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Thread: Still confused about offsets

  1. #1

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    Still confused about offsets

    Hi all,

    I have been trying to get to the bottom of this particular issue for a while. I appreciate everyone's help thus far, but I am still confused. If my drive's read offset is +6, then I know it is very minor and not typically audible. However, that is only for CDs on which there are large enough gaps between tracks. On gapless albums, or albums that do not separate tracks with silence, the offset of samples is noticeable. Take for instance Enya's "A Day Without Rain" CD. Track 5 begins gapless from track 4 and an audible pop is heard. Hear the snippet below. Also, the second snippet is from Madonna's "American Life" album, which I think is an example of a strange mastering job as parts of the last 5 tracks are clearly audible at the end of each, giving me the impression that my read offset is only partially to blame.

    https://drive.google.com/open?id=1Go...tG0atHAYLzhnTs

    https://drive.google.com/open?id=1Zn...ZWsQw-N6qp4oak

    These discrepancies are not heard when I test the songs out with a Spotify listen. I assume this is because the files on Spotify come from the original masters and there is no offset to be applied as the music is just being played back from a server. I know some can excuse the offset samples but I find them to be frustrating. I want to create a mirror image of what I hear on a CD. I know that an option for adjusting the samples is to use Audacity to edit the files, but that is a tedious process that involves finding out which tracks have discrepancies and then making individual edits. I have looked into using CueTools as a way to "fix offset" as it describes, but that is proving to be complicated. I know that different pressings of CDs can result in differing track times, which further complicates things because it begs the question; are the discrepancies caused by my read offset or are the discs pressed or mastered in a strange way? I'm not confident that such a large number of gapless or no-silence albums are poorly pressed/mastered.

    I appreciate any advice anyone may have with this.

  2. #2
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    Re: Still confused about offsets

    >Track 5 begins gapless from track 4 and an audible pop is heard

    This just means your player is not gapless, any ripper ripping with any offset would rip gaplessly between tracks 4 and 5, because the offset is just a offset for the whole disc at the start. For example if you set the offset to -10000 a huge number, then track 4 would end early and track 5 would take over at that exact point, it would not matter if your player is gapless as it would sound as one continuous audio.

  3. #3

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    Re: Still confused about offsets

    I see what you mean. I should clarify that the audible pop is heard only when isolating track 5 and not playing it as part of the sequential album. This happens with other albums that are structured in a similar way. With respect to the Enya example, if I am playing the music with a shuffle feature enabled, the pop from track 4 that bleeds into track 5 is especially noticeable if track 5 begins after a track from another album ends with silence.

    Another issue with using Audacity is that it introduces complications with dithering and I want to keep any edited files bit-for-bit when compared with my original rips.
    Last edited by joeyc410; 03-26-2020 at 10:18 AM.

  4. #4
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    Re: Still confused about offsets

    A gapless album will always have pop if playing one of the tracks in the middle because there is no silence between the tracks.

  5. #5

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    Re: Still confused about offsets

    Quote Originally Posted by Spoon View Post
    A gapless album will always have pop if playing one of the tracks in the middle because there is no silence between the tracks.
    That makes sense. However, what can I do about albums that arenít gapless? If an album plays without a pop on Spotify, then why does it have a pop if played from a CD rip? The only explanation I can think of is because of the offset, or there is variation in how the album is pressed to a physical medium. Either way, is there nothing I can do to edit the files without damaging or altering their bits?

  6. #6
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    Re: Still confused about offsets

    Albums which are not gapless tend to have silence at the start and end, very few do not.

    All your tracks have a pop at the start?

  7. #7

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    Re: Still confused about offsets

    Not all albums, just certain ones. It happens with specific tracks, usually ones that end abruptly without any seamless transitions or silence.

  8. #8
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    Re: Still confused about offsets

    Maybe I missed it, but what codec are you ripping the files to (FLAC, mp3, m4a, ALAC, WAV, or ???). And what player are you using. Many years ago I had a "pop" problem with m4a files on a squeezebox Boom player.

  9. #9

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    Re: Still confused about offsets

    I rip to AIFF and play music on my iPhone XS. The pops are heard when playing the music on my computer as well. The pops vary in severity. It has to do with how much of a previous track is extending into a new one.

  10. #10
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    Re: Still confused about offsets

    Off hand I can think of three causes of pops or clicks at the beginning (or end) of your music tracks. All of them involve the player not the actual rip. Two of them result in what are sometimes called "Fourier clicks or pops". More on that shortly. The third one is if the player is stupid and tries to play the tag data as audio.

    Now back to the first two. For a deep understanding of this you need to understand Fourier's Theorem and what it tells you about what you hear. But I'll try to explain in simple terms. Basically, if there is a sudden change in amplitude in a short period of time, the theorem says that there is significant high frequency content present at the instant of the change in amplitude. You may hear that as a click at that moment. And if there is an edit from silence to audio at a moment where the instantaneous voltage of the audio is not zero (called a zero crossing) or worse still, there is DC offset with the audio (The AC voltage of the audio is riding on a DC voltage, usually due to a circuit defect), you will usually hear a pop or click at that point. Most good audio editors give the option of making the actual edit point at a zero crossing near the point you chose to reduce the audibility of Fourier clicks or pops. But it could be unselected or not available in your editor. Note that you still may get an audible click on an edit at a zero crossing, but it usually is much less audible.

    Now why you don't hear it on a CD. Because most if not all CD players actually fade the audio in when you hit "play". The click happens before the audio is turned up. That is why most CD tracks that aren't "gapless" between tracks are made with nothing of consequence (like the first note) in the first fraction of a second. If the music started hard at the cue point, the first note would be "upcut".

    While most CD players may fade into the track (but only the track where you start it, not the later tracks when you play the whole CD), apparently some digital file players don't fade in, and digital editors shouldn't fade in, as you want to hear everything from the play point. So you hear the pops.

    In addition to having silence at the start, most audio tracks are edited with a brief fade at the beginning, specifically so they won't have a pop. But you don't want to do that with tracks that play without a break. like live concerts, because then they would have a brief dropout between tracks. That is why it has to be the player that fades in when you press Play, not the ripped track.

    Sorry, this is all physics and math.

    Actually, there is another thing I've seen on poorly produced CDs, usually homemade CDRs. And this applies to individual tracks, not "concert" albums. I've run into some where the index point for the beginning of the track is mis-located, so the end of track 1 actually plays at the beginning of track 2 or the other way around. That's the fault of the CD manufacturer. Because the CD player fades in, you might not hear it when playing the CD, but if you rip the CD and look at the waveform on an editor, it is very visible.

  11. #11

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    Re: Still confused about offsets

    Quote Originally Posted by schmidj View Post
    Off hand I can think of three causes of pops or clicks at the beginning (or end) of your music tracks. All of them involve the player not the actual rip. Two of them result in what are sometimes called "Fourier clicks or pops". More on that shortly. The third one is if the player is stupid and tries to play the tag data as audio.

    Now back to the first two. For a deep understanding of this you need to understand Fourier's Theorem and what it tells you about what you hear. But I'll try to explain in simple terms. Basically, if there is a sudden change in amplitude in a short period of time, the theorem says that there is significant high frequency content present at the instant of the change in amplitude. You may hear that as a click at that moment. And if there is an edit from silence to audio at a moment where the instantaneous voltage of the audio is not zero (called a zero crossing) or worse still, there is DC offset with the audio (The AC voltage of the audio is riding on a DC voltage, usually due to a circuit defect), you will usually hear a pop or click at that point. Most good audio editors give the option of making the actual edit point at a zero crossing near the point you chose to reduce the audibility of Fourier clicks or pops. But it could be unselected or not available in your editor. Note that you still may get an audible click on an edit at a zero crossing, but it usually is much less audible.

    Now why you don't hear it on a CD. Because most if not all CD players actually fade the audio in when you hit "play". The click happens before the audio is turned up. That is why most CD tracks that aren't "gapless" between tracks are made with nothing of consequence (like the first note) in the first fraction of a second. If the music started hard at the cue point, the first note would be "upcut".

    While most CD players may fade into the track (but only the track where you start it, not the later tracks when you play the whole CD), apparently some digital file players don't fade in, and digital editors shouldn't fade in, as you want to hear everything from the play point. So you hear the pops.

    In addition to having silence at the start, most audio tracks are edited with a brief fade at the beginning, specifically so they won't have a pop. But you don't want to do that with tracks that play without a break. like live concerts, because then they would have a brief dropout between tracks. That is why it has to be the player that fades in when you press Play, not the ripped track.

    Sorry, this is all physics and math.

    Actually, there is another thing I've seen on poorly produced CDs, usually homemade CDRs. And this applies to individual tracks, not "concert" albums. I've run into some where the index point for the beginning of the track is mis-located, so the end of track 1 actually plays at the beginning of track 2 or the other way around. That's the fault of the CD manufacturer. Because the CD player fades in, you might not hear it when playing the CD, but if you rip the CD and look at the waveform on an editor, it is very visible.
    Thank you for this response. I have heard about the tagging issue as well as the fact that CD players use fading techniques to mask unwanted sounds. I have definitely encountered the issue of wrongly placed index points. I am beginning to think this a more common issue than I previously thought. The pressing of audio to discs is different than just providing albums as part of a streaming service. I'm thinking this relates to what I have read about there being variations in how music is pressed to CDs, which can cause tracks to start and begin at different places but be the same in terms of the data that comprises them.

  12. #12
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    Re: Still confused about offsets

    As a test rip to ALAC, then Play on phone? Still pops?

  13. #13

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    Re: Still confused about offsets

    Quote Originally Posted by garym View Post
    As a test rip to ALAC, then Play on phone? Still pops?
    Yes, I play the music on my phone or Mac. I must emphasize that the pops only take place if there is no silence between tracks. I'm gathering that this isn't supposed to happen, regardless of whether or not my read offset is +6 or -700 or any other number?

  14. #14
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    Re: Still confused about offsets

    Quote Originally Posted by joeyc410 View Post
    Yes, I play the music on my phone or Mac. I must emphasize that the pops only take place if there is no silence between tracks. I'm gathering that this isn't supposed to happen, regardless of whether or not my read offset is +6 or -700 or any other number?
    correct. Should NOT be any pops. And I very much doubt this has anything at all to do with offsets. I play music some on my iPhone and have no issues. Then again, I do NOT use aiff or ALAC.

  15. #15
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    Re: Still confused about offsets

    Quote Originally Posted by joeyc410 View Post
    Yes, I play the music on my phone or Mac. I must emphasize that the pops only take place if there is no silence between tracks.
    Please can you specify which software players you are using on the phone and the mac? Perhaps you can try different (gapless) player software?

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