In audio playback systems, various signal processing can be applied to improve the user experience. For example, dynamic range compression (DRC) can be applied to an audio signal when playback occurs in a noisy scenario, a peak limiter can be applied to avoid hard clipping, loudness equalization (EQ) can be applied if the playback loudness is lower than the loudness at which the content was mastered, EQ can be applied to improve the spectral balance, and automatic gain control (AGC) can be applied to achieve consistent loudness in a similar way as loudness normalization. Most of these signal processing algorithms include some kind of audio signal analysis or measurement, which is used to adapt parameters of the algorithm. For instance, the DRC, loudness EQ, and automatic gain control are commonly based on a short-term level or loudness estimate of the audio signal, to control the gain that is applied to the audio signal by the algorithm.
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