Method and apparatus for providing a content control signal in a media player via color burst phase modifications
The “color stripe” process is well known in the video field for preventing copying of video by analog video tape recorders, and operates by altering the phase of a portion of the video signal color burst. Here, a weakened version of the color stripe process is installed in a video signal by a digital media player which plays or stores conventional digital media, such as an optical disc (e.g., DVD or CD) player, a hard disc drive, a digital tape drive, or solid state memory. Thereby in an analog video signal output by such a digital media player the color burst phase alterations are reduced or attenuated so there is no copy prevention effect on a conventional downstream (receiving) analog video tape recorder. However the weakened color stripe process is still sufficient to be detectable by a suitable detector located in a downstream compliant device such as a video recorder, so the detected presence of the installed color stripe serves as an encoded indication of copy control or other content control for the video signal by the compliant device.
1. A method of providing a content control indication in a video signal output by a digital media player, comprising the acts of:
providing a digital video signal from a video storage medium;
providing a command;
modifying the video signal in response to the command to include a weakened color stripe signal in selected scan lines of the video signal, the weakened color stripe signal having an incorrect color burst in a horizontal blanking interval of the selected scan lines, wherein the incorrect color burst includes more subcarrier cycles of correct phase angle than non-attenuated subcarrier cycles of incorrect phase angle, and is detectable by a color stripe process detector but inadequate to provide color copy protection effects in a video tape recording of the modified video signal, wherein the weakened color stripe signal is an indication of content control to inhibit recording of the modified video signal by a compliant recording apparatus;
converting the modified video signal in a digital to analog converter to an analog video signal; and
outputting the analog video signal.
2. The method of claim 1 , wherein the video storage medium is one of an optical disc, a hard disc, a magnetic tape, or a solid state memory device.
3. The method of claim 1 , wherein the output modified video signal conforms to an NTSC, PAL or SECAM television standard.
4. The method of claim 1 , wherein the incorrect color burst includes as plurality of subcarrier cycles of incorrect phase angle that are attenuated.
5. The method of claim 1 , wherein the incorrect color burst includes at least a first and a second portion, the first portion having subcarrier cycles of correct phase angle and the second portion having subcarrier cycles of incorrect phase angle.
6. The method of claim 1 , wherein a length of the incorrect color burst is extended beyond that of a normal color burst.
7. The method of claim 1 , further comprising the acts of:
providing a copy protection signal; and
inserting the copy protection signal into the output video signal.
8. The method of claim 1 , further comprising detecting the command in the video signal.
9. The method of claim 1 , wherein a phase angle shill of subcarrier cycles in the incorrect color burst is at least 120° from normal.
10. The method of claim 1 , wherein the weakened color stripe signal encodes one of a plurality of content control states.
11. The method of claim 1 , wherein the command is received from the video storage medium.
12. The method of claim 1 , wherein the command is received from a source external to the digital media player.
13. A digital media player which provides a content control indication in a video signal, comprising:
a video source which outputs a digital video signal;
a signal generator coupled to the video source to generate, for selected scan lines of the video signal, a weakened color stripe signal having an incorrect color burst for a horizontal blanking interval of the selected scan lines, wherein the incorrect color burst includes more subcarrier cycles of correct phase angle than non-attenuated subcarrier cycles of incorrect phase angle, and is detectable by a color stripe process detector, but inadequate to provide color copy protection effects in a video tape recording of the modified video signal; and
wherein the weakened color stripe signal is combined with the digital video signal:
a digital to analog converter coupled to receive the digital video signal; and
an output terminal coupled to the digital to analog converter for outputting an analog video signal, wherein the weakened color stripe signal in the analog video signal is an indication of content control to inhibit recording of the modified video signal by a compliant recording apparatus.
14. The player of claim 13 , wherein the video source includes one of an optical disc drive, a hard disc drive, a magnetic tape drive, or a solid state memory device.
15. The player of claim 13 , wherein the output analog video signal conforms to an NTSC, PAL, or SECAM television standard.
16. The player of claim 13 , wherein the incorrect color burst includes a plurality of subcarrier cycles of incorrect phase angle that are attenuated.
17. The player of claim 13 , wherein the incorrect color burst includes at least a first and a second portion, the first portion having subcarrier cycles of correct phase angle and the second portion having subcarrier cycles of incorrect phase angle.
18. The player of claim 13 , wherein a length of the incorrect color burst is extended beyond that of a normal color burst.
19. The player of claim 13 , wherein the signal generator further provides a copy protection signal.
20. The player of claim 13 , further comprising: a control data reader or detector coupled to the signal generator and the video source to detect a command in the digital video signal.
21. The player of claim 13 , wherein a phase angle shift of subcarrier cycles in the incorrect color burst is at least 120° from normal.
22. The player of claim 13 , wherein the weakened color stripe signal encodes one of a plurality of content control states.
23. The player of claim 13 , wherein the signal generator is programmable from a source external to the digital media player.