Video watermarking

A device for watermarking a video signal, the device comprising:

• an encoder arranged to encode a video signal using a plurality of encoding parameters;
• and
• control means arranged to control the encoder, the control means being further arranged to:
• vary a value of at least one the encoding parameters with time, while the encoder is encoding a video signal, according to a watermark pattern, wherein the at least one parameter is a parameter that affects at least a type or an amount of information lost in encoding the signal,
• determine a sequence of quantization matrices according to a watermark pattern, wherein the quantization matrices comprise the encoding parameters;
• and
• encode the video signal using the sequence of quantization matrices, wherein the quantization matrices used to encode the video signal varies with time, and that the at least one selected parameters comprises two quantization factors comprising a first quantization factor corresponding to a coefficient of a horizontal frequency and a second quantization factor corresponding to a coefficient of a vertical frequency of a spatial frequency transform.

A method of watermarking a compressed video signal, the method comprising:

• demultiplexing the compressed video signal;
• multiplexing the video signal using a plurality of encoding parameters;
• and
• during the multiplexing, modifying a value of at least a selected one of the parameters of the demultiplexed compressed video signal with time according to a watermarking pattern, the selected parameter being a parameter that affects at least a type or an amount of information lost in encoding the signal,
• wherein the value of the at least one parameter is constant per frame or group of frames of the video signal;
• and
• wherein the step of varying comprises:
• determining a sequence of quantization matrices according to a watermark pattern, wherein the quantization matrices comprise the encoding parameters;
• and
• encoding the video signal using the sequence of quantization matrices, wherein the quantization matrices used to encode the video signal varies with time, and
• wherein the at least one selected parameter comprises two quantization factors comprising a first quantization factor corresponding to a coefficient of a horizontal frequency and a second quantization factor corresponding to a coefficient of a vertical frequency of a spatial frequency transform.

A device for watermarking a compressed video signal, the device comprising:

• a demultiplexer for demultiplexing the compressed video signal;
• a multiplexer arranged to encode a video signal using a plurality of encoding parameters;
• control means arranged to:
• modify a value of at least one the encoding parameters of the demultiplexed compressed video signal with time, while the encoder is encoding a video signal, according to a watermark pattern, wherein the at least one parameter being a parameter that affects at least a type or an amount of information lost in encoding the signal,
• determine a sequence of quantication matrices according to a watermark pattern, wherein the quantization matrices comprise the encoding parameters;
• and
• encode the video signal using the sequence of quantization matrices, wherein the quantization matrices used to encode the video signal varies with time, and
• wherein the at least one selected parameters comprises two quantization factors comprising a first quantization factor corresponding to a particular coefficient of a horizontal frequency and a quantization factor corresponding to a particular coefficient of a vertical frequency of a spatial frequency transform, each of the two selected quantization factors having a value.