True Peak: A Peak Value That Can Exceed the Actual Peak?
In digital audio, even if the sample data is below the Peak value, the actual analog waveform can exceed the Peak value when played back. This phenomenon arises from the characteristics of the digital signal’s quantization stage and the functioning of the D/A converter. To estimate the maximum amplitude when the sample data is converted into an actual analog waveform, True Peak values are utilized.
True Peak is defined according to the ITU-R BS.1770 recommendation and represents the “actual maximum level” of the signal waveform. This refers to the maximum amplitude that can actually occur when the digital signal is played back in analog form. True Peak is denoted in dBTP (decibels True Peak), which indicates the decibel level of the peak value.
True Peak values play a critical role in digital signal processing and mixing to prevent overload and clipping. For example, in audio mastering, the True Peak value is carefully adjusted to ensure it does not exceed a specific level, thereby preventing clipping or distortion. For a more accurate measurement of sample peaks, it’s highly recommended to actively use features like oversampling.