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 Post subject: Understanding CD-ROM/XA
PostPosted: Sun Mar 21, 2010 5:20 pm 
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Hi,

maybe you can answer a question I have on those CD-ROM modes/forms.

cdrfaq.org summarises the modes and forms like this:

Code:
MODE-1
    standard 2048-byte Yellow Book sectors, with error correction
MODE-2
    2336-byte sectors, usually used for CD-ROM/XA
CD-ROM/XA
    eXtended Architecture; CD-ROM/XA MODE-2 defines two forms:

    FORM-1
        2048 bytes of data, with error correction, for data
    FORM-2
        2324 bytes of data, no ecc, for audio/video


Based on the other information I have found on the internet "CD-ROM/XA" is not actually widely used. For example, Wikipedia states:

Quote:
It was intended as a bridge between CD-ROM and CD-i (Green Book), and was developed by Sony and Philips. "XA" stands for "eXtended Architecture".


and http://www.ardenwoodsnd-dvd.com/glossary/glossary_c.html#cd-rom%20xa says:

Quote:
An extension to the Yellow Book standard which utilizes the Mode 2 data format,[...] CD-ROM XA did not develop very far as a multimedia format, but Photo CD discs are written in the CD-ROM XA physical format.


Yet, you write in the ImageBurner docs:

Quote:
VARIANT_BOOL IsXA Indicates that image (IsXA) will be burned in MODE2 mode. Specify the IsXA parameter if you try to burn DATA image and keep this parameter FALSE if you try to burn AUDIO content.


So in other words: All data is written as Mode2 (XA)/Form1, even though the XA format doesn't seem to be of any significance.
Then again, you also write:

Quote:
STARBURN_TRACK_MODE2_FORM1: This mode usually used for computer data, has the same user data and error correction as STARBURN_TRACK_MODE::MODE1, but with a slightly different layout. Its use is not recommended for compatibility reasons.


Why burn as XA if it causes compatibility problems? Can you explain this to me please? :)


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 Post subject: Re: Understanding CD-ROM/XA
PostPosted: Sun Mar 21, 2010 8:29 pm 
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CDROM XA is used for extended capacity when burning video tracks (Video CD & Super Video CD). For MODE1 and MODE2/Form1 there's no difference to the user, payload is still 2K, it's only raw sector format is different (the one you don't see).


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 Post subject: Re: Understanding CD-ROM/XA
PostPosted: Mon Mar 22, 2010 4:45 am 
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Sorry, but I still do not understand.

Why has CDROM/XA (Mode2/Form-2) an extended capacity? Wouldn't just Mode2 have this as well?

If Mode1 and Mode2/Form-1 is basically the same, why is there an "XA" Parameter that suggests that StarBurn uses the less compatible Mode2/Form-1 mode instead of Mode 1?

Please be a bit more specific, I won't stop asking anyway if you do not precisely answer my questions ;)


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 Post subject: Re: Understanding CD-ROM/XA
PostPosted: Mon Mar 22, 2010 8:27 am 
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B/c raw sector format is 2448 bytes and you use only 2048 bytes for user data in case of data, 2324 bytes for video content and 2352 for audio (both later ones has no ECC/EDC recovery).

I did not say MODE2/Form1 is less compatible them MODE1.

flöle wrote:
Sorry, but I still do not understand.

Why has CDROM/XA (Mode2/Form-2) an extended capacity? Wouldn't just Mode2 have this as well?

If Mode1 and Mode2/Form-1 is basically the same, why is there an "XA" Parameter that suggests that StarBurn uses the less compatible Mode2/Form-1 mode instead of Mode 1?

Please be a bit more specific, I won't stop asking anyway if you do not precisely answer my questions ;)


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 Post subject: Re: Understanding CD-ROM/XA
PostPosted: Mon Mar 22, 2010 3:45 pm 
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Quote:
I did not say MODE2/Form1 is less compatible them MODE1.


You didn't, but the docs say so. Why?

anton (staff) wrote:
B/c raw sector format is 2448 bytes and you use only 2048 bytes for user data in case of data, 2324 bytes for video content and 2352 for audio (both later ones has no ECC/EDC recovery).


So is video Mode2/Form-2 (XA) and audio Mode2 (CDDA)? Is that the difference between the usage of XA and non XA? Still, why use XA for data and not Mode1?
I hate to say that, but so far you didn't actually answer my questions.


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 Post subject: Re: Understanding CD-ROM/XA
PostPosted: Mon Mar 22, 2010 5:02 pm 
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When you burn Video CD first track is always data, it's written in MODE2/Form1 (as the whole disc is CD-ROM XA) and second (and other) tracks are MODE2/Form2. So you can assume pure MODE2/Form1 disc as Video CD w/o main MPEG track.


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 Post subject: Re: Understanding CD-ROM/XA
PostPosted: Mon Mar 22, 2010 5:17 pm 
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OK, and what about the docs? Why does it say that one mode is less compatible?
And if data == IsXA, are all data discs (putting special cases like VCDs aside) XA? And if so, is Mode1 used for anything at all?


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 Post subject: Re: Understanding CD-ROM/XA
PostPosted: Mon Mar 22, 2010 5:44 pm 
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B/c MODE1 was first and MODE2/Form1 is it's successor.

Yes.

flöle wrote:
OK, and what about the docs? Why does it say that one mode is less compatible?
And if data == IsXA, are all data discs (putting special cases like VCDs aside) XA? And if so, is Mode1 used for anything at all?


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 Post subject: Re: Understanding CD-ROM/XA
PostPosted: Mon Mar 22, 2010 5:51 pm 
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So if I understand you correctly, your documentation is wrong about this one?

Quote:
STARBURN_TRACK_MODE2_FORM1: This mode usually used for computer data, has the same user data and error correction as STARBURN_TRACK_MODE::MODE1, but with a slightly different layout. Its use is not recommended for compatibility reasons.


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 Post subject: Re: Understanding CD-ROM/XA
PostPosted: Mon Mar 22, 2010 6:33 pm 
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If there's no need to burn in MODE2/Form1 - burn in MODE1.


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 Post subject: Re: Understanding CD-ROM/XA
PostPosted: Mon Mar 22, 2010 6:52 pm 
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Here are some old discussions:

http://www.cdrlabs.com/forums/mode-versus-mode-discs-t8075.html

MODE1 is always supported but I can bet all the hardware imcompatible with MODE2/Form1 is dead for ages :)


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 Post subject: Re: Understanding CD-ROM/XA
PostPosted: Mon Mar 22, 2010 8:08 pm 
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Thanks, seems like we are getting closer.
For now, one last question: If XA is basically "better" or just as good as Mode1/Mode2, is there any reason to set the IsXACDROM property of the AudioBurner class to false? (Or true?) What difference does it make for audio discs in particular? Does it only matter for mixing audio tracks with data tracks?


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 Post subject: Re: Understanding CD-ROM/XA
PostPosted: Tue Mar 23, 2010 6:59 pm 
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For Audio CD it does not matter at all :)

flöle wrote:
Thanks, seems like we are getting closer.
For now, one last question: If XA is basically "better" or just as good as Mode1/Mode2, is there any reason to set the IsXACDROM property of the AudioBurner class to false? (Or true?) What difference does it make for audio discs in particular? Does it only matter for mixing audio tracks with data tracks?


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 Post subject: Re: Understanding CD-ROM/XA
PostPosted: Tue Mar 23, 2010 7:19 pm 
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Then...why does this option actually exist? At some point I suppose someone requested that feature because he wanted to do {X} which is only possible with XA (or without). I mean, if I expose this option in my GUI (I do), I should be able to explain why someone would need that. But right now, I can't.


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 Post subject: Re: Understanding CD-ROM/XA
PostPosted: Tue Mar 23, 2010 7:42 pm 
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B/c it's general option for Track-At-Once burning. And it's set in the "write parameters mode page" for all of the possible write types: data, audio & video. For data & video it make sense for audio it's simply ignored.


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