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Thread: Another AccurateRip/PefectTUNES question.

  1. #16

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    Re: Another AccurateRip/PefectTUNES question.

    OK. I just found something that throws a wrench into all of this. Back in the day before I was introduced to "lossless ripping" I would rip all my CDs as 192 AAC files with iTunes. I remember the first Wall CD I had. And I just found the 192 AAC rip of it. This was a direct 192 AAC rip from the CD. I just played it in isolation with iTunes and there was NO pop at the end of Comfortably Numb.

    Now my ALAC rip comes from this same exact CD. My other Wall copy I ripped as WAV (for whatever reason.) But as I have mentioned, the "pop" exists on this ALAC rip. (Keep in mind that the whole CD was verified as accurate. See original post for just Comfortably Numb stats.) Anyway, I just converted the ALAC file with the 'Pop" to 192 AAC and I am hearing the same pop! I don't understand. If my ALAC rip of this CD is supposed to be lossless, and is verified with a confidence of over 150, how is it that the 192 AAC rip directly from the CD has NO pop, yet the 192 AAC conversion from the ALAC has the pop?

    Please help! Thank you.

  2. #17
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    Re: Another AccurateRip/PefectTUNES question.

    Quote Originally Posted by mathmat View Post
    I don't think it's a problem with the digital files. My question is simply why the "pops" sound different. I just think that since the tracks are from the same remasters the pops should sound the same, since they're supposedly identical files. I say they are identical because of the AccurateRip dtata. That's all.

    I don't use VLC really. I think it sucks as a music player as well. I'm just saying that when I play on that program I get the "pop.' Same with iTunes and my iPod.
    You seem to be missing my point. The identical nature of files proved by accuraterip is irrelevant. The files are irrelevant. The *player* is creating the pops--not the files. With better players, THERE ARE NO POPS. You even have no pops when played under certain circumstances.

  3. #18

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    Re: Another AccurateRip/PefectTUNES question.

    Quote Originally Posted by garym View Post
    You seem to be missing my point. The identical nature of files proved by accuraterip is irrelevant. The files are irrelevant. The *player* is creating the pops--not the files. With better players, THERE ARE NO POPS. You even have no pops when played under certain circumstances.
    I do understand what you are saying and I greatly appreciate all your input. Please keep it coming! :smile:

    My point is simply if you have 2 identical files played under identical conditions, shouldn't they sound identical? I believe the answer to that should be "yes." But when I do play the identical files under identical conditions I get 2 different sounding pops. I think that if there is a "pop" that a specific player is causing, it should sound the same for identical files. But it's not. That's confusing me. Maybe I'm missing something here, as I am new to all this, but commom sense seems to suggest what I just said should be the case.

    Also my post *16 above seems to confuse things more.

  4. #19
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    Re: Another AccurateRip/PefectTUNES question.

    Quote Originally Posted by mathmat View Post
    I do understand what you are saying and I greatly appreciate all your input. Please keep it coming! :smile:

    My point is simply if you have 2 identical files played under identical conditions, shouldn't they sound identical? I believe the answer to that should be "yes." But when I do play the identical files under identical conditions I get 2 different sounding pops. I think that if there is a "pop" that a specific player is causing, it should sound the same for identical files. But it's not. That's confusing me. Maybe I'm missing something here, as I am new to all this, but commom sense seems to suggest what I just said should be the case.

    Also my post *16 above seems to confuse things more.
    pops can be random with the player. To confirm, if you just let the album play through you have no pops between songs. Correct?

  5. #20

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    Re: Another AccurateRip/PefectTUNES question.

    Quote Originally Posted by garym View Post
    pops can be random with the player. To confirm, if you just let the album play through you have no pops between songs. Correct?
    The pops for Rip1 sound identical for both iTunes and VLC every time I've played them. And I've played them too many times now. lol. Same for Rip2. But yes, if the album plays through I hear nothing out of the ordinary, and I like to think I'm pretty good at picking up anomalies. lol.

    Is it possible that the reason that WAV+Windows Media Player produces no pops be that WMP is somehow stopping the track a few fractions of a second earlier?

    Also I just did another experiment. I burned one of the Comfortably Numb tracks to a CD by itself, then played it in my car CD player. I did hear something as the song ended that sounded similar to the pop I was hearing. I don't know if that's normal, as I don't ever use the CD player. I will burn another song to another CD and see if I hear the same sound when the song ends.

    Anyway garym, I was hoping you could give some feedback for my post *16. Thanks!
    Last edited by mathmat; 12-18-2014 at 10:41 PM.

  6. #21
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    Re: Another AccurateRip/PefectTUNES question.

    No clue about post 16. At this point I would rerip cd with dbpa and try playing the new rips.

  7. #22

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    Re: Another AccurateRip/PefectTUNES question.

    Quote Originally Posted by garym View Post
    No clue about post 16. At this point I would rerip cd with dbpa and try playing the new rips.
    Unfortunately I don't have access to the CDs so I can't do a re-rip. I can see if I can somehow track down some Wall CDs. But the fact that they all came back as Accurately ripped should be reason enough that no further rips are necessary, correct?

    Also regarding post 16, I did rip the original 192 AAC with a much earlier version of iTunes than my ALAC rip so maybe it somehow chopped off the end? I'm guessing it could be the ripping software. I don't know...
    Last edited by mathmat; 12-18-2014 at 10:48 PM.

  8. #23
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    Re: Another AccurateRip/PefectTUNES question.

    Quote Originally Posted by mathmat View Post
    Unfortunately I don't have access to the CDs so I can't do a re-rip. I can see if I can somehow track down some Wall CDs. But the fact that they all came back as Accurately ripped should be reason enough that no further rips are necessary, correct?

    Also regarding post 16, I did rip the original 192 AAC with a much earlier version of iTunes than my ALAC rip so maybe it somehow chopped off the end? I'm guessing it could be the ripping software. I don't know...
    Itunes doesn't necesarily do secure rips. But I can't really think of anything else to add to this inquiry.

  9. #24

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    Re: Another AccurateRip/PefectTUNES question.

    Quote Originally Posted by garym View Post
    Itunes doesn't necesarily do secure rips. But I can't really think of anything else to add to this inquiry.
    But if an iTunes rip comes back as Accurate when tested against AccurateRip, that means the rip is identical to the CD, right? So at that point it doesn't matter what ripper was used. (Of course that doesn't explain the original 192 AAC rip.)

    I have a theory as to what is happening here, but I'm in the process of doing some more experiments first. Also it depends on my understanding of exactly how AccurateRip compares a rip to its database, which I'm hoping is correct, at least on a basic level. I will report back as soon as I get my thoughts together and my experiments done. I hope to have it by tomorrow. If not it will be after the weekend most likely.

    Anyway, thank you again, garym, for responding to me and giving me stuff to ponder. I really appreciate your time and effort a lot. :smile:

  10. #25
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    Re: Another AccurateRip/PefectTUNES question.

    If you use PerfectTUNES to check the files and one is verified as Accurate then yes it is identical to the CD.

  11. #26

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    Re: Another AccurateRip/PefectTUNES question.

    Ok. I think I have figured out what was happening with my "pop" problem. Mind you, this is all speculation so if Spoon, garym, or anyone else can point out any errors in my analysis that would be tremendously welcome! I apologize in advance for the long post.

    So to reiterate, the problem I'm having is I have 2 lossless rips of The Wall from 2 different physical discs. Now at the VERY end of the Comfortably Numb track (track 6 on CD2) I was hearing some sort of "pop" sound from both rips of the track when I played them in isolation. But these "pops" sounded different for each rip, even though they occurred at the exact spot on the track, that is at the very end as the track stopped playing. But everytime I played Rip1 the "pop" sounded the same and everytime I played Rip2 the "pop" sounded the same. But the 2 "pops" sounded different from each other. (This was with both VLC and iTunes.) Just to note these "pops" occur within the last few hundreths of a second at the end of the track

    When I checked the 2 CD Rips (Rip1 and Rip2) against AccurateRip using PerfectTUNES I got identical results. Accurately Ripped with identical CRCs, confidence level, and Disc Ids. I know both CDs are the same 1992 remaster so the Accurate Rip results were not surprising.

    But what confused me was why, if the 2 Comfortably Numb rips were different due to the different sounding "pops," did the AccurateRip results come back as verified accurate with identical data. It seemd to me that if the files were different (and they are because the pops are different &*8211; they are clearly NOT bit-for-bit copies of each other) then at least one of the Comfortably Numb tracks should come back as InAccurate. That just seems to be common sense. (As an aside, if you have a 1000 page word document and you change just 1 period to a comma the 2 word documents are no longer bit for bit identical. They will have different checksums.)

    Now I thought that maybe it was the players I was using that were causing these pops. But I don't believe it's the players anymore. I believe the "pops" to be inherent to the Cds.

    I decided to go on a "treasure hunt" and scoured the local library system to see if I could track down any copies of The Wall, since mine are inaccessible. And I luckily found 2 identical CD copies!

    So I played the Cds (not rips and specifically Comfortably Numb) with iTunes and VLC and Comfortably Numb on BOTH Cds on BOTH players gave me the Identical sounding "pop" in the identical place. Itunes and VLC may not be the favorite music players of some, but my results here make me confident that the "pops' are inherent in the Cds. I mentioned that when I played my original 2 rips of Comfortably Numb as WAV files using Windows Media Player, I heard no "pops." I now believe that is because WMP cuts a track slightly short when it plays it. The VLC and iTunes results just seemed too coincidental to be the player.

    Now the question is what is the cause of the "pops?" Spoon suggested it could be a bad master, and BOTH my original Cds that I ripped are the same 1992 remaster (although different releases.) That's definitely a possibility. The other possibility is that the "pops" are the beginning of the next song (Track 7, The Show Must Go On.) I tend to think it's the beginning of the next song, as Pink Floyd albums usually do not have breaks between songs, as they are intended to be listened to as a whole. If you listen to the 2011 remaster of The Wall, specifcally Comfortably Numb with the volume up and with headphones, you will hear at the first fraction of a second the end of the previous song, Bring the Boys Back Home. The fact that there is a smooth transition from Comfortably Numb to the next track (no "pop") further makes me think the "pop" is the beginning of the next song.

    Now I also mentioned in a previous post that I had ripped Comfortably Numb as 192 AAC from the same CD that produced Rip1. But this compressed file did NOT have the "pop" at the end. I did a closer inspection and noticed that the file length of this track was approximately 3/100ths of a second SHORTER that the lossless rips. So it seems iTunes cut those fractions of a second off, hence resulting in NO "pop." Now the length of the lossless rips is 6:23.066. I tried converting the file to 192 AAC but the time came back as 6:23.066, and hence the "pop" was still there. So I decided to adjust the lossless file to an ending time of 6:23.033 and NO "pop." This was very encouraging and explained a lot. The reason the ALAC to 192 AAC came back with the same time (and pop) but the CD to 192 AAC I did many years ago came back as 6:23.033 I attribute to an earlier version of iTunes where the compresssion wasn't as good as today's version of iTunes.

    But I was still left wondering why 2 different files (that is, the 2 rips of Comfortably Numb with DIFFERENT pops would both come back as Accurately Ripped with Identical CRCs, confidence, etc. So I tried to figure out how AccurateRip was checking rips against its database. I believe I saw a post by Spoon somewhere talking about how the MUSICAL data was compared, not metadata or anything else. So that got me thinking. How do you compare 2 digital files to see if they are identical? (Which is EXACTLY what AccurateRip is doing.) The only way I know, and again I am no expert at this stuff, would be through some sort of checksum process. It's certainly some bit for bit analysis.

    Now for those who remember, Comfortably Numb was originally issued on LP as the last track on side 3. That means there would be silence after the track. And my "pops" occur after about 1-2 seconds of silence at the end of the tracks. I'm GUESSING what AccurateRip is doing (and this is a VERY simplified non-technical description) is taking a track, finding the first bit of sound, going through the rest of the track until it reaches a point of silence. And silence is, after all, by definition, the ABSENCE of muscial information. So once AccurateRip sees that silence on my 2 rips of Comfortably Numb it stops, performs some type of bit for bit comparison with its database on the data it's already analyzed, checks it against other rips, and reports Accurate or InAccurate. That would be the only way to explain why the 2 Comfortably Numb tracks (which are NOT identical due to the different sounding "pops") came back with the same exact AccurateRip results. (Please, Spoon, correct me if I'm wrong. Again, I'm sure this is not exactly how it works, but I'm guessing the basic idea is the same.)

    In conclusion, I never doubted AccurateRips results but I couldn't explain why 2 different files both came back as Accurate. Luckily after checking 2 library Cds and getting the results I was hoping to with them, I am fairly confident that my analysis is correct. I may be WAY off, but I can't come up with any other explanation.

    One final note. I mentioned the "pops" sounded different for each rip, but they were consistent with whichever player I used. I now think my first rip, with the louder sounding "pop" was an error in ripping. (That's the only explanation. The ripper somehow made the "pop" louder.) But as I reasoned above, since it occurred after 1-2 seconds of silence, AccurateRip ignored it and hence reported the track as Accurate. I believe there are certain CD rippers that allow you to add silence at the beginning or end of a track, or to move silence from the end to the beginning, or vice versa. I am convinced that if I ripped the same CD and added silence to the beginnning of the tracks on one rip, then added silence to the ends of the tracks on a second rip, both would be verified as Accurate, and come back with identical CRCs as well as confidence levels, disc id, etc.

    Sorry for the novel, but as you can see I'm quite passionate about this stuff. Lol.

    Any feedback is greatly appreciated!

    Thanks again.

  12. #27
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    Re: Another AccurateRip/PefectTUNES question.

    Your explanation is plausible. Particularly because I recall (but I'm not 100% sure), that the first few or last few "frames" of a CD are not counted when checking against AR database. I could be wrong about this. And the fact that you don't here the pop when you let the track play naturally from one song to the next supports your hypothesis (and confirms that this pop is not inherent in the rip itself).

  13. #28
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    Re: Another AccurateRip/PefectTUNES question.

    FYI, I have ripped both the 1994 UK Remaster and the 2011 Discovery Remaster of Pink Floyd - The Wall, AccurateRip reports tracks ripped accurately.

    I have listened to the Comfortably Numb/The Show Must Go On transitions on both rips in foobar2000 and there are no pops.

  14. #29
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    Re: Another AccurateRip/PefectTUNES question.

    I have the discovery box set 2011 remaster. I don't here any pops before or after comfortably numb transition in foobar2000 or in LMS/Squeezeboxes. Then again, I can often hear a pop on beginning of ANY song in Squeezebox if I simply click to start an otherwise gapless album song without letting it naturally transition from the prior song. This "pop" is very "discrete" and is certainly not embedded in the file itself.

  15. #30

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    Re: Another AccurateRip/PefectTUNES question.

    Hi garym. Thanks for replying. I was worried the length of my post would scare people off. lol.

    I just got the 2011 remaster (verified accurate) and NO popping when I played the track in isolation in iTunes, VLC, or my iPod. I think this problem is strictly for the 1992 remaster. But the thing with the 2011 remaster is if you put on headphones and turn the volume up high and play the track, the first maybe 3/100ths of a second are actually the end of the previous song! (Bring the Boys Back Home.) Listen carefully and you'll hear it. If it's not a problem at the end of the track, it's a problem at the beginning. lol. (Although in this case it's really not a "problem.")

    I racked my brain trying to figure out what those "pops" were and why I got the AccurateRip results I did and that's all I could come up with. I just wish I knew what the "pops" actually were. The fact that the 2 identical copies I managed to get from the library both gave identical results, which were identical with my original Rip2 that I did way back when, made me stop worrying (for the most part. lol.)

    I'm fairly convinced my Rip1 is a ripping error at the very end, but I explained my reasons in my novel length post for why I think it came back as Accurately Ripped.

    Basically at this point I have 2 hypotheses. The "pop" is either a "glitch" in the mastering process (as Spoon suggested it could be) or the first few hundreths of a second of the next song. To summarize what I think are the possibilities:

    Rip1: a) "Glitch" in mastering with a possible ripping errror, or
    b) Beginning of next song with a definite ripping error

    Rip2: a) "Glitch" in mastering with NO ripping error (due to the 2 CDs that produced identical results), or
    b) Beginning of next track with NO ripping error.

    I think at this point I'm going to "retire" my Rip1 of The Wall and either go with my Rip2 or the new 2011 remaster. (I'm leaning towards the 2011 remaster.)

    As long as my analysis of how AccurateRip checks rips is correct (or at least along my line reasoning), and the fact that the 2 library CDs gave identical results, I'm certain of the possibilities above and fairly content with accepting them and willing to move on from this.

    If you have the 1992 remaster, try playing it in iTunes in a playlist by itself. I'd be curious what would happen.

    Also, to reply to mville, I get the same results as you when playing Comfortably Numb immediately followed by The Show Must Go On. It's only when Comfortably Numb is played in isolation, as if it were the last track of the album, that the "pop" occurs. (These are the US 1992 remasters. As I mentioned the 2011 remaster does NOT have this issue.)

    One last point. I did an "experiment" where I "snipped" the last 3/100ths of a second off the end of Comfortably Numb so I still had silence at the end of the track, but NO "pop." I then checked AccurateRip using this new version and I got an error saying the track length was too short. I thought that interesting. It implies that AccurateRip actually checks the ENTIRE length of the track to identify the CD, but I still think it VERIFIES using only musical data, and not silence.

    (Actually, as I'm writing this I just had an insight. When I snipped the end of the track (about 3/100ths of a second) I got no "pop." Regardless of any player I used. This reinforces my belief that the "pop" is either a mastering "glitch" or the beginning of the next song.)

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