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atrac3: Generalize gain compensation code

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Move it to the ATRAC common code, to reuse in the upcoming ATRAC3+ decoder.

Signed-off-by: Diego Biurrun <diego@biurrun.de>
pull/37/merge
Maxim Poliakovski 11 years ago committed by Diego Biurrun
parent 5ce04c14dd
commit 79cbac8cd4
3 changed files with 118 additions and 75 deletions
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  1. 61
      libavcodec/atrac.c
  2. 45
      libavcodec/atrac.h
  3. 87
      libavcodec/atrac3.c

61
libavcodec/atrac.c
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@ -63,6 +63,67 @@ void ff_atrac_generate_tables(void)
}
}
av_cold void ff_atrac_init_gain_compensation(AtracGCContext *gctx, int id2exp_offset,
int loc_scale)
{
int i;
gctx->loc_scale = loc_scale;
gctx->loc_size = 1 << loc_scale;
gctx->id2exp_offset = id2exp_offset;
/* Generate gain level table. */
for (i = 0; i < 16; i++)
gctx->gain_tab1[i] = powf(2.0, id2exp_offset - i);
/* Generate gain interpolation table. */
for (i = -15; i < 16; i++)
gctx->gain_tab2[i + 15] = powf(2.0, -1.0f / gctx->loc_size * i);
}
void ff_atrac_gain_compensation(AtracGCContext *gctx, float *in, float *prev,
AtracGainInfo *gc_now, AtracGainInfo *gc_next,
int num_samples, float *out)
{
float lev, gc_scale, gain_inc;
int i, pos, lastpos;
gc_scale = gc_next->num_points ? gctx->gain_tab1[gc_next->lev_code[0]]
: 1.0f;
if (!gc_now->num_points) {
for (pos = 0; pos < num_samples; pos++)
out[pos] = in[pos] * gc_scale + prev[pos];
} else {
pos = 0;
for (i = 0; i < gc_now->num_points; i++) {
lastpos = gc_now->loc_code[i] << gctx->loc_scale;
lev = gctx->gain_tab1[gc_now->lev_code[i]];
gain_inc = gctx->gain_tab2[(i + 1 < gc_now->num_points ? gc_now->lev_code[i + 1]
: gctx->id2exp_offset) -
gc_now->lev_code[i] + 15];
/* apply constant gain level and overlap */
for (; pos < lastpos; pos++)
out[pos] = (in[pos] * gc_scale + prev[pos]) * lev;
/* interpolate between two different gain levels */
for (; pos < lastpos + gctx->loc_size; pos++) {
out[pos] = (in[pos] * gc_scale + prev[pos]) * lev;
lev *= gain_inc;
}
}
for (; pos < num_samples; pos++)
out[pos] = in[pos] * gc_scale + prev[pos];
}
/* copy the overlapping part into the delay buffer */
memcpy(prev, &in[num_samples], num_samples * sizeof(float));
}
void ff_atrac_iqmf (float *inlo, float *inhi, unsigned int nIn, float *pOut, float *delayBuf, float *temp)
{
int i, j;

45
libavcodec/atrac.h
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@ -29,6 +29,26 @@
#ifndef AVCODEC_ATRAC_H
#define AVCODEC_ATRAC_H
/**
* Gain control parameters for one subband.
*/
typedef struct AtracGainInfo {
int num_points; ///< number of gain control points
int lev_code[7]; ///< level at corresponding control point
int loc_code[7]; ///< location of gain control points
} AtracGainInfo;
/**
* Gain compensation context structure.
*/
typedef struct AtracGCContext {
float gain_tab1[16]; ///< gain compensation level table
float gain_tab2[31]; ///< gain compensation interpolation table
int id2exp_offset; ///< offset for converting level index into level exponent
int loc_scale; ///< scale of location code = 2^loc_scale samples
int loc_size; ///< size of location code in samples
} AtracGCContext;
extern float ff_atrac_sf_table[64];
/**
@ -36,6 +56,31 @@ extern float ff_atrac_sf_table[64];
*/
void ff_atrac_generate_tables(void);
/**
* Initialize gain compensation context.
*
* @param gctx pointer to gain compensation context to initialize
* @param id2exp_offset offset for converting level index into level exponent
* @param loc_scale location size factor
*/
void ff_atrac_init_gain_compensation(AtracGCContext *gctx, int id2exp_offset,
int loc_scale);
/**
* Apply gain compensation and perform the MDCT overlapping part.
*
* @param gctx pointer to gain compensation context
* @param in input buffer
* @param prev previous buffer to perform overlap against
* @param gc_now gain control information for current frame
* @param gc_next gain control information for next frame
* @param num_samples number of samples to process
* @param out output data goes here
*/
void ff_atrac_gain_compensation(AtracGCContext *gctx, float *in, float *prev,
AtracGainInfo *gc_now, AtracGainInfo *gc_next,
int num_samples, float *out);
/**
* Quadrature mirror synthesis filter.
*

87
libavcodec/atrac3.c
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@ -54,14 +54,8 @@
#define SAMPLES_PER_FRAME 1024
#define MDCT_SIZE 512
typedef struct GainInfo {
int num_gain_data;
int lev_code[8];
int loc_code[8];
} GainInfo;
typedef struct GainBlock {
GainInfo g_block[4];
AtracGainInfo g_block[4];
} GainBlock;
typedef struct TonalComponent {
@ -111,6 +105,7 @@ typedef struct ATRAC3Context {
int scrambled_stream;
//@}
AtracGCContext gainc_ctx;
FFTContext mdct_ctx;
FmtConvertContext fmt_conv;
AVFloatDSPContext fdsp;
@ -417,18 +412,17 @@ static int decode_tonal_components(GetBitContext *gb,
static int decode_gain_control(GetBitContext *gb, GainBlock *block,
int num_bands)
{
int i, j, num_data;
int i, j;
int *level, *loc;
GainInfo *gain = block->g_block;
AtracGainInfo *gain = block->g_block;
for (i = 0; i <= num_bands; i++) {
num_data = get_bits(gb, 3);
gain[i].num_gain_data = num_data;
gain[i].num_points = get_bits(gb, 3);
level = gain[i].lev_code;
loc = gain[i].loc_code;
for (j = 0; j < gain[i].num_gain_data; j++) {
for (j = 0; j < gain[i].num_points; j++) {
level[j] = get_bits(gb, 4);
loc[j] = get_bits(gb, 5);
if (j && loc[j] <= loc[j - 1])
@ -438,68 +432,11 @@ static int decode_gain_control(GetBitContext *gb, GainBlock *block,
/* Clear the unused blocks. */
for (; i < 4 ; i++)
gain[i].num_gain_data = 0;
gain[i].num_points = 0;
return 0;
}
/**
* Apply gain parameters and perform the MDCT overlapping part
*
* @param input input buffer
* @param prev previous buffer to perform overlap against
* @param output output buffer
* @param gain1 current band gain info
* @param gain2 next band gain info
*/
static void gain_compensate_and_overlap(float *input, float *prev,
float *output, GainInfo *gain1,
GainInfo *gain2)
{
float g1, g2, gain_inc;
int i, j, num_data, start_loc, end_loc;
if (gain2->num_gain_data == 0)
g1 = 1.0;
else
g1 = gain_tab1[gain2->lev_code[0]];
if (gain1->num_gain_data == 0) {
for (i = 0; i < 256; i++)
output[i] = input[i] * g1 + prev[i];
} else {
num_data = gain1->num_gain_data;
gain1->loc_code[num_data] = 32;
gain1->lev_code[num_data] = 4;
for (i = 0, j = 0; i < num_data; i++) {
start_loc = gain1->loc_code[i] * 8;
end_loc = start_loc + 8;
g2 = gain_tab1[gain1->lev_code[i]];
gain_inc = gain_tab2[gain1->lev_code[i + 1] -
gain1->lev_code[i ] + 15];
/* interpolate */
for (; j < start_loc; j++)
output[j] = (input[j] * g1 + prev[j]) * g2;
/* interpolation is done over eight samples */
for (; j < end_loc; j++) {
output[j] = (input[j] * g1 + prev[j]) * g2;
g2 *= gain_inc;
}
}
for (; j < 256; j++)
output[j] = input[j] * g1 + prev[j];
}
/* Delay for the overlapping part. */
memcpy(prev, &input[256], 256 * sizeof(*prev));
}
/**
* Combine the tonal band spectrum and regular band spectrum
*
@ -690,11 +627,10 @@ static int decode_channel_sound_unit(ATRAC3Context *q, GetBitContext *gb,
memset(snd->imdct_buf, 0, 512 * sizeof(*snd->imdct_buf));
/* gain compensation and overlapping */
gain_compensate_and_overlap(snd->imdct_buf,
&snd->prev_frame[band * 256],
&output[band * 256],
&gain1->g_block[band],
&gain2->g_block[band]);
ff_atrac_gain_compensation(&q->gainc_ctx, snd->imdct_buf,
&snd->prev_frame[band * 256],
&gain1->g_block[band], &gain2->g_block[band],
256, &output[band * 256]);
}
/* Swap the gain control buffers for the next frame. */
@ -982,6 +918,7 @@ static av_cold int atrac3_decode_init(AVCodecContext *avctx)
q->matrix_coeff_index_next[i] = 3;
}
ff_atrac_init_gain_compensation(&q->gainc_ctx, 4, 3);
avpriv_float_dsp_init(&q->fdsp, avctx->flags & CODEC_FLAG_BITEXACT);
ff_fmt_convert_init(&q->fmt_conv, avctx);

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