Processing an MPEG elementary stream in a conditional access overlay environment
View Patent ↗Processing an MPEG elementary stream contained in multiple PID streams in a conditional access overlay environment. A multi-program transport stream contains numerous video and audio elementary streams. Critical packets in the elementary streams are encrypted with two different encryption schemes creating a stream having multiple PID values. The streams are then sent from the headend to individual set-top boxes. One encryption scheme can be decoded by the incumbent set-top box and the second encryption scheme can be decoded by the overlay set-top box. The overlay set-top box uses a dual filter system to filter and decode the PIDs for each video and audio stream of the desired program.
1. A set-top box apparatus comprising:
a first filter configured to receive a transport stream comprising packets having a first PID value of a first program, at least some packets having said first PID value being encrypted with a first encryption scheme, said first filter being configured to filter out said encrypted packets having said first PID value of said first program from said transport stream and to output unencrypted packets having said first PID value of said first program; and
a second filter configured to receive a transport stream comprising packets having a second PID value of said first program, at least some packets having said second PID value for the first program being encrypted with a second encryption scheme, said second filter being configured to filter out packets other than said encrypted packets having said second PID value of said first program from said transport stream and to decrypt said encrypted packets having said second PID value of said first program without remapping PID values to output decrypted packets having said second PID value for said first program.
2. The set-top box apparatus of claim 1 , and further comprising a first decoder coupled to the first filter and to the second filter, wherein the first decoder is configured to decode unencrypted packets having said first PID value and the decrypted packets having said second PID value to produce a first single elementary stream.
3. The set-top box apparatus of claim 1 , and further comprising a third filter and a fourth filter each configured to receive the transport stream which further comprises packets for a second program having said first PID value, at least some packets for said second program having said first PID value being encrypted with the first encryption scheme and packets having said second PID value for the second program, at least some packets having said second PID value for the second program being encrypted with the second encryption scheme, wherein the third filter is configured to filter out said encrypted packets having said first PID value of said second program from said transport stream to output unencrypted packets having said first PID value for said second program, and the third filter is configured to filter out packets other than said encrypted packets having said second PID value of said second program from said transport stream and to decrypt said encrypted packets having said second PID value of said second program without remapping PID values in order to output decrypted packets having said second PID value for said second program wherein said packets.
4. The set-top box apparatus of claim 3 , and further comprising a second decoder coupled to the third filter and fourth filter, wherein the second decoder is configured to decode the encrypted packets having said first PID value for said second program and to decode the decrypted packets having said second PID value for said second program to produce a second single elementary stream.
5. A method comprising:
receiving a transport stream comprising packets having a first PID value of a first program, at least some packets having said first PID value being encrypted with a first encryption scheme, and packets having a second PID value of said first program, at least some packets having said second PID value for the first program being encrypted with a second encryption scheme;
filtering out said encrypted packets having said first PID value of said first program from said transport stream to output unencrypted packets having said first PID value of said first program;
filtering out packets other than said encrypted packets having said second PID value of said first program from said transport stream; and
decrypting said encrypted packets having said second PID value of said first program without remapping PID values in order to output decrypted packets having said second PID value for said first program.
6. The method of claim 5 , wherein receiving comprises receiving packets for a first elementary video stream.
7. The method of claim 5 , wherein said filtering out said encrypted packets having said first PID value of said first program from said transport stream is performed with a first filter; and said filtering out packets other than said encrypted packets having said second PID value of said first program from said transport stream is performed with a second filter.
8. The method of claim 5 , wherein said decrypting of said encrypted packets having said second PID value of said first program is performed with said second filter.
9. The method of claim 8 , and further comprising decoding said unencrypted packets having said first PID value for the first program and the decrypted packets having said second PID value for the first program thereby producing a single elementary stream.
10. The method of claim 5 , wherein receiving comprises the transport stream comprising packets for a second program having said first PID value, at least some packets for said second program having said first PID value being encrypted with the first encryption scheme and packets having said second PID value for the second program, at least some packets having said second PID value for the second program being encrypted with the second encryption scheme.
11. The method of claim 10 , and further comprising:
filtering out said encrypted packets having said first PID value of said second program from said transport stream to output unencrypted packets having said first PID value for said second program;
filtering out packets other than said encrypted packets having said second PID value of said second program from said transport stream; and
decrypting said encrypted packets having said second PID value of said second program without remapping PID values to output decrypted packets having said second PID value for said second program.
12. The method of claim 11 , wherein the packets having the first PID value for the first program and the packets the second PID value for the first program are video packets.
13. The method of claim 12 , wherein the packets having the first PID value for the second program and the packets having the second PID value for the second program are audio packets.
14. The method of claim 5 , wherein the packets having the first PID value for the second program and the packets having the second PID value for the second program are video packets.