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  #1  
Old 2005-01-09, 07:52 PM
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What is a SBE?

This may be a stuipd question, but I did a search on TTD and on Google and I couldn't really figure it out. What is a sector boundary error? Thanks for the help in advance.

-Phil
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  #2  
Old 2005-01-10, 01:15 AM
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Re: What is a SBE?

Sector Boundary Errors occur when an audio cdr is burned. If the original files aren't cut in just the right place, then you'll get a pop sound between tracks.

**a more technical explanation is sure to follow**
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  #3  
Old 2005-01-10, 06:40 AM
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Re: What is a SBE?

Audio CDs hold data in minimum block ("sector") sizes of 1/75th second (0.01333 seconds / 2352 bytes of data / 588 stereo samples). If you try to burn an audio file to an audio CD, and its length is not an exact number of sectors, the last sector will usually be padded with digital silence (zeros). This gap is referred to as a "sector boundary error" because it is an error caused by a large audio file having been split into individual tracks at places other than sector boundaries (1/75th second intervals).

As such, an SBE is a silence of less-than-but-not-equal-to 1/75th second found "between" audio tracks on a CD. I say "between" because technically it is at the end of the preceeding track and has nothing to do with the one that follows. In some cases, this flaw could be completely unnoticeable, as it could be only one sample, and could fit neatly into the current flow of samples. However, more likely it will leave an audible silence, or an audible click. The click is caused when the silence interrupts a "loud" part of the waveform, i.e. one that is not close to digital silence. The waveform makes a sudden jump from a loud value to silence, and then back up again to carry on when it left off. I'll add some images in a minute for clarification.

Once you burn an audio CD with SBEs, the silences become part of the audio data - they won't disappear again if/when you extract back to your computer. An audio file extracted from a CD can never have an SBE because it's come from a CD and is as such sector-boundary-aligned.

It should be noted that "SBE" has falsely become something of a catch-all term for anything that has a short (non-two-second) silence between tracks. There was an Ozric Tentacles show seeded on STG over summer straight from the master, which had silences at the end of each track that were maybe 0.05-0.1 seconds in length. I've no idea what the taper did to achieve these, but I've seen the show on tradelists noting "quite a large SBE between each track" - there's no such thing as a "large" SBE - it's by definition less than 1/75th second in length.

If you wish to avoid creating files with SBEs, split using CDWave. For assured reliability, don't actually split the files - just save the cuesheet and burn using software that can handle cuesheets (CDRWin, newer versions of Nero etc).

Thankfully, pure SBEs don't damage the audio data in any way, they just interrupt it, so with care can can be perfectly fixed by just removing the silence. The waveforms either side of the silence should automatically line up perfectly. TAO, and especially mp3 gaps, are not so easy to remedy as small parts of the audio data can be lost in the gap generation process.

I think that's pretty much everything!
see also http://www.cdrfaq.org and http://www.ambfaq.cjb.net
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  #4  
Old 2005-01-10, 12:05 PM
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Re: What is a SBE?

There's nothing I can add to that explanation, and so I'll chime in to say "what he said" .
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  #5  
Old 2005-01-10, 12:26 PM
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Re: What is a SBE?

Nice one, Rob.
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  #6  
Old 2005-01-10, 01:17 PM
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Re: What is a SBE?

yes, very comprehensive!

other programs like CEP/Audition and GoldWave can also cut on sector boundaries. The thing is, these aren't freeware (and neither is CDWave). Another way to align the sector boundaries is to split a show to separate WAV files for each track, then compress to FLAC using FLAC frontend with the option "align on sector boundaries" enabled.
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  #7  
Old 2005-01-10, 01:49 PM
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Re: What is a SBE?

Cheers guys - glad to know the time I spend avoiding revision isn't completely wasted However, Five's mention of Goldwave has made me realise I forgot something.

I'm 99% sure Goldwave can NOT split at sector boundaries, and I'm not entirely sure Cool Edit can either but I think it can but anyway. Goldwave can split at zero-crossings, but this is not the same as sector boundaries and can often be confused. Splitting at zero-crossings (i.e. when the waveform is at digital silence, as I mentioned earlier) will mean you don't get clicks, because there won't be a sudden jump in the sound level. However, you will still get a silence, which is infact almost inevitable if you use zero-crossings because the chances of a randomly place marker magically landing on a sector boundary are obviously severely limited if you insist the marker lands at zero amplitude.

There we go, can't think of anything else missing now. I promised pictures but I still haven't done them, although I have managed to read some more about management control as ethically problematic :geek: If anyone else wants to do some while I'm being all academic please feel free
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Old 2005-01-10, 02:36 PM
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Re: What is a SBE?

with all due respect...

trust me, I've tried it with GoldWave and CEP, then double-checked the end result with FLAC frontend's align on sector boundary feature. If it didn't work with these progs I wouldn've had my ass nailed to the wall by now for seeding shows with SBEs!

ps demonstrations can be arranged!
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  #9  
Old 2005-01-10, 03:14 PM
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Re: What is a SBE?

oops! Ah well, always healthy to be proven wrong once in a while! (and hey, I saved myself a 1% error margin anyway )

Where's the feature in Goldwave? I use that for a lot of my editing and it could come in useful. I had a quick look around to check before posting the above and couldn't spot anything

Last edited by oldbrokentapes; 2005-01-10 at 03:22 PM.
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  #10  
Old 2005-01-10, 04:04 PM
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Re: What is a SBE?

For GoldWave it's in the cuelist section somewhere... there's a function to split a WAV on the cues and a little checkbox-type thing to make cd compatable tracks (I'm not at home right now, so I'm just going by memory).

For CEP, when you go to the cuelist there's a dropdown that lets you select cue types, I think they call it "track".

I can up screenshots tomorrow if my descriptions are a little vague! Like I said, not at home right now.
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  #11  
Old 2005-01-10, 04:11 PM
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Re: What is a SBE?

Yes, CEP (and Goldwave I guess, though I don't use it) can be configured to split on SBs, but it is not set that way by default and is sometime more diifcult to configure than it's worth. You have to set selection block sizes so that it will only permit selections on every 588 samples instead of the default, which is 1. The just select>cut>paste and it'll be SB aligned. Still, this is not the default, and if you didn't set this up the chances are that you're not cutting on SBs with CEP.

Again, I am guessing that Goldwave and Soundforge are similar in this respect. Audacity, which is freeware, I believe can be configured to split on SBs in this way, though I have not tried it yet.

Always, always do shntool sbe check before burning just to MAKE SURE it wasn't screwed up because, as Rob said, once you burn it that way, the click is there for good.
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  #12  
Old 2005-01-10, 05:41 PM
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Re: What is a SBE?

GoldWave and CEP/Audition (at least more recent versions) can be set to cut on sector boundaries without inputing the 588 jazz... I'll post some screenshots and stuff in the next while. If anybody knows about how to do this with Soundforge, & Audacity, please post here.
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  #13  
Old 2005-01-10, 05:56 PM
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Re: What is a SBE?

So say i found a show on TTD that a multiple SBE's lik this one (scroll down to my post where i show shntool results):

http://www.thetradersden.org/forums/...ead.php?t=2335

Does that mean it would be pulled?
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  #14  
Old 2005-01-10, 06:07 PM
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Re: What is a SBE?

I believe this has to be pulled... hopefully the SBEs will get fixed and this will be reseeded. I'll call everyone's attention to this right away, thanks for letting us know.
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  #15  
Old 2005-01-10, 06:17 PM
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Re: What is a SBE?

Or maybe we could just make a note for people to correct the SBE's before they burn to cd and leave the thread as is because it aleady has 42 completes
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