audio watermarking implementation

1. AUDIO WATERMARKING
James Huang

2. WHAT IS DIGITAL
WATERMARK?
• A technique that embed specific info into digital
signals
• Audio Watermarking - hiding information in music
• DC WatermarkingVS Frequency Watermarking

3. PSYCHOACOUSTICS
• Masking Effect - A “weak” sound is difficult to be
heard while a “strong” sound is also being played
• Temporal Masking Effect - Amplitude (Volume)
• Frequency Masking Effect - Amplitude in frequency

4. MASKING EFFECT
DC Watermarking Frequency Watermarking

5. DC WATERMARKING
• Framing - divide the audio into equal frames
• Spectral Analysis
• DC Removal
• Watermark Signal Addition
• K(scaling factor) - assure the magnitude of watermark signal is lower than the
threshold
• W(n) - watermark signal
• Pframe(n) - sum of amplitude spectrum squared

6. FREQUENCY WATERMARKING
• Framing and FFT
• Get frequency threshold
• In-audible Removal - replace the signal under
threshold to the watermark signal
• Watermark signal addition

7. RESULT
• Original audio signal
• Length : 30 seconds
• Sampling rate : 44100 (1/s)
• Frame length : 512 samples
• Watermark signal
• A 150*150 pixel image

8. RESULT
FrequencyThreshold

9. RESULT
Original Signal FFT Watermarked Signal FFT

10. RESULT
Masked audio
Original audio

11. RESULT
Original Image Extracted Image