From 9458a62decfcaa1313b1ba69276466de536d0768 Mon Sep 17 00:00:00 2001 From: Claudio Freire Date: Fri, 25 Sep 2015 03:56:32 -0300 Subject: AAC encoder: tweak PNS usage to be more aggressive This patch tweaks search_for_pns to be both more aggressive and more careful when applying PNS. On the one side, it will again try to use PNS on zero (or effectively zero) bands. For this, both zeroes and band_type have to be checked (some ZERO bands aren't marked in zeroes). On the other side, a more accurate rate-distortion measure avoids using PNS where it would cause audible distortion. Also fixed a small bug in the computation of freq that caused PNS usage on low-frequency bands during 8-short windows. This allows re-enabling PNS during 8-short. --- libavcodec/aaccoder.c | 47 +++++++++++++++++++++-------------------------- 1 file changed, 21 insertions(+), 26 deletions(-) (limited to 'libavcodec/aaccoder.c') diff --git a/libavcodec/aaccoder.c b/libavcodec/aaccoder.c index 8d5ea77..4749d8c 100644 --- a/libavcodec/aaccoder.c +++ b/libavcodec/aaccoder.c @@ -593,19 +593,18 @@ static void search_for_pns(AACEncContext *s, AVCodecContext *avctx, SingleChanne const float lambda = s->lambda; const float freq_mult = avctx->sample_rate/(1024.0f/sce->ics.num_windows)/2.0f; const float thr_mult = NOISE_LAMBDA_REPLACE*(100.0f/lambda); - const float spread_threshold = NOISE_SPREAD_THRESHOLD*(lambda/100.f); - - if (sce->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE) - return; + const float spread_threshold = NOISE_SPREAD_THRESHOLD*FFMAX(0.5f, lambda/100.f); + memcpy(sce->band_alt, sce->band_type, sizeof(sce->band_type)); for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) { + int wstart = sce->ics.swb_offset[w*16]; for (g = 0; g < sce->ics.num_swb; g++) { int noise_sfi; float dist1 = 0.0f, dist2 = 0.0f, noise_amp; - float pns_energy = 0.0f, energy_ratio, dist_thresh; + float pns_energy = 0.0f, pns_tgt_energy, energy_ratio, dist_thresh; float sfb_energy = 0.0f, threshold = 0.0f, spread = 0.0f; const int start = sce->ics.swb_offset[w*16+g]; - const float freq = start*freq_mult; + const float freq = (start-wstart)*freq_mult; const float freq_boost = FFMAX(0.88f*freq/NOISE_LOW_LIMIT, 1.0f); if (freq < NOISE_LOW_LIMIT || avctx->cutoff && freq >= avctx->cutoff) continue; @@ -617,18 +616,22 @@ static void search_for_pns(AACEncContext *s, AVCodecContext *avctx, SingleChanne } /* Ramps down at ~8000Hz and loosens the dist threshold */ - dist_thresh = FFMIN(2.5f*NOISE_LOW_LIMIT/freq, 1.27f); + dist_thresh = FFMIN(2.5f*NOISE_LOW_LIMIT/freq, 2.5f); - if (sce->zeroes[w*16+g] || spread < spread_threshold || - sfb_energy > threshold*thr_mult*freq_boost) { + /* zero and energy close to threshold usually means hole avoidance, + * we do want to remain avoiding holes with PNS + */ + if (((sce->zeroes[w*16+g] || !sce->band_alt[w*16+g]) && sfb_energy < threshold*sqrtf(1.5f/freq_boost)) || spread < spread_threshold || + (sce->band_alt[w*16+g] && sfb_energy > threshold*thr_mult*freq_boost)) { sce->pns_ener[w*16+g] = sfb_energy; continue; } - noise_sfi = av_clip(roundf(log2f(sfb_energy)*2), -100, 155); /* Quantize */ + pns_tgt_energy = sfb_energy*spread*spread/sce->ics.group_len[w]; + noise_sfi = av_clip(roundf(log2f(pns_tgt_energy)*2), -100, 155); /* Quantize */ noise_amp = -ff_aac_pow2sf_tab[noise_sfi + POW_SF2_ZERO]; /* Dequantize */ for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) { - float band_energy, scale; + float band_energy, scale, pns_senergy; const int start_c = sce->ics.swb_offset[(w+w2)*16+g]; band = &s->psy.ch[s->cur_channel].psy_bands[(w+w2)*16+g]; for (i = 0; i < sce->ics.swb_sizes[g]; i++) @@ -636,7 +639,8 @@ static void search_for_pns(AACEncContext *s, AVCodecContext *avctx, SingleChanne band_energy = s->fdsp->scalarproduct_float(PNS, PNS, sce->ics.swb_sizes[g]); scale = noise_amp/sqrtf(band_energy); s->fdsp->vector_fmul_scalar(PNS, PNS, scale, sce->ics.swb_sizes[g]); - pns_energy += s->fdsp->scalarproduct_float(PNS, PNS, sce->ics.swb_sizes[g]); + pns_senergy = s->fdsp->scalarproduct_float(PNS, PNS, sce->ics.swb_sizes[g]); + pns_energy += pns_senergy; abs_pow34_v(NOR34, &sce->coeffs[start_c], sce->ics.swb_sizes[g]); abs_pow34_v(PNS34, PNS, sce->ics.swb_sizes[g]); dist1 += quantize_band_cost(s, &sce->coeffs[start_c], @@ -645,23 +649,14 @@ static void search_for_pns(AACEncContext *s, AVCodecContext *avctx, SingleChanne sce->sf_idx[(w+w2)*16+g], sce->band_alt[(w+w2)*16+g], lambda/band->threshold, INFINITY, NULL, 0); - dist2 += quantize_band_cost(s, PNS, - PNS34, - sce->ics.swb_sizes[g], - noise_sfi, - NOISE_BT, - lambda/band->threshold, INFINITY, NULL, 0); + /* Estimate rd on average as 9 bits for CB and sf + spread energy * lambda/thr */ + dist2 += 9+band->energy/(band->spread*band->spread)*lambda/band->threshold; } - energy_ratio = sfb_energy/pns_energy; /* Compensates for quantization error */ - sce->pns_ener[w*16+g] = energy_ratio*sfb_energy; - if (energy_ratio > 0.85f && energy_ratio < 1.25f && dist1/dist2 > dist_thresh) { + energy_ratio = pns_tgt_energy/pns_energy; /* Compensates for quantization error */ + sce->pns_ener[w*16+g] = energy_ratio*pns_tgt_energy; + if (energy_ratio > 0.85f && energy_ratio < 1.25f && (sce->zeroes[w*16+g] || !sce->band_alt[w*16+g] || dist2*dist_thresh < dist1)) { sce->band_type[w*16+g] = NOISE_BT; sce->zeroes[w*16+g] = 0; - if (sce->band_type[w*16+g-1] != NOISE_BT && /* Prevent holes */ - sce->band_type[w*16+g-2] == NOISE_BT) { - sce->band_type[w*16+g-1] = NOISE_BT; - sce->zeroes[w*16+g-1] = 0; - } } } } -- cgit v1.1