MPEG2 moving picture encoding/decoding system

• US 6,310,962 B1
• Filed: 08/19/1998
• Issued: 10/30/2001
• Est. Priority Date: 08/20/1997
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Oh, Young-nam, Chung, Tae-yun
• Primary Examiner(s): Mehta, Bhavesh
• Assistant Examiner(s): AZARIAN, SEYED H
• Application Number:
  US09/136,685
• Time in Patent Office: 1,168 Days
• Field of Search: 382/232, 382/233, 382/234, 382/235, 382/236, 382/237, 382/238, 382/239, 382/100, 382/162, 382/250, 380/202, 380/280, 380/217, 380/287
• US Class Current: 382/100
• CPC Class Codes: G06T 1/0085 Time domain based watermarking, e.g. watermarks spread over several images
• CPC Class Codes: G06T 2201/0052 Embedding of the watermark in the frequency domain
• CPC Class Codes: G06T 2201/0053 Embedding of the watermark in the coding stream, possibly without decoding; Embedding of the watermark in the compressed domain
• CPC Class Codes: H04N 19/467 characterised by the embedded information being invisible, e.g. watermarking
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 2005/91335 the copy protection signal being a watermark
• CPC Class Codes: H04N 21/23892 involving embedding information at multiplex stream level, e.g. embedding a watermark at packet level
• CPC Class Codes: H04N 21/8358 involving watermark protecting executable software by watermarking G06F21/16; image watermarking in general G06T1/0021; watermarks inserted in still images for transmission purposes H04N1/32144; inserting watermarks during video coding H04N19/467
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection

Abstract

An MPEG2 moving picture and encoding/decoding system to provide digital copy protection of digital moving picture data. The MPEG2 moving picture encoder discrete cosine transforms a video input signal and uses a digital watermark inserter to embed digital watermark information on a frequency domain of the discrete cosine transformed video input signal. The MPEG2 moving picture decoder receives the encoded video output signal from the MPEG2 moving picture encoder and removes the embedded visual watermark information to locally decode the encoded video signal.

Claims

1. An MPEG2 moving picture encoder to encode a video signal with digital watermark information and including a frame memory, a frame/field memory, an activity calculator, a rate controller, a Discrete Cosine Transform (DCT) unit, a quantizer, a dequantizer, an Inverse Discrete Cosine Transform (IDCT) unit, an adaptive estimator, a motion estimator, a variable length coder and multiplexer (VLC &

a MUX) and a buffer, the MPEG2 moving picture encoder comprising;

a digital watermark inserter installed between said DCT and said VLC &

MUX, to generate and discrete-cosine-transform the digital watermark information, and then embed the digital watermark information on a frequency domain of the video signal; and

a digital watermark remover, installed between said dequantizer and said IDCT, to remove the digital watermark information on a spatial domain of the video signal, so as to prevent an error during estimating motion on a temporal domain for P and B pictures of the video signal.

2. The MPEG2 moving picture encoder as set forth in claim 1, wherein said digital watermark inserter is located between said DCT and said quantizer.

3. The MPEG2 moving picture encoder as set forth in claim 1, wherein said digital watermark inserter is located between said quantizer and said VLC &

MUX.

4. The MPEG2 moving picture encoder as set forth in claim 2, wherein said digital watermark inserter uses an 8×

8 DCT to embed the watermark information on the frequency domain of the video signal.

5. The MPEG2 moving picture encoder as set forth in claim 1, wherein said IDCT prevents an error of a temporal domain coding by the digital watermark information.

6. An MPEG2 moving picture decoder to decode an encoding bit stream comprising:

a first buffer to receive and save the encoding bit stream;

a variable length decoder and multiplexer (VLD &

DEMUX) to receive the encoding bit stream from said first buffer and to various-length-code the encoding bit stream;

a dequantizer to dequantize the various length coded signal from said VLD &

DEMUX;

a digital watermark remover to remove a digital watermark embedded in the dequantized signal to locally decode by reading the digital watermark and information from said dequantizer, to generate a dequantized signal without the digital watermark;

a first Inverse Discrete Transform (IDCT) unit to inverse-discrete-cosine-transform the dequantized signal without the digital watermark from said digital watermark remover, to generate a first IDCT signal;

a digital watermark inserter to embed again the digital watermark removed by said digital watermark remover in the dequantized signal without the digital watermark for performing local decoding;

a second IDCT unit to inverse-discrete-cosine-transform the signal from said digital watermark inserter, to generate a second IDCT signal;

a first adder to add the second IDCT signal from said second IDCT unit and motion compensation data, to generate a first added signal;

a second buffer to temporarily save the first added signal and output the first added signal so that the first added signal is replayed;

a multiplexer (MUX) to multiplex a first saved signal, a second saved signal, a third signal having a predetermined value and a fourth signal to output a multiplexed signal;

a second adder to add the first IDCT signal and the multiplexed signal, to generate a second added signal, the second added signal being the motion compensation data;

a previous picture store block to temporarily save the second added signal and the second saved signal to generate the first saved signal;

a future picture store block to temporarily save the second added signal and to transmit the saved second added signal to said previous picture store block and said multiplexer as the second saved signal;

a ½

multiplier to all the first and second saved signals and ½

multiplying the added first and second saved signals, to generate the fourth signal.

7. The MPEG2 moving picture decoder as set forth in claim 6, wherein said digital watermark remover prevents an error of temporal domain coding by the digital watermark.

8. The MPEG2 moving picture decoder as set forth in claim 7, wherein the digital watermark is embedded by the watermark inserter within I-picture-codes or P-picture-codes of the dequantized signal, and said dequantizer dequantizes quantized coefficients of the variable length coded signal, and then said digital watermark remover removes the digital watermark, in order to prevent the error of the temporal domain coding.

9. The MPEG2 moving picture decoder as set forth in claim 6, wherein said digital watermark remover correctly predicts motion information relating to an image of the encoding bit stream.

10. The MPEG2 moving picture decoder as set forth in claim 8, wherein the digital watermark is embedded by the watermark inserter within said the I-picture-codes or P-picture-codes, and said dequantizer dequantizes the quantized coefficients, and then said digital watermark remover removes the digital watermark, in order to predict correctly motion information relating to an image of the encoding bit stream.

11. The MPEG2 moving picture decoder as set forth in claim 6, wherein the MPEG2 moving picture decoder receives the watermark from a recording medium.

12. The MPEG2 moving picture decoder as set forth in claim 11, wherein the recording medium is a disk.

13. The MPEG2 moving picture decoder as set forth in claim 11, wherein the digital watermark is embedded into a domain which a user cannot access directly and a correct motion restoration is performed by reference to the digital watermark when embedding and decoding the digital watermark.

14. The MPEG2 moving picture decoder as set forth in claim 13, wherein the domain, which the user can not access directly, is a lead-in domain.

15. The MPEG2 moving picture decoder as set forth in claim 6, wherein the MPEG2 moving picture decoder has the function to decrease encoding efficiency by embedded digital watermark information.

16. The MPEG2 moving picture decoder as set forth in claim 15, wherein the MPEG2 moving picture decoder for carrying out the function decreases an error while predicting motion of P and B pictures by embedding the digital watermark information.

17. The MPEG2 moving picture decoder as set forth in claim 6, wherein the MPEG2 moving picture decoder has a function to prevent degradation of image quality by embedding the digital watermark.

18. The MPEG2 moving picture decoder as set forth in claim 17, wherein the MPEG2 moving picture decoder carries out the function by decreasing an error while predicting motion of P and B pictures by embedding the digital watermark information.