Date post: | 18-Feb-2017 |
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Engineering |
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AUDIO WATERMARKING
Eslam Omar Mohamed Faculty of Engineering, Alexandria university
Fourth-year student ,communication and electronics [email protected] : 011 11 95 98 39
Information Hiding
Steganography Cryptography Watermarking
After the theater, all clients keep a tab down at Wesley’s Nook.
Attack at dawn
A t t a c K a t d a w N
Steganography
Cryptography
Watermarking
Digital watermarking is a technology which allows a secret message to be hidden in a computer file.
AudioWatermarking
Applications of Watermarking
Rights management
Contents management
Access/copy control
Authentication
WATERMARKING TECHNIQUES
Watermarking
Spatial Domain
Watermarking
Least Significant Bit
SSM-Modulation
Frequency Domain
Watermarking
Discrete Cosine
Transformation
Discrete Wavelet
Transformation
Imperceptibility Robustness Capacity Security not affect the quality of the original signal
resist common signal processing manipulations such as : filteringCompression filteringCropping Resampling
bits that can be embedded in one secondof the host signal
-directly embedded in the signalsnot in a header of the signal.
-only be detected by authorized person
BASIC REQUIREMENTS OF WATERMARKING
Embedding in Dual Channel – More Security
Audio Sample
Right Channel
Left Channel
Synchronization Code Selects the ChannelWatermarked
AudioTrack
5 6 7 8
1 2 3 4
13 14 15 16
9 10 11 12
8 5 6 7
4 1 2 3
16 13 14 15
12 9 10 11
1 2 3 4
13 14 15 16
9 10 11 12
5 6 7 8
Original Watermark
Circular Shifted Watermark- Type 1
Circular Shifted Watermark- Type 2
Circular Shifting of Original Watermark
Spatial domain Least Significant Bit
DC LEVEL SHIFTING
Here watermark is embedded by shifting the DC level of the audio signal.
An input signal is divided into frames of fixed length.
DC level of each frame =Mean of a frame-value in the frame
After that a binary watermark sequence generated randomly is introduced to the shifted signal. This is
achieved by introducing a DC offset level to each frame in the signal according to the watermark bits.
If the watermark bit is 0, the signal is shifted downward.
If the watermark bit is 1, the signal is shifted upward.
DC LEVEL SHIFTING
level0
=-DCBiasMultiplier x FramePower
level1
=+DCBiasMultiplier x FramePower
where
level0
->DC level introduced when a watermark bit is 0
level1
-> the DC level introduced when a watermark bit is 1.
To extract a watermark, a watermarked signal is first divided into frames. Then, the mean of each frame
is calculated. If the mean of a frame is positive, the corresponding watermark bit is 1. Else, the
watermark bit is 0.
The original signal and watermark is not needed in the extraction process. Therefore, DC level shifting is
a blind watermarking scheme
Inverse Discrete Cosine Transform
Audio Data
Block 1
Block 2
Block 3
Block n
Discrete Cosine Transform
DCTData
DCTData
DCTData
DCTData
DCT’Data
DCT’Data
DCT’Data
DCT’Data
Watermark Embedded in Audio
Selecting Mid-Range of DCT Block
…
Mid Range
…
…
DCT- DISCRETE COSINE TRANSFORM
Frequency Domain Watermarking signal to embed
Host signal
Frequency components(using DCT)
Embedding
Extraction
NvvvV ,...,, 10
NxxxX ,...,, 10
NfffF ,...,, 10
iii xff
iii ffx
if = watermared singal
Import audio :
Decode Encode
Embedded info :
Watermark generation for client (unique key)
Upload Audio
Add Client for Audio
Watermarked Audio is sent to client
Unique Watermark stored in database for theft detection
Login Panel
Enter Client Details
PUBLISHER MODULE
Watermark Extraction from audioUpload Audio
Client Information Displayed
Fetching from Database
[ FOUND ]
DETECTION & TRACKING MODULE
Login Panel
KEY BASED
THANK YOU