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  #31  
Old 2007-07-21, 06:14 PM
Tubular
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Re: EAC configuration, offsets, etc...

OK, scratch the above Nero example, at least with a Lite On SlimtypeDVDRW SSW-8015S. I burned a disc with Nero (no 2 second gaps) with this lineage:

source: DSBD->DAT@48K
transfer: DAP1-> echo MIA-> SF7.0-> CD-Wave-> FLAC

This fileset had no SBEs or other errors.

My drive has a read offset correction of +594 and a write offset correction of -6. So I used a combined read/write offset correction of +588 and extracted the last track of disc 1 and EAC reported missing sample errors in the log file. Then I tried extracting a track from the middle of the disc, combined read/write offset +588, got missing sample errors in the log file. I tried a commercial CD, combined read/write offset +588, got missing sample errors in the log file. Then I tried the commercial CD again, read offset +594 and got no missing sample errors. Then I tried the burned CD again with combined read/write offset +588 with "overread" enabled and got missing sample errors. So using a read offset of anything other than the correct +594 in my drive/ASPI interface/laptop results in missing sample errors.

I remember extracting with the combined read/write offset working fine on an old HL-DT-ST CD-RW drive I had on a different computer though.

Last thing, when you extract a Nero burned CD with the read offset corrected, the missing sample errors won't show up in the log file of EAC, because they aren't read errors. The missing samples will show up when you are using the compare WAVs feature of EAC in Tools > Compare WAVs. I'm not sure what the difference is between these two types of 'missing sample' errors.
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  #32  
Old 2007-07-21, 06:46 PM
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Re: EAC configuration, offsets, etc...

Quote:
Originally Posted by Five
if you extract a cd to one folder, then burn that using EAC and extract again from this burned copy to another folder, then you can generate st5 checksums for both sets to see if you've got it 100% perfect. even wholefile md5s will work, if you're more comfortable with that.

for instructions look at the "checksums" link below in my signature. on my system I get a perfect match.
I have determined that my read offset correction is 102. I then used the earlier thread from tubular to determine that I should enter 30 into EAC for my write offset. I tried converting original flacs to wavs and burning to cd. Then extracting those wavs from that cd... I used EAC to compare and they match! The md5's for these wavs are a match, also.

However, when I encode the newly ripped wav to flac (level 8 encoding) the st5's are a match, but the md5's do NOT match the original flac files. Is this because I use flac8 to encode? What would cause this?
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  #33  
Old 2007-07-21, 06:58 PM
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Re: EAC configuration, offsets, etc...

cicada, you've got it!

st5 works from the decompressed audio information only, so different flac compression levels, tags, even encoding to shn, ape or reading from wav will all match.

now when comparing flac files using md5 there are many factors that can introduce minor changes that will throw the md5 off such as presence of tags, compression level, and version # of the flac binaries used for the encode. that is the main reason that st5 is much better, because it compares if the decompressed audio only is a match without being sensitive to non-audio things.
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  #34  
Old 2007-07-21, 07:15 PM
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Re: EAC configuration, offsets, etc...

Tubular,

wow I am getting a headache thinking about that! we will get to the bottom of it, I've got to research a little.

a couple things that come to mind

I don't think it has anything to do with the dat source, unless you do the identical steps with eg a cassette source and it comes out different. are you getting "no sector boundary errors" using a shntool/tlh len check on the original set? cdwave leaves a SBE on the final track, if that's what you're using (could be a cause, just a shot in the dark)

combined read and write offsets should not be used, they are only useful when all else fails setting them separately. when using combined read and write offsets it is expected that the checksums will be different after extracting a disc, and that the sample slide intentionally introduced here will correct itself when a copy is burned from these files. so what you're experiencing seems strange, also I have to look up my facts on this since I have never used that feature personally...

if you have the two last files that are ever so slightly different I am capable of checking them for you for a) sample slide and amount in # of samples and b) exact difference between them, if that is at all useful here.

...still thinking about this, we should be able to get it sorted
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  #35  
Old 2007-07-21, 07:26 PM
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Re: EAC configuration, offsets, etc...

Cool! Thanks a ton for all your help.

So, I can say that I have performed an exact extraction because I have matching ST5's (even though it I do not have matching MD5's). Technically these are not the orignal lossless filesets, but this is a exact extraction... and that's a first for me! Thanks again to you guys (Tubular and Five).
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  #36  
Old 2007-07-21, 10:23 PM
Tubular
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Re: EAC configuration, offsets, etc...

Cicada, I'm glad I was able to help!

Well shit, I just burned the same DAT > soundcard > SF > CD Wav sourced show with EAC .95 beta 4 with the write offset corrected with my Lite On, then extracted with EAC with the read offset corrected and all the tracks I extracted matched. I extracted the first track, a middle track, and the last track and they all match (my audio CD read speeds suck with this drive, so I didn't want to extract all the tracks). Yay! Maybe it was my old HD-DT-ST CD-RW drive that couldn't overwrite into the lead out correctly? That was probably it. &*@$% cheap factory supplied stock drives. So if your drive can't overwrite into lead in and/or out, then you have to add a short bonus track to the beginning and/or end so all your concert wavs will match on extraction.

I just extracted the last track of an audio CD (didn't add a short bonus track on this one disc) I burned a while ago with the old drive with EAC with the write offset corrected and got DIFFERENT samples at the very end of the track when I compared it with the original FLAC > WAV with EAC's compare WAVs feature. Different samples in the compare WAVs feature as opposed to MISSING samples when you extract a Nero burned disc with EAC with the read offset corrected.

If you extract a CD that has been burned without write offset correction with Nero or EAC, then extract with EAC with the combined read/write offset, then all your files will match the original FLAC set. So if you have burned a bunch of audio CDs with Nero (not normalized, no 2 second gaps) but you deleted the FLAC sets, then you can still get the original files back by extracting with with EAC with the combined read/write offset (assuming no SBEs on original FLAC set).
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  #37  
Old 2007-07-22, 02:17 AM
Tubular
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Re: EAC configuration, offsets, etc...

If you snip off the very last part of the last wav of a set with CD-Wave Editor you won't get a SBE.

I think it was anything that was transferred through a soundcard, data port, or external AD converter: DAT, cassette, MiniDisc, vinyl, reels, hard disk recorder, flash recorder, 8 track , DCC (remember those?) All of these types of transfers would give me problems matching the last track of original filesets with no SBEs on extracting a burned disc with the HL-DT-STRW/DVD GCC-4240N CD-RW/DVD-ROM drive.

But if the transfer was: drive capable of overwriting into lead out > burn audio CD > EAC > WAV > FLAC then there would be no problems matching the last track on extraction on my burned disc, even though my drive can't overwrite on lead out correctly. I'm clueless as to why this is. Sounds crazy, but it happened. Maybe the source audio CD for the FLAC seed wasn't burned with the write offset corrected and/or wasn't extracted with the read offset corrected, and then when I burn with EAC with the write offset corrected on a drive that can't overwrite into lead out, it burns the silence at the end correctly even though it can't overwrite into lead out? Does that make any sense?

Anyway, it doesn't matter now that I have a drive that can overwrite into lead out correctly on every show.
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  #38  
Old 2007-07-22, 03:01 AM
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Re: EAC configuration, offsets, etc...

You got me there? I'll let you and Five take it from here. I will continue to rely on the orignal filesets (external HD and datadiscs backup for now). Nice to finally have EAC set up correctly even though the cheapy drive has limits.

All from me for now... peace!
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  #39  
Old 2007-07-22, 11:06 AM
Tubular
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Re: EAC configuration, offsets, etc...

I alone didn't get you there. Five helped, I helped, and you helped yourself.

Yeah it would be good to still archive the FLACs and SHNs on data DVD+Rs as a backup. What if the audio CD-Rs are lost or borrowed and never returned? Plus data discs have built in error correction so they will copy more reliably as time goes by.
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  #40  
Old 2007-07-22, 09:51 PM
Tubular
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Re: EAC configuration, offsets, etc...

Sorry, just realized what you meant by 'you got me there'; that I stumped you. Haven't heard that expression in a while.
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