Item | Type | Description |
---|---|---|
A | Resampling | Conducting downsampling to 8 kHz and then upsampling back to 16 kHz. |
B | Requantization | Quantizing the watermarked signal to 8 bits/sample and then back to 16 bits/sample. |
C | Low-pass filtering (I) | Applying a low-pass filter with a cutoff frequency of 4 kHz. |
D | Low-pass filtering (II) | Applying a low-pass filter with a cutoff frequency of 1 kHz. |
E | High-pass filtering | Applying a high-pass filter with a cutoff frequency of 1 kHz. |
F | Amplitude scaling | Scaling the amplitude of the watermarked signal by 0.85. |
G | Noise corruption (I) | Adding zero-mean white Gaussian noise to the watermarked audio signal with SNR = 30 dB. |
H | Noise corruption (II) | Adding zero-mean white Gaussian noise to the watermarked audio signal with SNR = 20 dB. |
I | DA/AD conversion | Converting the digital audio file to an analog signal and then resampling the analog signal at 16 kHz. The DA/AD conversion is performed through an onboard Realtek ALC892 audio codec, of which the line-out is linked with the line-in using a cable line during playback and recording. |
J | Echo addition | Adding an echo signal with a delay of 50 ms and a decay to 5% to the watermarked audio signal. |
K | Jittering | Randomly deleting or adding one sample for every 100 samples within each frame. |
L | G.722 speech coding | Encoding and decoding the watermarked speech signal with a G.722 wideband audio codec at 64 kbps. |
M | G.726 speech coding | Encoding and decoding the watermarked speech signal with a G.726 wideband audio codec at 32 kbps. |
N | Time-shift by 1 sample | Purposely shifting the watermarked audio signal by one sample. |