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137 lines
3.9 KiB
C
137 lines
3.9 KiB
C
/*
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* G.729 decoder
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* Copyright (c) 2008 Vladimir Voroshilov
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <stdlib.h>
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#include <inttypes.h>
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#include <limits.h>
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#include <stdio.h>
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#include <string.h>
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#include <math.h>
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#include <assert.h>
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#include "avcodec.h"
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#include "libavutil/avutil.h"
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#include "bitstream.h"
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/**
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* minimum quantized LSF value (3.2.4)
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* 0.005 in Q13
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*/
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#define LSFQ_MIN 40
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/**
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* maximum quantized LSF value (3.2.4)
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* 3.135 in Q13
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*/
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#define LSFQ_MAX 25681
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/**
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* minimum LSF distance (3.2.4)
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* 0.0391 in Q13
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*/
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#define LSFQ_DIFF_MIN 321
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/**
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* minimum gain pitch value (3.8, Equation 47)
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* 0.2 in (1.14)
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*/
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#define SHARP_MIN 3277
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/**
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* maximum gain pitch value (3.8, Equation 47)
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* (EE) This does not comply with the specification.
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* Specification says about 0.8, which should be
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* 13107 in (1.14), but reference C code uses
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* 13017 (equals to 0.7945) instead of it.
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*/
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#define SHARP_MAX 13017
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/**
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* \brief pseudo random number generator
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*/
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static inline uint16_t g729_random(uint16_t value)
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{
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return 31821 * value + 13849;
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}
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/**
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* Get parity bit of bit 2..7
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*/
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static inline int g729_get_parity(uint8_t value)
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{
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return (0x6996966996696996ULL >> (value >> 2)) & 1;
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}
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/*
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This filter enhances harmonic components of the fixed-codebook vector to
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improve the quality of the reconstructed speech.
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/ fc_v[i], i < pitch_delay
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fc_v[i] = <
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\ fc_v[i] + gain_pitch * fc_v[i-pitch_delay], i >= pitch_delay
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*/
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ff_acelp_weighted_vector_sum(
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fc + pitch_delay_int[i],
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fc + pitch_delay_int[i],
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fc,
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1 << 14,
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av_clip(ctx->gain_pitch, SHARP_MIN, SHARP_MAX),
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0,
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14,
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ctx->subframe_size - pitch_delay_int[i]);
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ctx->gain_pitch = cb_gain_1st_8k[parm->gc_1st_index[i]][0] +
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cb_gain_2nd_8k[parm->gc_2nd_index[i]][0];
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gain_corr_factor = cb_gain_1st_8k[parm->gc_1st_index[i]][1] +
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cb_gain_2nd_8k[parm->gc_2nd_index[i]][1];
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/* Routine requires rounding to lowest. */
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ff_acelp_interpolate(
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ctx->exc + i*ctx->subframe_size,
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ctx->exc + i*ctx->subframe_size - pitch_delay_3x/3,
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ff_acelp_interp_filter,
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6,
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(pitch_delay_3x%3)<<1,
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10,
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ctx->subframe_size);
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ff_acelp_weighted_vector_sum(
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ctx->exc + i * ctx->subframe_size,
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ctx->exc + i * ctx->subframe_size,
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fc,
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(!voicing && ctx->frame_erasure) ? 0 : ctx->gain_pitch,
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( voicing && ctx->frame_erasure) ? 0 : ctx->gain_code,
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1<<13,
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14,
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ctx->subframe_size);
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AVCodec g729_decoder =
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{
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"g729",
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CODEC_TYPE_AUDIO,
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CODEC_ID_G729,
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sizeof(G729_Context),
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ff_g729_decoder_init,
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NULL,
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NULL,
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ff_g729_decode_frame,
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.long_name = NULL_IF_CONFIG_SMALL("G.729"),
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};
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