| /* |
| * Audio Processing Technology codec for Bluetooth (aptX) |
| * |
| * Copyright (C) 2017 Aurelien Jacobs <aurel@gnuage.org> |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2.1 of the License, or (at your option) any later version. |
| * |
| * FFmpeg is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| #ifndef AVCODEC_APTX_H |
| #define AVCODEC_APTX_H |
| |
| #include "libavutil/intreadwrite.h" |
| #include "avcodec.h" |
| #include "internal.h" |
| #include "mathops.h" |
| #include "audio_frame_queue.h" |
| |
| |
| enum channels { |
| LEFT, |
| RIGHT, |
| NB_CHANNELS |
| }; |
| |
| enum subbands { |
| LF, // Low Frequency (0-5.5 kHz) |
| MLF, // Medium-Low Frequency (5.5-11kHz) |
| MHF, // Medium-High Frequency (11-16.5kHz) |
| HF, // High Frequency (16.5-22kHz) |
| NB_SUBBANDS |
| }; |
| |
| #define NB_FILTERS 2 |
| #define FILTER_TAPS 16 |
| |
| typedef struct { |
| int pos; |
| int32_t buffer[2*FILTER_TAPS]; |
| } FilterSignal; |
| |
| typedef struct { |
| FilterSignal outer_filter_signal[NB_FILTERS]; |
| FilterSignal inner_filter_signal[NB_FILTERS][NB_FILTERS]; |
| } QMFAnalysis; |
| |
| typedef struct { |
| int32_t quantized_sample; |
| int32_t quantized_sample_parity_change; |
| int32_t error; |
| } Quantize; |
| |
| typedef struct { |
| int32_t quantization_factor; |
| int32_t factor_select; |
| int32_t reconstructed_difference; |
| } InvertQuantize; |
| |
| typedef struct { |
| int32_t prev_sign[2]; |
| int32_t s_weight[2]; |
| int32_t d_weight[24]; |
| int32_t pos; |
| int32_t reconstructed_differences[48]; |
| int32_t previous_reconstructed_sample; |
| int32_t predicted_difference; |
| int32_t predicted_sample; |
| } Prediction; |
| |
| typedef struct { |
| int32_t codeword_history; |
| int32_t dither_parity; |
| int32_t dither[NB_SUBBANDS]; |
| |
| QMFAnalysis qmf; |
| Quantize quantize[NB_SUBBANDS]; |
| InvertQuantize invert_quantize[NB_SUBBANDS]; |
| Prediction prediction[NB_SUBBANDS]; |
| } Channel; |
| |
| typedef struct { |
| int hd; |
| int block_size; |
| int32_t sync_idx; |
| Channel channels[NB_CHANNELS]; |
| AudioFrameQueue afq; |
| } AptXContext; |
| |
| typedef const struct { |
| const int32_t *quantize_intervals; |
| const int32_t *invert_quantize_dither_factors; |
| const int32_t *quantize_dither_factors; |
| const int16_t *quantize_factor_select_offset; |
| int tables_size; |
| int32_t factor_max; |
| int32_t prediction_order; |
| } ConstTables; |
| |
| extern ConstTables ff_aptx_quant_tables[2][NB_SUBBANDS]; |
| |
| /* Rounded right shift with optionnal clipping */ |
| #define RSHIFT_SIZE(size) \ |
| av_always_inline \ |
| static int##size##_t rshift##size(int##size##_t value, int shift) \ |
| { \ |
| int##size##_t rounding = (int##size##_t)1 << (shift - 1); \ |
| int##size##_t mask = ((int##size##_t)1 << (shift + 1)) - 1; \ |
| return ((value + rounding) >> shift) - ((value & mask) == rounding); \ |
| } \ |
| av_always_inline \ |
| static int##size##_t rshift##size##_clip24(int##size##_t value, int shift) \ |
| { \ |
| return av_clip_intp2(rshift##size(value, shift), 23); \ |
| } |
| RSHIFT_SIZE(32) |
| RSHIFT_SIZE(64) |
| |
| /* |
| * Convolution filter coefficients for the outer QMF of the QMF tree. |
| * The 2 sets are a mirror of each other. |
| */ |
| static const int32_t aptx_qmf_outer_coeffs[NB_FILTERS][FILTER_TAPS] = { |
| { |
| 730, -413, -9611, 43626, -121026, 269973, -585547, 2801966, |
| 697128, -160481, 27611, 8478, -10043, 3511, 688, -897, |
| }, |
| { |
| -897, 688, 3511, -10043, 8478, 27611, -160481, 697128, |
| 2801966, -585547, 269973, -121026, 43626, -9611, -413, 730, |
| }, |
| }; |
| |
| /* |
| * Convolution filter coefficients for the inner QMF of the QMF tree. |
| * The 2 sets are a mirror of each other. |
| */ |
| static const int32_t aptx_qmf_inner_coeffs[NB_FILTERS][FILTER_TAPS] = { |
| { |
| 1033, -584, -13592, 61697, -171156, 381799, -828088, 3962579, |
| 985888, -226954, 39048, 11990, -14203, 4966, 973, -1268, |
| }, |
| { |
| -1268, 973, 4966, -14203, 11990, 39048, -226954, 985888, |
| 3962579, -828088, 381799, -171156, 61697, -13592, -584, 1033, |
| }, |
| }; |
| |
| /* |
| * Push one sample into a circular signal buffer. |
| */ |
| av_always_inline |
| static void aptx_qmf_filter_signal_push(FilterSignal *signal, int32_t sample) |
| { |
| signal->buffer[signal->pos ] = sample; |
| signal->buffer[signal->pos+FILTER_TAPS] = sample; |
| signal->pos = (signal->pos + 1) & (FILTER_TAPS - 1); |
| } |
| |
| /* |
| * Compute the convolution of the signal with the coefficients, and reduce |
| * to 24 bits by applying the specified right shifting. |
| */ |
| av_always_inline |
| static int32_t aptx_qmf_convolution(FilterSignal *signal, |
| const int32_t coeffs[FILTER_TAPS], |
| int shift) |
| { |
| int32_t *sig = &signal->buffer[signal->pos]; |
| int64_t e = 0; |
| int i; |
| |
| for (i = 0; i < FILTER_TAPS; i++) |
| e += MUL64(sig[i], coeffs[i]); |
| |
| return rshift64_clip24(e, shift); |
| } |
| |
| static inline int32_t aptx_quantized_parity(Channel *channel) |
| { |
| int32_t parity = channel->dither_parity; |
| int subband; |
| |
| for (subband = 0; subband < NB_SUBBANDS; subband++) |
| parity ^= channel->quantize[subband].quantized_sample; |
| |
| return parity & 1; |
| } |
| |
| /* For each sample, ensure that the parity of all subbands of all channels |
| * is 0 except once every 8 samples where the parity is forced to 1. */ |
| static inline int aptx_check_parity(Channel channels[NB_CHANNELS], int32_t *idx) |
| { |
| int32_t parity = aptx_quantized_parity(&channels[LEFT]) |
| ^ aptx_quantized_parity(&channels[RIGHT]); |
| |
| int eighth = *idx == 7; |
| *idx = (*idx + 1) & 7; |
| |
| return parity ^ eighth; |
| } |
| |
| void ff_aptx_invert_quantize_and_prediction(Channel *channel, int hd); |
| void ff_aptx_generate_dither(Channel *channel); |
| |
| int ff_aptx_init(AVCodecContext *avctx); |
| |
| #endif /* AVCODEC_APTX_H */ |