yading@10: /*
yading@10:  * Enhanced Variable Rate Codec, Service Option 3 decoder
yading@10:  * Copyright (c) 2013 Paul B Mahol
yading@10:  *
yading@10:  * This file is part of FFmpeg.
yading@10:  *
yading@10:  * FFmpeg is free software; you can redistribute it and/or
yading@10:  * modify it under the terms of the GNU Lesser General Public
yading@10:  * License as published by the Free Software Foundation; either
yading@10:  * version 2.1 of the License, or (at your option) any later version.
yading@10:  *
yading@10:  * FFmpeg is distributed in the hope that it will be useful,
yading@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@10:  * Lesser General Public License for more details.
yading@10:  *
yading@10:  * You should have received a copy of the GNU Lesser General Public
yading@10:  * License along with FFmpeg; if not, write to the Free Software
yading@10:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@10:  */
yading@10: 
yading@10: /**
yading@10:  * @file
yading@10:  * Enhanced Variable Rate Codec, Service Option 3 decoder
yading@10:  * @author Paul B Mahol
yading@10:  */
yading@10: 
yading@10: #include "libavutil/mathematics.h"
yading@10: #include "avcodec.h"
yading@10: #include "internal.h"
yading@10: #include "get_bits.h"
yading@10: #include "evrcdata.h"
yading@10: #include "acelp_vectors.h"
yading@10: #include "lsp.h"
yading@10: 
yading@10: #define MIN_LSP_SEP (0.05 / (2.0 * M_PI))
yading@10: #define MIN_DELAY      20
yading@10: #define MAX_DELAY     120
yading@10: #define NB_SUBFRAMES    3
yading@10: #define SUBFRAME_SIZE  54
yading@10: #define FILTER_ORDER   10
yading@10: #define ACB_SIZE      128
yading@10: 
yading@10: typedef enum {
yading@10:     RATE_ERRS = -1,
yading@10:     SILENCE,
yading@10:     RATE_QUANT,
yading@10:     RATE_QUARTER,
yading@10:     RATE_HALF,
yading@10:     RATE_FULL,
yading@10: } evrc_packet_rate;
yading@10: 
yading@10: /**
yading@10:  * EVRC-A unpacked data frame
yading@10:  */
yading@10: typedef struct EVRCAFrame {
yading@10:     uint8_t  lpc_flag;        ///< spectral change indicator
yading@10:     uint16_t lsp[4];          ///< index into LSP codebook
yading@10:     uint8_t  pitch_delay;     ///< pitch delay for entire frame
yading@10:     uint8_t  delay_diff;      ///< delay difference for entire frame
yading@10:     uint8_t  acb_gain[3];     ///< adaptive codebook gain
yading@10:     uint16_t fcb_shape[3][4]; ///< fixed codebook shape
yading@10:     uint8_t  fcb_gain[3];     ///< fixed codebook gain index
yading@10:     uint8_t  energy_gain;     ///< frame energy gain index
yading@10:     uint8_t  tty;             ///< tty baud rate bit
yading@10: } EVRCAFrame;
yading@10: 
yading@10: typedef struct EVRCContext {
yading@10:     GetBitContext    gb;
yading@10:     evrc_packet_rate bitrate;
yading@10:     evrc_packet_rate last_valid_bitrate;
yading@10:     EVRCAFrame       frame;
yading@10: 
yading@10:     float            lspf[FILTER_ORDER];
yading@10:     float            prev_lspf[FILTER_ORDER];
yading@10:     float            synthesis[FILTER_ORDER];
yading@10:     float            postfilter_fir[FILTER_ORDER];
yading@10:     float            postfilter_iir[FILTER_ORDER];
yading@10:     float            postfilter_residual[ACB_SIZE + SUBFRAME_SIZE];
yading@10:     float            pitch_delay;
yading@10:     float            prev_pitch_delay;
yading@10:     float            avg_acb_gain;  ///< average adaptive codebook gain
yading@10:     float            avg_fcb_gain;  ///< average fixed codebook gain
yading@10:     float            pitch[ACB_SIZE + FILTER_ORDER + SUBFRAME_SIZE];
yading@10:     float            pitch_back[ACB_SIZE];
yading@10:     float            interpolation_coeffs[136];
yading@10:     float            energy_vector[NB_SUBFRAMES];
yading@10:     float            fade_scale;
yading@10:     float            last;
yading@10: 
yading@10:     uint8_t          prev_energy_gain;
yading@10:     uint8_t          prev_error_flag;
yading@10:     uint8_t          warned_buf_mismatch_bitrate;
yading@10: } EVRCContext;
yading@10: 
yading@10: /**
yading@10:  * Frame unpacking for RATE_FULL, RATE_HALF and RATE_QUANT
yading@10:  *
yading@10:  * @param e the context
yading@10:  *
yading@10:  * TIA/IS-127 Table 4.21-1
yading@10:  */
yading@10: static void unpack_frame(EVRCContext *e)
yading@10: {
yading@10:     EVRCAFrame *frame = &e->frame;
yading@10:     GetBitContext *gb = &e->gb;
yading@10: 
yading@10:     switch (e->bitrate) {
yading@10:     case RATE_FULL:
yading@10:         frame->lpc_flag        = get_bits1(gb);
yading@10:         frame->lsp[0]          = get_bits(gb,  6);
yading@10:         frame->lsp[1]          = get_bits(gb,  6);
yading@10:         frame->lsp[2]          = get_bits(gb,  9);
yading@10:         frame->lsp[3]          = get_bits(gb,  7);
yading@10:         frame->pitch_delay     = get_bits(gb,  7);
yading@10:         frame->delay_diff      = get_bits(gb,  5);
yading@10:         frame->acb_gain[0]     = get_bits(gb,  3);
yading@10:         frame->fcb_shape[0][0] = get_bits(gb,  8);
yading@10:         frame->fcb_shape[0][1] = get_bits(gb,  8);
yading@10:         frame->fcb_shape[0][2] = get_bits(gb,  8);
yading@10:         frame->fcb_shape[0][3] = get_bits(gb, 11);
yading@10:         frame->fcb_gain[0]     = get_bits(gb,  5);
yading@10:         frame->acb_gain[1]     = get_bits(gb,  3);
yading@10:         frame->fcb_shape[1][0] = get_bits(gb,  8);
yading@10:         frame->fcb_shape[1][1] = get_bits(gb,  8);
yading@10:         frame->fcb_shape[1][2] = get_bits(gb,  8);
yading@10:         frame->fcb_shape[1][3] = get_bits(gb, 11);
yading@10:         frame->fcb_gain    [1] = get_bits(gb,  5);
yading@10:         frame->acb_gain    [2] = get_bits(gb,  3);
yading@10:         frame->fcb_shape[2][0] = get_bits(gb,  8);
yading@10:         frame->fcb_shape[2][1] = get_bits(gb,  8);
yading@10:         frame->fcb_shape[2][2] = get_bits(gb,  8);
yading@10:         frame->fcb_shape[2][3] = get_bits(gb, 11);
yading@10:         frame->fcb_gain    [2] = get_bits(gb,  5);
yading@10:         frame->tty             = get_bits1(gb);
yading@10:         break;
yading@10:     case RATE_HALF:
yading@10:         frame->lsp         [0] = get_bits(gb,  7);
yading@10:         frame->lsp         [1] = get_bits(gb,  7);
yading@10:         frame->lsp         [2] = get_bits(gb,  8);
yading@10:         frame->pitch_delay     = get_bits(gb,  7);
yading@10:         frame->acb_gain    [0] = get_bits(gb,  3);
yading@10:         frame->fcb_shape[0][0] = get_bits(gb, 10);
yading@10:         frame->fcb_gain    [0] = get_bits(gb,  4);
yading@10:         frame->acb_gain    [1] = get_bits(gb,  3);
yading@10:         frame->fcb_shape[1][0] = get_bits(gb, 10);
yading@10:         frame->fcb_gain    [1] = get_bits(gb,  4);
yading@10:         frame->acb_gain    [2] = get_bits(gb,  3);
yading@10:         frame->fcb_shape[2][0] = get_bits(gb, 10);
yading@10:         frame->fcb_gain    [2] = get_bits(gb,  4);
yading@10:         break;
yading@10:     case RATE_QUANT:
yading@10:         frame->lsp         [0] = get_bits(gb, 4);
yading@10:         frame->lsp         [1] = get_bits(gb, 4);
yading@10:         frame->energy_gain     = get_bits(gb, 8);
yading@10:         break;
yading@10:     }
yading@10: }
yading@10: 
yading@10: static evrc_packet_rate buf_size2bitrate(const int buf_size)
yading@10: {
yading@10:     switch (buf_size) {
yading@10:     case 23: return RATE_FULL;
yading@10:     case 11: return RATE_HALF;
yading@10:     case  6: return RATE_QUARTER;
yading@10:     case  3: return RATE_QUANT;
yading@10:     case  1: return SILENCE;
yading@10:     }
yading@10: 
yading@10:     return RATE_ERRS;
yading@10: }
yading@10: 
yading@10: /**
yading@10:  * Determine the bitrate from the frame size and/or the first byte of the frame.
yading@10:  *
yading@10:  * @param avctx the AV codec context
yading@10:  * @param buf_size length of the buffer
yading@10:  * @param buf the bufffer
yading@10:  *
yading@10:  * @return the bitrate on success,
yading@10:  *         RATE_ERRS  if the bitrate cannot be satisfactorily determined
yading@10:  */
yading@10: static evrc_packet_rate determine_bitrate(AVCodecContext *avctx,
yading@10:                                           int *buf_size,
yading@10:                                           const uint8_t **buf)
yading@10: {
yading@10:     evrc_packet_rate bitrate;
yading@10: 
yading@10:     if ((bitrate = buf_size2bitrate(*buf_size)) >= 0) {
yading@10:         if (bitrate > **buf) {
yading@10:             EVRCContext *e = avctx->priv_data;
yading@10:             if (!e->warned_buf_mismatch_bitrate) {
yading@10:                 av_log(avctx, AV_LOG_WARNING,
yading@10:                        "Claimed bitrate and buffer size mismatch.\n");
yading@10:                 e->warned_buf_mismatch_bitrate = 1;
yading@10:             }
yading@10:             bitrate = **buf;
yading@10:         } else if (bitrate < **buf) {
yading@10:             av_log(avctx, AV_LOG_ERROR,
yading@10:                    "Buffer is too small for the claimed bitrate.\n");
yading@10:             return RATE_ERRS;
yading@10:         }
yading@10:         (*buf)++;
yading@10:         *buf_size -= 1;
yading@10:     } else if ((bitrate = buf_size2bitrate(*buf_size + 1)) >= 0) {
yading@10:         av_log(avctx, AV_LOG_DEBUG,
yading@10:                "Bitrate byte is missing, guessing the bitrate from packet size.\n");
yading@10:     } else
yading@10:         return RATE_ERRS;
yading@10: 
yading@10:     return bitrate;
yading@10: }
yading@10: 
yading@10: static void warn_insufficient_frame_quality(AVCodecContext *avctx,
yading@10:                                             const char *message)
yading@10: {
yading@10:     av_log(avctx, AV_LOG_WARNING, "Frame #%d, %s\n",
yading@10:            avctx->frame_number, message);
yading@10: }
yading@10: 
yading@10: /**
yading@10:  * Initialize the speech codec according to the specification.
yading@10:  *
yading@10:  * TIA/IS-127 5.2
yading@10:  */
yading@10: static av_cold int evrc_decode_init(AVCodecContext *avctx)
yading@10: {
yading@10:     EVRCContext *e = avctx->priv_data;
yading@10:     int i, n, idx = 0;
yading@10:     float denom = 2.0 / (2.0 * 8.0 + 1.0);
yading@10: 
yading@10:     avctx->channels       = 1;
yading@10:     avctx->channel_layout = AV_CH_LAYOUT_MONO;
yading@10:     avctx->sample_fmt     = AV_SAMPLE_FMT_FLT;
yading@10: 
yading@10:     for (i = 0; i < FILTER_ORDER; i++) {
yading@10:         e->prev_lspf[i] = (i + 1) * 0.048;
yading@10:         e->synthesis[i] = 0.0;
yading@10:     }
yading@10: 
yading@10:     for (i = 0; i < ACB_SIZE; i++)
yading@10:         e->pitch[i] = e->pitch_back[i] = 0.0;
yading@10: 
yading@10:     e->last_valid_bitrate = RATE_QUANT;
yading@10:     e->prev_pitch_delay   = 40.0;
yading@10:     e->fade_scale         = 1.0;
yading@10:     e->prev_error_flag    = 0;
yading@10:     e->avg_acb_gain = e->avg_fcb_gain = 0.0;
yading@10: 
yading@10:     for (i = 0; i < 8; i++) {
yading@10:         float tt = ((float)i - 8.0 / 2.0) / 8.0;
yading@10: 
yading@10:         for (n = -8; n <= 8; n++, idx++) {
yading@10:             float arg1 = M_PI * 0.9 * (tt - n);
yading@10:             float arg2 = M_PI * (tt - n);
yading@10: 
yading@10:             e->interpolation_coeffs[idx] = 0.9;
yading@10:             if (arg1)
yading@10:                 e->interpolation_coeffs[idx] *= (0.54 + 0.46 * cos(arg2 * denom)) *
yading@10:                                                  sin(arg1) / arg1;
yading@10:         }
yading@10:     }
yading@10: 
yading@10:     return 0;
yading@10: }
yading@10: 
yading@10: /**
yading@10:  * Decode the 10 vector quantized line spectral pair frequencies from the LSP
yading@10:  * transmission codes of any bitrate and check for badly received packets.
yading@10:  *
yading@10:  * @param e the context
yading@10:  *
yading@10:  * @return 0 on success, -1 if the packet is badly received
yading@10:  *
yading@10:  * TIA/IS-127 5.2.1, 5.7.1
yading@10:  */
yading@10: static int decode_lspf(EVRCContext *e)
yading@10: {
yading@10:     const float **codebooks = evrc_lspq_codebooks[e->bitrate];
yading@10:     int i, j, k = 0;
yading@10: 
yading@10:     for (i = 0; i < evrc_lspq_nb_codebooks[e->bitrate]; i++) {
yading@10:         int row_size = evrc_lspq_codebooks_row_sizes[e->bitrate][i];
yading@10:         const float *codebook = codebooks[i];
yading@10: 
yading@10:         for (j = 0; j < row_size; j++)
yading@10:             e->lspf[k++] = codebook[e->frame.lsp[i] * row_size + j];
yading@10:     }
yading@10: 
yading@10:     // check for monotonic LSPs
yading@10:     for (i = 1; i < FILTER_ORDER; i++)
yading@10:         if (e->lspf[i] <= e->lspf[i - 1])
yading@10:             return -1;
yading@10: 
yading@10:     // check for minimum separation of LSPs at the splits
yading@10:     for (i = 0, k = 0; i < evrc_lspq_nb_codebooks[e->bitrate] - 1; i++) {
yading@10:         k += evrc_lspq_codebooks_row_sizes[e->bitrate][i];
yading@10:         if (e->lspf[k] - e->lspf[k - 1] <= MIN_LSP_SEP)
yading@10:             return -1;
yading@10:     }
yading@10: 
yading@10:     return 0;
yading@10: }
yading@10: 
yading@10: /*
yading@10:  * Interpolation of LSP parameters.
yading@10:  *
yading@10:  * TIA/IS-127 5.2.3.1, 5.7.3.2
yading@10:  */
yading@10: static void interpolate_lsp(float *ilsp, const float *lsp,
yading@10:                             const float *prev, int index)
yading@10: {
yading@10:     static const float lsp_interpolation_factors[] = { 0.1667, 0.5, 0.8333 };
yading@10:     ff_weighted_vector_sumf(ilsp, prev, lsp,
yading@10:                             1.0 - lsp_interpolation_factors[index],
yading@10:                             lsp_interpolation_factors[index], FILTER_ORDER);
yading@10: }
yading@10: 
yading@10: /*
yading@10:  * Reconstruction of the delay contour.
yading@10:  *
yading@10:  * TIA/IS-127 5.2.2.3.2
yading@10:  */
yading@10: static void interpolate_delay(float *dst, float current, float prev, int index)
yading@10: {
yading@10:     static const float d_interpolation_factors[] = { 0, 0.3313, 0.6625, 1, 1 };
yading@10:     dst[0] = (1.0 - d_interpolation_factors[index    ]) * prev
yading@10:                   + d_interpolation_factors[index    ]  * current;
yading@10:     dst[1] = (1.0 - d_interpolation_factors[index + 1]) * prev
yading@10:                   + d_interpolation_factors[index + 1]  * current;
yading@10:     dst[2] = (1.0 - d_interpolation_factors[index + 2]) * prev
yading@10:                   + d_interpolation_factors[index + 2]  * current;
yading@10: }
yading@10: 
yading@10: /*
yading@10:  * Convert the quantized, interpolated line spectral frequencies,
yading@10:  * to prediction coefficients.
yading@10:  *
yading@10:  * TIA/IS-127 5.2.3.2, 4.7.2.2
yading@10:  */
yading@10: static void decode_predictor_coeffs(const float *ilspf, float *ilpc)
yading@10: {
yading@10:     double lsp[FILTER_ORDER];
yading@10:     float a[FILTER_ORDER / 2 + 1], b[FILTER_ORDER / 2 + 1];
yading@10:     float a1[FILTER_ORDER / 2] = { 0 };
yading@10:     float a2[FILTER_ORDER / 2] = { 0 };
yading@10:     float b1[FILTER_ORDER / 2] = { 0 };
yading@10:     float b2[FILTER_ORDER / 2] = { 0 };
yading@10:     int i, k;
yading@10: 
yading@10:     ff_acelp_lsf2lspd(lsp, ilspf, FILTER_ORDER);
yading@10: 
yading@10:     for (k = 0; k <= FILTER_ORDER; k++) {
yading@10:         a[0] = k < 2 ? 0.25 : 0;
yading@10:         b[0] = k < 2 ? k < 1 ? 0.25 : -0.25 : 0;
yading@10: 
yading@10:         for (i = 0; i < FILTER_ORDER / 2; i++) {
yading@10:             a[i + 1] = a[i] - 2 * lsp[i * 2    ] * a1[i] + a2[i];
yading@10:             b[i + 1] = b[i] - 2 * lsp[i * 2 + 1] * b1[i] + b2[i];
yading@10:             a2[i] = a1[i];
yading@10:             a1[i] = a[i];
yading@10:             b2[i] = b1[i];
yading@10:             b1[i] = b[i];
yading@10:         }
yading@10: 
yading@10:         if (k)
yading@10:             ilpc[k - 1] = 2.0 * (a[FILTER_ORDER / 2] + b[FILTER_ORDER / 2]);
yading@10:     }
yading@10: }
yading@10: 
yading@10: static void bl_intrp(EVRCContext *e, float *ex, float delay)
yading@10: {
yading@10:     float *f;
yading@10:     int offset, i, coef_idx;
yading@10:     int16_t t;
yading@10: 
yading@10:     offset = lrintf(fabs(delay));
yading@10: 
yading@10:     t = (offset - delay + 0.5) * 8.0 + 0.5;
yading@10:     if (t == 8) {
yading@10:         t = 0;
yading@10:         offset--;
yading@10:     }
yading@10: 
yading@10:     f = ex - offset - 8;
yading@10: 
yading@10:     coef_idx = t * (2 * 8 + 1);
yading@10: 
yading@10:     ex[0] = 0.0;
yading@10:     for (i = 0; i < 2 * 8 + 1; i++)
yading@10:         ex[0] += e->interpolation_coeffs[coef_idx + i] * f[i];
yading@10: }
yading@10: 
yading@10: /*
yading@10:  * Adaptive codebook excitation.
yading@10:  *
yading@10:  * TIA/IS-127 5.2.2.3.3, 4.12.5.2
yading@10:  */
yading@10: static void acb_excitation(EVRCContext *e, float *excitation, float gain,
yading@10:                            const float delay[3], int length)
yading@10: {
yading@10:     float denom, locdelay, dpr, invl;
yading@10:     int i;
yading@10: 
yading@10:     invl = 1.0 / ((float) length);
yading@10:     dpr = length;
yading@10: 
yading@10:     /* first at-most extra samples */
yading@10:     denom = (delay[1] - delay[0]) * invl;
yading@10:     for (i = 0; i < dpr; i++) {
yading@10:         locdelay = delay[0] + i * denom;
yading@10:         bl_intrp(e, excitation + i, locdelay);
yading@10:     }
yading@10: 
yading@10:     denom = (delay[2] - delay[1]) * invl;
yading@10:     /* interpolation */
yading@10:     for (i = dpr; i < dpr + 10; i++) {
yading@10:         locdelay = delay[1] + (i - dpr) * denom;
yading@10:         bl_intrp(e, excitation + i, locdelay);
yading@10:     }
yading@10: 
yading@10:     for (i = 0; i < length; i++)
yading@10:         excitation[i] *= gain;
yading@10: }
yading@10: 
yading@10: static void decode_8_pulses_35bits(const uint16_t *fixed_index, float *cod)
yading@10: {
yading@10:     int i, pos1, pos2, offset;
yading@10: 
yading@10:     offset = (fixed_index[3] >> 9) & 3;
yading@10: 
yading@10:     for (i = 0; i < 3; i++) {
yading@10:         pos1 = ((fixed_index[i] & 0x7f) / 11) * 5 + ((i + offset) % 5);
yading@10:         pos2 = ((fixed_index[i] & 0x7f) % 11) * 5 + ((i + offset) % 5);
yading@10: 
yading@10:         cod[pos1] = (fixed_index[i] & 0x80) ? -1.0 : 1.0;
yading@10: 
yading@10:         if (pos2 < pos1)
yading@10:             cod[pos2]  = -cod[pos1];
yading@10:         else
yading@10:             cod[pos2] +=  cod[pos1];
yading@10:     }
yading@10: 
yading@10:     pos1 = ((fixed_index[3] & 0x7f) / 11) * 5 + ((3 + offset) % 5);
yading@10:     pos2 = ((fixed_index[3] & 0x7f) % 11) * 5 + ((4 + offset) % 5);
yading@10: 
yading@10:     cod[pos1] = (fixed_index[3] & 0x100) ? -1.0 : 1.0;
yading@10:     cod[pos2] = (fixed_index[3] & 0x80 ) ? -1.0 : 1.0;
yading@10: }
yading@10: 
yading@10: static void decode_3_pulses_10bits(uint16_t fixed_index, float *cod)
yading@10: {
yading@10:     float sign;
yading@10:     int pos;
yading@10: 
yading@10:     sign = (fixed_index & 0x200) ? -1.0 : 1.0;
yading@10: 
yading@10:     pos = ((fixed_index        & 0x7) * 7) + 4;
yading@10:     cod[pos] += sign;
yading@10:     pos = (((fixed_index >> 3) & 0x7) * 7) + 2;
yading@10:     cod[pos] -= sign;
yading@10:     pos = (((fixed_index >> 6) & 0x7) * 7);
yading@10:     cod[pos] += sign;
yading@10: }
yading@10: 
yading@10: /*
yading@10:  * Reconstruction of ACELP fixed codebook excitation for full and half rate.
yading@10:  *
yading@10:  * TIA/IS-127 5.2.3.7
yading@10:  */
yading@10: static void fcb_excitation(EVRCContext *e, const uint16_t *codebook,
yading@10:                            float *excitation, float pitch_gain,
yading@10:                            int pitch_lag, int subframe_size)
yading@10: {
yading@10:     int i;
yading@10: 
yading@10:     if (e->bitrate == RATE_FULL)
yading@10:         decode_8_pulses_35bits(codebook, excitation);
yading@10:     else
yading@10:         decode_3_pulses_10bits(*codebook, excitation);
yading@10: 
yading@10:     pitch_gain = av_clipf(pitch_gain, 0.2, 0.9);
yading@10: 
yading@10:     for (i = pitch_lag; i < subframe_size; i++)
yading@10:         excitation[i] += pitch_gain * excitation[i - pitch_lag];
yading@10: }
yading@10: 
yading@10: /**
yading@10:  * Synthesis of the decoder output signal.
yading@10:  *
yading@10:  * param[in]     in              input signal
yading@10:  * param[in]     filter_coeffs   LPC coefficients
yading@10:  * param[in/out] memory          synthesis filter memory
yading@10:  * param         buffer_length   amount of data to process
yading@10:  * param[out]    samples         output samples
yading@10:  *
yading@10:  * TIA/IS-127 5.2.3.15, 5.7.3.4
yading@10:  */
yading@10: static void synthesis_filter(const float *in, const float *filter_coeffs,
yading@10:                              float *memory, int buffer_length, float *samples)
yading@10: {
yading@10:     int i, j;
yading@10: 
yading@10:     for (i = 0; i < buffer_length; i++) {
yading@10:         samples[i] = in[i];
yading@10:         for (j = FILTER_ORDER - 1; j > 0; j--) {
yading@10:             samples[i] -= filter_coeffs[j] * memory[j];
yading@10:             memory[j]   = memory[j - 1];
yading@10:         }
yading@10:         samples[i] -= filter_coeffs[0] * memory[0];
yading@10:         memory[0]   = samples[i];
yading@10:     }
yading@10: }
yading@10: 
yading@10: static void bandwidth_expansion(float *coeff, const float *inbuf, float gamma)
yading@10: {
yading@10:     double fac = gamma;
yading@10:     int i;
yading@10: 
yading@10:     for (i = 0; i < FILTER_ORDER; i++) {
yading@10:         coeff[i] = inbuf[i] * fac;
yading@10:         fac *= gamma;
yading@10:     }
yading@10: }
yading@10: 
yading@10: static void residual_filter(float *output, const float *input,
yading@10:                             const float *coef, float *memory, int length)
yading@10: {
yading@10:     float sum;
yading@10:     int i, j;
yading@10: 
yading@10:     for (i = 0; i < length; i++) {
yading@10:         sum = input[i];
yading@10: 
yading@10:         for (j = FILTER_ORDER - 1; j > 0; j--) {
yading@10:             sum      += coef[j] * memory[j];
yading@10:             memory[j] = memory[j - 1];
yading@10:         }
yading@10:         sum += coef[0] * memory[0];
yading@10:         memory[0] = input[i];
yading@10:         output[i] = sum;
yading@10:     }
yading@10: }
yading@10: 
yading@10: /*
yading@10:  * TIA/IS-127 Table 5.9.1-1.
yading@10:  */
yading@10: static const struct PfCoeff {
yading@10:     float tilt;
yading@10:     float ltgain;
yading@10:     float p1;
yading@10:     float p2;
yading@10: } postfilter_coeffs[5] = {
yading@10:     { 0.0 , 0.0 , 0.0 , 0.0  },
yading@10:     { 0.0 , 0.0 , 0.57, 0.57 },
yading@10:     { 0.0 , 0.0 , 0.0 , 0.0  },
yading@10:     { 0.35, 0.50, 0.50, 0.75 },
yading@10:     { 0.20, 0.50, 0.57, 0.75 },
yading@10: };
yading@10: 
yading@10: /*
yading@10:  * Adaptive postfilter.
yading@10:  *
yading@10:  * TIA/IS-127 5.9
yading@10:  */
yading@10: static void postfilter(EVRCContext *e, float *in, const float *coeff,
yading@10:                        float *out, int idx, const struct PfCoeff *pfc,
yading@10:                        int length)
yading@10: {
yading@10:     float wcoef1[FILTER_ORDER], wcoef2[FILTER_ORDER],
yading@10:           scratch[SUBFRAME_SIZE], temp[SUBFRAME_SIZE],
yading@10:           mem[SUBFRAME_SIZE];
yading@10:     float sum1 = 0.0, sum2 = 0.0, gamma, gain;
yading@10:     float tilt = pfc->tilt;
yading@10:     int i, n, best;
yading@10: 
yading@10:     bandwidth_expansion(wcoef1, coeff, pfc->p1);
yading@10:     bandwidth_expansion(wcoef2, coeff, pfc->p2);
yading@10: 
yading@10:     /* Tilt compensation filter, TIA/IS-127 5.9.1 */
yading@10:     for (i = 0; i < length - 1; i++)
yading@10:         sum2 += in[i] * in[i + 1];
yading@10:     if (sum2 < 0.0)
yading@10:         tilt = 0.0;
yading@10: 
yading@10:     for (i = 0; i < length; i++) {
yading@10:         scratch[i] = in[i] - tilt * e->last;
yading@10:         e->last = in[i];
yading@10:     }
yading@10: 
yading@10:     /* Short term residual filter, TIA/IS-127 5.9.2 */
yading@10:     residual_filter(&e->postfilter_residual[ACB_SIZE], scratch, wcoef1, e->postfilter_fir, length);
yading@10: 
yading@10:     /* Long term postfilter */
yading@10:     best = idx;
yading@10:     for (i = FFMIN(MIN_DELAY, idx - 3); i <= FFMAX(MAX_DELAY, idx + 3); i++) {
yading@10:         for (n = ACB_SIZE, sum2 = 0; n < ACB_SIZE + length; n++)
yading@10:             sum2 += e->postfilter_residual[n] * e->postfilter_residual[n - i];
yading@10:         if (sum2 > sum1) {
yading@10:             sum1 = sum2;
yading@10:             best = i;
yading@10:         }
yading@10:     }
yading@10: 
yading@10:     for (i = ACB_SIZE, sum1 = 0; i < ACB_SIZE + length; i++)
yading@10:         sum1 += e->postfilter_residual[i - best] * e->postfilter_residual[i - best];
yading@10:     for (i = ACB_SIZE, sum2 = 0; i < ACB_SIZE + length; i++)
yading@10:         sum2 += e->postfilter_residual[i] * e->postfilter_residual[i - best];
yading@10: 
yading@10:     if (sum2 * sum1 == 0 || e->bitrate == RATE_QUANT) {
yading@10:         memcpy(temp, e->postfilter_residual + ACB_SIZE, length * sizeof(float));
yading@10:     } else {
yading@10:         gamma = sum2 / sum1;
yading@10:         if (gamma < 0.5)
yading@10:             memcpy(temp, e->postfilter_residual + ACB_SIZE, length * sizeof(float));
yading@10:         else {
yading@10:             gamma = FFMIN(gamma, 1.0);
yading@10: 
yading@10:             for (i = 0; i < length; i++) {
yading@10:                 temp[i] = e->postfilter_residual[ACB_SIZE + i] + gamma *
yading@10:                     pfc->ltgain * e->postfilter_residual[ACB_SIZE + i - best];
yading@10:             }
yading@10:         }
yading@10:     }
yading@10: 
yading@10:     memcpy(scratch, temp, length * sizeof(float));
yading@10:     memcpy(mem, e->postfilter_iir, FILTER_ORDER * sizeof(float));
yading@10:     synthesis_filter(scratch, wcoef2, mem, length, scratch);
yading@10: 
yading@10:     /* Gain computation, TIA/IS-127 5.9.4-2 */
yading@10:     for (i = 0, sum1 = 0, sum2 = 0; i < length; i++) {
yading@10:         sum1 += in[i] * in[i];
yading@10:         sum2 += scratch[i] * scratch[i];
yading@10:     }
yading@10:     gain = sum2 ? sqrt(sum1 / sum2) : 1.0;
yading@10: 
yading@10:     for (i = 0; i < length; i++)
yading@10:         temp[i] *= gain;
yading@10: 
yading@10:     /* Short term postfilter */
yading@10:     synthesis_filter(temp, wcoef2, e->postfilter_iir, length, out);
yading@10: 
yading@10:     memmove(e->postfilter_residual,
yading@10:            e->postfilter_residual + length, ACB_SIZE * sizeof(float));
yading@10: }
yading@10: 
yading@10: static void frame_erasure(EVRCContext *e, float *samples)
yading@10: {
yading@10:     float ilspf[FILTER_ORDER], ilpc[FILTER_ORDER], idelay[NB_SUBFRAMES],
yading@10:           tmp[SUBFRAME_SIZE + 6], f;
yading@10:     int i, j;
yading@10: 
yading@10:     for (i = 0; i < FILTER_ORDER; i++) {
yading@10:         if (e->bitrate != RATE_QUANT)
yading@10:             e->lspf[i] = e->prev_lspf[i] * 0.875 + 0.125 * (i + 1) * 0.048;
yading@10:         else
yading@10:             e->lspf[i] = e->prev_lspf[i];
yading@10:     }
yading@10: 
yading@10:     if (e->prev_error_flag)
yading@10:         e->avg_acb_gain *= 0.75;
yading@10:     if (e->bitrate == RATE_FULL)
yading@10:         memcpy(e->pitch_back, e->pitch, ACB_SIZE * sizeof(float));
yading@10:     if (e->last_valid_bitrate == RATE_QUANT)
yading@10:         e->bitrate = RATE_QUANT;
yading@10:     else
yading@10:         e->bitrate = RATE_FULL;
yading@10: 
yading@10:     if (e->bitrate == RATE_FULL || e->bitrate == RATE_HALF) {
yading@10:         e->pitch_delay = e->prev_pitch_delay;
yading@10:     } else {
yading@10:         float sum = 0;
yading@10: 
yading@10:         idelay[0] = idelay[1] = idelay[2] = MIN_DELAY;
yading@10: 
yading@10:         for (i = 0; i < NB_SUBFRAMES; i++)
yading@10:             sum += evrc_energy_quant[e->prev_energy_gain][i];
yading@10:         sum /= (float) NB_SUBFRAMES;
yading@10:         sum  = pow(10, sum);
yading@10:         for (i = 0; i < NB_SUBFRAMES; i++)
yading@10:             e->energy_vector[i] = sum;
yading@10:     }
yading@10: 
yading@10:     if (fabs(e->pitch_delay - e->prev_pitch_delay) > 15)
yading@10:         e->prev_pitch_delay = e->pitch_delay;
yading@10: 
yading@10:     for (i = 0; i < NB_SUBFRAMES; i++) {
yading@10:         int subframe_size = subframe_sizes[i];
yading@10:         int pitch_lag;
yading@10: 
yading@10:         interpolate_lsp(ilspf, e->lspf, e->prev_lspf, i);
yading@10: 
yading@10:         if (e->bitrate != RATE_QUANT) {
yading@10:             if (e->avg_acb_gain < 0.3) {
yading@10:                 idelay[0] = estimation_delay[i];
yading@10:                 idelay[1] = estimation_delay[i + 1];
yading@10:                 idelay[2] = estimation_delay[i + 2];
yading@10:             } else {
yading@10:                 interpolate_delay(idelay, e->pitch_delay, e->prev_pitch_delay, i);
yading@10:             }
yading@10:         }
yading@10: 
yading@10:         pitch_lag = lrintf((idelay[1] + idelay[0]) / 2.0);
yading@10:         decode_predictor_coeffs(ilspf, ilpc);
yading@10: 
yading@10:         if (e->bitrate != RATE_QUANT) {
yading@10:             acb_excitation(e, e->pitch + ACB_SIZE,
yading@10:                            e->avg_acb_gain, idelay, subframe_size);
yading@10:             for (j = 0; j < subframe_size; j++)
yading@10:                 e->pitch[ACB_SIZE + j] *= e->fade_scale;
yading@10:             e->fade_scale = FFMAX(e->fade_scale - 0.05, 0.0);
yading@10:         } else {
yading@10:             for (j = 0; j < subframe_size; j++)
yading@10:                 e->pitch[ACB_SIZE + j] = e->energy_vector[i];
yading@10:         }
yading@10: 
yading@10:         memmove(e->pitch, e->pitch + subframe_size, ACB_SIZE * sizeof(float));
yading@10: 
yading@10:         if (e->bitrate != RATE_QUANT && e->avg_acb_gain < 0.4) {
yading@10:             f = 0.1 * e->avg_fcb_gain;
yading@10:             for (j = 0; j < subframe_size; j++)
yading@10:                 e->pitch[ACB_SIZE + j] += f;
yading@10:         } else if (e->bitrate == RATE_QUANT) {
yading@10:             for (j = 0; j < subframe_size; j++)
yading@10:                 e->pitch[ACB_SIZE + j] = e->energy_vector[i];
yading@10:         }
yading@10: 
yading@10:         synthesis_filter(e->pitch + ACB_SIZE, ilpc,
yading@10:                          e->synthesis, subframe_size, tmp);
yading@10:         postfilter(e, tmp, ilpc, samples, pitch_lag,
yading@10:                    &postfilter_coeffs[e->bitrate], subframe_size);
yading@10: 
yading@10:         samples += subframe_size;
yading@10:     }
yading@10: }
yading@10: 
yading@10: static int evrc_decode_frame(AVCodecContext *avctx, void *data,
yading@10:                              int *got_frame_ptr, AVPacket *avpkt)
yading@10: {
yading@10:     const uint8_t *buf = avpkt->data;
yading@10:     AVFrame *frame     = data;
yading@10:     EVRCContext *e     = avctx->priv_data;
yading@10:     int buf_size       = avpkt->size;
yading@10:     float ilspf[FILTER_ORDER], ilpc[FILTER_ORDER], idelay[NB_SUBFRAMES];
yading@10:     float *samples;
yading@10:     int   i, j, ret, error_flag = 0;
yading@10: 
yading@10:     frame->nb_samples = 160;
yading@10:     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
yading@10:         return ret;
yading@10:     samples = (float *)frame->data[0];
yading@10: 
yading@10:     if ((e->bitrate = determine_bitrate(avctx, &buf_size, &buf)) == RATE_ERRS) {
yading@10:         warn_insufficient_frame_quality(avctx, "bitrate cannot be determined.");
yading@10:         goto erasure;
yading@10:     }
yading@10:     if (e->bitrate <= SILENCE || e->bitrate == RATE_QUARTER)
yading@10:         goto erasure;
yading@10:     if (e->bitrate == RATE_QUANT && e->last_valid_bitrate == RATE_FULL
yading@10:                                  && !e->prev_error_flag)
yading@10:         goto erasure;
yading@10: 
yading@10:     init_get_bits(&e->gb, buf, 8 * buf_size);
yading@10:     memset(&e->frame, 0, sizeof(EVRCAFrame));
yading@10: 
yading@10:     unpack_frame(e);
yading@10: 
yading@10:     if (e->bitrate != RATE_QUANT) {
yading@10:         uint8_t *p = (uint8_t *) &e->frame;
yading@10:         for (i = 0; i < sizeof(EVRCAFrame); i++) {
yading@10:             if (p[i])
yading@10:                 break;
yading@10:         }
yading@10:         if (i == sizeof(EVRCAFrame))
yading@10:             goto erasure;
yading@10:     } else if (e->frame.lsp[0] == 0xf &&
yading@10:                e->frame.lsp[1] == 0xf &&
yading@10:                e->frame.energy_gain == 0xff) {
yading@10:         goto erasure;
yading@10:     }
yading@10: 
yading@10:     if (decode_lspf(e) < 0)
yading@10:         goto erasure;
yading@10: 
yading@10:     if (e->bitrate == RATE_FULL || e->bitrate == RATE_HALF) {
yading@10:         /* Pitch delay parameter checking as per TIA/IS-127 5.1.5.1 */
yading@10:         if (e->frame.pitch_delay > MAX_DELAY - MIN_DELAY)
yading@10:             goto erasure;
yading@10: 
yading@10:         e->pitch_delay = e->frame.pitch_delay + MIN_DELAY;
yading@10: 
yading@10:         /* Delay diff parameter checking as per TIA/IS-127 5.1.5.2 */
yading@10:         if (e->frame.delay_diff) {
yading@10:             int p = e->pitch_delay - e->frame.delay_diff + 16;
yading@10:             if (p < MIN_DELAY || p > MAX_DELAY)
yading@10:                 goto erasure;
yading@10:         }
yading@10: 
yading@10:         /* Delay contour reconstruction as per TIA/IS-127 5.2.2.2 */
yading@10:         if (e->frame.delay_diff &&
yading@10:             e->bitrate == RATE_FULL && e->prev_error_flag) {
yading@10:             float delay;
yading@10: 
yading@10:             memcpy(e->pitch, e->pitch_back, ACB_SIZE * sizeof(float));
yading@10: 
yading@10:             delay = e->prev_pitch_delay;
yading@10:             e->prev_pitch_delay = delay - e->frame.delay_diff + 16.0;
yading@10: 
yading@10:             if (fabs(e->pitch_delay - delay) > 15)
yading@10:                 delay = e->pitch_delay;
yading@10: 
yading@10:             for (i = 0; i < NB_SUBFRAMES; i++) {
yading@10:                 int subframe_size = subframe_sizes[i];
yading@10: 
yading@10:                 interpolate_delay(idelay, delay, e->prev_pitch_delay, i);
yading@10:                 acb_excitation(e, e->pitch + ACB_SIZE, e->avg_acb_gain, idelay, subframe_size);
yading@10:                 memmove(e->pitch, e->pitch + subframe_size, ACB_SIZE * sizeof(float));
yading@10:             }
yading@10:         }
yading@10: 
yading@10:         /* Smoothing of the decoded delay as per TIA/IS-127 5.2.2.5 */
yading@10:         if (fabs(e->pitch_delay - e->prev_pitch_delay) > 15)
yading@10:             e->prev_pitch_delay = e->pitch_delay;
yading@10: 
yading@10:         e->avg_acb_gain = e->avg_fcb_gain = 0.0;
yading@10:     } else {
yading@10:         idelay[0] = idelay[1] = idelay[2] = MIN_DELAY;
yading@10: 
yading@10:         /* Decode frame energy vectors as per TIA/IS-127 5.7.2 */
yading@10:         for (i = 0; i < NB_SUBFRAMES; i++)
yading@10:             e->energy_vector[i] = pow(10, evrc_energy_quant[e->frame.energy_gain][i]);
yading@10:         e->prev_energy_gain = e->frame.energy_gain;
yading@10:     }
yading@10: 
yading@10:     for (i = 0; i < NB_SUBFRAMES; i++) {
yading@10:         float tmp[SUBFRAME_SIZE + 6] = { 0 };
yading@10:         int subframe_size = subframe_sizes[i];
yading@10:         int pitch_lag;
yading@10: 
yading@10:         interpolate_lsp(ilspf, e->lspf, e->prev_lspf, i);
yading@10: 
yading@10:         if (e->bitrate != RATE_QUANT)
yading@10:             interpolate_delay(idelay, e->pitch_delay, e->prev_pitch_delay, i);
yading@10: 
yading@10:         pitch_lag = lrintf((idelay[1] + idelay[0]) / 2.0);
yading@10:         decode_predictor_coeffs(ilspf, ilpc);
yading@10: 
yading@10:         /* Bandwidth expansion as per TIA/IS-127 5.2.3.3 */
yading@10:         if (e->frame.lpc_flag && e->prev_error_flag)
yading@10:             bandwidth_expansion(ilpc, ilpc, 0.75);
yading@10: 
yading@10:         if (e->bitrate != RATE_QUANT) {
yading@10:             float acb_sum, f;
yading@10: 
yading@10:             f = exp((e->bitrate == RATE_HALF ? 0.5 : 0.25)
yading@10:                          * (e->frame.fcb_gain[i] + 1));
yading@10:             acb_sum = pitch_gain_vq[e->frame.acb_gain[i]];
yading@10:             e->avg_acb_gain += acb_sum / NB_SUBFRAMES;
yading@10:             e->avg_fcb_gain += f / NB_SUBFRAMES;
yading@10: 
yading@10:             acb_excitation(e, e->pitch + ACB_SIZE,
yading@10:                            acb_sum, idelay, subframe_size);
yading@10:             fcb_excitation(e, e->frame.fcb_shape[i], tmp,
yading@10:                            acb_sum, pitch_lag, subframe_size);
yading@10: 
yading@10:             /* Total excitation generation as per TIA/IS-127 5.2.3.9 */
yading@10:             for (j = 0; j < subframe_size; j++)
yading@10:                 e->pitch[ACB_SIZE + j] += f * tmp[j];
yading@10:             e->fade_scale = FFMIN(e->fade_scale + 0.2, 1.0);
yading@10:         } else {
yading@10:             for (j = 0; j < subframe_size; j++)
yading@10:                 e->pitch[ACB_SIZE + j] = e->energy_vector[i];
yading@10:         }
yading@10: 
yading@10:         memmove(e->pitch, e->pitch + subframe_size, ACB_SIZE * sizeof(float));
yading@10: 
yading@10:         synthesis_filter(e->pitch + ACB_SIZE, ilpc,
yading@10:                          e->synthesis, subframe_size, tmp);
yading@10:         postfilter(e, tmp, ilpc, samples, pitch_lag,
yading@10:                    &postfilter_coeffs[e->bitrate], subframe_size);
yading@10: 
yading@10:         samples += subframe_size;
yading@10:     }
yading@10: 
yading@10:     if (error_flag) {
yading@10: erasure:
yading@10:         error_flag = 1;
yading@10:         av_log(avctx, AV_LOG_WARNING, "frame erasure\n");
yading@10:         frame_erasure(e, samples);
yading@10:     }
yading@10: 
yading@10:     memcpy(e->prev_lspf, e->lspf, sizeof(e->prev_lspf));
yading@10:     e->prev_error_flag    = error_flag;
yading@10:     e->last_valid_bitrate = e->bitrate;
yading@10: 
yading@10:     if (e->bitrate != RATE_QUANT)
yading@10:         e->prev_pitch_delay = e->pitch_delay;
yading@10: 
yading@10:     samples = (float *)frame->data[0];
yading@10:     for (i = 0; i < 160; i++)
yading@10:         samples[i] /= 32768;
yading@10: 
yading@10:     *got_frame_ptr   = 1;
yading@10: 
yading@10:     return avpkt->size;
yading@10: }
yading@10: 
yading@10: AVCodec ff_evrc_decoder = {
yading@10:     .name           = "evrc",
yading@10:     .type           = AVMEDIA_TYPE_AUDIO,
yading@10:     .id             = AV_CODEC_ID_EVRC,
yading@10:     .init           = evrc_decode_init,
yading@10:     .decode         = evrc_decode_frame,
yading@10:     .capabilities   = CODEC_CAP_DR1,
yading@10:     .priv_data_size = sizeof(EVRCContext),
yading@10:     .long_name      = NULL_IF_CONFIG_SMALL("EVRC (Enhanced Variable Rate Codec)"),
yading@10: };