On Wed, Mar 19, 2008 at 11:33 PM, Robert William Fuller <[EMAIL PROTECTED]> wrote: > Basically, READ SUB-CHANNEL is a great interface for displaying track > time when you're playing a disc. It otherwise sucks. That is why in > cued I use MMC READ CD to get the Q sub-channel data. It works at high > speed and it doesn't play music. It's great for ripping. > Unfortunately, not all drives support reading the Q sub-channel with MMC > READ CD because that part of MMC READ CD is optional, and there's no > feature test to answer the question "does MMC READ CD support reading > the Q sub-channel?"
You're definitely right to avoid the READ SUB-CHANNEL command. I remember looking into it some time ago and thinking it was a mess too. But what about using READ CD to read RAW P-W subchannel data? I thought RAW P-W was more widely supported, as it required the drive to do less. (It's still optional, but it's a lot easier to implement than Q extraction.) I also thought that reading RAW P-W allowed you get a better sync with the audio, whereas Q was not guaranteed to be sector-matched with the audio you're playing. Among other things, it looks like RAW P-W format (2448 = 2352+96) can also be used to get the subchannel data for the disc lead-in. I doesn't appear that you can do that with just Q queries. And P-W seems to be required to support CD+G, if we ever get there. So what do you think about issuing a RAW P-W read and then extracting whatever subchannels you want in software?
