the discs he had with him. I wanted to use a similar Dye formulation
    that was used on the master, but he wouldn't have it.

    He had his wife do a "blind test" and he could pick the original - so he
    says.

    Yeah, the MP3 thing has got me curious. What I can't figure out is why he
    doesn't find out how & what was done to create the master CD's that he likes
    in the first place.

    For me at this point, I want to make sure I am not missing something. I
    think this guy is going a bit overboard - but if there IS something that can
    be pinpointed, it would make his day.

    Thanks for the reply
     
    Tom Jancauskas, Sep 6, 2005
    #3
  4. [...]

    Can you make two further copies in AIFF, one from the master and one
    from the copy disc. Line them up precisely and invert the phase of one
    of them, then mono the result.

    With luck you will hear just the difference, if any.
     
    Adrian Tuddenham, Sep 6, 2005
    #4
  5. Tom Jancauskas

    Mike Rivers Guest

    If it's a bad enough CD player, you can unload and re-load the same CD
    and it will sound different to someone who really wants to be picky.
    And if it's a home-made (CD-R or worse, CD-RW) disk, there's even
    greater margin of difference. CDs may be digital, but they aren't
    perfect.

    Unless you can find something clearly wrong with what you're doing, I
    think your friend is being too picky.
     
    Mike Rivers, Sep 6, 2005
    #5
  6. Tom Jancauskas

    Arny Krueger Guest

    The well-knkown failings of sighted evaluations?

    It's pretty easy to do a technical test that will shed
    light.

    (1) Rip a track from the origional
    (2) Rip a track from a copy
    (3) compare the two .wav files using one of the standard
    utilities for comparing files. Good file comparison programs
    are built into the two leading ripping programs - CDEX or
    EAC.

    It's pretty easy to do a blind listening test that will shed
    light.

    (1) Rip a track from the origional
    (2) Rip a track from a copy
    (3) compare the two .wav files using one of the standard
    utilities for audibly comparing files under blind,
    time-synched conditions: www.pcabx.com .

    It might be possible that there's something wrong with his
    copying procedures that is adding a lot of data errors.
     
    Arny Krueger, Sep 6, 2005
    #6

  7. This is what I will try next. I'll post the results later today.

    Thanks,
     
    Tom Jancauskas, Sep 6, 2005
    #7

  8. The CD player I was using was a sony from about 9 or 10 years ago with VERY
    little use. He says he hears the same problems on his home system.

    I agree that CDs may be digital, but they aren't perfect.

    Geez, you get more loss of quality by making an analog copy of the CD to
    another CD than what he is hearing. Go figure...

    Thanks all. This seems to be one of those things that just is. He won't ever
    be happy and will be looking to find a difference in ALL of his projects.
    Lucky me.
     
    Tom Jancauskas, Sep 6, 2005
    #8

  9. Thank you for the info Arny. I am thinking is has to do with the original
    disks and how they were made.

    He couldn't tell me what was used to make the original transfer as well as
    what they did to the file before or after the fact. I'd like to know the
    path of production.

    I have had experiences recently with DVD-R burning (of original video tapes)
    that certain programs make a disc that is OK as a 1 off, but if you try to
    copy it, it comes out with all kinds of problems. Maybe this is related to
    what this guy is hearing.

    Oh well...
     
    Tom Jancauskas, Sep 6, 2005
    #9
  10. Tom Jancauskas

    Arny Krueger Guest

    Warning: some CD players have subtle problems playing CD-Rs.
    It's a very much a hit-or-miss proposition. So much so that
    good operation with other than CD players from the post-CDR
    period (last 3-5 years) can't be guaranteed.

    Or, he's cursed with two CD players that have subtle
    problems with CD-Rs.
    It could be psychological or it could be technical.
    At the media level, they are analog.
    Really good analog-analog copies can be made, but it takes
    really good equipment.
    The DBT and technical comparison approaches either find
    problems or satisfy a certain fairly large percentage of
    doubters. But 100% desired results are not guaranteed.

    Unfortunately, if the core problem is personal CD players
    that have subtle problems with CDRs, neither of the tests I
    suggested will be relevant. ;-(
     
    Arny Krueger, Sep 6, 2005
    #10
  11. Tom Jancauskas

    Scott Dorsey Guest

    Try loaning him a high-grade D/A to put between his CD player and his
    receiver. Ask if that eliminates the differences.

    Also check the error rates on the discs.
    Very lucky, if you charge by the hour. If he gives up on the whole thing
    and decides to issue LPs instead, let me know.
    --scott
     
    Scott Dorsey, Sep 6, 2005
    #11

  12. I understand that different CD players handle CD-R's differently. I started
    with the CD-R technology in 1996, and there were certain players that
    wouldn't play a CD-R disc AT ALL!

    I made the analog cd-cd transfer comment to illustrate the small change in
    sound he is hearing. I was giving the example with the idea that really good
    equipment was to be used.

    He asked me before he left, "how can I eliminate the problem in the future?"

    I told him "You can minimize it, but you may not elimiate the problem 100%
    if you are hearing things like this! All you can do to minimize it is by
    having control over the entire production chain of events, from getting the
    original masters (or as close as you can) and having the same company do the
    transfers, cleanup, and produce data files or audio disc for producttion."

    His answer to all that was "I can't do that." that's when I sent him on his
    way with the different versions of what we did.

    I don't think I'll hear from him again. This whole thread is to really see
    if anyone else has experienced anything like this recently and to maybe give
    him at least an understanding of what he might be hearing.

    Thanks all- to what may be just a long therapy session.
     
    Tom Jancauskas, Sep 6, 2005
    #12
  13. Thanks Scott. If he does release the LP's you are my first call.

    I am very curious as to WHERE he is getting his material from.

    I have approached the subject several times & he can't (or won't) give me an
    answer.
     
    Tom Jancauskas, Sep 6, 2005
    #13
  14. Tom Jancauskas

    Mike Rivers Guest

    I would expect a CD player of that vintage to be somehwat inconsistent
    when playing a CD-R. You probably should consider yourself lucky that
    they play at all.

    Give this client a dope slap, or give him to someone else who needs the
    money more than you do <g>
     
    Mike Rivers, Sep 6, 2005
    #14
  15. Tom Jancauskas

    Scott Dorsey Guest

    He may well not even know. He may be getting these things either from
    the label or under the counter from someone at the label. All you can do
    is shrug and ask for the master tapes which he probably can't get.

    Still, this is really the best kind of customer to have, if you are
    charging by the hour. You can spend an awful lot of time tracking
    something like this down, and usually these guys are very willing to
    pay for it.
    --scott
     
    Scott Dorsey, Sep 6, 2005
    #15
  16. that's OK. The guys seems to be getting the material from not too reliable
    sources as it turns out.

    I have just been told by the replication house that the files the client is
    using are from South Africa. These are AMERICAN 60's bands HMMM...

    I am not dealing with him anymore and won't take his business. Something
    semms amiss and I don't think I want to be involved.

    He isn't willing to get the master tapes either or pay to track all of this
    down.

    His answer to the question "is there any way you can get the masters?" It is
    a flat out no i can't. Not even a I can try...

    Thanks for all of the info though! I'll keep it in mind for future projects.

    I would love to have one of those long term projects that pays by the hour
    for tracking down all of the material. He isn't it unfortunatly...
     
    Tom Jancauskas, Sep 6, 2005
    #16
  17. Is Samplitude good at extracting audio from CD's? Does your CD drive read
    audio CD's properly? You need to know the answers to those questions
    before going any further.

    If you don't know then try using EAC - it will be slow but at least you'll
    know that you are getting the most accurate transfer possible with your
    hardware. If you are using a Plextor drive that supports the reading of C2
    error flags (most do) then Plextools will also extract CD audio accurately.

    Once you've accurately extracted the audio from both CD's then invert the
    polarity of one, paste it over the other and see if there is any signal
    remaining. If there isn't a perfect null then your client is right.

    Without knowing the results of the null test we can't really help much
    further.

    Cheers.

    James.
     
    James Perrett, Sep 7, 2005
    #17

  18. I have actually done the null test on the same song but 2 different files.
    One was the Samplitude extraction, and the other was an AIFF file he brought
    me. The null was total silence.

    Thanks,
     
    Tom Jancauskas, Sep 7, 2005
    #18
  19. Tom Jancauskas

    Geoff@work Guest


    *Total* silence (as in identical data) , or low level noise (= difference,
    even if very low) ?

    geoff
     
    Geoff@work, Sep 7, 2005
    #19
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