The new AWT2 0.09.00 is a major AWT2 release. Here is what’s new:
– AWT2 encoder uses new, redesigned encoding algorithm (backward compatible with the older one). The new algorithm features new “-modulation_gain” parameter that triggers an additional modulation mechanism of the encoder aimed to increase watermark robustness. With default setting (0 dB) the modulation of the signal is not performed. Lower values (e.g. -6 dB) enable special modulation of sub-band signals that helps the watermarks to withstand audio transformations and corruptions. In addition, the use of the modulation improves watermarking reliability of monotonous signals. “Safe” (imperceptible) modulation gain values are from 0 to -12 dB. The setting is available in the command-line encoder tool only (not in the GUI front-end).
– new “-noise_level” parameter in the encoder which defines a level of artificially generated noise mixed into the processed audio signal. This feature resolves a problem with watermarking of speech recordings. Typical speech recordings usually contain many regions of silence (pauses between words and phrases). Due to the lack of any audible information in these regions, the watermarks cannot be added into them, that reduces overall watermark robustness in the output signal. To overcome this problem, artificially generated low-level “comfort noise” can be mixed into the source audio signal to fill the silent gaps and allow carrying watermarks even in originally silent regions. It is recommended to use this feature to watermark speech recordings. Recommended noise level setting is around -50 dB (optimal setting can vary depending on input signal level and content). The setting is available in the command-line encoder tool only (not in the GUI front-end).
– new “-output_gain” parameter in the encoder that defines attenuation level of the output (watermarked) signal. As a result of encoder’s signal processing, the output signal amplitude can become higher than the input. To prevent possible saturation/clipping of the output signal, limiter is applied on the very last stage of the processing. However, in some cases use of the limiter may be not desirable. The user can specify a desired output attenuation gain to avoid automatic limitation of the output signal. The setting is available in the command-line encoder tool only (not in the GUI front-end).
– increased encoder and decoder execution speed (various memory and code optimizations made)
– fixed bug in SDK (“high capacity” mode was set incorrectly)
– fixed minor problem with encoding of tailing 200ms of audio
– fixed potential encoder crash in case of wrong -skip_first / -skip_last values
– updated AWT2 User Guide and AWT2 SDK.
AWT2 free evaluation package is available here.