Inexpensive Media Recognition for Optical Disks Maurice Maes Joop Talstra

CPTWG 28 november, Problem Setting (1) For copy-protection, a DVD player must distinguish between: – read-only disks DVD-Video – recordable/rewritable disks DVD-R(W) DVD+R(W) DVD-RAM

CPTWG 28 november, Problem Setting (2) Pre-recorded content is encrypted (CSS/CPPM). Encryption alone does not offer protection against bit- copies. Therefore, Recordable Media Playback Control is needed: refuse to play back (CSS/CPPM) encrypted content on recordable media. Problem: how to implement this for all recordable media at low cost

CPTWG 28 november, Previously Proposed Solutions How to distinguish a (re)writable disk from a read- only disc? –ROM-wobble (proposed by Philips) –reflectivity & single/dual-layer & book-type (WG9) useful, but not very reliable –pre-embossed area useful, but doesn’t exist for all disk-formats –pregroove-wobble

CPTWG 28 november, Pregroove on (Re)Writable Disks (Re)Writable Disk empty track land mark (data) laser beam written track wobbled pregroove

CPTWG 28 november, Pregroove-wobble Characteristics only exists on (re)writable media pregroove wobble-detector present in recorders pregroove wobble-detector not present in players –media detection with pregroove adds cost to players wobble-frequency is different for different standards –DVD+R(W): 820 KHz –DVD-R(W), DVD-RAM: 141 KHz so are multiple wobble detectors needed?

CPTWG 28 november, Inexpensive wobble detector (1) Tests show that the Channel Decoder IC can also detect the wobble… –channel decoder is an essential component of any player or recorder –measure the presence/absence of a pregroove wobble by reading the PLL-frequency in the Channel Decoder Only Additional Cost: –extra switch to the input of the Channel Decoder IC –firmware

CPTWG 28 november, How does it work? (1) (Re)Writable Disk Analog Preprocessor Radial Servo OPU Channel Decoder radial error signal HF Application MPEG decoder Data Clock micro processor DVD Player PP

CPTWG 28 november, How does it work? (2) PLL EFM Decoder Error Correction Data Clock Slicer … Clock to microprocessor Channel Decoder HF PP

CPTWG 28 november, How does it work? (3) phase detector  KiKi KpKp  VCO PLL FLL D to microprocessor proportional to frequency of signal Clock HF PP frequency lock-aid –measures approx. frequency

CPTWG 28 november, Test Results (1) DVD+RW, 1.2  (f wobble =  ) time [msec] PLL/FLL frequency [KHz] DVD+RW 1.2x Empty Track DVD+RW 1.2x Written Track

CPTWG 28 november, Test Results (2) DVD-RW, 1.2  & 2.4  ( f wobble =  ) time [msec] PLL/FLL frequency [KHz] DVD-RW 2.4x Written Track DVD-RW 1.2x Empty Track

CPTWG 28 november, Test Results (3) DVD+R, 1.2  (f wobble =  ) time [msec] PLL/FLL frequency [KHz] DVD+R 1.2x Written Track

CPTWG 28 november, How does it work (4) Start Switch decoder input to PP-signal Bring the disc speed and the associated wobble frequency in frequency range of EFM-PLL (or preset VCO to the expected wobble frequency) Wait until PLL acquires frequency lock Is it consistent with disk speed and expected disk type? Read VCO-freq. Try another disk-type N Y Positive disk-type recognition

CPTWG 28 november, Conclusion We propose a very cheap way to detect the pregroove wobble using Channel Decoder IC –additional cost: multiplexer firmware change –fast (few msec) –positive recognition of all DVD-recordable formats: DVD-R(W), DVD+R(W), DVD-RAM Please test this with your own chip-set

Thank You For Your Attention

CPTWG 28 november, Back-up Slides

CPTWG 28 november, Analog Preprocessor HF PP Radial Error Signal DPD- Detector circuit d + – a b c