| /*************************************************************************** |
| * __________ __ ___. |
| * Open \______ \ ____ ____ | | _\_ |__ _______ ___ |
| * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ / |
| * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < < |
| * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \ |
| * \/ \/ \/ \/ \/ |
| * $Id$ |
| * |
| * Copyright (C) 2009 Jeffrey Goode |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License |
| * as published by the Free Software Foundation; either version 2 |
| * of the License, or (at your option) any later version. |
| * |
| * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY |
| * KIND, either express or implied. |
| * |
| ****************************************************************************/ |
| #include "config.h" |
| #include "fixedpoint.h" |
| #include "fracmul.h" |
| #include "settings.h" |
| #include "dsp.h" |
| #include "compressor.h" |
| |
| /* Define LOGF_ENABLE to enable logf output in this file */ |
| /*#define LOGF_ENABLE*/ |
| #include "logf.h" |
| |
| static int32_t comp_rel_slope IBSS_ATTR; /* S7.24 format */ |
| static int32_t comp_makeup_gain IBSS_ATTR; /* S7.24 format */ |
| static int32_t comp_curve[66] IBSS_ATTR; /* S7.24 format */ |
| static int32_t release_gain IBSS_ATTR; /* S7.24 format */ |
| |
| #define UNITY (1L << 24) /* unity gain in S7.24 format */ |
| |
| /** COMPRESSOR UPDATE |
| * Called via the menu system to configure the compressor process */ |
| bool compressor_update(void) |
| { |
| static int curr_set[5]; |
| int new_set[5] = { |
| global_settings.compressor_threshold, |
| global_settings.compressor_makeup_gain, |
| global_settings.compressor_ratio, |
| global_settings.compressor_knee, |
| global_settings.compressor_release_time}; |
| |
| /* make menu values useful */ |
| int threshold = new_set[0]; |
| bool auto_gain = (new_set[1] == 1); |
| const int comp_ratios[] = {2, 4, 6, 10, 0}; |
| int ratio = comp_ratios[new_set[2]]; |
| bool soft_knee = (new_set[3] == 1); |
| int release = new_set[4] * NATIVE_FREQUENCY / 1000; |
| |
| bool changed = false; |
| bool active = (threshold < 0); |
| |
| for (int i = 0; i < 5; i++) |
| { |
| if (curr_set[i] != new_set[i]) |
| { |
| changed = true; |
| curr_set[i] = new_set[i]; |
| |
| #if defined(ROCKBOX_HAS_LOGF) && defined(LOGF_ENABLE) |
| switch (i) |
| { |
| case 0: |
| logf(" Compressor Threshold: %d dB\tEnabled: %s", |
| threshold, active ? "Yes" : "No"); |
| break; |
| case 1: |
| logf(" Compressor Makeup Gain: %s", |
| auto_gain ? "Auto" : "Off"); |
| break; |
| case 2: |
| if (ratio) |
| { logf(" Compressor Ratio: %d:1", ratio); } |
| else |
| { logf(" Compressor Ratio: Limit"); } |
| break; |
| case 3: |
| logf(" Compressor Knee: %s", soft_knee?"Soft":"Hard"); |
| break; |
| case 4: |
| logf(" Compressor Release: %d", release); |
| break; |
| } |
| #endif |
| } |
| } |
| |
| if (changed && active) |
| { |
| /* configure variables for compressor operation */ |
| static const int32_t db[] = { |
| /* positive db equivalents in S15.16 format */ |
| 0x000000, 0x241FA4, 0x1E1A5E, 0x1A94C8, |
| 0x181518, 0x1624EA, 0x148F82, 0x1338BD, |
| 0x120FD2, 0x1109EB, 0x101FA4, 0x0F4BB6, |
| 0x0E8A3C, 0x0DD840, 0x0D3377, 0x0C9A0E, |
| 0x0C0A8C, 0x0B83BE, 0x0B04A5, 0x0A8C6C, |
| 0x0A1A5E, 0x09ADE1, 0x094670, 0x08E398, |
| 0x0884F6, 0x082A30, 0x07D2FA, 0x077F0F, |
| 0x072E31, 0x06E02A, 0x0694C8, 0x064BDF, |
| 0x060546, 0x05C0DA, 0x057E78, 0x053E03, |
| 0x04FF5F, 0x04C273, 0x048726, 0x044D64, |
| 0x041518, 0x03DE30, 0x03A89B, 0x037448, |
| 0x03412A, 0x030F32, 0x02DE52, 0x02AE80, |
| 0x027FB0, 0x0251D6, 0x0224EA, 0x01F8E2, |
| 0x01CDB4, 0x01A359, 0x0179C9, 0x0150FC, |
| 0x0128EB, 0x010190, 0x00DAE4, 0x00B4E1, |
| 0x008F82, 0x006AC1, 0x004699, 0x002305}; |
| |
| struct curve_point |
| { |
| int32_t db; /* S15.16 format */ |
| int32_t offset; /* S15.16 format */ |
| } db_curve[5]; |
| |
| /** Set up the shape of the compression curve first as decibel |
| values */ |
| /* db_curve[0] = bottom of knee |
| [1] = threshold |
| [2] = top of knee |
| [3] = 0 db input |
| [4] = ~+12db input (2 bits clipping overhead) */ |
| |
| db_curve[1].db = threshold << 16; |
| if (soft_knee) |
| { |
| /* bottom of knee is 3dB below the threshold for soft knee*/ |
| db_curve[0].db = db_curve[1].db - (3 << 16); |
| /* top of knee is 3dB above the threshold for soft knee */ |
| db_curve[2].db = db_curve[1].db + (3 << 16); |
| if (ratio) |
| /* offset = -3db * (ratio - 1) / ratio */ |
| db_curve[2].offset = (int32_t)((long long)(-3 << 16) |
| * (ratio - 1) / ratio); |
| else |
| /* offset = -3db for hard limit */ |
| db_curve[2].offset = (-3 << 16); |
| } |
| else |
| { |
| /* bottom of knee is at the threshold for hard knee */ |
| db_curve[0].db = threshold << 16; |
| /* top of knee is at the threshold for hard knee */ |
| db_curve[2].db = threshold << 16; |
| db_curve[2].offset = 0; |
| } |
| |
| /* Calculate 0db and ~+12db offsets */ |
| db_curve[4].db = 0xC0A8C; /* db of 2 bits clipping */ |
| if (ratio) |
| { |
| /* offset = threshold * (ratio - 1) / ratio */ |
| db_curve[3].offset = (int32_t)((long long)(threshold << 16) |
| * (ratio - 1) / ratio); |
| db_curve[4].offset = (int32_t)((long long)-db_curve[4].db |
| * (ratio - 1) / ratio) + db_curve[3].offset; |
| } |
| else |
| { |
| /* offset = threshold for hard limit */ |
| db_curve[3].offset = (threshold << 16); |
| db_curve[4].offset = -db_curve[4].db + db_curve[3].offset; |
| } |
| |
| /** Now set up the comp_curve table with compression offsets in the |
| form of gain factors in S7.24 format */ |
| /* comp_curve[0] is 0 (-infinity db) input */ |
| comp_curve[0] = UNITY; |
| /* comp_curve[1 to 63] are intermediate compression values |
| corresponding to the 6 MSB of the input values of a non-clipped |
| signal */ |
| for (int i = 1; i < 64; i++) |
| { |
| /* db constants are stored as positive numbers; |
| make them negative here */ |
| int32_t this_db = -db[i]; |
| |
| /* no compression below the knee */ |
| if (this_db <= db_curve[0].db) |
| comp_curve[i] = UNITY; |
| |
| /* if soft knee and below top of knee, |
| interpolate along soft knee slope */ |
| else if (soft_knee && (this_db <= db_curve[2].db)) |
| comp_curve[i] = fp_factor(fp_mul( |
| ((this_db - db_curve[0].db) / 6), |
| db_curve[2].offset, 16), 16) << 8; |
| |
| /* interpolate along ratio slope above the knee */ |
| else |
| comp_curve[i] = fp_factor(fp_mul( |
| fp_div((db_curve[1].db - this_db), db_curve[1].db, 16), |
| db_curve[3].offset, 16), 16) << 8; |
| } |
| /* comp_curve[64] is the compression level of a maximum level, |
| non-clipped signal */ |
| comp_curve[64] = fp_factor(db_curve[3].offset, 16) << 8; |
| |
| /* comp_curve[65] is the compression level of a maximum level, |
| clipped signal */ |
| comp_curve[65] = fp_factor(db_curve[4].offset, 16) << 8; |
| |
| #if defined(ROCKBOX_HAS_LOGF) && defined(LOGF_ENABLE) |
| logf("\n *** Compression Offsets ***"); |
| /* some settings for display only, not used in calculations */ |
| db_curve[0].offset = 0; |
| db_curve[1].offset = 0; |
| db_curve[3].db = 0; |
| |
| for (int i = 0; i <= 4; i++) |
| { |
| logf("Curve[%d]: db: % 6.2f\toffset: % 6.2f", i, |
| (float)db_curve[i].db / (1 << 16), |
| (float)db_curve[i].offset / (1 << 16)); |
| } |
| |
| logf("\nGain factors:"); |
| for (int i = 1; i <= 65; i++) |
| { |
| debugf("%02d: %.6f ", i, (float)comp_curve[i] / UNITY); |
| if (i % 4 == 0) debugf("\n"); |
| } |
| debugf("\n"); |
| #endif |
| |
| /* if using auto peak, then makeup gain is max offset - |
| .1dB headroom */ |
| comp_makeup_gain = auto_gain ? |
| fp_factor(-(db_curve[3].offset) - 0x199A, 16) << 8 : UNITY; |
| logf("Makeup gain:\t%.6f", (float)comp_makeup_gain / UNITY); |
| |
| /* calculate per-sample gain change a rate of 10db over release time |
| */ |
| comp_rel_slope = 0xAF0BB2 / release; |
| logf("Release slope:\t%.6f", (float)comp_rel_slope / UNITY); |
| |
| release_gain = UNITY; |
| } |
| |
| return active; |
| } |
| |
| /** GET COMPRESSION GAIN |
| * Returns the required gain factor in S7.24 format in order to compress the |
| * sample in accordance with the compression curve. Always 1 or less. |
| */ |
| static inline int32_t get_compression_gain(struct dsp_data *data, |
| int32_t sample) |
| { |
| const int frac_bits_offset = data->frac_bits - 15; |
| |
| /* sample must be positive */ |
| if (sample < 0) |
| sample = -(sample + 1); |
| |
| /* shift sample into 15 frac bit range */ |
| if (frac_bits_offset > 0) |
| sample >>= frac_bits_offset; |
| if (frac_bits_offset < 0) |
| sample <<= -frac_bits_offset; |
| |
| /* normal case: sample isn't clipped */ |
| if (sample < (1 << 15)) |
| { |
| /* index is 6 MSB, rem is 9 LSB */ |
| int index = sample >> 9; |
| int32_t rem = (sample & 0x1FF) << 22; |
| |
| /* interpolate from the compression curve: |
| higher gain - ((rem / (1 << 31)) * (higher gain - lower gain)) */ |
| return comp_curve[index] - (FRACMUL(rem, |
| (comp_curve[index] - comp_curve[index + 1]))); |
| } |
| /* sample is somewhat clipped, up to 2 bits of overhead */ |
| if (sample < (1 << 17)) |
| { |
| /* straight interpolation: |
| higher gain - ((clipped portion of sample * 4/3 |
| / (1 << 31)) * (higher gain - lower gain)) */ |
| return comp_curve[64] - (FRACMUL(((sample - (1 << 15)) / 3) << 16, |
| (comp_curve[64] - comp_curve[65]))); |
| } |
| |
| /* sample is too clipped, return invalid value */ |
| return -1; |
| } |
| |
| /** COMPRESSOR PROCESS |
| * Changes the gain of the samples according to the compressor curve |
| */ |
| void compressor_process(int count, struct dsp_data *data, int32_t *buf[]) |
| { |
| const int num_chan = data->num_channels; |
| int32_t *in_buf[2] = {buf[0], buf[1]}; |
| |
| while (count-- > 0) |
| { |
| int ch; |
| /* use lowest (most compressed) gain factor of the output buffer |
| sample pair for both samples (mono is also handled correctly here) |
| */ |
| int32_t sample_gain = UNITY; |
| for (ch = 0; ch < num_chan; ch++) |
| { |
| int32_t this_gain = get_compression_gain(data, *in_buf[ch]); |
| if (this_gain < sample_gain) |
| sample_gain = this_gain; |
| } |
| |
| /* perform release slope; skip if no compression and no release slope |
| */ |
| if ((sample_gain != UNITY) || (release_gain != UNITY)) |
| { |
| /* if larger offset than previous slope, start new release slope |
| */ |
| if ((sample_gain <= release_gain) && (sample_gain > 0)) |
| { |
| release_gain = sample_gain; |
| } |
| else |
| /* keep sloping towards unity gain (and ignore invalid value) */ |
| { |
| release_gain += comp_rel_slope; |
| if (release_gain > UNITY) |
| { |
| release_gain = UNITY; |
| } |
| } |
| } |
| |
| /* total gain factor is the product of release gain and makeup gain, |
| but avoid computation if possible */ |
| int32_t total_gain = ((release_gain == UNITY) ? comp_makeup_gain : |
| (comp_makeup_gain == UNITY) ? release_gain : |
| FRACMUL_SHL(release_gain, comp_makeup_gain, 7)); |
| |
| /* Implement the compressor: apply total gain factor (if any) to the |
| output buffer sample pair/mono sample */ |
| if (total_gain != UNITY) |
| { |
| for (ch = 0; ch < num_chan; ch++) |
| { |
| *in_buf[ch] = FRACMUL_SHL(total_gain, *in_buf[ch], 7); |
| } |
| } |
| in_buf[0]++; |
| in_buf[1]++; |
| } |
| } |
| |
| void compressor_reset(void) |
| { |
| release_gain = UNITY; |
| } |