Now that we have some facts on what is on the DVD chip, I would like to comment on what I saw in the press release. Surely there are some others out there on the thread who know more about drive and channel technology or the DVD market who can also comment. This is a new market for Cirrus and it seems like it could potentially be a big one.
Does anyone know what competition they face on the controller side? From my understanding of the press release they are not competing with the MPEG2 decoder chips from people like CUBE. (The release says "the CR3700 provides a direct interface to MPEG-2 audio and video decoders for DVD-Player applications.") Are the other read channel players (Lucent, TI, etc.) going to get into DVD controllers? Does anyone know who competed with CRUS in CD-ROM controllers? Presumably they would be potential DVD competitors as well.
I found the description of the DVD chip interesting and have some questions and comments:
"The new chip combines an RF Amp"
Presumably this is similar to the variable-gain amplifier used in their read-channel disk-drive chips. However, they don't say that's it's variable gain, which it would have to be if they are using true PRML.
"PRML data channel (read-channel),"
I still have trouble believing they're implementing true PRML; more on that later.
"servo controller,"
Recently (within the last couple generations) integrated onto the disk-drive controller, it makes sense that it would be integrated on DVD as well.
"content scramble system (CSS),"
I presume this is the encoding system that Hollywood wanted to prevent DVD's from being copied. Does anyone know for sure?
"DVD Error Correction Code (ECC),"
CRUS had a lot of expertise and patents in ECC for disk drives. Again, it makes sense to see that applied to DVD.
"and a decoder with an ATAPI interface."
This is presumably copied from CRUS CD-ROM controllers. In fact the release goes on to say later that the firmware for this chip is compatible with CRUS CD-ROM line of chips.
Now for more on PRML:
"The CR3700 integrates Cirrus Logic's industry-leading read-channel architecture with PRML technology. With PRML, analog pulses are converted onto the digital domain so that the inherent noise generated by the analog signal can be digitally filtered. This proven technique allows data to be read in worst-case signal-to-noise-ratio scenarios, significantly improving the drive's overall performance and enhancing
the end-user's experience."
Unless somebody can show me why I'm wrong, I think CRUS is using the term PRML in a bastardized sense to try to get marketing value out of it. I do not see how partial response can be implemented with optical drives. What they are describing above appears to be the application of a maximum likelihood detector. That is a nice idea, but it's not really PRML and I doubt if it's covered by CRUS patents. I think the heart of CRUS PRML patents deal with EEPR4 partial response technology and the Viterbi detector algorithms needed to decode and encode the data. Don't see either of those being applicable here. So while they appear to have incorporated some nice things from PRML into the DVD read/write channel, it's not really as revolutionary as they are trying to make it seem. Anyone care to disagree or have any additional insight into this?
Overall I am happy to see this chip come out, and I think it should be a good market for CRUS.
G.P. |
