Splicing of encrypted video/audio content
View Patent ↗System and method for performing a splice operation on an encrypted or unencrypted MPEG-2 transport stream. A splice trigger is received at a pre-conditioning encoder. In response, the encoder generates, e.g., an SCTE-35 cue message that is intended to be received by a splicer. Also in response to the splice trigger, the encoder encodes/conditions a network feed such that a decoder buffer delay reaches a predefined value at a video frame of the network feed that corresponds to a splice point indicated by the SCTE-35 cue message. The network feed may then be encrypted in a known fashion. At the splicer, another feed is switched into the stream at the splice point, wherein the another feed is encoded such that a decoder buffer delay at a video frame of the another feed corresponding to the splice point is the same as the predefined value. The predefined value is defined as DTS-STC, where DTS is a Decoding Time Stamp and STC is a System Time Clock. The pre-conditioning encoder generates around the splice point audio PES packets that contain a single aligned audio frame.
1. A method of splicing into a first video feed, a second video feed, the method comprising:
receiving a first video feed at an encoder, and encoding the first video feed to generate an encoded first transport stream;
passing the encoded first transport stream to a splicer;
receiving a splice trigger at the encoder and generating a cue message that includes a Presentation Time Stamp (PTS) value that corresponds with a PTS value of an intended splice point in the first video feed;
in response to the splice trigger, conditioning the first video feed by further encoding the first video feed such that a decoder buffer delay defined by DTS-STC, wherein DTS is a Decoding Time Stamp and STC is a System Time Clock, is equivalent to a predetermined value at a video frame that corresponds to the intended splice point;
processing, by the encoder, the video frame that corresponds with the intended splice point by closing group of picture (GOP) and encoding the video frame as a random access point(RAP);
encrypting the first video feed prior to executing a splice, wherein encrypting the first video feed comprises encrypting the first video feed and the cue message; and
executing the splice at the intended splice point by switching to a second video feed, wherein the second video feed is conditioned in a manner identically to the first video feed such that a seamless splice is achieved without decoder buffer overflow or underflow.
2. The method of claim 1 , wherein the first video feed is encoded in accordance with MPEG-2.
3. The method of claim 1 , further comprising encoding a first audio feed that is associated with the first video feed.
4. The method of claim 3 , further comprising, in response to the splice trigger, generating a plurality of audio random access points (RAPS) from the first audio feed around the intended splice point.
5. The method of claim 4 , further comprising:
generating all audio frames within the splice point,
encoding each of the all audio frames as audio RAP; and
mapping each of audio frames into a separate packetized elementary stream (PES) packet each starting a new MPEG-2 packet.
6. The method of claim 1 , wherein the conditioning comprises applying predetermined constraints to the first video feed and the second feed.
7. The method of claim 6 , wherein one of the predetermined constraints applied to the first video feed is that the DTS-STC value is equal at a beginning and at an end of an avail.
8. The method of claim 6 , wherein one of the predetermined constraints applied to the first video feed is that the DTS-STC value of all frames between RAP frames of the first video feed is less than or equal to the DTS-STC value of the RAP frames.
9. The method of claim 6 , wherein one of the predetermined constraints applied to the second video feed is that the DTS-STC value is equal at a beginning and an end of a spliced segment of the second video feed.
10. The method of claim 6 , wherein one of the predetermined constraints applied to the second video feed is that the DTS-STC value at a beginning and an end of a segment of the second video feed is less than or equal to the DTS-STC value of the first video feed at intended splice points.
11. The method of claim 6 wherein one of the predetermined constraints applied to the second video feed is that the DTS-STC value of all frames between a beginning and an end of a segment of the second video feed is less than or equal to the DTS-STC value at a beginning and an end of the segment of the second video feed,
12. The method of claim 6 , wherein one of the predetermined constraints applied to the second video feed is that a bit rate of the second video feed is lower than or equal to a bit rate of the first video feed.
13. The method of claim 1 , wherein the first video feed is a network feed.
14. The method of claim 1 , wherein the second video feed is an advertisement.
15. The method of claim 1 , further comprising compensating for a difference in timebase between the first video feed and the second video feed by increasing or decreasing a speed of streaming of one or both video feeds, based on their difference with respect to a system dock frequency.
16. The method of claim 1 , further comprising correcting errors that result from a limited accuracy with which the conditioning can be executed in an encoder, by adding an offset to the DTS-STC value at the splice point.
17. The method of claim 16 , further comprising inserting a delay at the splice point.
18. The method of claim 1 , further comprising providing the splicer information to decrypt the cue message.
19. The method of claim 1 , wherein the RAP frame is mapped into a new packetized elementary stream (PES) packet which, in turn, starts a new MPEG-2 packet.
20. A method of performing a splice operation on an encrypted MPEG-2 transport stream, comprising:
receiving a splice trigger and generating a corresponding cue message that is intended to be received by a splicer;
in response to the splice trigger, encoding a network feed such that a decoder buffer delay reaches a predefined value at a video frame of the network feed that corresponds to a splice point indicated by the corresponding cue message, wherein the predefined value is defined by DTS-STC, wherein DTS is a Decoding Time Stamp and STC is a System Time Clock;
processing, by the encoder, the video frame that corresponds with the intended splice point by closing group of picture (GOP) and encoding the video frame as a random access point (RAP);
encrypting the network feed and supplying a resulting encrypted MPEG-2 transport stream to the splicer, wherein encrypting the first video feed comprises encrypting the first video feed, and the corresponding cue message; and
splicing into the network feed at the splice point another MPEG-2 transport stream, wherein the another MPEG-2 transport stream is encoded such that a decoder buffer delay at a video frame of the another MPEG-2 transport stream corresponding to the splice point is the same as the predefined value.
21. The method of claim 20 , wherein the network feed comprises a first program, and the another MPEG-2 transport stream comprises a second, different, program.
22. The method of claim 20 , wherein the another MPEG-2 transport stream is an advertisement.
23. The method of claim 20 , further comprising applying predetermined constraints to the network feed.
24. The method of daim 23 , wherein one of the predetermined constraints applied to the network feed is that the DTS-STC value is equal at a beginning and at an end of an avail.
25. The method of claim 23 , wherein one of the predetermined constraints applied to the network feed is that the DTS-STC value of all frames between RAP Thames of the network feed is less than or equal to the DTS-STC value of the RAP frames.
26. The method of claim 20 , wherein the another MPEG-2 transport stream is a program, the method further comprising applying predetermined constraints to the network feed and the another MPEG-2 transport stream.
27. The method of claim 26 , wherein one of the predetermined constraints is that a DTS-STC value is equal For both the network feed and the another MPEG-2 transport stream at Random Access Point (RAP) frames.
28. The method of claim 26 , wherein one of the predetermined constraints is that a DTS-STC value of all frames other than Random Access Point (RAP) frames a the splice point is less than or equal to the DTS-CTC value of RAP frames at the splice point.
29. The method of claim 26 , wherein one of the predetermined constraints is that a bit rate of each of the network feed and the another MPEG-2 transport stream are equal.
30. The method of claim 20 , further comprising, in response to the splice trigger, generating a plurality of audio random access points (RAPs) from a first audio feed that is associated with the network feed around the splice point.
31. The method of claim 30 , wherein the plurality of audio RAPs are generated within a predetermined timeframe around the splice point.
32. The method of claim 31 , wherein the predetermined timeframe is around one second.
33. A non transitory tangible media for execution and when executed operable to:
receive a splice trigger and generating a corresponding cue message that is intended to be received by a splicer;
in response to the splice trigger, encode a network feed such that a decoder buffer delay reaches a predefined value at a video frame of the network feed that corresponds to a splice point indicated by the corresponding cue message, wherein the predefined value is defined by DTS-CTC, wherein DTS is a Decoding Time Stamp and STC is a System Time Clock;
processing, by the encoder, the video frame that corresponds with the intended splice point by closing group of picture (GOP) and encoding the video frame as a random access point (RAP);
encrypt the network feed and supplying a resulting encrypted MPEG-2 transport stream to the splicer, wherein encrypting the first video feed comprises encrypting the first video feed, and encrypting the corresponding cue message; and
splice into the network feed at the splice point another MPEG-2 transport stream, wherein the another MPEG-2 transport stream is encoded such that a decoder buffer delay at a video frame of the another MPEG-2 transport stream corresponding to the splice point is the same as the predefined value.