1. Inexpensive Media Recognition for Optical Disks Maurice Maes Joop Talstra joop.talstra@philips.com

2. CPTWG 28 november, 2001 2 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

3. CPTWG 28 november, 2001 3 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

4. CPTWG 28 november, 2001 4 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

5. CPTWG 28 november, 2001 5 Pregroove on (Re)Writable Disks (Re)Writable Disk empty track land mark (data) laser beam written track wobbled pregroove

6. CPTWG 28 november, 2001 6 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?

7. CPTWG 28 november, 2001 7 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

8. CPTWG 28 november, 2001 8 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

9. CPTWG 28 november, 2001 9 How does it work? (2) PLL EFM Decoder Error Correction Data Clock Slicer …011010... Clock to microprocessor Channel Decoder HF PP

10. CPTWG 28 november, 2001 10 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

11. CPTWG 28 november, 2001 11 Test Results (1) DVD+RW, 1.2  (f wobble = 820 KHz @ 1  ) 0 200 400 600 800 1000 020406080 time [msec] PLL/FLL frequency [KHz] DVD+RW 1.2x Empty Track DVD+RW 1.2x Written Track

12. CPTWG 28 november, 2001 12 Test Results (2) DVD-RW, 1.2  & 2.4  ( f wobble = 141 KH @ 1  ) 0 50 100 150 200 250 300 350 400 020406080 time [msec] PLL/FLL frequency [KHz] DVD-RW 2.4x Written Track DVD-RW 1.2x Empty Track

13. CPTWG 28 november, 2001 13 Test Results (3) DVD+R, 1.2  (f wobble = 820 KHz @ 1  ) 0 250 500 750 1000 1250 1500 1750 2000 020406080 time [msec] PLL/FLL frequency [KHz] DVD+R 1.2x Written Track

14. CPTWG 28 november, 2001 14 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

15. CPTWG 28 november, 2001 15 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

16. Thank You For Your Attention

17. CPTWG 28 november, 2001 17 Back-up Slides

18. CPTWG 28 november, 2001 18 Analog Preprocessor HF PP Radial Error Signal DPD- Detector circuit + + + + + + d + – + + + + a b c