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Re: [Libcdio-devel] CD-TEXT documentation
From: |
Thomas Schmitt |
Subject: |
Re: [Libcdio-devel] CD-TEXT documentation |
Date: |
Mon, 06 Feb 2012 14:38:39 +0100 |
Hi,
> One small thing I've noticed is that there is mention to mm5r03.pdf
> and that is not in the references.
Good point. I have looked up the equivalent spots in MMC-3:
mmc5r03c.pdf, table 490 TOC Track Descriptor Format, Q Sub-channel
=>
mmc3r10g.pdf, table 237 TOC Track Descriptor Format, Q Sub-channel
mmc5r03.pdf 4.2.3.7.4
=>
mmc3r10g.pdf 4.2.3.6.3
> Overall the cdtext.txt feels to me like the audience is a computer
> rather than a person.
It is a description for developing CD-TEXT software.
Goal was to collect everything that is known and can be confirmed.
> Instead, I think it better to assume the audience are humans.
Well, man cdrskin explains some user aspects of CD-TEXT.
http://scdbackup.webframe.org/man_1_cdrskin.html
The libburn API description mentions CD-TEXT with several calls:
http://libburnia-project.org/browser/libburn/trunk/libburn/libburn.h
I simply lack of any user experience with audio CDs and/or CD-TEXT.
I can compose the packs, i can write them, i can read them, i can parse
them, but whether and how they work on a CD player: no clue.
> So I find it more user friendly to say you can store information
> about 8 languages rather than say there is a limit on 8 blocks.
Agreed.
> The same kind of thing with mentions of xor'ing 0xffff. That is
> C-centric computer jargon. The intent is that there's a 16-bit number
> there, that's what I think the designers were interested in. So it is
> equally valid to use a modulo 2**16 or if (x > 2**16) if the language
> you have doesn't provide xor.
I am currently not aware of the mathematical reason for the final
bit inversion of the division residue. It is not equivalent to modulo
alone (that would be and-ing, rather than xor-ing).
In the model of polynoms there would be a subtraction or addition involved.
To my knowledge the CD-TEXT CRC algorithm differs only by this final
bit inversion from the CRC algorithm that is mentioned in ECMA-167 7.2.6
for UDF descriptor tags.
The ECMA-167 example {0x70, 0x6a, 0x77} yields division residue 0x3299 and
CD-TEXT CRC 0xcd66. ECMA-167 predicts 0x3299.
Have a nice day :)
Thomas
- Re: [Libcdio-devel] CD-TEXT documentation, (continued)
- Re: [Libcdio-devel] CD-TEXT documentation, Rocky Bernstein, 2012/02/04
- Re: [Libcdio-devel] CD-TEXT documentation, Thomas Schmitt, 2012/02/04
- Re: [Libcdio-devel] CD-TEXT documentation, Leon Merten Lohse, 2012/02/04
- Re: [Libcdio-devel] CD-TEXT documentation, Thomas Schmitt, 2012/02/04
- Re: [Libcdio-devel] CD-TEXT documentation, Rocky Bernstein, 2012/02/04
- Re: [Libcdio-devel] CD-TEXT documentation, Thomas Schmitt, 2012/02/05
- Re: [Libcdio-devel] CD-TEXT documentation, Rocky Bernstein, 2012/02/05
- Re: [Libcdio-devel] CD-TEXT documentation, Thomas Schmitt, 2012/02/05
- Re: [Libcdio-devel] CD-TEXT documentation, Rocky Bernstein, 2012/02/05
Re: [Libcdio-devel] CD-TEXT documentation,
Thomas Schmitt <=
- Re: [Libcdio-devel] CD-TEXT documentation, Rocky Bernstein, 2012/02/06
- Re: [Libcdio-devel] CD-TEXT documentation, Thomas Schmitt, 2012/02/06
- Re: [Libcdio-devel] CD-TEXT documentation, Rocky Bernstein, 2012/02/06
- Re: [Libcdio-devel] CD-TEXT documentation, Thomas Schmitt, 2012/02/06
- Re: [Libcdio-devel] CD-TEXT documentation, Rocky Bernstein, 2012/02/07
- Re: [Libcdio-devel] CD-TEXT documentation, Thomas Schmitt, 2012/02/08
- Re: [Libcdio-devel] CD-TEXT documentation, Rocky Bernstein, 2012/02/08
- Re: [Libcdio-devel] CD-TEXT documentation, Thomas Schmitt, 2012/02/08
- Re: [Libcdio-devel] CD-TEXT documentation, Rocky Bernstein, 2012/02/08
- Re: [Libcdio-devel] CD-TEXT documentation, Thomas Schmitt, 2012/02/08