Gap and CUE Sheet 101: A simple tutorial for Dummies like me ;)
After so many discussions on how to correctly read and write gap information on CD-Rs burn using EAC (aka "How to make perfect CD copies"), I guess we have enough info to write a small tutorial regarding how gaps and cuesheets are handled by EAC
First, just to make things clear: Im NOT a CD expert. Im a EAC 1st time user, with very few experience in the ripping/encoding/burning/etc area. So Im no authority. BUT ive spend last 12 hours reading almost every message in this forum regarding gaps and cuesheets, every EAC tutorial out there, configuring a lot of parameters, and doing a lot of testing. My ideia was to gather all knowlegde spreaded in all these sources.
The goal of this little tutorial is just to save begginers like me a lot of time. I wanted to use EAC for both copying and encoding Audio CDs, but was hard to figure out how. I knew what a gap was, but didnt understand how the Gap menu options worked. Also I didnt have a clear ideia of what a CUE Sheet was, why there were so many options for creating them, and how were they related to Gap settings.
Here's what I wanted:
- Extract a CD into several WAV files, so I could rip, encode and tag them with a single click (actually, using Shift+F5
- Since the extraction was already done, I wish I could be able to burn an exact copy of the original CD without having to read the CD all over again. So, the already extracted wavs should be used fo this job
- I wanted things to be as easy and straightforward as they could be. The less clicks the better
Reading from Masters like Andre, Pio, and many others, I realized that to accomplish this I should learn a bit about Gaps, Cue Sheets and stuff. So, after 12 hours of browsig, reading, testing and learning, here is my humble tutotial. Lets go!
Lets imagine an hypotetical CD with this layout:
- Index 01: 1 minute
- Index 00: 2 secs
- Index 01: 2 minutes
- Index 00: 3 secs
- Index 01: 3 minutes
- Index 00: 4 secs
- Index 01: 4 minutes
If you dont "Action -> Detect Gaps (F4)" before extraction (for 'extraction' I mean "Action -> Copy Selected Tracks -> Uncompressed"), the gaps will be automatically appended to the end of the previous track in the wav files. So you wav files will be like this:
Track1.wav : 1:02 (1st song + gap of the 2nd track)
Track2.wav : 2:03 (2nd song + gap of the 3nd track)
Track3.wav : 3:04 (3rd song + gap of the 4nd track)
Track4.wav : 4:00 (4th song)
But, if you do detect the gaps before extracting the wavs, you can have more control over them. Doing so, you have now 3 ways to handle gaps (the last 3 options in the Action menu):
- Leave Out Gaps
- Append Gaps to Previous Track
- Append Gaps to Next Track
Leave Out Gaps will simply ignore Gap data (00 indexes). Only indexes 01 and over will be recorded to the wavs. Wavs will look like this:
Track1.wav : 1:00 (1st song)
Track2.wav : 2:00 (2nd song)
Track3.wav : 3:00 (3rd song)
Track4.wav : 4:00 (4th song)
The big problem with this option is that the gap data from the CD is lost in this process. If our goal is an exact copy this option is not a good ideia.
But this option might be useful under some circunstances. The gap data lost may be only "useless" silence between tracks, and you might want to store only actual music content. Or perhaps you want to manually change the silent between tracks when writing the CD, so having "trimmed" wavs can help controlling the silent spacing when writing the CD-R.
But gaps are not only silence. This may be true for most albums, but not all. Rembember that gaps can be silence, but also can be anything from audience clapping to actual music. (By the way, use "Action - Test Gaps On Silence" to find out if the gaps are just silent or have actual data)
Nevertheless, we want our copy to be as exact as possible. So if the gaps are in the original, they must be in the copy just the way they are.
- Append Gaps to Previous Track: this is the default action, works the same way as if no gap detection is made, and was explained above.
- Append Gaps to Next Track: similar to the default, but the gap is written in the begging of the track, like this:
Track1.wav : 1:00 (1st song)
Track2.wav : 2:02 (pregap of the 2nd track + 2nd song)
Track3.wav : 3:03 (pregap of the 3nd track + 3nd song)
Track4.wav : 4:04 (pregap of the 4nd track + 4nd song)
This might look the most "natural" way to store the gaps, but actually its very odd: usually the gaps are silences, so its a bit weird for a track to start with a silence, instead of ending with it
Also, when you use the Seek button in any standalone player, for, say, Track 3, it will begin playing the Track 3 - index 01 (aka 3rd song), not its 00 index! So the only way for you to listen to the 3 secs pregap is to listen all the way from Track 2. The player will play Track 2 - index 01, then the pregap (will display negative -3s). So, if the only way to listen this gap is by playing track 2 until the end, it makes sense to say that the 3s pregap actually belongs to the 2nd track, not the 3rd! (even if in the actual CD layout the 3s gap is called "track 3 - index 00").
So, bottom line for reading gaps: for things to go perfect, you dont even have to detect gaps! If you dont, EAC will automatically read them and store them in the end of the previous track. If you do, make sure that the default option is selected, or select something else being very sure of what you're doing
Wavs recorded, you're ready to burn the CD-R. f you just the CD copy to sound the same as the original, just go to Tools -> Write CD-R -> Layout -> Append Files As New Tracks (Index 1), select all the wavs, and be happy
As the gaps are recorded within the wag files, the resulting cd will have the same "song, gap, song, gap" pattern. Also, gaps will behave like they ought to:if you seek to Track 3, it will jump directly to the 3rd song. To hear the gap before track 3, just listen track 2 until the end.
But, if you look carefully, something is different: In the CD layout, there will be no Index 0 in any of the tracks. Afterall, all data on the gaps were apeended to the songs (01 indexes). Should you care? Probably not. As far as I learned here, no software or hardware make any useful use of indexes. Most (if not all) PC Players just ignore this information. The only perceptible difference is the time count used in standalone players. In the original CD, the 1st track will play from 00:00 to 01:00, then a negative -00:02 countdown will be displayed while the gap (track 02, index 00) is being played, and finally track 2 will start at 00:00. In the CD-R copy, track 1 will be 01:02 long. Display will go from 00:00 to 01:00 and continue to 01:01, 01:02 as the 1st song and the subsequent gap is played, and then track 2 will start at 00:00. If you close your eyes and just listen, all will be the same. If you use Seek and Search buttons, all will be the same. Only the fancy -2s display countdown will now be displayed as part of the 1st track. Thats it.
But do you, like me, care for this fancy display effect? Do you want to keep the index marking for the sake of fidelity, even if this is completely useless? Then the job can easiy be done using CUE Sheets.
Cuesheets are a text file that defines a CD Layout. It tells the burner program what tracks and indexes the CD will have, its lenght, and how the source wavs will be "sliced" in these tracks and indexes. So, before burning the blank CD, you must first Create a CUE Sheet based on the album you're reading (and also base on how you extracted the wav files from it). EAC Gives 4 options for creating this CUE Sheet, the only difference, as far as I can see, being the way they handle the gaps found in the original CD. The options, accessed through the "Action -> Create CUE Sheet", are:
- Current Gap Settings
- Single WAV File
- Multiple Files With Gaps (Noncompliant)
- Multiple Files With Left Out Gaps
- Multiple Files With Corrected Gaps
I find very few (if any) detailed and accurate information of what is the actual difference of these options. So, after a bit of testing (ie, creating then comparing all 5 cuesheets), I was able to draw some notes:
- "Single WAV File" generated a CUE Sheet where a single .wav is sliced in all the tracks in indexes. So, as the name suggests, it must be used when you extracted the full album to a single .wav file (presumably using the Action -> Create Image option). It creates both 01 and 00 indexes, thus preserving original CD layout and content
- "Multiple Files With Left Out Gaps" creates a CD Layout identical to the original, but, as whe source wavs presumably lack the gap content (hence the name), its data is entirely recorded in the 01 indexes, and the 00 indexes are filled with silence. So, altought it perfectly preserves the CD layout, the copy is only identical *if* the content of the gaps in the original CD is only silence too! In other words, all the data in the gaps is lost and replaced by silence of the same lenght.
- "Multiple Files With Gaps (Noncompliant)" slices the wavs assuming that the gaps were appended to the end of each (previous) track. So, using our imaginary album, the first 2 minutes of Track2.wav would be recorded in Track 02 - Index 01, and the last 3 seconds would be Track 03 - Index 00. No need to say that this is the option that should be used when the wavs are extracted the default way. The scary "Noncompliant" term, as far as I could learn, means that many other burners, like CDRWin, cant correctly recognize CUE Sheets where wavs are sliced this way as valid CUE Sheets. So thats something you should only care if you EAC only for extraction (thus for creating the CUE Sheets) and such external programs for burning. If you use EAC for extraction AND burning, there's nothing to fear, as EAC can properly read its own generated CUE Sheet quite well.
- "Multiple Files With Corrected Gaps" slices the wavs assuming that the gaps were appended to the begging of the next track, ie, this option should be used to correctly recreate the original CD layout and content when you used the "Append Gaps to Next Track" option when extracting the wavs
- Last but not Least, "Current Gap Settings" creates a CUE Sheet based on the currently selected gap settings (duh)
So, create the CUE Sheet that best represent the gap format you used when extrated the wavs. Now its very easy to burn a CD-R. Just go to Tools -> Write CD-R -> File -> Load CUE Sheet. Now see how the wavs are properly sliced? (if not, you did something wrong Time to burn! Go to Cd-R -> Write CD and be happy!
I guess this covers many questions about gaps and cuesheets. I hope that with this info, all begginers like me will be able to use EAC for both extracting and burning. This text may (and probably does) have some mistakes, so please feel free to highlight them.
Btw, sorry for the poor english. Im Brazilian, so English is not my native language.
Senior Member (Board-Inventar)
Very good job. Thank you !
In fact two marginal uses for indexes zero were pointed out.
The first one was found by Infrared Archer in http://www.hydrogenaudio.org/index.p...ST&f=20&t=1642 : in a hardware CD player, when you program a playback with a different track order than the natural one, the gaps are left out in the playback, as the player jumps from track to track.
You mentionned the other one : if someone, for a given reason, wants to get rid of the original gaps on purpose, it will be possible from the copy only if indexes zero were copied with a cuesheet from the original CD.
I don't see a "Detect Gaps (F4)" option in the Action Menu.
Originally Posted by MestreLion
I have installed eac095pb4.zip - (1748kb ZIP) and "Help -> About EAC" reports I am running this 18 Nov 2003 version.
In a nutshell: Making a CD copy using multiple files and CUE Sheets.
When I combine MestreLion tutorial and my own experience I reach the following conclusion:
To make an exact copy of an audio CD you just put (or keep) EAC in beginners mode, rip the CD in multiple wave files and create the (default) CUE Sheet.
Now you can simply write your copy by loading this CUE Sheet in EAC's CD Layout Editor.
Just what you expect from a program called "Exact Audio Copy".
If you activate the advanced features (switch off beginners mode) you should create the CUE Sheet choosing "Multiple Files With Gaps (Noncompliant)".
This will create the same CUE Sheet as in beginners mode.
If you need a CUE Sheet compatible with other burn software use the (second best) option "Multiple Files With Corrected Gaps" .
Good Stuff MestreLion.
Just to make sure I understand everything correctly. If all I want to do is have accurate seperate wav files so I can convert to mp3 or make CD duplicates, then leaving EAC in its default configuration will be good enough. The only downside to this is that the time display will not accurately depict the original CD, which I don't care about.
I just want to make sure I don't have to make cue sheets, especially after Frixzi's comment about keeping EAC in beginner mode and utilizing the cue sheets to burn.
What if I just rip my CD's in default (advanced) mode with no cue sheets and then burn them with no cue sheet. Wouldn't they have the same gaps, etc. without a cue sheet since the gaps are appended by default?
Any help is appreciated since I've been really sweating lately. I have ripped about 280GB of CDs and don't really want to do this again. I have about another 250+ GB left to do.
There is still a problem with the default method of appending gaps to the next track, in terms of there being a pregap before track 1. Since EAC completely dismisses this gap (since there is no previous track to append it to), you lose that bit of silence at the beginning.
Originally Posted by Pio2001
As such, the gap is gone and the CD's TOC will look different, and in essence, this isn't a perfect copy, especially if you want your copy to hash out a similar workman (old UNIX program) offset string or a CDDB value.
I emailed Andre personally on this issue, because while the musical data is perfectly preserved, on CDs (with pregaps before track) 1, the CD is not perfectly replicated, whether you want to be a purist about it, want to preserve the identical experience, or just care about the thing popping up CDDB when you put it in. (Yes, I know abou CD-Text, and use it, but there could be other reasons to want this functionality, and if we CAN do it, why not?)
What's wrong with "Copy Image & Create CUE Sheet"?
Default action is to append gap to the _previous track_ ... For the gap in front of track #1, there is _no_ previous track to append to, which means that EAC would have to change its behavior (an exception) for gaps in front of track #1 and append to next track for track #1, and then carry on with default method of append to previous track from thereon in.
Originally Posted by geexer
maybe just a silly question but why is there no option to extract a cd as multiple wave files with gaps extractet in own files. it would be perfect for using files theirselves and also you have got the ability to reproduce the cd 1:1 (exactly)
sorry for my bad english i'm in a hurry
Life's to short for all this angst and turmoil!
Create Image & Copy CUE sheet iis the way to go.
Foobar will convert to mp3 even from an ape image,
and Feurio is the the tool to burn with.
I agree 100% on the image/CUE issue, however, until Winamp (yes, I know about Foobar, but I am way entrenched into Winamp) supports CUE play comprehensively, this is a difficult way to go.
Originally Posted by geexer
I still think this is an easy anomaly to address, its just that it hasn't really hit the radar 'til the past few months (or maybe its been on and off the radar again and again...)
Anyhow, I'm _all about_ CUE-play, but I want to wait 'til Winamp does it--its on the official 5.x WishList: http://tinyurl.com/3xhnm ... but who knows how long (if ever) 'til its implemented.
I downloaded Foobar but don't see an option to convert a CD Image with cue sheet to multiple MP3s. I don't even see mp3 listed.
Originally Posted by geexer
Make this thread sticky!!
Append The Gap Before Track 1 To Track 1 ???
OK, that is clear:
The only way to make an exact copy is by CD image and CUE sheet, but I have 2 things in mind when I rip a CD:
1. Adding the CD to the music library on my hard disk, using a lossless format like Flac.
2. Archiving the CD, by using the same Flac files from my library, so I always can make a copy of the CD (by decompressing those Flac files to Wave and burning them with the CUE sheet).
For the library I prefer seperate files for each track.
The price for that convenience is that I lose the gap prior to track1 (index 0).
Maybe we have to ask Andre to add an extra option "Append Gaps To The Previous Track and Append The Gap Before Track 1 To Track 1".
Usually this first pregap is a quarter of a second of silence, but it could be the announcing of the artist on a live CD (Actually it should always be that way, sadly only very few technicians in the music industrie make proper use of the index).
In either way, putting this pregap in front of track 1, instead of leaving it out, would have more pros than cons.
Bytemastr, what was Andre's reply when you mailed him on this issue?