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Hi. I've been tinkering a bit with cd image contents, and noticed that whenever I make an image of an image mounted onto a daemon tools virtual drive, only the initial sector of a track contains '1's in the P subchannel. Everything preceding it is zeroes.
On real cds, every track is preceded by a 2+ second (149+ sectors) interval where P = 1, ending with the first sector of the track, so 150 sectors in total. This also applies to the final track, followed by the lead-out track (which is not accessible).
According to the spec,
"The minimum length of a Flag (i.e. a continuous sequence of ONEs in the p-channel) shall be 2 s (i.e. 150
Sections). The p-channel of the last Information Track in the User Data area shall end with a Flag of 2 s to 3 s (i.e. 150 to
225 Sections). Its end shall indicate the beginning of the Lead-out Track."
Current DT behavior can be exploited to identify images that were made from a daemon tools virtual drive, and to identify that a drive is a daemon tools virtual drive (assuming that a real drive would have to conform to the standard to get a license). I can provide a proof-of-concept DT virtual drive/image detection tool if you're interested.
Also, burning of such cd images in DAO96 mode might cause playback issues in drives that might, for some reason, rely on the P subchannel. Not sure if drives like that still exist, but if hardware still conforms to the standard, then why not make DT do it too?
On real cds, every track is preceded by a 2+ second (149+ sectors) interval where P = 1, ending with the first sector of the track, so 150 sectors in total. This also applies to the final track, followed by the lead-out track (which is not accessible).
According to the spec,
"The minimum length of a Flag (i.e. a continuous sequence of ONEs in the p-channel) shall be 2 s (i.e. 150
Sections). The p-channel of the last Information Track in the User Data area shall end with a Flag of 2 s to 3 s (i.e. 150 to
225 Sections). Its end shall indicate the beginning of the Lead-out Track."
Current DT behavior can be exploited to identify images that were made from a daemon tools virtual drive, and to identify that a drive is a daemon tools virtual drive (assuming that a real drive would have to conform to the standard to get a license). I can provide a proof-of-concept DT virtual drive/image detection tool if you're interested.
Also, burning of such cd images in DAO96 mode might cause playback issues in drives that might, for some reason, rely on the P subchannel. Not sure if drives like that still exist, but if hardware still conforms to the standard, then why not make DT do it too?