Bit-stream watermarking

• US 20070052560A1
• Filed: 05/19/2004
• Published: 03/08/2007
• Est. Priority Date: 05/28/2003
• Status: Abandoned Application

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Van Der Veen, Minne, Lemma, Aweke, Eindhoven, Alphons Antonius
• Application Number:
  US10/557,681
• Publication Number:
  US 20070052560A1
• Time in Patent Office: Days
• US Class Current: 341/51
• CPC Class Codes: G06T 1/0035 Output size adaptive watermarking
• CPC Class Codes: G06T 2200/28 involving image processing hardware
• CPC Class Codes: G06T 2201/0052 Embedding of the watermark in the frequency domain
• CPC Class Codes: G10L 19/002 Dynamic bit allocation for perceptual audio coders G10L19/032
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal
• CPC Class Codes: G10L 19/0204 using subband decomposition
• CPC Class Codes: G10L 19/167 Audio streaming, i.e. formatting and decoding of an encoded audio signal representation into a data stream for transmission or storage purposes
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: G11B 20/00891 embedded in audio data
• CPC Class Codes: H04N 2005/91335 the copy protection signal being a watermark
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection
• CPC Class Codes: H04N 9/8042 involving data reduction

Abstract

The present invention relates to methods, devices, a media signal and a recorded medium for watermarks embedded in the sub-band domain of compressed media. Watermarks (w[n]) are embedded into the sub-band signals (x_i−1[n], x_i[n], x_i+1[n]) of at least one selected sub-band of a compressed bit-stream (b_k) using a watermark inserting unit (18). In this way there is no need to fully decode and re-encode the media signal for embedding the watermark. The watermark is embedded in selected sub-bands (e.g. sub-bands 7-15 of 32). In a preferred embodiment, the selected sub-bands are upsampled before embedding and downsampled therafter to avoid aliasing. The invention also allows embedding multiple watermarks in different sub-bands (e.g. one watermark in sub-bands 7-11, and a different watermark in sub-bands 12-16).

Claims

1. A method of embedding additional data into the bit-stream of a media signal comprising the steps of:

obtaining (30) a number of sub-band bit-streams of an input bit-stream,

converting (31) at least one sub-band bit-stream into a primary sub-band signal that is semantically compatible with said additional data, and

modifying (32) said sub-band signal with said additional data, in order to provide an output bit-stream carrying said embedded additional data.

2. Method according to claim 1, wherein the step of obtaining sub-band bit-streams comprises splitting the input bit-stream into a number of sub-band bit-streams.

3. Method according to claim 1, further including the step of converting (34) the modified sub-band signal into a corresponding sub-band bit-stream, and combining (38) the modified sub-band bit-stream with the unmodified sub-band bit-streams into a single output bit-stream carrying said additional data.

4. Method according to claim 1, further including the step of delaying (36) the unmodified sub-band bit-streams.

5. Method according to claim 1, further comprising the step of selecting at least one sub-band which is to include additional data.

6. Method according to claim 1, wherein the additional data is provided in the time, frequency or spatial domain.

7. Method according to claim 1, further including the step of upsampling (U) the primary sub-band signal to obtain a secondary sub-band signal;

the step of modifying said secondary sub-band signal to obtain a modified secondary sub-band signal; and

the step of downsampling (D) said modified secondary sub-band signal.

8. Method according to claim 7, wherein the step of upsampling also comprises upsampling (U) the additional data before performing the step of modifying.

9. Method according to claim 7, further comprising the step of splitting said modified secondary sub-band signal into a number of primary modified sub-band signals;

the step of downsampling the primary modified sub-band signals; and

the step of adding each modified primary sub-band signal to a corresponding unmodified primary sub-band signal for provision in a number of neighbouring sub-band bit-streams.

10. Method according to claim 9, further comprising the step of scaling said modified secondary sub-band signal prior to the step of splitting.

11. Method according to claim 1, wherein the step of converting comprises converting at least two of the sub-band bit-streams into primary sub-band signals that are semantically compatible with the intended additional data and further comprising the step of merging (S) said at least two primary sub-band signals into a single secondary sub-band signal and performing the step of modifying on said secondary sub-band signal.

12. Method according to claim 10, further comprising the steps of splitting said modified secondary sub-band signal into at least two modified primary sub-band signals, converting the modified primary sub-band signals into modified sub-band bit-streams and combining the modified and non-modified sub-band bit-streams into a single output bit-stream carrying said additional data.

13. A method of detecting additional data provided in a media signal comprising the steps of:

selecting (42) a frequency range at least approximately corresponding to at least one sub-band signal where the additional data is embedded, and

detecting (44) the additional data.

14. Method according to claim 13, wherein the step of selecting is performed by temporal, spatial or spectral filtering of the media signal.

15. Method according to claim 13, wherein the media signal is a compressed media bit-stream and the step of selecting is performed through splitting the bit-stream into a number of sub-band bit-streams, selecting the bit-stream of at east one sub-band where additional data is embedded and detecting the additional data in the sub-band.

16. Method according to claim 15, further comprising the step of converting the selected sub-band bit-stream into a corresponding sub-band signal and performing the step of detecting on the sub-band signal.

17. Method according to claim 16, wherein the step of converting the sub-band bit-stream to a sub-band signal comprises converting at least two of the sub-band bit-streams into primary sub-band signals and further comprising the step of merging (S) said at least two primary sub-band signals into a single secondary sub-band signal and performing the step of detecting on said secondary sub-band signal.

18. A device for embedding additional data in the bit-stream of a media signal comprising:

a unit (12) for converting at least one sub-band bit-stream, which is to carry additional data and is related to an input bit-stream, into a primary sub-band signal semantically compatible with the intended additional data, and

at least one data inserting unit (18;

56) for modifying said sub-band signal with additional data for provision in an output bit-stream.

19. Device according to claim 18, further comprising a unit (10) for receiving an input bit-stream and splitting it into a number of sub-band bit-streams.

20. Device according to claim 19, further comprising a unit (14) for converting the modified sub-band signal to output sub-band bit-streams and a unit (16) for combining sub-band bit-streams including modified and unmodified sub-band bit-streams in order to provide an output bit-stream carrying said additional data.

21. Device according to claim 18, further comprising at least one unit (46;

58) for upsampling a primary sub-band signal to obtain a secondary sub-band signal before performing modification and at least one unit (48;

66) for downsampling the modified secondary sub-band signal.

22. Device according to claim 21, further comprising a unit (46) for upsampling the additional data before performing embedding.

23. Device according to claim 21, wherein the unit (66) for downsampling is further arranged to split the modified secondary sub-band signal into a number of primary sub-band signals and further comprising:

a number of adding units (68, 70, 72) corresponding to the number of split signals for adding the split signals to a number of neighbouring sub-band signals.

24. Device according to claim 18, wherein the unit (12) for converting at least one sub-band bit-stream to a sub-band signal is arranged to convert at least two sub-band bit-streams into two primary sub-band signals and further comprising a unit (52) for merging the primary sub-band signals into a single secondary sub-band signal for provision to the inserting unit and a unit (54) for splitting the modified secondary sub-band signal into at least two modified primary sub-band signals in order to provide sub-band signals having additional data.

25. A device for detecting additional data provided in a media signal, comprising:

a control unit (78) for selecting a frequency range at least approximately corresponding to at least one sub-band where the additional data is provided, and

an additional data detector (76;

88) for detecting the additional data.

26. Device according to claim 25, further comprising at least one unit (74) for filtering the media signal in the temporal, spectral or spatial domain.

27. Device according to claim 25, wherein the media signal is a compressed media bit-stream and further comprising a unit (80) for splitting the bit-stream into a number of sub-band bit-streams and the control unit (78) is arranged to connect the additional data detector (84) for receiving signals of a selected sub-band where additional data is embedded and detecting the additional data in the signals of the sub-band.

28. Device according to claim 27, further comprising a unit (82) for converting at least one sub-band bit-stream which includes additional data into a sub-band signal.

29. Device according to claim 28, wherein the unit (82) for converting the sub-band bit-stream to a sub-band signal is arranged to convert at least two of the sub-band bit-streams into sub-band signals and further comprising a unit (86) for merging (S) said at least two primary sub-band signals into a single secondary sub-band signal and the detector is connected to the unit for merging primary sub-band signals for performing the detection on said secondary sub-band signal.

30. A media signal (b_y;

y_W[n]) having additional embedded data (w[n]), wherein the additional data is embedded in at least one sub-band signal (x<sub>i−

1</sub>[n], x_i[n], x_i+1[n]) of the media signal.

31. A recorded medium (88) having additional embedded data (w[n]) in a media signal, wherein the additional data is embedded in at least one sub-band signal (x_i−

1[n], x_i[n], x_i+1[n]) of the media signal.