**2. Digital watermarking**

Watermarking is a method through which the protected data conveyed without much observable change in the watermarked content. The watermarking process

comprises of two main steps: (i) embedding method and (ii) extraction method. The secret key could be used for additional level of security. There are fundamentally three sorts of watermarking methods and are described here: (1) non-blind watermarking, (2) semi-blind and (3) blind watermarking. The process of watermarking that uses the original sound signal during the extraction procedure termed as "non-blind watermarking". The watermarking system uses a portion of the segment or some a part of the input audio signal then it is term as a "semi-blind watermarking". The watermarking system helps to retrieve the watermark without use of original audio signal or a part of an audio signal for extraction process termed as "blind watermarking" [14]. The paper covers proposed novel blind audio watermarking scheme and its hardware implementation is performed in Xilinx ISE. The steps of algorithms are covered in Section 3. The watermark consists of a data sequence of binary bits which is inserted into the host signal. The audio watermarking scheme should have following basic characteristics: inaudibility, payload and robustness. **Figure 1** gives the visual representation of the requirements of data watermarking concept in digital audio, these three requirements forms the corners of the magic triangle.

**3. Proposed audio watermarking**

*DOI: http://dx.doi.org/10.5772/intechopen.86087*

The proposed audio watermarking scheme is blind and robust and is based on DWT transformation. In the proposed scheme, only eight-audio samples of a single frame from two channels, is considered for watermarking process. The details of the

Step 1: The original audio signal of 16 samples is considered from two channels

Step 2: DWT transform is applied to obtain an approximate and detailed coefficient of the both channels. Here the approximate and detailed coefficients are low

Step 3: Then, binary bits are embedded in the detailed component of an input

where P\_1' = detailed component after watermarking, P\_1 = detailed component

before watermarking, I = intensity factor and if watermark bit is 0, then 2nd channel detailed component is changed with the first channel detailed component.

P1' <sup>¼</sup> P1 <sup>þ</sup> <sup>I</sup> <sup>∗</sup> ð Þ P1 in the first channel (1)

embedded and extracted process are shown in the following section.

*Hardware Implementation of Audio Watermarking Based on DWT Transform*

Input: original audio, watermark; output: watermarked audio.

**3.1 Embedding process of DWT-based audio watermarking**

The steps of embedding process are as follows:

and high pass filter component of the original input signal.

audio signal. If watermark bit is one then according to

for further watermark embedding process.

**Figure 2.**

**199**

*Flowchart of the embedded process.*


**Figure 1.** *Performance parameter magic triangle.*
