How many ways are there to inhibit video copying?

By David Broberg © October 12, 2006

 

Trying to understand what might trigger copy protection is a complicated matter. When copy protection woes stop our video recording dead in their tracks, we can't be too quick to put the blame on one single source for the message that tells video recorders to stop. I put together a list of just some of the standardized ones. There are many more that are proprietary and used with private DRM system.

Here's a list of some that come to mind:

 

  1. Copy Control Information (CCI) sent by the CableCARD (POD). This is defined in ANSI/SCTE-41 and DFAST
  2. Copy-Generation-Management-System-Analog (CGMS-A). There are many sub-flavors of this:
    1. CGMS-A as defined by IEC-61880 as an analog signal on line-20
    2. CGMS-A as defined by CEA-608-C, carried as XDS data on line-21 of analog signals.
    3. CGMS-A as defined by CEA-805-C, carried as data on component analog signals
    4. CGMS-A as defined by (b) above, but carried in an MPEG digital stream as defined by ANSI/SCTE-20 data.
    5. CGMS-A as defined by (b) above, but carried in an MPEG digital stream as defined by ANSI/SCTE-21 data.
    6. CGMS-A as defined by (a) above, but carried in an MPEG digital stream as defined by DVS-708-C as cc_type 01
  3. DTCP_Descriptor for MPEG Transport Streams (DTCP-descriptor). This is defined in Appendix B of Digital Transmission Content Protection Specification Revision 1.4.
  4. Macrovision, Analog Copy Protection (ACP) this is a type of sync distortion added to an analog signal to prevent copying. It was designed to inhibit VHS copying but was protected under the DMCA. 
  5. Dwight Cavendish analog protection system, (ADAPT) similar to Macrovision, but different algorithms
  6. Analog Protection System (APS), digital signals used to trigger or control Macrovision or other analog protection systems. Like CGMS-A, there are many sub-flavors
    1. APS bits as defined by IEC-61880as an analog signal on line-20
    2. APS bits as defined by CEA-608-C, carried as XDS data on line-21 of analog signals.
    3. APS bits as defined by CEA-805-C, carried as data on component analog signals
    4. APS bits as defined by (b) above, but carried in an MPEG digital stream as defined by ANSI/SCTE-20 data.
    5. APS bits as defined by (b) above, but carried in an MPEG digital stream as defined by ANSI/SCTE-21 data.
    6. APS bits as defined by (a) above, but carried in an MPEG digital stream as defined by DVS-708-C as cc_type 01
    7. APS bits are also carried in the CCI data sent by the CableCARD (POD). This is defined in ANSI/SCTE-41 and DFAST
    8. APS bits can also be carried in the DTCP Descriptor
  7. Broadcast Flag or the RC Descriptor, carried in an MPEG transport stream as defined by ATSC A/65C
  8. Redistribution Control Descriptor (RCD) as defined by CEA-608-C
  9. Redistribution Control Descriptor (RCD) as defined by CEA-805-C
  10. Constrained Image Trigger, (CIT) as defined by DFAST and carried in the CCI signal from the CableCARD

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    Last updated: Tuesday, Saturday, August 18, 2007

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