Additional Ripping Stratagies

[EliC]

I am VERY new to this. I have been reading and exploring quite a bit trying to learn about the hardware end of ripping. I have also been looking at ways of detecting copy protected discs so that these could be automatically identified and dealt with.

In a previous thread I had asked about a theoretical drive with the ability to disable drive interpolation. This would increase the randomness of errors and decrease the risk of consistent errors.

I have also asked about reading subcode data. There is a fair amount of information in the subcodes. I started looking at this because the Cactus Data Shields discs use DATA frames in the middle of AUDIO frames to create intentional errors. By reading the subcode the CD player knows that its a DATA frame, interpolates/mutes the frame and the disc is read without problem. It should be easy to identify these discs if the SubCode is read because there should not be DATA frames in the middle of a normal AUDIO disc.

Most CD drives can respond to a RAW ReadCD command that will read the disc WITHOUT interpolation AND report subcode.

This is not currently taken advantage of in dBpoweramp (or EAC).

Ideally, there should be an option to do a first pass in RAW mode, reading the interleaved audio and subcode. From here software can/could identify CDS discs AND reconstruct C1/2 error data, and well as utilize the de-interlaced audio and check against accuraterip.

[Spoon]

Re: Additional Ripping Stratagies

>Most CD drives can respond to a RAW ReadCD command that will read the disc WITHOUT interpolation AND report subcode.

This would not read without interpolation, infact reading audio off the disc is in raw read mode.

[EliC]

Re: Additional Ripping Stratagies

Sorry, I certainly don't claim to be an expert. Just going off what the guys over at CDFreaks are indicating, and they seem to know way more then me. I may have well gotten something wrong. I am actively trying to educate myself on the subject.

[EliC]

Re: Additional Ripping Stratagies

Hmmm, looks like there may be a way to rip without interprolation. Still alot of understanding to do on my part:

http://club.cdfreaks.com/f52/firmware-vs-chipset-vs-hardware-features-299668/

read the last post by Spath

You just have to look up the datasheets of chipsets and
read them. For instance, take this NXP datasheet :
http://www.nxp.com/*blooper*/pip/pip=[pip=SAF784X_2]|pp=[t=pip,i=SAF784X_2]

On page 18 you will see after the CIRC a multiplexer, which
allows to bypass the interpolator, and which is apparently
controlled by some bits in register 01F0. So a firmware just
has to toggle this bit to disable interpolation.

Note that the DAP bit in the READ-CD command allows disabling
of interpolation by any PC tool for mmc-4 compliant drives.

[bhoar]

Re: Additional Ripping Stratagies

Hmmm, looks like there may be a way to rip without interprolation. Still alot of understanding to do on my part:

http://club.cdfreaks.com/f52/firmware-vs-chipset-vs-hardware-features-299668/

read the last post by Spath

I suspect the ability to harness:

Note that the DAP bit in the READ-CD command allows disabling
of interpolation by any PC tool for mmc-4 compliant drives.

...seems likely to have poor support in the marketplace due to complex audio features being a much less strong area of interest (vs. dvd/hd support) now that drives are basic commodities. I would love to be wrong about this.

EDIT: looking closer at 06-155r0.pdf (the Mt. Fuji extensions v6 March 9, 2006), I assume most software coded to pre-MMC-4 (that is, 99% of what is out there) already puts a 0 bit in that field when making the call. Which for MMC-4 drives that support the DAP bit would tell the drive to disable drive interpolation. The question is, do pre-DAP-bit drives tend to default to active interpolation in READ CD and READ CD MSF commands...or not? I do not know, and therefore don't know if MMC-4 drives that support the optional DAP bit (note that this is still an optional feature with MMC-4) would act any different than older drives (in general...) when accessed using existing software.

-brendan