libavcodec/g722.c File Reference

G.722 ADPCM audio codec. More...

#include "mathops.h"
#include "g722.h"

Go to the source code of this file.

Functions

static void do_adaptive_prediction (struct G722Band *band, const int cur_diff)
 adaptive predictor
static int linear_scale_factor (const int log_factor)
void ff_g722_update_low_predictor (struct G722Band *band, const int ilow)
void ff_g722_update_high_predictor (struct G722Band *band, const int dhigh, const int ihigh)
void ff_g722_apply_qmf (const int16_t *prev_samples, int *xout1, int *xout2)

Variables

static const int8_t sign_lookup [2] = { -1, 1 }
static const int16_t inv_log2_table [32]
static const int16_t high_log_factor_step [2] = { 798, -214 }
const int16_t ff_g722_high_inv_quant [4] = { -926, -202, 926, 202 }
static const int16_t low_log_factor_step [16]
 low_log_factor_step[index] == wl[rl42[index]]
const int16_t ff_g722_low_inv_quant4 [16]
const int16_t ff_g722_low_inv_quant6 [64]
static const int16_t qmf_coeffs [12]
 quadrature mirror filter (QMF) coefficients


Detailed Description

G.722 ADPCM audio codec.

This G.722 decoder is a bit-exact implementation of the ITU G.722 specification for all three specified bitrates - 64000bps, 56000bps and 48000bps. It passes the ITU tests.

Note:
For the 56000bps and 48000bps bitrates, the lowest 1 or 2 bits respectively of each byte are ignored.

Definition in file g722.c.


Function Documentation

static void do_adaptive_prediction ( struct G722Band *  band,
const int  cur_diff 
) [static]

adaptive predictor

Parameters:
cur_diff the dequantized and scaled delta calculated from the current codeword

Definition at line 90 of file g722.c.

Referenced by ff_g722_update_high_predictor(), and ff_g722_update_low_predictor().

void ff_g722_apply_qmf ( const int16_t prev_samples,
int xout1,
int xout2 
)

Definition at line 161 of file g722.c.

Referenced by filter_samples(), and g722_decode_frame().

void ff_g722_update_high_predictor ( struct G722Band *  band,
const int  dhigh,
const int  ihigh 
)

Definition at line 150 of file g722.c.

Referenced by g722_decode_frame(), and g722_encode_trellis().

void ff_g722_update_low_predictor ( struct G722Band *  band,
const int  ilow 
)

Definition at line 139 of file g722.c.

Referenced by g722_decode_frame(), and g722_encode_trellis().

static int linear_scale_factor ( const int  log_factor  )  [inline, static]

Definition at line 132 of file g722.c.

Referenced by ff_g722_update_high_predictor(), and ff_g722_update_low_predictor().


Variable Documentation

const int16_t ff_g722_high_inv_quant[4] = { -926, -202, 926, 202 }

Definition at line 51 of file g722.c.

Referenced by g722_decode_frame(), and g722_encode_trellis().

Initial value:

 {
       0, -2557, -1612, -1121,  -786,  -530,  -323,  -150,
    2557,  1612,  1121,   786,   530,   323,   150,     0
}

Definition at line 59 of file g722.c.

Referenced by ff_g722_update_low_predictor().

Initial value:

 {
     -17,   -17,   -17,   -17, -3101, -2738, -2376, -2088,
   -1873, -1689, -1535, -1399, -1279, -1170, -1072,  -982,
    -899,  -822,  -750,  -682,  -618,  -558,  -501,  -447,
    -396,  -347,  -300,  -254,  -211,  -170,  -130,   -91,
    3101,  2738,  2376,  2088,  1873,  1689,  1535,  1399,
    1279,  1170,  1072,   982,   899,   822,   750,   682,
     618,   558,   501,   447,   396,   347,   300,   254,
     211,   170,   130,    91,    54,    17,   -54,   -17
}

Definition at line 63 of file g722.c.

Referenced by g722_encode_trellis().

const int16_t high_log_factor_step[2] = { 798, -214 } [static]

Definition at line 50 of file g722.c.

Referenced by ff_g722_update_high_predictor().

const int16_t inv_log2_table[32] [static]

Initial value:

 {
    2048, 2093, 2139, 2186, 2233, 2282, 2332, 2383,
    2435, 2489, 2543, 2599, 2656, 2714, 2774, 2834,
    2896, 2960, 3025, 3091, 3158, 3228, 3298, 3371,
    3444, 3520, 3597, 3676, 3756, 3838, 3922, 4008
}

Definition at line 44 of file g722.c.

Referenced by linear_scale_factor().

const int16_t low_log_factor_step[16] [static]

Initial value:

 {
     -60, 3042, 1198, 538, 334, 172,  58, -30,
    3042, 1198,  538, 334, 172,  58, -30, -60
}
low_log_factor_step[index] == wl[rl42[index]]

Definition at line 55 of file g722.c.

Referenced by ff_g722_update_low_predictor().

const int16_t qmf_coeffs[12] [static]

Initial value:

 {
    3, -11, 12, 32, -210, 951, 3876, -805, 362, -156, 53, -11,
}
quadrature mirror filter (QMF) coefficients

ITU-T G.722 Table 11

Definition at line 79 of file g722.c.

Referenced by ff_g722_apply_qmf().

const int8_t sign_lookup[2] = { -1, 1 } [static]

Definition at line 42 of file g722.c.

Referenced by do_adaptive_prediction().


Generated on Thu Oct 25 19:21:32 2012 for FFmpeg by  doxygen 1.5.8