PrecisEQ is designed to deliver professional audio effects when used with other music players. It allows users to enjoy the convenience of streaming services and the high sound quality of professional DSP at the same time, without requiring root access.

Regarding Foreground Services:
The application relies on the AudioPlaybackCapture API—provided via the PROJECT_MEDIA permission—to capture audio from other apps. This requires the execution of a foreground service, which simultaneously displays the processing status and sampling rate in real-time within a notification.

Key Features:

- Spatial Audio:
By performing real-time HRTF computation based on Brüel & Kjær HATS data and cross-convolving four-channel "True Stereo IR" reverb, PrecisEQ reconstructs a realistic and accurate sound field, making your headphones sound like a pair of 2.0 monitors in an RFZ (Reflection-Free Zone) mixing room. It supports simulating arbitrary azimuth angles and importing third-party SOFA files.

- Headphone Calibration:
Based on a proprietary and constantly updated high-precision headphone database, PrecisEQ can precisely calibrate your headphones to any target frequency response while displaying the real-time frequency response curve. With the built-in FR Editor, you can freely create, save, and share your own target curves or import those from other users. It also supports building and importing custom headphone repositories.

- IIR Parametric Equalizer:
Touch-enabled and fully visualized, this EQ balances professional capability with ease of use. It supports an unlimited number of EQ bands and allows setting the filter type (including Peak, Low Shelf, High Shelf, Notch, Band Pass, Low Pass, and High Pass), Gain, and Q value for any band. All IIR filters are designed to be minimum-phase.

- Convolver:
Supports importing IR files for sample rates of 44.1k, 48k, 96k, and 192kHz, automatically selecting the appropriate IR file based on the working sample rate. It displays detailed IR metadata including channel count, bit depth, duration, Taps, and the frequency response graph. Users can choose channels mapping modes: 1.map each IR channel to its corresponding audio channel; 2.use the first IR channel for all audio channels; 3. True Stereo IR Mode