Nero and CD+G cuesheets

vbimport

#1

Hello all.

While I was looking for a burning program as recommendation to PerfectRip users
so they can write their CD+G cuesheets I got sadly surprised, not much software available…
and I got even more frustrated when I realised all of the few write only out of spec discs.

If one of the “compatible” programs had to be chosen it would be Nero, given its few flaws
in comparation with the others. Nero writes Philps style pauses, of course this is not a fault,
just letting you know, well, it’s time to describe this program’s ugly mistakes…

Here comes a dump from the original disc:

I enclosed R-W subcoding blocks inside the red rectangles, please note the offsets.


#2

Now compare them with the ones of this dump from the burnt disc:



#3

See? Channels R-W (graphics information) are shifted by two zeroed subcoding blocks,
probably this is not against the spec, but makes copy unfaithful to the original,
especially compared with the ones from programs like CloneCD.

Now look at this dump from the original CD+G, note the beginning and end of the start flag:



#4

Now compare with the start flag’s beginning and end in this burnt disc’s dump.



#5

Spec says “The encoding of channel P is delayed by one subcoding block
with respect to the encoding of channel Q.”, as you can see, the track’s
start flag gets shifted back by the size of a subcoding block
with respect to the original, rendering an out of spec copy.

Finally, a rewritable disc, a Premium II and CDTool allowed me
to explore inside the leadout. Focusing again on the P channel,
I saw a sequence like this: 225 Lo, 18 Hi, 37 Lo, 37 Hi, 37 Lo, 37 Hi…

[LEFT]“The lead-out track shall be preceded by a start flag of 2 s to 3 s
(during the last audio track on the disc). The end of the start flag
shall indicate the beginning of the lead-out track. Channel P shall
remain zero for 2 s to 3 s after the start of the lead-out track,
next P switches between 0 and 1 in a 2 Hz ± 2 % rhythm
(duty cycle 50 % ± 10 %).”[/LEFT]

[LEFT]Mentioned spec’s statement’s compliant sequence would be this:
1 Hi, 150 Lo to 225 Lo, 19 Hi, 19 Lo, 19 Hi, 19 Lo…[/LEFT]

[LEFT]I definitely don’t like what Nero does, let alone the rest of the software
(one of them even mixes subcode blocks inside main channel! :a ).
If you come across a CD+G cuesheet you can burn it and make a
clonic image of the resultant disc so you can fix the start flags
shifting them forward by a block in an hexadecimal editor
before burning, however, if you know how many subcode
blocks has the start of the graphics advanced you can
shift them back in place too, of course you need to code,
after burning the leadout will be fixed automatically.[/LEFT]


#6

I have to say this is all very impressive, I am trying to understand most of it but I am afraid my knowledge of this is very limited, but as I said, great work and hopefully following this thread I can figure it out.:bigsmile::bigsmile: