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aacenc: Refactor the parts of the AAC psymodel. 

3GPP:
Remove ffac from and move min_snr out of AacPsyBand.
Rearrange AacPsyCoeffs to make it easier to implement energy spreading.
Rename the band[] array to bands[]
Copy energies and thresholds at the end of analysis.

LAME:
Use a loop instead of an if chain in LAME windowing.
tags/n0.8
Nathan Caldwell Ronald S. Bultje 14 years ago
parent
f578854efc
commit
b7c96769c5
1 changed files with 37 additions and 40 deletions
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  1. +37
    -40
      libavcodec/aacpsy.c

+ 37
- 40
libavcodec/aacpsy.c View File

@@ -61,9 +61,7 @@
*/
typedef struct AacPsyBand{
float energy; ///< band energy
float ffac; ///< form factor
float thr; ///< energy threshold
float min_snr; ///< minimal SNR
float thr_quiet; ///< threshold in quiet
}AacPsyBand;

@@ -88,17 +86,18 @@ typedef struct AacPsyChannel{
* psychoacoustic model frame type-dependent coefficients
*/
typedef struct AacPsyCoeffs{
float ath [64]; ///< absolute threshold of hearing per bands
float barks [64]; ///< Bark value for each spectral band in long frame
float spread_low[64]; ///< spreading factor for low-to-high threshold spreading in long frame
float spread_hi [64]; ///< spreading factor for high-to-low threshold spreading in long frame
float ath; ///< absolute threshold of hearing per bands
float barks; ///< Bark value for each spectral band in long frame
float spread_low[2]; ///< spreading factor for low-to-high threshold spreading in long frame
float spread_hi [2]; ///< spreading factor for high-to-low threshold spreading in long frame
float min_snr; ///< minimal SNR
}AacPsyCoeffs;

/**
* 3GPP TS26.403-inspired psychoacoustic model specific data
*/
typedef struct AacPsyContext{
AacPsyCoeffs psy_coef[2];
AacPsyCoeffs psy_coef[2][64];
AacPsyChannel *ch;
}AacPsyContext;

@@ -243,27 +242,30 @@ static av_cold int psy_3gpp_init(FFPsyContext *ctx) {

minath = ath(3410, ATH_ADD);
for (j = 0; j < 2; j++) {
AacPsyCoeffs *coeffs = &pctx->psy_coef[j];
AacPsyCoeffs *coeffs = pctx->psy_coef[j];
const uint8_t *band_sizes = ctx->bands[j];
float line_to_frequency = ctx->avctx->sample_rate / (j ? 256.f : 2048.0f);
i = 0;
prev = 0.0;
for (g = 0; g < ctx->num_bands[j]; g++) {
i += ctx->bands[j][g];
i += band_sizes[g];
bark = calc_bark((i-1) * line_to_frequency);
coeffs->barks[g] = (bark + prev) / 2.0;
coeffs[g].barks = (bark + prev) / 2.0;
prev = bark;
}
for (g = 0; g < ctx->num_bands[j] - 1; g++) {
coeffs->spread_low[g] = pow(10.0, -(coeffs->barks[g+1] - coeffs->barks[g]) * PSY_3GPP_SPREAD_LOW);
coeffs->spread_hi [g] = pow(10.0, -(coeffs->barks[g+1] - coeffs->barks[g]) * PSY_3GPP_SPREAD_HI);
AacPsyCoeffs *coeff = &coeffs[g];
float bark_width = coeffs[g+1].barks - coeffs->barks;
coeff->spread_low[0] = pow(10.0, -bark_width * PSY_3GPP_SPREAD_LOW);
coeff->spread_hi [0] = pow(10.0, -bark_width * PSY_3GPP_SPREAD_HI);
}
start = 0;
for (g = 0; g < ctx->num_bands[j]; g++) {
minscale = ath(start * line_to_frequency, ATH_ADD);
for (i = 1; i < ctx->bands[j][g]; i++)
for (i = 1; i < band_sizes[g]; i++)
minscale = FFMIN(minscale, ath((start + i) * line_to_frequency, ATH_ADD));
coeffs->ath[g] = minscale - minath;
start += ctx->bands[j][g];
coeffs[g].ath = minscale - minath;
start += band_sizes[g];
}
}

@@ -406,24 +408,32 @@ static void psy_3gpp_analyze(FFPsyContext *ctx, int channel,
band->energy += coefs[start+i] * coefs[start+i];
band->thr = band->energy * 0.001258925f;
start += band_sizes[g];

ctx->psy_bands[channel*PSY_MAX_BANDS+w+g].energy = band->energy;
}
}
//modify thresholds - spread, threshold in quiet - 5.4.3 "Spreaded Energy Calculation"
for (w = 0; w < wi->num_windows*16; w += 16) {
AacPsyBand *band = &pch->band[w];

AacPsyBand *bands = &pch->band[w];
for (g = 1; g < num_bands; g++)
band[g].thr = FFMAX(band[g].thr, band[g-1].thr * coeffs->spread_hi [g]);
bands[g].thr = FFMAX(bands[g].thr, bands[g-1].thr * coeffs[g].spread_hi[0]);
for (g = num_bands - 2; g >= 0; g--)
band[g].thr = FFMAX(band[g].thr, band[g+1].thr * coeffs->spread_low[g]);
bands[g].thr = FFMAX(bands[g].thr, bands[g+1].thr * coeffs[g].spread_low[0]);
for (g = 0; g < num_bands; g++) {
band[g].thr_quiet = band[g].thr = FFMAX(band[g].thr, coeffs->ath[g]);
AacPsyBand *band = &bands[g];
band->thr_quiet = band->thr = FFMAX(band->thr, coeffs[g].ath);
if (!(wi->window_type[0] == LONG_STOP_SEQUENCE || (wi->window_type[1] == LONG_START_SEQUENCE && !w)))
band[g].thr = FFMAX(PSY_3GPP_RPEMIN*band[g].thr, FFMIN(band[g].thr,
PSY_3GPP_RPELEV*pch->prev_band[w+g].thr_quiet));
band->thr = FFMAX(PSY_3GPP_RPEMIN*band->thr, FFMIN(band->thr,
PSY_3GPP_RPELEV*pch->prev_band[w+g].thr_quiet));
}
}

ctx->psy_bands[channel*PSY_MAX_BANDS+w+g].threshold = band[g].thr;
for (w = 0; w < wi->num_windows*16; w += 16) {
for (g = 0; g < num_bands; g++) {
AacPsyBand *band = &pch->band[w+g];
FFPsyBand *psy_band = &ctx->psy_bands[channel*PSY_MAX_BANDS+w+g];

psy_band->threshold = band->thr;
psy_band->energy = band->energy;
}
}
memcpy(pch->prev_band, pch->band, sizeof(pch->band));
@@ -553,22 +563,9 @@ static FFPsyWindowInfo psy_lame_window(FFPsyContext *ctx,
if (pch->prev_attack == 3 || att_sum) {
uselongblock = 0;

if (attacks[1] && attacks[0])
attacks[1] = 0;
if (attacks[2] && attacks[1])
attacks[2] = 0;
if (attacks[3] && attacks[2])
attacks[3] = 0;
if (attacks[4] && attacks[3])
attacks[4] = 0;
if (attacks[5] && attacks[4])
attacks[5] = 0;
if (attacks[6] && attacks[5])
attacks[6] = 0;
if (attacks[7] && attacks[6])
attacks[7] = 0;
if (attacks[8] && attacks[7])
attacks[8] = 0;
for (i = 1; i < AAC_NUM_BLOCKS_SHORT + 1; i++)
if (attacks[i] && attacks[i-1])
attacks[i] = 0;
}
} else {
/* We have no lookahead info, so just use same type as the previous sequence. */


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