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libavcodec/g729dec.c

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00001 /*
00002  * G.729 decoder
00003  * Copyright (c) 2008 Vladimir Voroshilov
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 #include <stdlib.h>
00022 #include <inttypes.h>
00023 #include <limits.h>
00024 #include <stdio.h>
00025 #include <string.h>
00026 #include <math.h>
00027 #include <assert.h>
00028 
00029 #include "avcodec.h"
00030 #include "libavutil/avutil.h"
00031 #include "get_bits.h"
00032 
00033 #include "lsp.h"
00034 #include "celp_math.h"
00035 #include "acelp_filters.h"
00036 #include "acelp_pitch_delay.h"
00037 #include "acelp_vectors.h"
00038 #include "g729data.h"
00039 
00044 #define LSFQ_MIN                   40
00045 
00050 #define LSFQ_MAX                   25681
00051 
00056 #define LSFQ_DIFF_MIN              321
00057 
00062 #define SHARP_MIN                  3277
00063 
00071 #define SHARP_MAX                  13017
00072 
00076 #define SUBFRAME_SIZE              40
00077 
00078 
00079 typedef struct {
00080     uint8_t ac_index_bits[2];   
00081     uint8_t parity_bit;         
00082     uint8_t gc_1st_index_bits;  
00083     uint8_t gc_2nd_index_bits;  
00084     uint8_t fc_signs_bits;      
00085     uint8_t fc_indexes_bits;    
00086 } G729FormatDescription;
00087 
00088 typedef struct {
00089     int pitch_delay_int_prev;   
00090 
00092     int16_t  past_quantizer_output_buf[MA_NP + 1][10];
00093     int16_t* past_quantizer_outputs[MA_NP + 1];
00094 
00095     int16_t lsfq[10];           
00096     int16_t lsp_buf[2][10];     
00097     int16_t *lsp[2];            
00098 }  G729Context;
00099 
00100 static const G729FormatDescription format_g729_8k = {
00101     .ac_index_bits     = {8,5},
00102     .parity_bit        = 1,
00103     .gc_1st_index_bits = GC_1ST_IDX_BITS_8K,
00104     .gc_2nd_index_bits = GC_2ND_IDX_BITS_8K,
00105     .fc_signs_bits     = 4,
00106     .fc_indexes_bits   = 13,
00107 };
00108 
00109 static const G729FormatDescription format_g729d_6k4 = {
00110     .ac_index_bits     = {8,4},
00111     .parity_bit        = 0,
00112     .gc_1st_index_bits = GC_1ST_IDX_BITS_6K4,
00113     .gc_2nd_index_bits = GC_2ND_IDX_BITS_6K4,
00114     .fc_signs_bits     = 2,
00115     .fc_indexes_bits   = 9,
00116 };
00117 
00121 static inline uint16_t g729_prng(uint16_t value)
00122 {
00123     return 31821 * value + 13849;
00124 }
00125 
00129 static inline int get_parity(uint8_t value)
00130 {
00131    return (0x6996966996696996ULL >> (value >> 2)) & 1;
00132 }
00133 
00134 static void lsf_decode(int16_t* lsfq, int16_t* past_quantizer_outputs[MA_NP + 1],
00135                        int16_t ma_predictor,
00136                        int16_t vq_1st, int16_t vq_2nd_low, int16_t vq_2nd_high)
00137 {
00138     int i,j;
00139     static const uint8_t min_distance[2]={10, 5}; //(2.13)
00140     int16_t* quantizer_output = past_quantizer_outputs[MA_NP];
00141 
00142     for (i = 0; i < 5; i++) {
00143         quantizer_output[i]     = cb_lsp_1st[vq_1st][i    ] + cb_lsp_2nd[vq_2nd_low ][i    ];
00144         quantizer_output[i + 5] = cb_lsp_1st[vq_1st][i + 5] + cb_lsp_2nd[vq_2nd_high][i + 5];
00145     }
00146 
00147     for (j = 0; j < 2; j++) {
00148         for (i = 1; i < 10; i++) {
00149             int diff = (quantizer_output[i - 1] - quantizer_output[i] + min_distance[j]) >> 1;
00150             if (diff > 0) {
00151                 quantizer_output[i - 1] -= diff;
00152                 quantizer_output[i    ] += diff;
00153             }
00154         }
00155     }
00156 
00157     for (i = 0; i < 10; i++) {
00158         int sum = quantizer_output[i] * cb_ma_predictor_sum[ma_predictor][i];
00159         for (j = 0; j < MA_NP; j++)
00160             sum += past_quantizer_outputs[j][i] * cb_ma_predictor[ma_predictor][j][i];
00161 
00162         lsfq[i] = sum >> 15;
00163     }
00164 
00165     /* Rotate past_quantizer_outputs. */
00166     memmove(past_quantizer_outputs + 1, past_quantizer_outputs, MA_NP * sizeof(int16_t*));
00167     past_quantizer_outputs[0] = quantizer_output;
00168 
00169     ff_acelp_reorder_lsf(lsfq, LSFQ_DIFF_MIN, LSFQ_MIN, LSFQ_MAX, 10);
00170 }
00171 
00172 static av_cold int decoder_init(AVCodecContext * avctx)
00173 {
00174     G729Context* ctx = avctx->priv_data;
00175     int i,k;
00176 
00177     if (avctx->channels != 1) {
00178         av_log(avctx, AV_LOG_ERROR, "Only mono sound is supported (requested channels: %d).\n", avctx->channels);
00179         return AVERROR(EINVAL);
00180     }
00181 
00182     /* Both 8kbit/s and 6.4kbit/s modes uses two subframes per frame. */
00183     avctx->frame_size = SUBFRAME_SIZE << 1;
00184 
00185     for (k = 0; k < MA_NP + 1; k++) {
00186         ctx->past_quantizer_outputs[k] = ctx->past_quantizer_output_buf[k];
00187         for (i = 1; i < 11; i++)
00188             ctx->past_quantizer_outputs[k][i - 1] = (18717 * i) >> 3;
00189     }
00190 
00191     ctx->lsp[0] = ctx->lsp_buf[0];
00192     ctx->lsp[1] = ctx->lsp_buf[1];
00193     memcpy(ctx->lsp[0], lsp_init, 10 * sizeof(int16_t));
00194 
00195     return 0;
00196 }
00197 
00198 static int decode_frame(AVCodecContext *avctx, void *data, int *data_size,
00199                         AVPacket *avpkt)
00200 {
00201     const uint8_t *buf = avpkt->data;
00202     int buf_size       = avpkt->size;
00203     int16_t *out_frame = data;
00204     GetBitContext gb;
00205     G729FormatDescription format;
00206     int frame_erasure = 0;    
00207     int bad_pitch = 0;        
00208     int i;
00209     G729Context *ctx = avctx->priv_data;
00210     int16_t lp[2][11];           // (3.12)
00211     uint8_t ma_predictor;     
00212     uint8_t quantizer_1st;    
00213     uint8_t quantizer_2nd_lo; 
00214     uint8_t quantizer_2nd_hi; 
00215 
00216     int pitch_delay_int;         // pitch delay, integer part
00217     int pitch_delay_3x;          // pitch delay, multiplied by 3
00218 
00219     if (*data_size < SUBFRAME_SIZE << 2) {
00220         av_log(avctx, AV_LOG_ERROR, "Error processing packet: output buffer too small\n");
00221         return AVERROR(EIO);
00222     }
00223 
00224     if (buf_size == 10) {
00225         format = format_g729_8k;
00226         av_log(avctx, AV_LOG_DEBUG, "Packet type: %s\n", "G.729 @ 8kbit/s");
00227     } else if (buf_size == 8) {
00228         format = format_g729d_6k4;
00229         av_log(avctx, AV_LOG_DEBUG, "Packet type: %s\n", "G.729D @ 6.4kbit/s");
00230     } else {
00231         av_log(avctx, AV_LOG_ERROR, "Packet size %d is unknown.\n", buf_size);
00232         return AVERROR_INVALIDDATA;
00233     }
00234 
00235     for (i=0; i < buf_size; i++)
00236         frame_erasure |= buf[i];
00237     frame_erasure = !frame_erasure;
00238 
00239     init_get_bits(&gb, buf, buf_size);
00240 
00241     ma_predictor     = get_bits(&gb, 1);
00242     quantizer_1st    = get_bits(&gb, VQ_1ST_BITS);
00243     quantizer_2nd_lo = get_bits(&gb, VQ_2ND_BITS);
00244     quantizer_2nd_hi = get_bits(&gb, VQ_2ND_BITS);
00245 
00246     lsf_decode(ctx->lsfq, ctx->past_quantizer_outputs,
00247                ma_predictor,
00248                quantizer_1st, quantizer_2nd_lo, quantizer_2nd_hi);
00249 
00250     ff_acelp_lsf2lsp(ctx->lsp[1], ctx->lsfq, 10);
00251 
00252     ff_acelp_lp_decode(&lp[0][0], &lp[1][0], ctx->lsp[1], ctx->lsp[0], 10);
00253 
00254     FFSWAP(int16_t*, ctx->lsp[1], ctx->lsp[0]);
00255 
00256     for (i = 0; i < 2; i++) {
00257         uint8_t ac_index;      
00258         uint8_t pulses_signs;  
00259         int fc_indexes;        
00260         uint8_t gc_1st_index;  
00261         uint8_t gc_2nd_index;  
00262 
00263         ac_index      = get_bits(&gb, format.ac_index_bits[i]);
00264         if(!i && format.parity_bit)
00265             bad_pitch = get_parity(ac_index) == get_bits1(&gb);
00266         fc_indexes    = get_bits(&gb, format.fc_indexes_bits);
00267         pulses_signs  = get_bits(&gb, format.fc_signs_bits);
00268         gc_1st_index  = get_bits(&gb, format.gc_1st_index_bits);
00269         gc_2nd_index  = get_bits(&gb, format.gc_2nd_index_bits);
00270 
00271         if(!i) {
00272             if (bad_pitch)
00273                 pitch_delay_3x   = 3 * ctx->pitch_delay_int_prev;
00274             else
00275                 pitch_delay_3x = ff_acelp_decode_8bit_to_1st_delay3(ac_index);
00276         } else {
00277             int pitch_delay_min = av_clip(ctx->pitch_delay_int_prev - 5,
00278                                           PITCH_DELAY_MIN, PITCH_DELAY_MAX - 9);
00279 
00280             if(packet_type == FORMAT_G729D_6K4)
00281                 pitch_delay_3x = ff_acelp_decode_4bit_to_2nd_delay3(ac_index, pitch_delay_min);
00282             else
00283                 pitch_delay_3x = ff_acelp_decode_5_6_bit_to_2nd_delay3(ac_index, pitch_delay_min);
00284         }
00285 
00286         /* Round pitch delay to nearest (used everywhere except ff_acelp_interpolate). */
00287         pitch_delay_int  = (pitch_delay_3x + 1) / 3;
00288 
00289         ff_acelp_weighted_vector_sum(fc + pitch_delay_int,
00290                                      fc + pitch_delay_int,
00291                                      fc, 1 << 14,
00292                                      av_clip(ctx->gain_pitch, SHARP_MIN, SHARP_MAX),
00293                                      0, 14,
00294                                      SUBFRAME_SIZE - pitch_delay_int);
00295 
00296         if (frame_erasure) {
00297             ctx->gain_pitch = (29491 * ctx->gain_pitch) >> 15; // 0.90 (0.15)
00298             ctx->gain_code  = ( 2007 * ctx->gain_code ) >> 11; // 0.98 (0.11)
00299 
00300             gain_corr_factor = 0;
00301         } else {
00302             ctx->gain_pitch  = cb_gain_1st_8k[gc_1st_index][0] +
00303                                cb_gain_2nd_8k[gc_2nd_index][0];
00304             gain_corr_factor = cb_gain_1st_8k[gc_1st_index][1] +
00305                                cb_gain_2nd_8k[gc_2nd_index][1];
00306 
00307         ff_acelp_weighted_vector_sum(ctx->exc + i * SUBFRAME_SIZE,
00308                                      ctx->exc + i * SUBFRAME_SIZE, fc,
00309                                      (!voicing && frame_erasure) ? 0 : ctx->gain_pitch,
00310                                      ( voicing && frame_erasure) ? 0 : ctx->gain_code,
00311                                      1 << 13, 14, SUBFRAME_SIZE);
00312 
00313             ctx->pitch_delay_int_prev = pitch_delay_int;
00314     }
00315 
00316     *data_size = SUBFRAME_SIZE << 2;
00317     return buf_size;
00318 }
00319 
00320 AVCodec ff_g729_decoder =
00321 {
00322     "g729",
00323     AVMEDIA_TYPE_AUDIO,
00324     CODEC_ID_G729,
00325     sizeof(G729Context),
00326     decoder_init,
00327     NULL,
00328     NULL,
00329     decode_frame,
00330     .long_name = NULL_IF_CONFIG_SMALL("G.729"),
00331 };

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