cridecoder 0.1.0

CRI codec library for ACB/AWB, HCA audio, and USM video extraction
Documentation 
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//! ATH (Audio Threshold Hearing) curve initialization

use super::decoder::HCA_SAMPLES_PER_SUBFRAME;

/// Base ATH curve data
const ATH_BASE_CURVE: [u8; 656] = [
    0x78, 0x5F, 0x56, 0x51, 0x4E, 0x4C, 0x4B, 0x49, 0x48, 0x48, 0x47, 0x46, 0x46, 0x45, 0x45, 0x45,
    0x44, 0x44, 0x44, 0x44, 0x43, 0x43, 0x43, 0x43, 0x43, 0x43, 0x42, 0x42, 0x42, 0x42, 0x42, 0x42,
    0x42, 0x42, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x40, 0x40, 0x40, 0x40,
    0x40, 0x40, 0x40, 0x40, 0x40, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,
    0x3F, 0x3F, 0x3F, 0x3E, 0x3E, 0x3E, 0x3E, 0x3E, 0x3E, 0x3D, 0x3D, 0x3D, 0x3D, 0x3D, 0x3D, 0x3D,
    0x3C, 0x3C, 0x3C, 0x3C, 0x3C, 0x3C, 0x3C, 0x3C, 0x3B, 0x3B, 0x3B, 0x3B, 0x3B, 0x3B, 0x3B, 0x3B,
    0x3B, 0x3B, 0x3B, 0x3B, 0x3B, 0x3B, 0x3B, 0x3B, 0x3B, 0x3B, 0x3B, 0x3B, 0x3B, 0x3B, 0x3B, 0x3B,
    0x3B, 0x3B, 0x3B, 0x3B, 0x3B, 0x3B, 0x3B, 0x3B, 0x3C, 0x3C, 0x3C, 0x3C, 0x3C, 0x3C, 0x3C, 0x3C,
    0x3D, 0x3D, 0x3D, 0x3D, 0x3D, 0x3D, 0x3D, 0x3D, 0x3E, 0x3E, 0x3E, 0x3E, 0x3E, 0x3E, 0x3E, 0x3F,
    0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,
    0x3F, 0x3F, 0x3F, 0x3F, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
    0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41,
    0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41,
    0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x42, 0x42, 0x42, 0x42, 0x42, 0x42, 0x42, 0x42, 0x42,
    0x42, 0x42, 0x42, 0x42, 0x42, 0x42, 0x42, 0x42, 0x42, 0x42, 0x42, 0x42, 0x42, 0x43, 0x43, 0x43,
    0x43, 0x43, 0x43, 0x43, 0x43, 0x43, 0x43, 0x43, 0x43, 0x43, 0x43, 0x43, 0x43, 0x43, 0x44, 0x44,
    0x44, 0x44, 0x44, 0x44, 0x44, 0x44, 0x44, 0x44, 0x44, 0x44, 0x44, 0x44, 0x45, 0x45, 0x45, 0x45,
    0x45, 0x45, 0x45, 0x45, 0x45, 0x45, 0x45, 0x45, 0x46, 0x46, 0x46, 0x46, 0x46, 0x46, 0x46, 0x46,
    0x46, 0x46, 0x47, 0x47, 0x47, 0x47, 0x47, 0x47, 0x47, 0x47, 0x47, 0x47, 0x48, 0x48, 0x48, 0x48,
    0x48, 0x48, 0x48, 0x48, 0x49, 0x49, 0x49, 0x49, 0x49, 0x49, 0x49, 0x49, 0x4A, 0x4A, 0x4A, 0x4A,
    0x4A, 0x4A, 0x4A, 0x4A, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4B, 0x4C, 0x4C, 0x4C, 0x4C, 0x4C,
    0x4C, 0x4D, 0x4D, 0x4D, 0x4D, 0x4D, 0x4D, 0x4E, 0x4E, 0x4E, 0x4E, 0x4E, 0x4E, 0x4F, 0x4F, 0x4F,
    0x4F, 0x4F, 0x4F, 0x50, 0x50, 0x50, 0x50, 0x50, 0x51, 0x51, 0x51, 0x51, 0x51, 0x52, 0x52, 0x52,
    0x52, 0x52, 0x53, 0x53, 0x53, 0x53, 0x54, 0x54, 0x54, 0x54, 0x54, 0x55, 0x55, 0x55, 0x55, 0x56,
    0x56, 0x56, 0x56, 0x57, 0x57, 0x57, 0x57, 0x57, 0x58, 0x58, 0x58, 0x59, 0x59, 0x59, 0x59, 0x5A,
    0x5A, 0x5A, 0x5A, 0x5B, 0x5B, 0x5B, 0x5B, 0x5C, 0x5C, 0x5C, 0x5D, 0x5D, 0x5D, 0x5D, 0x5E, 0x5E,
    0x5E, 0x5F, 0x5F, 0x5F, 0x60, 0x60, 0x60, 0x61, 0x61, 0x61, 0x61, 0x62, 0x62, 0x62, 0x63, 0x63,
    0x63, 0x64, 0x64, 0x64, 0x65, 0x65, 0x66, 0x66, 0x66, 0x67, 0x67, 0x67, 0x68, 0x68, 0x68, 0x69,
    0x69, 0x6A, 0x6A, 0x6A, 0x6B, 0x6B, 0x6B, 0x6C, 0x6C, 0x6D, 0x6D, 0x6D, 0x6E, 0x6E, 0x6F, 0x6F,
    0x70, 0x70, 0x70, 0x71, 0x71, 0x72, 0x72, 0x73, 0x73, 0x73, 0x74, 0x74, 0x75, 0x75, 0x76, 0x76,
    0x77, 0x77, 0x78, 0x78, 0x78, 0x79, 0x79, 0x7A, 0x7A, 0x7B, 0x7B, 0x7C, 0x7C, 0x7D, 0x7D, 0x7E,
    0x7E, 0x7F, 0x7F, 0x80, 0x80, 0x81, 0x81, 0x82, 0x83, 0x83, 0x84, 0x84, 0x85, 0x85, 0x86, 0x86,
    0x87, 0x88, 0x88, 0x89, 0x89, 0x8A, 0x8A, 0x8B, 0x8C, 0x8C, 0x8D, 0x8D, 0x8E, 0x8F, 0x8F, 0x90,
    0x90, 0x91, 0x92, 0x92, 0x93, 0x94, 0x94, 0x95, 0x95, 0x96, 0x97, 0x97, 0x98, 0x99, 0x99, 0x9A,
    0x9B, 0x9B, 0x9C, 0x9D, 0x9D, 0x9E, 0x9F, 0xA0, 0xA0, 0xA1, 0xA2, 0xA2, 0xA3, 0xA4, 0xA5, 0xA5,
    0xA6, 0xA7, 0xA7, 0xA8, 0xA9, 0xAA, 0xAA, 0xAB, 0xAC, 0xAD, 0xAE, 0xAE, 0xAF, 0xB0, 0xB1, 0xB1,
    0xB2, 0xB3, 0xB4, 0xB5, 0xB6, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xBA, 0xBB, 0xBC, 0xBD, 0xBE, 0xBF,
    0xC0, 0xC1, 0xC1, 0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xC7, 0xC8, 0xC9, 0xC9, 0xCA, 0xCB, 0xCC, 0xCD,
    0xCE, 0xCF, 0xD0, 0xD1, 0xD2, 0xD3, 0xD4, 0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA, 0xDB, 0xDC, 0xDD,
    0xDE, 0xDF, 0xE0, 0xE1, 0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA, 0xEB, 0xED, 0xEE,
    0xEF, 0xF0, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5, 0xF7, 0xF8, 0xF9, 0xFA, 0xFB, 0xFC, 0xFD, 0xFF, 0xFF,
];

/// Initialize ATH curve type 0 (all zeros)
pub fn ath_init_0(ath_curve: &mut [u8; HCA_SAMPLES_PER_SUBFRAME]) {
    ath_curve.fill(0);
}

/// Initialize ATH curve type 1 (sample-rate dependent)
pub fn ath_init_1(ath_curve: &mut [u8; HCA_SAMPLES_PER_SUBFRAME], sample_rate: u32) {
    let mut acc: u32 = 0;
    for i in 0..HCA_SAMPLES_PER_SUBFRAME {
        acc += sample_rate;
        let index = (acc >> 13) as usize;

        if index >= 654 {
            ath_curve[i..HCA_SAMPLES_PER_SUBFRAME].fill(0xFF);
            break;
        }
        ath_curve[i] = ATH_BASE_CURVE[index];
    }
}

/// Initialize ATH curve based on type
pub fn ath_init(
    ath_curve: &mut [u8; HCA_SAMPLES_PER_SUBFRAME],
    ath_type: u32,
    sample_rate: u32,
) -> bool {
    match ath_type {
        0 => {
            ath_init_0(ath_curve);
            true
        }
        1 => {
            ath_init_1(ath_curve, sample_rate);
            true
        }
        _ => false,
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_ath_init_0() {
        let mut curve = [0u8; HCA_SAMPLES_PER_SUBFRAME];
        ath_init_0(&mut curve);
        assert!(curve.iter().all(|&x| x == 0));
    }

    #[test]
    fn test_ath_init_1() {
        let mut curve = [0u8; HCA_SAMPLES_PER_SUBFRAME];
        ath_init_1(&mut curve, 44100);
        // With sample_rate=44100, acc starts at 44100, index = 44100 >> 13 = 5
        assert_eq!(curve[0], ATH_BASE_CURVE[5]);
        // Second iteration: acc=88200, index = 88200 >> 13 = 10
        assert_eq!(curve[1], ATH_BASE_CURVE[10]);
    }
}