14. Appendix D: Cue Sheets
14a. Introduction: CD/Single Files, Indices, and Pregaps
A copy/image/single file mirrors what the CD looks like: there is one single continuous track. The picture shows such a single .wav file. There are two sections, one for each channel (the right channel is below):
It is fairly easy to spot the six separate songs (the "tracks") in the waveform, but note that they are not really separate on the CD (or the CD copy/image/single file rip). You can skip to the different songs on the CD because there are indices that tell the CD player where a song (a "track") starts in this long continuous track. In the cue sheet, INDEX 01 entries tell you where the separate songs ("tracks") start.
Often, but not always, there are gaps between tracks, and usually, but not always, those gaps are silent. In the cue sheet, INDEX 00 entries tell you where the gaps are placed. Five of the six tracks on the CD used as example here have gaps. Track 5 is not preceded by any gap, and will thus show as having a gap length of 0:00:00:00 in the EAC window, and there will be no INDEX 00 entry for it in the cue sheets.
Some cue sheets contain indices with higher numbers than 01. These indices can be used to skip to different sections within a track if you use a CD player that supports indices over 01. The example CD used here has an INDEX 02 entry for the first track: it allows you to skip straight to the allegro part of the track Sonata in B flat major, K. 454: 1. Largo - Allegro (if you play the CD on a player that can handle such indices).
A standard CD has a default 2 second pregap before the audio track starts, which is not shown in the cue sheet precisely because it is the standard. It gets automatically added when you burn an audio CD. (If you detect gaps before ripping, as you should, you will see that standard 2 second gap in the EAC window and in the log.) Some cue sheets will show an introductory pregap, though. This happens when the pregap is longer than 2 seconds. Long pregaps may contain a hidden songs, see Hidden Tracks. The CD used as example here shows only a small pregap of 33 frames/0.44 seconds. There is no hidden song there, it is just that the pregap is 2.44 seconds long instead of the standard 2 seconds.
So, ripping a CD to a single file would be the "natural" way to replicate a CD, but more often than not you will want to rip a CD not only as backup but also for listening to it on your computer and/or your portable player. The indices that make it possible to detect where tracks start also make it possible to rip a CD to separate files, which is a great advantage when you want to be able to skip to a certain track while listening on your computer or portable player.
If you turn the continuous file into separate files for the tracks, you have to decide how to handle the gaps, though. EAC offers three methods for gap handling: the default setting is to append them to the previous track, so that each of the files will start when the tracks would start if you skipped to them on the CD. You can also leave gaps out as you rip, which again makes the files start when the tracks would start if you skipped to them on the CD, but in this case the gaps are simply lost. The third method for handling gaps is to append them to the "next" file: the files will not start where the tracks would start if you skipped to them on the CD, but will start with x seconds of silence for every track with a pregap of x number of seconds of silence.
The different kinds of gap handling need to be combined with different kinds of cue sheet in order for it to be possible to re-create the CD structure:
- Copy Image = Rip to single file - Single WAV File Cue Sheet
Multiple WAV files:
- Append Gaps To Previous Track (default) - Noncompliant Cue Sheet
- Append Gaps To Next Track - Corrected Gaps Cue Sheet
- Leave Out Gaps - Leftout Gaps Cue Sheet
The different options, with the correct respective combinations of gap handling and cue sheet, are described in some detail (each in its own section) below. This is a "short version" of the differences:
It is easy to tell the single file cue sheet from the different kinds of multiple file cue sheet. The single file cue sheet references only one file. In the example used here, you find it in the line
FILE "Mozart - 2 Sonatas for Piano and Violin, KV 454 & 526 (Clara Haskil, Arthur Grumiaux).wav" WAVE
All the cue sheets for multiple files reference separate files that each contain a separate track. So you have references to
FILE "01 - Sonata in B flat major, K. 454- 1. Largo - Allegro.wav" WAVE
FILE "02 - Sonata in B flat major, K. 454- 2. Andante.wav" WAVE
etc., but there is no heading telling you which kind of cue sheet you are looking at. You have to deduce this by looking at the way the gap information is structured. (If there are no gaps apart from the standard 2 second pregap, you will not be able to tell the difference, but that is OK since it also will make no difference.)
The gap for Track 4 is highlighted by being coloured red in the detailed cue sheet sections below. It shows you how to tell the difference between the different kinds of multiple file cue sheets. What follows here are excerpts from those cue sheets, showing only the information for Track 4.
Noncompliant cue sheet (for gaps appended to previous files):
TRACK 03 AUDIO
TITLE "Sonata in B flat major, K. 454: 3. Allegretto"
PERFORMER "Mozart"
INDEX 00 06:33:00
FILE "04 - Sonata in A major, K. 526- 1. Allegro molto.wav" WAVE
INDEX 01 00:00:00
The gap appears as an INDEX 00 entry at the end of the information for the previous file, before the file "04 - Sonata in A major, K. 526- 1. Allegro molto.wav" is referenced. The cue sheet says that the pre-track gap for Track 4 starts at 06:33:00 and lasts until the end of the file "03 - Sonata in B flat major, K. 454- 3. Allegretto.wav". The INDEX 01 for Track 4 starts at 00:00:00, which is typically the case in a noncompliant cue sheet.
Corrected gaps cue sheet (for gaps appended to next files):
FILE "04 - Sonata in A major, K. 526- 1. Allegro molto.wav" WAVE
TRACK 04 AUDIO
TITLE "Sonata in A major, K. 526: 1. Allegro molto"
PERFORMER "Mozart"
INDEX 00 00:00:00
INDEX 01 00:09:00
The gap appears as an INDEX 00 entry right before the INDEX 01 entry after the file "04 - Sonata in A major, K. 526- 1. Allegro molto.wav" is referenced. Note that the gap starts at 00 00:00:00 and the audio track at 00:09:00: the cue sheet says that the first 9 seconds of the file is a pre-track gap.
Leftout gaps cue sheet (for gaps left out):
FILE "04 - Sonata in A major, K. 526- 1. Allegro molto.wav" WAVE
TRACK 04 AUDIO
TITLE "Sonata in A major, K. 526: 1. Allegro molto"
PERFORMER "Mozart"
PREGAP 00:09:00
INDEX 01 00:00:00
Similarly to the corrected gaps cue sheet, the gap information directly precedes the INDEX 01 information for Track 4, after the file "04 - Sonata in A major, K. 526- 1. Allegro molto.wav" is referenced. But in this case, the gap is indicated by a PREGAP entry, not an index. This is because the original gap is assumed to be left out, and the gap needs to be added in order for the CD structure to be similar to that of the original CD. INDEX 01 00:00:00 tells that the track itself starts where the file starts.
14b. Single WAV File Cue Sheet
This is the single file cue sheet for the .wav file above:
REM GENRE Classical
REM DATE 1956
REM DISCID 470A4106
REM COMMENT "ExactAudioCopy v0.99pb5"
PERFORMER "Mozart"
TITLE "2 Sonatas for Piano and Violin, KV 454 & 526 (Clara Haskil, Arthur Grumiaux)"
FILE "Mozart - 2 Sonatas for Piano and Violin, KV 454 & 526 (Clara Haskil, Arthur Grumiaux).vaw" WAVE
TRACK 01 AUDIO
TITLE "Sonata in B flat major, K. 454: 1. Largo - Allegro"
PERFORMER "Mozart"
INDEX 00 00:00:00
INDEX 01 00:00:33
INDEX 02 01:46:45
TRACK 02 AUDIO
TITLE "Sonata in B flat major, K. 454: 2. Andante"
PERFORMER "Mozart"
INDEX 00 07:13:33
INDEX 01 07:16:33
TRACK 03 AUDIO
TITLE "Sonata in B flat major, K. 454: 3. Allegretto"
PERFORMER "Mozart"
INDEX 00 15:23:33
INDEX 01 15:25:33
TRACK 04 AUDIO
TITLE "Sonata in A major, K. 526: 1. Allegro molto"
PERFORMER "Mozart"
INDEX 00 21:58:33
INDEX 01 22:07:33
TRACK 05 AUDIO
TITLE "Sonata in A major, K. 526: 2. Andante"
PERFORMER "Mozart"
INDEX 01 28:31:20
TRACK 06 AUDIO
TITLE "Sonata in A major, K. 526: 3. Presto"
PERFORMER "Mozart"
INDEX 00 36:49:70
INDEX 01 36:52:33
The single file cue sheet shows where the gaps (INDEX 00) and the songs (INDEX 01) start in terms of the full CD time. (The time is displayed according to Red Book standard, that is in minutes:seconds:frames - the last measure needs to be a frame, which equals the sector, in order to make sure that splits occur at sector boundaries. 1 frame (or sector) = 1/75th of a second.)
The pregap for Track 4 Sonata in A major, K. 526: 1. Allegro molto starts at 21:58:33, and the song itself starts at 22:07:33. Since this pregap is silent, you will hear 9 seconds of "extra" silence between Track 3 Sonata in B flat major, K. 454: 3. Allegretto and Track 4 Sonata in A major, K. 526: 1. Allegro molto if you listen through the CD without skipping. If you skip straight to Track 4 Sonata in A major, K. 526: 1. Allegro molto, it will start right away, though. (Actually it will start with the 2 seconds of silence that Track 4 starts with, but the point is this:) The CD player will skip past the pregap and start playing where the index indicates that the audio starts (INDEX 01 in the cue sheet).
If you use the single WAV file cue sheet for burning a copy of the CD from the single .wav file (= the "copied image"), the indices for the gap and start of the song will be inserted at the correct place. Here is the transition between Tracks 3 and 4 zoomed in: the greyish section shows where the gap will be.
14c. Multiple WAV Files With Gaps (Noncompliant) Cue Sheet
While a single file rip is most faithful to the original CD structure, it is not very convenient when you rip your CDs in order to listen to your music on your computer or a portable player. Even though you can use the cue sheet in order to skip between the tracks contained in long single file with some players, it is much more convenient to create separate files for the separate tracks.
That means that you have to decide what to do about the gaps between the tracks. The gap handling method that is set as default in EAC is the one that will make listening to the files on a computer or portable player mimic the way the CD behaves when using a stand-alone CD player: the gaps are appended to the previous files. If you play the files straight through (by enquing them or using a playlist), you will hear the silence when there are silent gaps between tracks, but if you skip straight to a track, the audio will start immediately.
This is the noncompliant cue sheet for the example CD:
REM GENRE Classical
REM DATE 1956
REM DISCID 470A4106
REM COMMENT "ExactAudioCopy v0.99pb5"
PERFORMER "Mozart"
TITLE "2 Sonatas for Piano and Violin, KV 454 & 526 (Clara Haskil, Arthur Grumiaux)"
FILE "01 - Sonata in B flat major, K. 454- 1. Largo - Allegro.wav" WAVE
TRACK 01 AUDIO
TITLE "Sonata in B flat major, K. 454: 1. Largo - Allegro"
PERFORMER "Mozart"
PREGAP 00:00:33
INDEX 01 00:00:00
INDEX 02 01:46:12
TRACK 02 AUDIO
TITLE "Sonata in B flat major, K. 454: 2. Andante"
PERFORMER "Mozart"
INDEX 00 07:13:00
FILE "02 - Sonata in B flat major, K. 454- 2. Andante.wav" WAVE
INDEX 01 00:00:00
TRACK 03 AUDIO
TITLE "Sonata in B flat major, K. 454: 3. Allegretto"
PERFORMER "Mozart"
INDEX 00 08:07:00
FILE "03 - Sonata in B flat major, K. 454- 3. Allegretto.wav" WAVE
INDEX 01 00:00:00
TRACK 04 AUDIO
TITLE "Sonata in A major, K. 526: 1. Allegro molto"
PERFORMER "Mozart"
INDEX 00 06:33:00
FILE "04 - Sonata in A major, K. 526- 1. Allegro molto.wav" WAVE
INDEX 01 00:00:00
FILE "05 - Sonata in A major, K. 526- 2. Andante.wav" WAVE
TRACK 05 AUDIO
TITLE "Sonata in A major, K. 526: 2. Andante"
PERFORMER "Mozart"
INDEX 01 00:00:00
TRACK 06 AUDIO
TITLE "Sonata in A major, K. 526: 3. Presto"
PERFORMER "Mozart"
INDEX 00 08:18:50
FILE "06 - Sonata in A major, K. 526- 3. Presto.wav" WAVE
INDEX 01 00:00:00
The below picture shows the end of Track 3, Sonata in B flat major, K. 454: 3. Allegretto ripped with the default gap handling. The gap that precedes Track 4 Sonata in A major, K. 526: 1. Allegro molto has been added to the end of the previous track, that is, Track 3. The cue sheet tells you that the gap for Track 4 starts at 06:33:00 in Track 3. You will find 9 "extra" seconds of silence there in addition to the 3 silent seconds that belong to the audio track itself:
The INDEX 01 for Track 4 says that it starts at 00:00:00, meaning that Track 4 will begin with the start of the referenced file, "04 - Sonata in A major, K. 526- 1. Allegro molto.wav".
14d. Multiple WAV Files With Corrected Gaps Cue Sheet
You can change the way EAC handles gaps after you have detected the gaps. If you for some reason want the gaps to "belong" to the tracks that they precede, you can choose the gap handling method "Append Gaps to Next Track". In this case, you need to create a cue sheet with "corrected gaps".
This is the "corrected gaps" cue sheet for the example CD:
REM GENRE Classical
REM DATE 1956
REM DISCID 470A4106
REM COMMENT "ExactAudioCopy v0.99pb5"
PERFORMER "Mozart"
TITLE "2 Sonatas for Piano and Violin, KV 454 & 526 (Clara Haskil, Arthur Grumiaux)"
FILE "01 - Sonata in B flat major, K. 454- 1. Largo - Allegro.wav" WAVE
TRACK 01 AUDIO
TITLE "Sonata in B flat major, K. 454: 1. Largo - Allegro"
PERFORMER "Mozart"
INDEX 00 00:00:00
INDEX 01 00:00:33
INDEX 02 01:46:45
FILE "02 - Sonata in B flat major, K. 454- 2. Andante.wav" WAVE
TRACK 02 AUDIO
TITLE "Sonata in B flat major, K. 454: 2. Andante"
PERFORMER "Mozart"
INDEX 00 00:00:00
INDEX 01 00:03:00
FILE "03 - Sonata in B flat major, K. 454- 3. Allegretto.wav" WAVE
TRACK 03 AUDIO
TITLE "Sonata in B flat major, K. 454: 3. Allegretto"
PERFORMER "Mozart"
INDEX 00 00:00:00
INDEX 01 00:02:00
FILE "04 - Sonata in A major, K. 526- 1. Allegro molto.wav" WAVE
TRACK 04 AUDIO
TITLE "Sonata in A major, K. 526: 1. Allegro molto"
PERFORMER "Mozart"
INDEX 00 00:00:00
INDEX 01 00:09:00
FILE "05 - Sonata in A major, K. 526- 2. Andante.wav" WAVE
TRACK 05 AUDIO
TITLE "Sonata in A major, K. 526: 2. Andante"
PERFORMER "Mozart"
INDEX 01 00:00:00
FILE "06 - Sonata in A major, K. 526- 3. Presto.wav" WAVE
TRACK 06 AUDIO
TITLE "Sonata in A major, K. 526: 3. Presto"
PERFORMER "Mozart"
INDEX 00 00:00:00
INDEX 01 00:02:38
Note that the gap, INDEX 00, for each track is listed after the file has been referenced; it "belongs" to the track itself.
When you tell EAC to rip with gaps appended to the next track, the gap for Track 4 will be found at the beginning of the file ""04 - Sonata in A major, K. 526- 1. Allegro molto.wav"". This will work nicely with the cue sheet with "corrected gaps". It will tell that the first 9 seconds of that file is to be indexed as a gap. INDEX 00 starts at the beginning of the file, at 00:00:00, and the audio starts at INDEX 01, at 00:09:00. There are 2 more seconds of silence at the beginning the audio track itself. If you skip to Track 4, the music will start after 2 seconds, but if you play through the CD and keep listening after Track 3 has ended, you will have to wait 11 seconds before the music starts. If you play the file ""04 - Sonata in A major, K. 526- 1. Allegro molto.wav"" on your computer or portable player, you will also have to wait 11 seconds for the music to start. This is why ripping with gaps appended to previous tracks is recommended over this method.
14e. Multiple WAV Files With Leftout Gaps Cue Sheet
When you rip a CD and choose the gaps handling method "Leave Out Tracks", the gaps will be stripped from the files.
There are no extra 9 seconds at the end of Track 3 when it has been ripped with gaps left out, there is only the 3 seconds of silence that belong to the audio track itself:
Also, there are no extra 9 seconds at the beginning of Track 4, there is only the 2 seconds of silence that belong to the audio track itself:
So, in order to be able to re-create the CD structure, you will need to have a cue sheet that adds the gaps as you burn the CD. Doing this will only create a copy that is similar to the original CD if the original gaps were indeed silent. If they contained audio and you left out the gaps when ripping, the original CD simply cannot be re-created even if you use the right kind of cue sheet, that is, the one for Multiple WAV Files With Leftout Gaps (shown below). This is because the gaps are added by means of PREGAP entries in the cue sheet, not indexed as parts of the existing files. This is the necessary consequence of leaving the gaps out while ripping the CD and it explains why this is not a recommended method for ripping your CDs.
REM GENRE Classical
REM DATE 1956
REM DISCID 470A4106
REM COMMENT "ExactAudioCopy v0.99pb5"
PERFORMER "Mozart"
TITLE "2 Sonatas for Piano and Violin, KV 454 & 526 (Clara Haskil, Arthur Grumiaux)"
FILE "01 - Sonata in B flat major, K. 454- 1. Largo - Allegro.wav" WAVE
TRACK 01 AUDIO
TITLE "Sonata in B flat major, K. 454: 1. Largo - Allegro"
PERFORMER "Mozart"
PREGAP 00:00:33
INDEX 01 00:00:00
INDEX 02 01:46:12
FILE "02 - Sonata in B flat major, K. 454- 2. Andante.wav" WAVE
TRACK 02 AUDIO
TITLE "Sonata in B flat major, K. 454: 2. Andante"
PERFORMER "Mozart"
PREGAP 00:03:00
INDEX 01 00:00:00
FILE "03 - Sonata in B flat major, K. 454- 3. Allegretto.wav" WAVE
TRACK 03 AUDIO
TITLE "Sonata in B flat major, K. 454: 3. Allegretto"
PERFORMER "Mozart"
PREGAP 00:02:00
INDEX 01 00:00:00
FILE "04 - Sonata in A major, K. 526- 1. Allegro molto.wav" WAVE
TRACK 04 AUDIO
TITLE "Sonata in A major, K. 526: 1. Allegro molto"
PERFORMER "Mozart"
PREGAP 00:09:00
INDEX 01 00:00:00
FILE "05 - Sonata in A major, K. 526- 2. Andante.wav" WAVE
TRACK 05 AUDIO
TITLE "Sonata in A major, K. 526: 2. Andante"
PERFORMER "Mozart"
INDEX 01 00:00:00
FILE "06 - Sonata in A major, K. 526- 3. Presto.wav" WAVE
TRACK 06 AUDIO
TITLE "Sonata in A major, K. 526: 3. Presto"
PERFORMER "Mozart"
PREGAP 00:02:38
INDEX 01 00:00:00
14f. Using the Wrong Kind of Cue Sheet
So, what happens if you use the wrong cue sheet for burning backups of your CDs? Well, the results will be variously disastrous depending on the combination of gap handling and cue sheet, and the length of the gaps on the CD (assuming that there are any, of course). Testing the example CD showed that EAC protested against using the noncompliant cue sheet, that should be used with files with gaps appended to previous tracks, with files ripped with gaps left out. That was luck, due to the length of the gaps.
EAC had no objection, though, to burning a CD from files ripped with gaps appended to previous tracks using a cue sheet for files with gaps appended to the next track. The result is undesirable: skipping to the example Track 4 on the CD player shows that the music has already started when the track starts. The beginning of the track is lost:
This is what happened: the file that was ripped with gaps appended to previous tracks was "told" by the cue sheet for files ripped with gaps appended to the next track that the first 9 seconds of the file is a gap, so that the audio track should start 9 seconds into the file. Here is the original file, with the "gap" greyed out (those 9 seconds can still be heard on the burnt CD if you listen to Track 3 and keep playing through the gap before Track 4):
This is just one example. Different wrong combinations of gap handling and cue sheet will have different results for different CDs, but if there are gaps, wrong combinations will always make a difference compared to the original CD. So, in the end I still strongly recommend ripping to multiple files using the default gap handling (append gaps to previous tracks) and creating a noncompliant cue sheet to go with it. After reading this you will be able to determine what it is if you encounter an old cue sheet that does not look like a noncompliant one does, and hopefully you will also be able to figure out how to deal with it.
