Hydrogenaudio Forums > Gaps and CD-Rom Drives

Hydrogenaudio Forums > CD-R and Audio Hardware > CD Hardware/Software

Xenion

Jul 8 2002, 08:10

Gaps seem to be a problem in connection with CD-Rom Drives (Plex 40TS). EAC detects the Gaps on the silence in tracks which is nonsence I think, because sometimes tracks begin with a silence or a fade in. so on my CDs EAC often gaps of 2-5 seconds where actually no gaps should be found, because there is a silence in a track. and between a gap and a silence is still a particular difference. I guess the problem is, that CD-Rom drives can't read gaps. I dont think that a standalone CD player detects a gap because of a silence in a track. a cd player would have to scan the track first and then if there would be a 0% peak level found it would display a pre gap.....

I think CD players only display a gap if they get the information from the CD that there <IS> a gap. why can't EAC detect it that way ?!? the only explanation I have is that cd rom drives can't read gaps. (only detect because of a silence/ peak level 0)

maybe there should be a feature implemented in eac where you can set the gaps manually, because you can easily find out which gap lenth a CD has when you put it into a CD player... and normally the gap setting should be same on the whole cd / all tracks.

the only thing you can do at the moment in EAC is to append the gap to the "next" track (and not the previous or even leave the gap completely out) and edit the cue sheet then manually.....

hm

GeSomeone

Jul 8 2002, 09:05

QUOTE

Originally posted by Xenion
I think CD players only display a gap if they get the information from the CD that there <IS> a gap. why can't EAC detect it that way ?!?

There are no real "gaps" on an (Audio) CD. It's (decoded as) one long track.
There are however also frames in between that contain so called "sub code". If I remember correctly those contain the track, index and time information (and room for extra stuff). The part usualy nicknamed gap is just the "index 0" part of a track. The Audio CD player then only displays what it reads.

In fact it is possible to stick audio in a "gap" (index 0). This is not compliant to the original specs, but has been done, I think on a Limp Bizkit CD.

EAC has 3 methods for determining the gaps, I'm not which does what (some don't work with all drives). But if it could use the sub-codes it would be the best.
--
Ge Someone

quellcore

Jul 8 2002, 09:35

QUOTE

Originally posted by Xenion
I think CD players only display a gap if they get the information from the CD that there <IS> a gap. why can't EAC detect it that way ?!? the only explanation I have is that cd rom drives can't read gaps. (only detect because of a silence/ peak level 0)

The gab informations are stored in the TOC, if the TOC is correct (I think it's pretty common to use wrong TOC information for copy protection) then EAC should place the (pre-)gaps correctly.
If you have [b]Feurio! installed, just check the helpfile for very useful hints about index, index0, etc....
If you haven't installed it here's the most importanat section about that subject, unfortunately just in german (but shouldn't be a problem for you i guess). Sorry, but i haven't installed the englisch part!

QUOTE

Feurio Fragen & Antworten - Begriffserklärung:
Indizies

Eine CD ist (wie sicher jedem bekannt) in mehrere Tracks eingeteilt.

Ein Track wiederum kann in mehrere Indizes eingeteilt werden.

Die Track-Indizes beginnen mit 0 oder 1 und können bis zu 99 gehen.

Die Track-Indizes (außer Index 0 und 1) werden aber heutzutage kaum noch verwendet. Bei z.B. einigen Klassikaufnahmen werden einzelne Sätze innerhalb eines Stückes mit Indexmarken “markiert”.

Einige CD-Player können Indizes direkt anspringen.

Eine besondere Rolle spielt der Index 0.

Index 0 enthält normalerweise Stille und stellt die Pause zwischen den Tracks dar.

Auf der CD wird im CD-Inhaltsverzeichnis (der “Table of Contents) die Startposition jedes Tracks gespeichert; allerdings wird hier die Position vom Index 1 angegeben.

Dies hat zur Folge, dass bei der direkten Anwahl eines Titel der Index 0 übersprungen wird! (Der CD-Spieler beginnt direkt mit Index 1)

Der Index 0 (und damit die Index-0-Stille) wird also NUR bei einem kontinuierlichen Abspielen der CD ausgegeben!

Manche CD-Spieler erlauben sogar das Überspringen der Index-0-Stille.

Praktisch alle CD-Spieler geben daher Index 1 eines Tracks als Position 0 aus, der Index-0-Bereich wird in der Regel durch negative Werte angezeigt. (Der Feurio!® CD-Player arbeitet genauso)

Ab Index 1 folgen dann die “normalen” Samples des Tracks.

Für besondere Anwendungen kann aber auch der Index-0 Bereich mit Musikdaten beschrieben werden - siehe “Index-0-Musik”.

aus: Feurio CD-Writer Online-Hilfe © by Fangmeier Systemprogrammierung

Xenion

Jul 8 2002, 10:14

yes I know that the gaps are in Track 00, because when you go to some track manually the CD player doesn't read track 00 but goes to 01 directly... my cd player (not cd rom) can also go the an index like 02, 03 04... directly (sony cdp xa 30es)...

but how can I make my cd rom/eac read the 00 track correctly ?

I dont understand why eac (at least at my drive) doesn't read the 00 track
why detect this stuff on a silence, which is something manual... and not exact

my drive also reads indexes like 02,03etc as EAC writes them properly in the cue sheet file if I copy a cd with 02,03etc indexes. so it should be able to read the 00 track also, shouldn't it ?

or is this feature just missing in EAC ?

I still don't know what the A,B,C methods mean...
I guess those are different methods of DETECTING the 0% peak level and not just READ the 00 track which would be the easiest and most efficient way

quellcore

Jul 8 2002, 16:20

I got a Plex 32TS, so should behave similar to yours! Have u tried to disable "Delete leading and trailing silent blocks"?
I usually have it enabled, but it's worth a try!

Xenion

Jul 8 2002, 17:50

QUOTE

Originally posted by quellcore
I got a Plex 32TS, so should behave similar to yours! Have u tried to disable \"[b]Delete leading and trailing silent blocks\"?
I usually have it enabled, but it's worth a try!

hm I have it enabled too
but it doesn't make a diffenrence anyway when have it disabled

Pio2001

Jul 9 2002, 05:04

What's the problem with gap detection ? Doesn't it work ? It's a basic function of EAC, just "detect gaps" and gaps are read from the subchannel data (I don't think they are in the TOC). A, B, and C are three ways of reading subchannel data.

Gaps contain audio data. CDs with digital silence between tracks are not common. Every old CD from analog masters have analog noises in the gaps (exept those that were digitally remastered), and most classical recording have background noise in the gaps.

Xenion, what's going wrong when you're detecting gaps ? Doesn't it work ?

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