Re: protocol analysis "disc get title"

On Thu, Jan 02, 2003 at 01:22:55PM +1100, Michael Davidson wrote:
> > Snip.
> 
> On the subject of obtaining the disc title...
> 
> A while ago I reported that the current get disc title command we send to the 
> player will only return a total length, including the protocol stuff, of 255. 
> I was just wondering if anyone else has encountered this or if anyone has any 
> clues on the way around it? Perhaps toggling some of the seemingly 
> insignificant bits will return the remainder of the disc title?

Doesn't seem so.  But good that you mention this, because I just tried a
very long raw title.  Wasn't easy to produce, the MZ-N707 only allows 200
characters per title.  But a title plus a group title does the trick:

09 18 06 02 20 18 01 00 00 30 00 0a 00 10 00 00 d8 00 00 01 55 00 0a 01 51
30 3b 41 42 20 ...

("51 30 3b 41 42 20" is `0;AB ')

Here we see that the total length is 0x0151.  The first packing of that has
0x0155 bytes.  But look at the third variable, which usually is the length
plus six!  Alas, it is 0x00d8.  The same 0x00d8 value is returned for all
title strings larger than 0xd2.

However, there also seems to be a limit to 255 in netmd_poll_for_reply.  I
don't know if this is a limitation in the USB code, the protocol, or if we
are not smart enough.  I don't have an OMG JukeBox sniffer environment,
maybe someone else can check what OMG does with such long titles.

Thanks,
Marcus

-- 
`Rhubarb is no Egyptian god.' GNU      http://www.gnu.org    [email protected]
Marcus Brinkmann              The Hurd http://www.gnu.org/software/hurd/
[email protected]
http://www.marcus-brinkmann.de/