Re: What exactly does DKIOCCDREAD return for kCDSectorAreaSubChannelQ?
Re: What exactly does DKIOCCDREAD return for kCDSectorAreaSubChannelQ?
- Subject: Re: What exactly does DKIOCCDREAD return for kCDSectorAreaSubChannelQ?
- From: Dan Markarian <email@hidden>
- Date: Mon, 5 Jun 2006 10:24:46 -0400
Hi Stephen,
My source for this MMC-2, section 4.2.2.
Here is my confusion: 96 bits of subcode data = 12 bytes of data.
Yet, according to IOCDTypes.h the Q subcode data returned by
DKIOCCDREAD is 16 bytes. Can anyone shed some light on this matter?
See tables 223 and 224 under READ CD. Its physical structure is a
different affair.
Dan
Le 4 Jun 2006 à 1:53 AM, Stephen F. Booth a écrit :
I am a bit confused as to the exact format of the data returned by
the result of a DKIOCCDREAD ioctl() when reading the Q sub-channel
of a CD-DA disc. Everything I have read up to this point states
that the subcode data from an audio CD is 96 bits long. With this
in mind, I expect to see (for a single CD-DA frame):
- 4 control bits
- 4 address bits
- 72 data bits
- 16 bits of CRC
= 96 bits for the general structure, with the data bits looking
like (for the program area):
- 8 bits each for TNO, INDEX, MIN, SEC, FRAME, ZERO, AMIN, ASEC,
AFRAME
My source for this MMC-2, section 4.2.2.
Here is my confusion: 96 bits of subcode data = 12 bytes of data.
Yet, according to IOCDTypes.h the Q subcode data returned by
DKIOCCDREAD is 16 bytes. Can anyone shed some light on this
matter? I've probably missed something obvious, but I'm stumped.
Thanks,
Stephen
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