Embedding a digital signature in a video sequence

A system for embedding digital information into a video signal such that the digital information can later be retrieved, the digital information including a plurality of bits, the system comprising:

• a selector that selects a first subset and a second subset of the video signal;
• a comparator that determines a relationship between the first subset and the second subset of the video signal;
• and
• a changer that changes the relationship between the first subset and the second subset of the video signal by encoding the information into the video signal to produce a changed video signal having a changed relationship;
• wherein the first subset belongs to one frame and the second subset belongs to a different frame of the video signal.

A method for embedding a retrievable watermark into a video signal, the video signal providing a series of video frames including a first frame and a second frame, the method comprising the steps of:

• detecting a change between the first frame and the second frame;
• producing change information based on the change;
• and
• encoding the retrievable watermark into the change information.

A method for embedding a retrievable watermark into a video signal, the video signal providing a series of video frames including a first frame and a second frame, the method comprising the steps of:

• detecting a change between the first frame and the second frame;
• producing change information based on the change;
• and
• encoding the watermark into the change information;
• wherein the step of encoding modifies a motion vector based on the watermark.

A method for embedding digital information into a video signal such that the digital information can later be retrieved;

• the digital information including a plurality of bits, the video signal providing a series of video frames including a first frame and a subsequent second frame, the first frame being subdivided into a plurality of blocks, the method comprising the steps of:
• obtaining a motion vector for each one of a subset of the blocks in the first frame, each motion vector representative of a displacement between a block in the first frame and a corresponding block in the second frame;
• and
• modifying one or more of said motion vectors based on a value of one or more bits of said digital information such that the digital information can later be retrieved.

A method for embedding digital information into a video signal such that the digital information can later be retrieved;

• the digital information including a plurality of bits, the video signal providing a series of video frames including a first frame and a subsequent second frame, the first frame being subdivided into a plurality of blocks, the method comprising the steps of:
• obtaining a motion vector for each one of a subset of the blocks in the first frame, each motion vector representative of a displacement between a block in the first frame and a corresponding block in the second frame;
• and
• modifying one or more of said motion vectors based on a value of one or more bits of said digital information;
• wherein the digital information includes a signature having a predefined bitset S(I), I=1, 2, . . . , L, where L is the number of bits in the signature, and wherein the step of modifying modifies a component of the motion vector based on one or more bits of said digital information.

A method for embedding digital information into a video signal, the video signal providing a series of video frames including a first frame and a subsequent second frame, the method comprising the steps of:

• detecting a motion between the first frame and the second frame;
• producing a motion vector set based on the motion;
• selecting change information that includes a suitable subset of the motion vector set that is suitable for coding;
• and
• encoding the digital information into the change information such that the digital information can later be retrieved.

A watermarking system for embedding digital information into a video signal such that the digital information can later be retrieved;

• the digital information including a plurality of bits, the video signal providing a series of video frames including a first frame and a subsequent second frame, the first frame being subdivided into a plurality of blocks, the watermarking system comprising:
• a block-based motion-estimation (BBME) coder, and wherein the BBME coder generates a motion vector for each one of a subset of the blocks in the first frame, each motion vector representative of a displacement between a block in the first frame and a corresponding block in the second frame;
• and
• a motion-vector modifier coupled to an output of the BBME coder that modifies one or more of said motion vectors based on a value of one or more bits of said digital information.

A storage medium having a computer program stored thereon for causing a suitably programmed system to embed information in a video signal by performing the following steps when such program is executed on the system:

• selecting a first subset and a second subset of the video signal;
• determining a relationship between the first subset and the second subset of the video signal;
• and
• changing the relationship between the first subset and the second subset of the video signal, wherein the step of changing includes encoding the information into the video signal to produce a changed video signal having a changed relationship;
• wherein the first subset belongs to one frame and the second subset belongs to a different frame of the video signal.