Devices and methods for digital watermarking

A method for embedding a message bit sequence in a video stream comprising a plurality of frames, the method comprising:

• determining one or more transformation frames of at least one frame of the plurality of frames of the video stream based on a wavelet kernel filter;
• encoding the message bit sequence by performing for each bit of the message bit sequence a pointwise multiplication of absolute values of elements of subframes of the one or more transformation frames, depending on a value of the respective message bit of the message bit sequence, with elements of a first encoding matrix or elements of a second encoding matrix to obtain one or more modified transformation frames;
• and
• adding the one or more modified transformation frames to the at least one frame of the plurality of frames of the video stream for embedding the message bit sequence in the at least one frame of the plurality of frames of the video stream.

A data processing apparatus for decoding a message bit sequence from a video stream comprising a plurality of frames, wherein the data processing apparatus comprises:

• a processing circuitry configured to decode the message bit sequence from at least one frame of the plurality of frames of the video stream, wherein the processing circuitry is further configured to:
• determine one or more transformation frames of the at least one frame of the plurality of frames of the video stream based on a wavelet kernel filter;
• determine a composite transformation frame based on the one or more transformation frames or a sum of the one or more transformation frames;
• decode the message bit sequence from the composite transformation frame by determining for one or more subframes of the composite transformation frame a first correlation value with a first encoding matrix and a second correlation value with a second encoding matrix and determine the message bit sequence based on the first correlation value and the second correlation value for each of the one or more subframes of the composite transformation frame.