xref: /third_party/ffmpeg/libavcodec/g729dec.c (revision cabdff1a)
1/*
2 * G.729, G729 Annex D decoders
3 * Copyright (c) 2008 Vladimir Voroshilov
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22#include <inttypes.h>
23#include <string.h>
24
25#include "avcodec.h"
26#include "libavutil/avutil.h"
27#include "get_bits.h"
28#include "audiodsp.h"
29#include "codec_internal.h"
30#include "internal.h"
31
32
33#include "g729.h"
34#include "lsp.h"
35#include "celp_math.h"
36#include "celp_filters.h"
37#include "acelp_filters.h"
38#include "acelp_pitch_delay.h"
39#include "acelp_vectors.h"
40#include "g729data.h"
41#include "g729postfilter.h"
42
43/**
44 * minimum quantized LSF value (3.2.4)
45 * 0.005 in Q13
46 */
47#define LSFQ_MIN                   40
48
49/**
50 * maximum quantized LSF value (3.2.4)
51 * 3.135 in Q13
52 */
53#define LSFQ_MAX                   25681
54
55/**
56 * minimum LSF distance (3.2.4)
57 * 0.0391 in Q13
58 */
59#define LSFQ_DIFF_MIN              321
60
61/// interpolation filter length
62#define INTERPOL_LEN              11
63
64/**
65 * minimum gain pitch value (3.8, Equation 47)
66 * 0.2 in (1.14)
67 */
68#define SHARP_MIN                  3277
69
70/**
71 * maximum gain pitch value (3.8, Equation 47)
72 * (EE) This does not comply with the specification.
73 * Specification says about 0.8, which should be
74 * 13107 in (1.14), but reference C code uses
75 * 13017 (equals to 0.7945) instead of it.
76 */
77#define SHARP_MAX                  13017
78
79/**
80 * MR_ENERGY (mean removed energy) = mean_energy + 10 * log10(2^26  * subframe_size) in (7.13)
81 */
82#define MR_ENERGY 1018156
83
84#define DECISION_NOISE        0
85#define DECISION_INTERMEDIATE 1
86#define DECISION_VOICE        2
87
88typedef enum {
89    FORMAT_G729_8K = 0,
90    FORMAT_G729D_6K4,
91    FORMAT_COUNT,
92} G729Formats;
93
94typedef struct {
95    uint8_t ac_index_bits[2];   ///< adaptive codebook index for second subframe (size in bits)
96    uint8_t parity_bit;         ///< parity bit for pitch delay
97    uint8_t gc_1st_index_bits;  ///< gain codebook (first stage) index (size in bits)
98    uint8_t gc_2nd_index_bits;  ///< gain codebook (second stage) index (size in bits)
99    uint8_t fc_signs_bits;      ///< number of pulses in fixed-codebook vector
100    uint8_t fc_indexes_bits;    ///< size (in bits) of fixed-codebook index entry
101    uint8_t block_size;
102} G729FormatDescription;
103
104typedef struct {
105    /// past excitation signal buffer
106    int16_t exc_base[2*SUBFRAME_SIZE+PITCH_DELAY_MAX+INTERPOL_LEN];
107
108    int16_t* exc;               ///< start of past excitation data in buffer
109    int pitch_delay_int_prev;   ///< integer part of previous subframe's pitch delay (4.1.3)
110
111    /// (2.13) LSP quantizer outputs
112    int16_t  past_quantizer_output_buf[MA_NP + 1][10];
113    int16_t* past_quantizer_outputs[MA_NP + 1];
114
115    int16_t lsfq[10];           ///< (2.13) quantized LSF coefficients from previous frame
116    int16_t lsp_buf[2][10];     ///< (0.15) LSP coefficients (previous and current frames) (3.2.5)
117    int16_t *lsp[2];            ///< pointers to lsp_buf
118
119    int16_t quant_energy[4];    ///< (5.10) past quantized energy
120
121    /// previous speech data for LP synthesis filter
122    int16_t syn_filter_data[10];
123
124
125    /// residual signal buffer (used in long-term postfilter)
126    int16_t residual[SUBFRAME_SIZE + RES_PREV_DATA_SIZE];
127
128    /// previous speech data for residual calculation filter
129    int16_t res_filter_data[SUBFRAME_SIZE+10];
130
131    /// previous speech data for short-term postfilter
132    int16_t pos_filter_data[SUBFRAME_SIZE+10];
133
134    /// (1.14) pitch gain of current and five previous subframes
135    int16_t past_gain_pitch[6];
136
137    /// (14.1) gain code from current and previous subframe
138    int16_t past_gain_code[2];
139
140    /// voice decision on previous subframe (0-noise, 1-intermediate, 2-voice), G.729D
141    int16_t voice_decision;
142
143    int16_t onset;              ///< detected onset level (0-2)
144    int16_t was_periodic;       ///< whether previous frame was declared as periodic or not (4.4)
145    int16_t ht_prev_data;       ///< previous data for 4.2.3, equation 86
146    int gain_coeff;             ///< (1.14) gain coefficient (4.2.4)
147    uint16_t rand_value;        ///< random number generator value (4.4.4)
148    int ma_predictor_prev;      ///< switched MA predictor of LSP quantizer from last good frame
149
150    /// (14.14) high-pass filter data (past input)
151    int hpf_f[2];
152
153    /// high-pass filter data (past output)
154    int16_t hpf_z[2];
155}  G729ChannelContext;
156
157typedef struct {
158    AudioDSPContext adsp;
159
160    G729ChannelContext *channel_context;
161} G729Context;
162
163static const G729FormatDescription format_g729_8k = {
164    .ac_index_bits     = {8,5},
165    .parity_bit        = 1,
166    .gc_1st_index_bits = GC_1ST_IDX_BITS_8K,
167    .gc_2nd_index_bits = GC_2ND_IDX_BITS_8K,
168    .fc_signs_bits     = 4,
169    .fc_indexes_bits   = 13,
170    .block_size        = G729_8K_BLOCK_SIZE,
171};
172
173static const G729FormatDescription format_g729d_6k4 = {
174    .ac_index_bits     = {8,4},
175    .parity_bit        = 0,
176    .gc_1st_index_bits = GC_1ST_IDX_BITS_6K4,
177    .gc_2nd_index_bits = GC_2ND_IDX_BITS_6K4,
178    .fc_signs_bits     = 2,
179    .fc_indexes_bits   = 9,
180    .block_size        = G729D_6K4_BLOCK_SIZE,
181};
182
183/**
184 * @brief pseudo random number generator
185 */
186static inline uint16_t g729_prng(uint16_t value)
187{
188    return 31821 * value + 13849;
189}
190
191/**
192 * Decodes LSF (Line Spectral Frequencies) from L0-L3 (3.2.4).
193 * @param[out] lsfq (2.13) quantized LSF coefficients
194 * @param[in,out] past_quantizer_outputs (2.13) quantizer outputs from previous frames
195 * @param ma_predictor switched MA predictor of LSP quantizer
196 * @param vq_1st first stage vector of quantizer
197 * @param vq_2nd_low second stage lower vector of LSP quantizer
198 * @param vq_2nd_high second stage higher vector of LSP quantizer
199 */
200static void lsf_decode(int16_t* lsfq, int16_t* past_quantizer_outputs[MA_NP + 1],
201                       int16_t ma_predictor,
202                       int16_t vq_1st, int16_t vq_2nd_low, int16_t vq_2nd_high)
203{
204    int i,j;
205    static const uint8_t min_distance[2]={10, 5}; //(2.13)
206    int16_t* quantizer_output = past_quantizer_outputs[MA_NP];
207
208    for (i = 0; i < 5; i++) {
209        quantizer_output[i]     = cb_lsp_1st[vq_1st][i    ] + cb_lsp_2nd[vq_2nd_low ][i    ];
210        quantizer_output[i + 5] = cb_lsp_1st[vq_1st][i + 5] + cb_lsp_2nd[vq_2nd_high][i + 5];
211    }
212
213    for (j = 0; j < 2; j++) {
214        for (i = 1; i < 10; i++) {
215            int diff = (quantizer_output[i - 1] - quantizer_output[i] + min_distance[j]) >> 1;
216            if (diff > 0) {
217                quantizer_output[i - 1] -= diff;
218                quantizer_output[i    ] += diff;
219            }
220        }
221    }
222
223    for (i = 0; i < 10; i++) {
224        int sum = quantizer_output[i] * cb_ma_predictor_sum[ma_predictor][i];
225        for (j = 0; j < MA_NP; j++)
226            sum += past_quantizer_outputs[j][i] * cb_ma_predictor[ma_predictor][j][i];
227
228        lsfq[i] = sum >> 15;
229    }
230
231    ff_acelp_reorder_lsf(lsfq, LSFQ_DIFF_MIN, LSFQ_MIN, LSFQ_MAX, 10);
232}
233
234/**
235 * Restores past LSP quantizer output using LSF from previous frame
236 * @param[in,out] lsfq (2.13) quantized LSF coefficients
237 * @param[in,out] past_quantizer_outputs (2.13) quantizer outputs from previous frames
238 * @param ma_predictor_prev MA predictor from previous frame
239 * @param lsfq_prev (2.13) quantized LSF coefficients from previous frame
240 */
241static void lsf_restore_from_previous(int16_t* lsfq,
242                                      int16_t* past_quantizer_outputs[MA_NP + 1],
243                                      int ma_predictor_prev)
244{
245    int16_t* quantizer_output = past_quantizer_outputs[MA_NP];
246    int i,k;
247
248    for (i = 0; i < 10; i++) {
249        int tmp = lsfq[i] << 15;
250
251        for (k = 0; k < MA_NP; k++)
252            tmp -= past_quantizer_outputs[k][i] * cb_ma_predictor[ma_predictor_prev][k][i];
253
254        quantizer_output[i] = ((tmp >> 15) * cb_ma_predictor_sum_inv[ma_predictor_prev][i]) >> 12;
255    }
256}
257
258/**
259 * Constructs new excitation signal and applies phase filter to it
260 * @param[out] out constructed speech signal
261 * @param in original excitation signal
262 * @param fc_cur (2.13) original fixed-codebook vector
263 * @param gain_code (14.1) gain code
264 * @param subframe_size length of the subframe
265 */
266static void g729d_get_new_exc(
267        int16_t* out,
268        const int16_t* in,
269        const int16_t* fc_cur,
270        int dstate,
271        int gain_code,
272        int subframe_size)
273{
274    int i;
275    int16_t fc_new[SUBFRAME_SIZE];
276
277    ff_celp_convolve_circ(fc_new, fc_cur, phase_filter[dstate], subframe_size);
278
279    for (i = 0; i < subframe_size; i++) {
280        out[i]  = in[i];
281        out[i] -= (gain_code * fc_cur[i] + 0x2000) >> 14;
282        out[i] += (gain_code * fc_new[i] + 0x2000) >> 14;
283    }
284}
285
286/**
287 * Makes decision about onset in current subframe
288 * @param past_onset decision result of previous subframe
289 * @param past_gain_code gain code of current and previous subframe
290 *
291 * @return onset decision result for current subframe
292 */
293static int g729d_onset_decision(int past_onset, const int16_t* past_gain_code)
294{
295    if ((past_gain_code[0] >> 1) > past_gain_code[1])
296        return 2;
297
298    return FFMAX(past_onset-1, 0);
299}
300
301/**
302 * Makes decision about voice presence in current subframe
303 * @param onset onset level
304 * @param prev_voice_decision voice decision result from previous subframe
305 * @param past_gain_pitch pitch gain of current and previous subframes
306 *
307 * @return voice decision result for current subframe
308 */
309static int16_t g729d_voice_decision(int onset, int prev_voice_decision, const int16_t* past_gain_pitch)
310{
311    int i, low_gain_pitch_cnt, voice_decision;
312
313    if (past_gain_pitch[0] >= 14745) {       // 0.9
314        voice_decision = DECISION_VOICE;
315    } else if (past_gain_pitch[0] <= 9830) { // 0.6
316        voice_decision = DECISION_NOISE;
317    } else {
318        voice_decision = DECISION_INTERMEDIATE;
319    }
320
321    for (i = 0, low_gain_pitch_cnt = 0; i < 6; i++)
322        if (past_gain_pitch[i] < 9830)
323            low_gain_pitch_cnt++;
324
325    if (low_gain_pitch_cnt > 2 && !onset)
326        voice_decision = DECISION_NOISE;
327
328    if (!onset && voice_decision > prev_voice_decision + 1)
329        voice_decision--;
330
331    if (onset && voice_decision < DECISION_VOICE)
332        voice_decision++;
333
334    return voice_decision;
335}
336
337static int32_t scalarproduct_int16_c(const int16_t * v1, const int16_t * v2, int order)
338{
339    int64_t res = 0;
340
341    while (order--)
342        res += *v1++ * *v2++;
343
344    if      (res > INT32_MAX) return INT32_MAX;
345    else if (res < INT32_MIN) return INT32_MIN;
346
347    return res;
348}
349
350static av_cold int decoder_init(AVCodecContext * avctx)
351{
352    G729Context *s = avctx->priv_data;
353    G729ChannelContext *ctx;
354    int channels = avctx->ch_layout.nb_channels;
355    int c,i,k;
356
357    if (channels < 1 || channels > 2) {
358        av_log(avctx, AV_LOG_ERROR, "Only mono and stereo are supported (requested channels: %d).\n", channels);
359        return AVERROR(EINVAL);
360    }
361    avctx->sample_fmt = AV_SAMPLE_FMT_S16P;
362
363    /* Both 8kbit/s and 6.4kbit/s modes uses two subframes per frame. */
364    avctx->frame_size = SUBFRAME_SIZE << 1;
365
366    ctx =
367    s->channel_context = av_mallocz(sizeof(G729ChannelContext) * channels);
368    if (!ctx)
369        return AVERROR(ENOMEM);
370
371    for (c = 0; c < channels; c++) {
372        ctx->gain_coeff = 16384; // 1.0 in (1.14)
373
374        for (k = 0; k < MA_NP + 1; k++) {
375            ctx->past_quantizer_outputs[k] = ctx->past_quantizer_output_buf[k];
376            for (i = 1; i < 11; i++)
377                ctx->past_quantizer_outputs[k][i - 1] = (18717 * i) >> 3;
378        }
379
380        ctx->lsp[0] = ctx->lsp_buf[0];
381        ctx->lsp[1] = ctx->lsp_buf[1];
382        memcpy(ctx->lsp[0], lsp_init, 10 * sizeof(int16_t));
383
384        ctx->exc = &ctx->exc_base[PITCH_DELAY_MAX+INTERPOL_LEN];
385
386        ctx->pitch_delay_int_prev = PITCH_DELAY_MIN;
387
388        /* random seed initialization */
389        ctx->rand_value = 21845;
390
391        /* quantized prediction error */
392        for (i = 0; i < 4; i++)
393            ctx->quant_energy[i] = -14336; // -14 in (5.10)
394
395        ctx++;
396    }
397
398    ff_audiodsp_init(&s->adsp);
399    s->adsp.scalarproduct_int16 = scalarproduct_int16_c;
400
401    return 0;
402}
403
404static int decode_frame(AVCodecContext *avctx, AVFrame *frame,
405                        int *got_frame_ptr, AVPacket *avpkt)
406{
407    const uint8_t *buf = avpkt->data;
408    int buf_size       = avpkt->size;
409    int16_t *out_frame;
410    GetBitContext gb;
411    const G729FormatDescription *format;
412    int c, i;
413    int16_t *tmp;
414    G729Formats packet_type;
415    G729Context *s = avctx->priv_data;
416    G729ChannelContext *ctx = s->channel_context;
417    int channels = avctx->ch_layout.nb_channels;
418    int16_t lp[2][11];           // (3.12)
419    uint8_t ma_predictor;     ///< switched MA predictor of LSP quantizer
420    uint8_t quantizer_1st;    ///< first stage vector of quantizer
421    uint8_t quantizer_2nd_lo; ///< second stage lower vector of quantizer (size in bits)
422    uint8_t quantizer_2nd_hi; ///< second stage higher vector of quantizer (size in bits)
423
424    int pitch_delay_int[2];      // pitch delay, integer part
425    int pitch_delay_3x;          // pitch delay, multiplied by 3
426    int16_t fc[SUBFRAME_SIZE];   // fixed-codebook vector
427    int16_t synth[SUBFRAME_SIZE+10]; // fixed-codebook vector
428    int j, ret;
429    int gain_before, gain_after;
430
431    frame->nb_samples = SUBFRAME_SIZE<<1;
432    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
433        return ret;
434
435    if (buf_size && buf_size % ((G729_8K_BLOCK_SIZE + (avctx->codec_id == AV_CODEC_ID_ACELP_KELVIN)) * channels) == 0) {
436        packet_type = FORMAT_G729_8K;
437        format = &format_g729_8k;
438        //Reset voice decision
439        ctx->onset = 0;
440        ctx->voice_decision = DECISION_VOICE;
441        av_log(avctx, AV_LOG_DEBUG, "Packet type: %s\n", "G.729 @ 8kbit/s");
442    } else if (buf_size == G729D_6K4_BLOCK_SIZE * channels && avctx->codec_id != AV_CODEC_ID_ACELP_KELVIN) {
443        packet_type = FORMAT_G729D_6K4;
444        format = &format_g729d_6k4;
445        av_log(avctx, AV_LOG_DEBUG, "Packet type: %s\n", "G.729D @ 6.4kbit/s");
446    } else {
447        av_log(avctx, AV_LOG_ERROR, "Packet size %d is unknown.\n", buf_size);
448        return AVERROR_INVALIDDATA;
449    }
450
451    for (c = 0; c < channels; c++) {
452        int frame_erasure = 0; ///< frame erasure detected during decoding
453        int bad_pitch = 0;     ///< parity check failed
454        int is_periodic = 0;   ///< whether one of the subframes is declared as periodic or not
455        out_frame = (int16_t*)frame->data[c];
456        if (avctx->codec_id == AV_CODEC_ID_ACELP_KELVIN) {
457            if (*buf != ((avctx->ch_layout.nb_channels - 1 - c) * 0x80 | 2))
458                avpriv_request_sample(avctx, "First byte value %x for channel %d", *buf, c);
459            buf++;
460        }
461
462        for (i = 0; i < format->block_size; i++)
463            frame_erasure |= buf[i];
464        frame_erasure = !frame_erasure;
465
466        init_get_bits8(&gb, buf, format->block_size);
467
468        ma_predictor     = get_bits(&gb, 1);
469        quantizer_1st    = get_bits(&gb, VQ_1ST_BITS);
470        quantizer_2nd_lo = get_bits(&gb, VQ_2ND_BITS);
471        quantizer_2nd_hi = get_bits(&gb, VQ_2ND_BITS);
472
473        if (frame_erasure) {
474            lsf_restore_from_previous(ctx->lsfq, ctx->past_quantizer_outputs,
475                                      ctx->ma_predictor_prev);
476        } else {
477            lsf_decode(ctx->lsfq, ctx->past_quantizer_outputs,
478                       ma_predictor,
479                       quantizer_1st, quantizer_2nd_lo, quantizer_2nd_hi);
480            ctx->ma_predictor_prev = ma_predictor;
481        }
482
483        tmp = ctx->past_quantizer_outputs[MA_NP];
484        memmove(ctx->past_quantizer_outputs + 1, ctx->past_quantizer_outputs,
485                MA_NP * sizeof(int16_t*));
486        ctx->past_quantizer_outputs[0] = tmp;
487
488        ff_acelp_lsf2lsp(ctx->lsp[1], ctx->lsfq, 10);
489
490        ff_acelp_lp_decode(&lp[0][0], &lp[1][0], ctx->lsp[1], ctx->lsp[0], 10);
491
492        FFSWAP(int16_t*, ctx->lsp[1], ctx->lsp[0]);
493
494        for (i = 0; i < 2; i++) {
495            int gain_corr_factor;
496
497            uint8_t ac_index;      ///< adaptive codebook index
498            uint8_t pulses_signs;  ///< fixed-codebook vector pulse signs
499            int fc_indexes;        ///< fixed-codebook indexes
500            uint8_t gc_1st_index;  ///< gain codebook (first stage) index
501            uint8_t gc_2nd_index;  ///< gain codebook (second stage) index
502
503            ac_index      = get_bits(&gb, format->ac_index_bits[i]);
504            if (!i && format->parity_bit)
505                bad_pitch = av_parity(ac_index >> 2) == get_bits1(&gb);
506            fc_indexes    = get_bits(&gb, format->fc_indexes_bits);
507            pulses_signs  = get_bits(&gb, format->fc_signs_bits);
508            gc_1st_index  = get_bits(&gb, format->gc_1st_index_bits);
509            gc_2nd_index  = get_bits(&gb, format->gc_2nd_index_bits);
510
511            if (frame_erasure) {
512                pitch_delay_3x = 3 * ctx->pitch_delay_int_prev;
513            } else if (!i) {
514                if (bad_pitch) {
515                    pitch_delay_3x = 3 * ctx->pitch_delay_int_prev;
516                } else {
517                    pitch_delay_3x = ff_acelp_decode_8bit_to_1st_delay3(ac_index);
518                }
519            } else {
520                int pitch_delay_min = av_clip(ctx->pitch_delay_int_prev - 5,
521                                              PITCH_DELAY_MIN, PITCH_DELAY_MAX - 9);
522
523                if (packet_type == FORMAT_G729D_6K4) {
524                    pitch_delay_3x = ff_acelp_decode_4bit_to_2nd_delay3(ac_index, pitch_delay_min);
525                } else {
526                    pitch_delay_3x = ff_acelp_decode_5_6_bit_to_2nd_delay3(ac_index, pitch_delay_min);
527                }
528            }
529
530            /* Round pitch delay to nearest (used everywhere except ff_acelp_interpolate). */
531            pitch_delay_int[i]  = (pitch_delay_3x + 1) / 3;
532            if (pitch_delay_int[i] > PITCH_DELAY_MAX) {
533                av_log(avctx, AV_LOG_WARNING, "pitch_delay_int %d is too large\n", pitch_delay_int[i]);
534                pitch_delay_int[i] = PITCH_DELAY_MAX;
535            }
536
537            if (frame_erasure) {
538                ctx->rand_value = g729_prng(ctx->rand_value);
539                fc_indexes   = av_mod_uintp2(ctx->rand_value, format->fc_indexes_bits);
540
541                ctx->rand_value = g729_prng(ctx->rand_value);
542                pulses_signs = ctx->rand_value;
543            }
544
545
546            memset(fc, 0, sizeof(int16_t) * SUBFRAME_SIZE);
547            switch (packet_type) {
548                case FORMAT_G729_8K:
549                    ff_acelp_fc_pulse_per_track(fc, ff_fc_4pulses_8bits_tracks_13,
550                                                ff_fc_4pulses_8bits_track_4,
551                                                fc_indexes, pulses_signs, 3, 3);
552                    break;
553                case FORMAT_G729D_6K4:
554                    ff_acelp_fc_pulse_per_track(fc, ff_fc_2pulses_9bits_track1_gray,
555                                                ff_fc_2pulses_9bits_track2_gray,
556                                                fc_indexes, pulses_signs, 1, 4);
557                    break;
558            }
559
560            /*
561              This filter enhances harmonic components of the fixed-codebook vector to
562              improve the quality of the reconstructed speech.
563
564                         / fc_v[i],                                    i < pitch_delay
565              fc_v[i] = <
566                         \ fc_v[i] + gain_pitch * fc_v[i-pitch_delay], i >= pitch_delay
567            */
568            if (SUBFRAME_SIZE > pitch_delay_int[i])
569                ff_acelp_weighted_vector_sum(fc + pitch_delay_int[i],
570                                             fc + pitch_delay_int[i],
571                                             fc, 1 << 14,
572                                             av_clip(ctx->past_gain_pitch[0], SHARP_MIN, SHARP_MAX),
573                                             0, 14,
574                                             SUBFRAME_SIZE - pitch_delay_int[i]);
575
576            memmove(ctx->past_gain_pitch+1, ctx->past_gain_pitch, 5 * sizeof(int16_t));
577            ctx->past_gain_code[1] = ctx->past_gain_code[0];
578
579            if (frame_erasure) {
580                ctx->past_gain_pitch[0] = (29491 * ctx->past_gain_pitch[0]) >> 15; // 0.90 (0.15)
581                ctx->past_gain_code[0]  = ( 2007 * ctx->past_gain_code[0] ) >> 11; // 0.98 (0.11)
582
583                gain_corr_factor = 0;
584            } else {
585                if (packet_type == FORMAT_G729D_6K4) {
586                    ctx->past_gain_pitch[0]  = cb_gain_1st_6k4[gc_1st_index][0] +
587                                               cb_gain_2nd_6k4[gc_2nd_index][0];
588                    gain_corr_factor = cb_gain_1st_6k4[gc_1st_index][1] +
589                                       cb_gain_2nd_6k4[gc_2nd_index][1];
590
591                    /* Without check below overflow can occur in ff_acelp_update_past_gain.
592                       It is not issue for G.729, because gain_corr_factor in it's case is always
593                       greater than 1024, while in G.729D it can be even zero. */
594                    gain_corr_factor = FFMAX(gain_corr_factor, 1024);
595    #ifndef G729_BITEXACT
596                    gain_corr_factor >>= 1;
597    #endif
598                } else {
599                    ctx->past_gain_pitch[0]  = cb_gain_1st_8k[gc_1st_index][0] +
600                                               cb_gain_2nd_8k[gc_2nd_index][0];
601                    gain_corr_factor = cb_gain_1st_8k[gc_1st_index][1] +
602                                       cb_gain_2nd_8k[gc_2nd_index][1];
603                }
604
605                /* Decode the fixed-codebook gain. */
606                ctx->past_gain_code[0] = ff_acelp_decode_gain_code(&s->adsp, gain_corr_factor,
607                                                                   fc, MR_ENERGY,
608                                                                   ctx->quant_energy,
609                                                                   ma_prediction_coeff,
610                                                                   SUBFRAME_SIZE, 4);
611    #ifdef G729_BITEXACT
612                /*
613                  This correction required to get bit-exact result with
614                  reference code, because gain_corr_factor in G.729D is
615                  two times larger than in original G.729.
616
617                  If bit-exact result is not issue then gain_corr_factor
618                  can be simpler divided by 2 before call to g729_get_gain_code
619                  instead of using correction below.
620                */
621                if (packet_type == FORMAT_G729D_6K4) {
622                    gain_corr_factor >>= 1;
623                    ctx->past_gain_code[0] >>= 1;
624                }
625    #endif
626            }
627            ff_acelp_update_past_gain(ctx->quant_energy, gain_corr_factor, 2, frame_erasure);
628
629            /* Routine requires rounding to lowest. */
630            ff_acelp_interpolate(ctx->exc + i * SUBFRAME_SIZE,
631                                 ctx->exc + i * SUBFRAME_SIZE - pitch_delay_3x / 3,
632                                 ff_acelp_interp_filter, 6,
633                                 (pitch_delay_3x % 3) << 1,
634                                 10, SUBFRAME_SIZE);
635
636            ff_acelp_weighted_vector_sum(ctx->exc + i * SUBFRAME_SIZE,
637                                         ctx->exc + i * SUBFRAME_SIZE, fc,
638                                         (!ctx->was_periodic && frame_erasure) ? 0 : ctx->past_gain_pitch[0],
639                                         ( ctx->was_periodic && frame_erasure) ? 0 : ctx->past_gain_code[0],
640                                         1 << 13, 14, SUBFRAME_SIZE);
641
642            memcpy(synth, ctx->syn_filter_data, 10 * sizeof(int16_t));
643
644            if (ff_celp_lp_synthesis_filter(
645                synth+10,
646                &lp[i][1],
647                ctx->exc  + i * SUBFRAME_SIZE,
648                SUBFRAME_SIZE,
649                10,
650                1,
651                0,
652                0x800))
653                /* Overflow occurred, downscale excitation signal... */
654                for (j = 0; j < 2 * SUBFRAME_SIZE + PITCH_DELAY_MAX + INTERPOL_LEN; j++)
655                    ctx->exc_base[j] >>= 2;
656
657            /* ... and make synthesis again. */
658            if (packet_type == FORMAT_G729D_6K4) {
659                int16_t exc_new[SUBFRAME_SIZE];
660
661                ctx->onset = g729d_onset_decision(ctx->onset, ctx->past_gain_code);
662                ctx->voice_decision = g729d_voice_decision(ctx->onset, ctx->voice_decision, ctx->past_gain_pitch);
663
664                g729d_get_new_exc(exc_new, ctx->exc  + i * SUBFRAME_SIZE, fc, ctx->voice_decision, ctx->past_gain_code[0], SUBFRAME_SIZE);
665
666                ff_celp_lp_synthesis_filter(
667                        synth+10,
668                        &lp[i][1],
669                        exc_new,
670                        SUBFRAME_SIZE,
671                        10,
672                        0,
673                        0,
674                        0x800);
675            } else {
676                ff_celp_lp_synthesis_filter(
677                        synth+10,
678                        &lp[i][1],
679                        ctx->exc  + i * SUBFRAME_SIZE,
680                        SUBFRAME_SIZE,
681                        10,
682                        0,
683                        0,
684                        0x800);
685            }
686            /* Save data (without postfilter) for use in next subframe. */
687            memcpy(ctx->syn_filter_data, synth+SUBFRAME_SIZE, 10 * sizeof(int16_t));
688
689            /* Calculate gain of unfiltered signal for use in AGC. */
690            gain_before = 0;
691            for (j = 0; j < SUBFRAME_SIZE; j++)
692                gain_before += FFABS(synth[j+10]);
693
694            /* Call postfilter and also update voicing decision for use in next frame. */
695            ff_g729_postfilter(
696                    &s->adsp,
697                    &ctx->ht_prev_data,
698                    &is_periodic,
699                    &lp[i][0],
700                    pitch_delay_int[0],
701                    ctx->residual,
702                    ctx->res_filter_data,
703                    ctx->pos_filter_data,
704                    synth+10,
705                    SUBFRAME_SIZE);
706
707            /* Calculate gain of filtered signal for use in AGC. */
708            gain_after = 0;
709            for (j = 0; j < SUBFRAME_SIZE; j++)
710                gain_after += FFABS(synth[j+10]);
711
712            ctx->gain_coeff = ff_g729_adaptive_gain_control(
713                    gain_before,
714                    gain_after,
715                    synth+10,
716                    SUBFRAME_SIZE,
717                    ctx->gain_coeff);
718
719            if (frame_erasure) {
720                ctx->pitch_delay_int_prev = FFMIN(ctx->pitch_delay_int_prev + 1, PITCH_DELAY_MAX);
721            } else {
722                ctx->pitch_delay_int_prev = pitch_delay_int[i];
723            }
724
725            memcpy(synth+8, ctx->hpf_z, 2*sizeof(int16_t));
726            ff_acelp_high_pass_filter(
727                    out_frame + i*SUBFRAME_SIZE,
728                    ctx->hpf_f,
729                    synth+10,
730                    SUBFRAME_SIZE);
731            memcpy(ctx->hpf_z, synth+8+SUBFRAME_SIZE, 2*sizeof(int16_t));
732        }
733
734        ctx->was_periodic = is_periodic;
735
736        /* Save signal for use in next frame. */
737        memmove(ctx->exc_base, ctx->exc_base + 2 * SUBFRAME_SIZE, (PITCH_DELAY_MAX+INTERPOL_LEN)*sizeof(int16_t));
738
739        buf += format->block_size;
740        ctx++;
741    }
742
743    *got_frame_ptr = 1;
744    return (format->block_size + (avctx->codec_id == AV_CODEC_ID_ACELP_KELVIN)) * channels;
745}
746
747static av_cold int decode_close(AVCodecContext *avctx)
748{
749    G729Context *s = avctx->priv_data;
750    av_freep(&s->channel_context);
751
752    return 0;
753}
754
755const FFCodec ff_g729_decoder = {
756    .p.name         = "g729",
757    .p.long_name    = NULL_IF_CONFIG_SMALL("G.729"),
758    .p.type         = AVMEDIA_TYPE_AUDIO,
759    .p.id           = AV_CODEC_ID_G729,
760    .priv_data_size = sizeof(G729Context),
761    .init           = decoder_init,
762    FF_CODEC_DECODE_CB(decode_frame),
763    .close          = decode_close,
764    .p.capabilities = AV_CODEC_CAP_SUBFRAMES | AV_CODEC_CAP_DR1,
765    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
766};
767
768const FFCodec ff_acelp_kelvin_decoder = {
769    .p.name         = "acelp.kelvin",
770    .p.long_name    = NULL_IF_CONFIG_SMALL("Sipro ACELP.KELVIN"),
771    .p.type         = AVMEDIA_TYPE_AUDIO,
772    .p.id           = AV_CODEC_ID_ACELP_KELVIN,
773    .priv_data_size = sizeof(G729Context),
774    .init           = decoder_init,
775    FF_CODEC_DECODE_CB(decode_frame),
776    .close          = decode_close,
777    .p.capabilities = AV_CODEC_CAP_SUBFRAMES | AV_CODEC_CAP_DR1,
778    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
779};
780