Audio watermarking is a technique used to embed information or a watermark into audio signals without significantly affecting the audio quality. This technology is widely used for various applications such as copyright protection, content identification, and data verification.

In this blog post, we will explore how to implement audio watermarking using C++. We will focus on a simple technique called least significant bit (LSB) substitution, which involves replacing the least significant bits of the audio samples with the watermark bits.

Prerequisites

Before we dive into the implementation, make sure you have the following prerequisites:

• C++ compiler installed on your machine
• Basic knowledge of C++ programming language
• An audio file in a supported format (e.g., WAV, MP3)

Implementation Steps

1. Read the audio file: Load the audio file using a suitable library or framework. The most commonly used libraries for audio processing in C++ are “libsndfile” and “PortAudio”.

2. Generate the watermark: Create the watermark that you want to embed into the audio. This can be a unique identifier, a copyright notice, or any other information that you want to associate with the audio.

3. Get audio sample data: Extract the audio samples from the loaded audio file. The samples are typically represented as 16-bit signed integers for each channel.

4. Convert the watermark to binary: Convert the watermark into a binary representation. This can be done by encoding each character into its binary ASCII value or using more advanced techniques like cryptographic hashing.

5. Embed the watermark using LSB substitution: Iterate over the audio sample data and, for each sample, replace the least significant bits with the corresponding watermark bits. It is important to ensure that the changes made to the audio samples are imperceptible to maintain audio quality.

6. Write the modified audio file: Save the modified audio sample data into a new audio file. Make sure to choose an appropriate audio format that supports the desired audio quality and compatibility.

Example Code

#include <iostream>
#include <fstream>
#include <vector>

std::vector<int> convertToBinary(int value) {
    std::vector<int> binary;
    while (value > 0) {
        binary.push_back(value % 2);
        value /= 2;
    }
    return binary;
}

void embedWatermark(std::vector<short>& audioSamples, const std::vector<int>& watermark) {
    int watermarkIndex = 0;
    for (int i = 0; i < audioSamples.size(); i++) {
        int sample = audioSamples[i];
        int watermarkBit = watermark[watermarkIndex];
        sample = (sample & 0xFFFE) | watermarkBit;
        audioSamples[i] = sample;
        
        watermarkIndex++;
        if (watermarkIndex >= watermark.size()) {
            watermarkIndex = 0;
        }
    }
}

int main() {
    // Read the audio file and get audio samples
    
    // Generate the watermark
    
    // Convert the watermark to binary
    
    // Embed the watermark using LSB substitution
    
    // Write the modified audio file
    
    return 0;
}

Conclusion

Audio watermarking is an important technique for protecting intellectual property and ensuring content identification. By following the steps outlined in this blog post, you can implement a basic audio watermarking system using C++. Remember to further research and explore different techniques for advanced watermarking and real-time watermark detection. #AudioWatermarking #C++