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Canít get same CRC when I burn/re-rip it. Due to absence of cue-sheet?, Was: Rip, Burn, Rip and CRC (TOS #6/unclear)
eahm
post Feb 11 2012, 19:29
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Hello again guys, I must ask another question again even though only few hours passed from my previous one.

I've did may simple test and none of them worked, I may know why it still not working but I need to hear from an expert.

Here's my problem:

Original CD Audio -> Rip to FLAC = Correct rip with AccurateRip. When I calculate the CRC/MD5 with dBpoweramp it gives me the same CRC for every lossless rip test I do with that very same track.

It seems though that I can't get the same CRC when I burn the track and re rip it. 1) Is my problem the absence of CUE files? 2) Does the track re rip correctly only if I burn it from the CUE file? 3) Is there a way to make a perfect burn without the CUE file? I've tried every possible burning software, burrrn, dBpoweramp, EAC etc.

Thank you again guys.
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psycho
post Feb 11 2012, 19:36
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Your problem comes from reading and more importantly writing offset of your optical drives. I'm very limited on time at the moment, so I can't provide more information ATM, but try googling for "set correct reading offset" and "set correct writing offset".


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eahm
post Feb 11 2012, 20:01
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I thought the CUE file was going to be the problem then I realized that they have only gaps information, then I was thinking about the writing speed etc.

Now that you said the offset all comes back from other ripping test I did before, I spent days learning about the reading offset and I had no idea there was another one to setup for writing.

Thank you, I will keep learning and testing and come back with more results.
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eahm
post Feb 11 2012, 20:20
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I am reading this guide http://blowfish.be/eac/Burn/burn.html#no4 and I can't find the same option on my EAC (1.0 Beta 3)...am I missing anything? http://i42.tinypic.com/212aj5l.png - http://i43.tinypic.com/2rpuyyo.png

I am going to test it anyway right now.

edit: this is good, I did the test and I am supposed to enter -6 (http://i42.tinypic.com/1411u9h.png) but I can't find where, if anyone can help here. Thanks again guys.

This post has been edited by eahm: Feb 11 2012, 20:45
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pdq
post Feb 11 2012, 20:55
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It would make more sense to compare the audio data using EAC. That will tell you if nearly all of the data match exactly, but one is longer than the other, or the data are offset, or if some of the values have been replaced with zero, etc.

This post has been edited by pdq: Feb 11 2012, 20:55
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eahm
post Feb 11 2012, 21:02
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What do you mean? That WAV Compare test I did is from EAC.

I just need to know where to enter the Write Offset (-6 in my case, if I am correct) on EAC 1.0 Beta 3.

This post has been edited by eahm: Feb 11 2012, 21:26
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pdq
post Feb 11 2012, 22:07
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Sorry, I only saw your mention of CRC and didn't know you had also done a WAV compare.

Did the data match but with an offset?
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eahm
post Feb 11 2012, 23:23
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Please look at the attached screenshots, there is no way/option to enter the write offset on this version of EAC.
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eahm
post Feb 12 2012, 04:55
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You've got to be kidding me. The write offset wasn't available because I selected beginner when I started EAC for the first time. It is available on expert mode.
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eahm
post Feb 12 2012, 06:53
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I did calculate the write offset and it supposed to be -6 but the CRC comparison after the rerip was different/bad. I give up until someone explains me few more things:

1) Does the writing speed influence the quality of the writing? I've read it does but how do I test all the speeds without throwing away 2000 CD-Rs? Are CD-RW good for tests and quality burning?

2) Once I set the write offset do I have to burn the full disc or just one song to rerip and test?

3) If one song is not enough (on question 2), does the CUE file make a difference when I burn the full album for the rerip's CRC?


Again, thanks guys.

This post has been edited by eahm: Feb 12 2012, 06:54
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pdq
post Feb 12 2012, 14:06
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You should really stop relying on CRC. If even a single bit is different the CRCs will be completely different, so this is no indication of how different they are.

I haven't used EAC in several years myself, but someone here will tell you how to compare the two WAV files to find out exactly how they differ and whether or not it matters.
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Bugs.Bunny
post Feb 12 2012, 15:05
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If you do want a bit exact copy you will need 2 things:
1) A drive that can read into lead-in/-out (eg. older Plextor drives)
2) A drive that has got a write offset of 0 (eg. many LG drives - I use a newer LG BD drive for exanple)
As far as I know there has never existed a drive that could read into lead-in/-out and had a write offset of 0. So you will need two different drives. One for reading and one for writing. Although drives that can read into lead-in/-out nowadays are probably harder to find.

I do use an older Plextor drive with accurate rip software for reading and EAC for writing.
If I re-rip a copy, the copy is 100% bit identical to the original rip.
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eahm
post Feb 12 2012, 19:36
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QUOTE (pdq @ Feb 12 2012, 06:06) *
You should really stop relying on CRC. If even a single bit is different the CRCs will be completely different, so this is no indication of how different they are.

I haven't used EAC in several years myself, but someone here will tell you how to compare the two WAV files to find out exactly how they differ and whether or not it matters.

Sorry, I don't accept anything less than perfect. I own two IT companies (support and mobile developing) and build big networks, if I think like that the connection goes down every day. In my opinion, no one is wrong it's just how I am, things must be 100% accurate, no excuses.

QUOTE (Bugs.Bunny @ Feb 12 2012, 07:05) *
If you do want a bit exact copy you will need 2 things:
1) A drive that can read into lead-in/-out (eg. older Plextor drives)
2) A drive that has got a write offset of 0 (eg. many LG drives - I use a newer LG BD drive for exanple)
As far as I know there has never existed a drive that could read into lead-in/-out and had a write offset of 0. So you will need two different drives. One for reading and one for writing. Although drives that can read into lead-in/-out nowadays are probably harder to find.

I do use an older Plextor drive with accurate rip software for reading and EAC for writing.
If I re-rip a copy, the copy is 100% bit identical to the original rip.

My Pioneer DVR-219LBK is perfect, I don't mind changing the Write Offset, I just need info about these three questions so I don't keep wasting CD-Rs for nothing smile.gif

Thanks for the info.

This post has been edited by eahm: Feb 12 2012, 20:01
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pdq
post Feb 13 2012, 05:09
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Your CRCs don't match. You don't know why your CRCs don't match. The CRC values are no help other than to tell you that they don't match. If you compared the wav data then you would know why your CRCs don't match and you could fix it.
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eahm
post Feb 13 2012, 06:59
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QUOTE (pdq @ Feb 12 2012, 21:09) *
Your CRCs don't match. You don't know why your CRCs don't match. The CRC values are no help other than to tell you that they don't match. If you compared the wav data then you would know why your CRCs don't match and you could fix it.

I did compare the WAV and saw the other message, then I did calculate the CD Write Offset... http://www.hydrogenaudio.org/forums/index....rt=#entry785756

...now I need to get answers about those three question before I keep testing and wasting more CD-Rs.

edit: do you mean comparing the WAV in any other way than with EAC?

This post has been edited by eahm: Feb 13 2012, 07:17
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pdq
post Feb 13 2012, 18:12
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Open EAC, click on Tools->Compare WAVs, select one version of the track, select the second version of the track, tell us what you see.
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JunkieXL
post Feb 13 2012, 19:07
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I have done the same thing you are testing. I was never able to get the resulting CRC's to match and I had the read and write offsets set up correctly. I even did a digital to digital rip using a virtual drive.

There are just far too many variables that can slightly offset the data to get an exact matching CRC/MD5 sum. I posted a similar thread several years back when I discovered this. The end result of said thread... don't worry about it. It's as close as it is going to get and any difference will be so minimal that you would not be able to know it anyways. Except said CRC/MD5 sum.
JXL
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eahm
post Feb 13 2012, 19:48
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QUOTE (pdq @ Feb 13 2012, 10:12) *
Open EAC, click on Tools->Compare WAVs, select one version of the track, select the second version of the track, tell us what you see.

Open Retail first then open CD-R = 6 missing samples. Enter -6 on CD Write Offset = the CRC is wrong when I rerip.

QUOTE (JunkieXL @ Feb 13 2012, 11:07) *
I have done the same thing you are testing. I was never able to get the resulting CRC's to match and I had the read and write offsets set up correctly. I even did a digital to digital rip using a virtual drive.

There are just far too many variables that can slightly offset the data to get an exact matching CRC/MD5 sum. I posted a similar thread several years back when I discovered this. The end result of said thread... don't worry about it. It's as close as it is going to get and any difference will be so minimal that you would not be able to know it anyways. Except said CRC/MD5 sum.
JXL

I understand what you mean, it's probably nothing to worry about. I am going to tell you something else, I've already wasted at least 10 CD-Rs to do testing and you know what? I don't even listen to music using CDs, I want to see the correct CRC when I rerip and I will be done testing. I want to see it at least once.


Again, I need answers here:

1) Does the writing speed influence the quality of the writing? I've read it does but how do I test all the speeds without throwing away 2000 CD-Rs? Are CD-RW good for tests and quality burning?

2) Once I set the write offset do I have to burn the full disc or just one song to rerip and test?

3) If one song is not enough (on question 2), does the CUE file make a difference when I burn the full album for the rerip's CRC?



Thanks.

This post has been edited by eahm: Feb 13 2012, 19:48
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pdq
post Feb 13 2012, 19:59
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Are the six missing samples at the beginning or the end? Was the track the first or last on the CD? What are your results with the new write offset? With more information we might be able to help you.
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eahm
post Feb 13 2012, 20:14
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QUOTE (pdq @ Feb 13 2012, 11:59) *
Are the six missing samples at the beginning or the end? Was the track the first or last on the CD? What are your results with the new write offset? With more information we might be able to help you.

The error was exactly like this one: http://blowfish.be/eac/Burn/Images/burn_wav-result1.png but again, I had no idea you have to burn the full disc because I still didn't get answers for the 2) question. Don't mean to be rude, I calculated few variabiles to do more testing that's why these three questions are so important right now.

The track was the number 2, again I had no idea you have to use the first or the last (did I understand correctly?). I get from this that there is no way to test only one song at the time if it's not the first track right? And no way this is going to work in a multisession disc?

I guess I will do few more test with the first track...

PS
Apologize for my grammar, English is my 3rd language.

This post has been edited by eahm: Feb 13 2012, 20:16
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pdq
post Feb 13 2012, 20:28
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The example shows the missing samples to be at the beginning. Does your drive overread the lead-in of a disc? If not then to get a CRC match it may be necessary for the first track on the CDR to have been the first track on the pressed CD, and vice versa.

I have read people's opinions about write speed and quality of the CDR, but I think it depends not only on the drive but also on the brand of CDR, so I would just go with a medium speed and not worry about it. If you want you can test the CDR with an application like Nero's CD Speed.

This post has been edited by pdq: Feb 13 2012, 20:32
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Bugs.Bunny
post Feb 13 2012, 21:32
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Offset (read or write) results in loosing some data at the beginning or the end, depending on the sign (+/-) the first or the last track will be affected.
There are (as far as I know) no drives with a read offset of 0. There are some drives that are able to read audio data form/into the lead-in/out and thus will not loose data with the offset set.
There are no drives (as far as I know) that can write audio data from/into lead-in/out and thus will always some samples. But there are some drives that have a write offset of 0 ant thus will not loose samples during writing.
If samples are lost due to offset, you will loose some milliseconds of audio data on the first or last track.
Often there is only silence in these milliseconds and so you will loose nothing.
If there is audio data in these samples, clearly the crc of the first or last track will not be the same. For all the other tracks the CRCs should match.

It is possible to get a copy that if ripped again will give you the same CRCs. (I've done it & explained it earlier).

For accurate rip, first and last samples of the CD are not taken into account due to the different offsets (of the drives) that are existing. So you will get a positive match with different drives/offsets even though if comparing these first/last tracks can result in different CRCs.

If CD-Rs are certified for a certain write speed, this speed should be OK. You should checks some reviews/tests of CD-R media to find out good types.
How long you will be able to use/read the CD-Rs depends on different things (temperature/humidity....) CD-Rs use organic material. Don't count on using CD-Rs longer than ~10 years. They will get unreadable after some time. I've started recording CD-Rs 1997. Some of that time I'm still able to read error free, others have degraded to a way that they are no longer readable error free. Especially the outer tracks. So investing in higher quality media does pay, if you want to use it for a longer period of time.
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pablogm123
post Feb 16 2012, 11:17
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"There are (as far as I know) no drives with a read offset of 0."

According to Accureterip's database, there is a drive with 0 offset correction:
BTC BDV-316E

This message shows a proper rip using such drive:
http://www.digital-inn.de/exact-audio-copy...html#post129426
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db1989
post Feb 16 2012, 11:26
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That depends. If one follows the meticulously hardware-derived conclusion of IpseDixit, the standard offset is 30 samples ahead of what it should be. In that case, Plextor drives (at least the old ones), which have a read offset of +30 according to the methods of EAC et al., have always had an actual read offset of 0.

This post has been edited by db1989: Feb 16 2012, 11:40
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eahm
post Feb 16 2012, 18:38
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QUOTE (db1989 @ Feb 16 2012, 03:26) *
That depends. If one follows the meticulously hardware-derived conclusion of IpseDixit, the standard offset is 30 samples ahead of what it should be. In that case, Plextor drives (at least the old ones), which have a read offset of +30 according to the methods of EAC et al., have always had an actual read offset of 0.

Wow this is funny, they would actually be perfect left alone.

Quick question, why doesn't EAC or even AccurateRip database fix this issue?
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