aacenc: remove support for AAC Main profile

The Main profile of AAC is... terrible.
It enables the use of delta coding across coefficients of two frames
to try to increase compression, and it enabled one more pole for TNS
filters.

What the AAC authors failed to take into account were basic
mathematics, as MDCT leakage (e.g. the spread of each frequency when
represented in a discrete spectrum) is significant in most audio codecs.
This leads to huge variations between each frame, basically rendering
prediction completely pointless.

In fact, enabling AAC-Main prediction does not, in general, even recoup
the metadata losses from signalling the profile and prediction properties
in the first place. So you lose efficiency by using AAC Main.

The rumor is that it was put in the AAC spec for patent reasons, though
patent-wise, it has about as much use as a patent for a bicycle designed
for use by snakes.

The only other thing AAC Main changes is it permits 3-pole TNS filters.
When AAC's bands are absolutely tiny, except for very high frequency bands,
where you're likely to use PNS instead.

Just get rid of it.

1 files changed, 0 insertions, 347 deletions

diff --git a/libavcodec/aacenc_pred.c b/libavcodec/aacenc_pred.c
deleted file mode 100644
index a486c44d42..0000000000
--- a/libavcodec/aacenc_pred.c
+++ /dev/null
@@ -1,347 +0,0 @@
-/*
- * AAC encoder main-type prediction
- * Copyright (C) 2015 Rostislav Pehlivanov
- *
- * This file is part of FFmpeg.
- *
- * FFmpeg is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * FFmpeg is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with FFmpeg; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-/**
- * @file
- * AAC encoder main-type prediction
- * @author Rostislav Pehlivanov ( atomnuker gmail com )
- */
-
-#include "aactab.h"
-#include "aacenc_pred.h"
-#include "aacenc_utils.h"
-#include "aacenc_is.h"            /* <- Needed for common window distortions */
-#include "aacenc_quantization.h"
-
-#define RESTORE_PRED(sce, sfb) \
-        if (sce->ics.prediction_used[sfb]) {\
-            sce->ics.prediction_used[sfb] = 0;\
-            sce->band_type[sfb] = sce->band_alt[sfb];\
-        }
-
-static inline float flt16_round(float pf)
-{
-    union av_intfloat32 tmp;
-    tmp.f = pf;
-    tmp.i = (tmp.i + 0x00008000U) & 0xFFFF0000U;
-    return tmp.f;
-}
-
-static inline float flt16_even(float pf)
-{
-    union av_intfloat32 tmp;
-    tmp.f = pf;
-    tmp.i = (tmp.i + 0x00007FFFU + (tmp.i & 0x00010000U >> 16)) & 0xFFFF0000U;
-    return tmp.f;
-}
-
-static inline float flt16_trunc(float pf)
-{
-    union av_intfloat32 pun;
-    pun.f = pf;
-    pun.i &= 0xFFFF0000U;
-    return pun.f;
-}
-
-static inline void predict(PredictorState *ps, float *coef, float *rcoef, int set)
-{
-    float k2;
-    const float a     = 0.953125; // 61.0 / 64
-    const float alpha = 0.90625;  // 29.0 / 32
-    const float   k1 = ps->k1;
-    const float   r0 = ps->r0,     r1 = ps->r1;
-    const float cor0 = ps->cor0, cor1 = ps->cor1;
-    const float var0 = ps->var0, var1 = ps->var1;
-    const float e0 = *coef - ps->x_est;
-    const float e1 = e0 - k1 * r0;
-
-    if (set)
-        *coef = e0;
-
-    ps->cor1 = flt16_trunc(alpha * cor1 + r1 * e1);
-    ps->var1 = flt16_trunc(alpha * var1 + 0.5f * (r1 * r1 + e1 * e1));
-    ps->cor0 = flt16_trunc(alpha * cor0 + r0 * e0);
-    ps->var0 = flt16_trunc(alpha * var0 + 0.5f * (r0 * r0 + e0 * e0));
-    ps->r1   = flt16_trunc(a * (r0 - k1 * e0));
-    ps->r0   = flt16_trunc(a * e0);
-
-    /* Prediction for next frame */
-    ps->k1   = ps->var0 > 1 ? ps->cor0 * flt16_even(a / ps->var0) : 0;
-    k2       = ps->var1 > 1 ? ps->cor1 * flt16_even(a / ps->var1) : 0;
-    *rcoef   = ps->x_est = flt16_round(ps->k1*ps->r0 + k2*ps->r1);
-}
-
-static inline void reset_predict_state(PredictorState *ps)
-{
-    ps->r0    = 0.0f;
-    ps->r1    = 0.0f;
-    ps->k1    = 0.0f;
-    ps->cor0  = 0.0f;
-    ps->cor1  = 0.0f;
-    ps->var0  = 1.0f;
-    ps->var1  = 1.0f;
-    ps->x_est = 0.0f;
-}
-
-static inline void reset_all_predictors(PredictorState *ps)
-{
-    int i;
-    for (i = 0; i < MAX_PREDICTORS; i++)
-        reset_predict_state(&ps[i]);
-}
-
-static inline void reset_predictor_group(SingleChannelElement *sce, int group_num)
-{
-    int i;
-    PredictorState *ps = sce->predictor_state;
-    for (i = group_num - 1; i < MAX_PREDICTORS; i += 30)
-        reset_predict_state(&ps[i]);
-}
-
-void ff_aac_apply_main_pred(AACEncContext *s, SingleChannelElement *sce)
-{
-    int sfb, k;
-    const int pmax = FFMIN(sce->ics.max_sfb, ff_aac_pred_sfb_max[s->samplerate_index]);
-
-    if (sce->ics.window_sequence[0] != EIGHT_SHORT_SEQUENCE) {
-        for (sfb = 0; sfb < pmax; sfb++) {
-            for (k = sce->ics.swb_offset[sfb]; k < sce->ics.swb_offset[sfb + 1]; k++) {
-                predict(&sce->predictor_state[k], &sce->coeffs[k], &sce->prcoeffs[k],
-                        sce->ics.predictor_present && sce->ics.prediction_used[sfb]);
-            }
-        }
-        if (sce->ics.predictor_reset_group) {
-            reset_predictor_group(sce, sce->ics.predictor_reset_group);
-        }
-    } else {
-        reset_all_predictors(sce->predictor_state);
-    }
-}
-
-/* If inc = 0 you can check if this returns 0 to see if you can reset freely */
-static inline int update_counters(IndividualChannelStream *ics, int inc)
-{
-    int i;
-    for (i = 1; i < 31; i++) {
-        ics->predictor_reset_count[i] += inc;
-        if (ics->predictor_reset_count[i] > PRED_RESET_FRAME_MIN)
-            return i; /* Reset this immediately */
-    }
-    return 0;
-}
-
-void ff_aac_adjust_common_pred(AACEncContext *s, ChannelElement *cpe)
-{
-    int start, w, w2, g, i, count = 0;
-    SingleChannelElement *sce0 = &cpe->ch[0];
-    SingleChannelElement *sce1 = &cpe->ch[1];
-    const int pmax0 = FFMIN(sce0->ics.max_sfb, ff_aac_pred_sfb_max[s->samplerate_index]);
-    const int pmax1 = FFMIN(sce1->ics.max_sfb, ff_aac_pred_sfb_max[s->samplerate_index]);
-    const int pmax  = FFMIN(pmax0, pmax1);
-
-    if (!cpe->common_window ||
-        sce0->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE ||
-        sce1->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE)
-        return;
-
-    for (w = 0; w < sce0->ics.num_windows; w += sce0->ics.group_len[w]) {
-        start = 0;
-        for (g = 0; g < sce0->ics.num_swb; g++) {
-            int sfb = w*16+g;
-            int sum = sce0->ics.prediction_used[sfb] + sce1->ics.prediction_used[sfb];
-            float ener0 = 0.0f, ener1 = 0.0f, ener01 = 0.0f;
-            struct AACISError ph_err1, ph_err2, *erf;
-            if (sfb < PRED_SFB_START || sfb > pmax || sum != 2) {
-                RESTORE_PRED(sce0, sfb);
-                RESTORE_PRED(sce1, sfb);
-                start += sce0->ics.swb_sizes[g];
-                continue;
-            }
-            for (w2 = 0; w2 < sce0->ics.group_len[w]; w2++) {
-                for (i = 0; i < sce0->ics.swb_sizes[g]; i++) {
-                    float coef0 = sce0->pcoeffs[start+(w+w2)*128+i];
-                    float coef1 = sce1->pcoeffs[start+(w+w2)*128+i];
-                    ener0  += coef0*coef0;
-                    ener1  += coef1*coef1;
-                    ener01 += (coef0 + coef1)*(coef0 + coef1);
-                }
-            }
-            ph_err1 = ff_aac_is_encoding_err(s, cpe, start, w, g,
-                                             ener0, ener1, ener01, 1, -1);
-            ph_err2 = ff_aac_is_encoding_err(s, cpe, start, w, g,
-                                             ener0, ener1, ener01, 1, +1);
-            erf = ph_err1.error < ph_err2.error ? &ph_err1 : &ph_err2;
-            if (erf->pass) {
-                sce0->ics.prediction_used[sfb] = 1;
-                sce1->ics.prediction_used[sfb] = 1;
-                count++;
-            } else {
-                RESTORE_PRED(sce0, sfb);
-                RESTORE_PRED(sce1, sfb);
-            }
-            start += sce0->ics.swb_sizes[g];
-        }
-    }
-
-    sce1->ics.predictor_present = sce0->ics.predictor_present = !!count;
-}
-
-static void update_pred_resets(SingleChannelElement *sce)
-{
-    int i, max_group_id_c, max_frame = 0;
-    float avg_frame = 0.0f;
-    IndividualChannelStream *ics = &sce->ics;
-
-    /* Update the counters and immediately update any frame behind schedule */
-    if ((ics->predictor_reset_group = update_counters(&sce->ics, 1)))
-        return;
-
-    for (i = 1; i < 31; i++) {
-        /* Count-based */
-        if (ics->predictor_reset_count[i] > max_frame) {
-            max_group_id_c = i;
-            max_frame = ics->predictor_reset_count[i];
-        }
-        avg_frame = (ics->predictor_reset_count[i] + avg_frame)/2;
-    }
-
-    if (max_frame > PRED_RESET_MIN) {
-        ics->predictor_reset_group = max_group_id_c;
-    } else {
-        ics->predictor_reset_group = 0;
-    }
-}
-
-void ff_aac_search_for_pred(AACEncContext *s, SingleChannelElement *sce)
-{
-    int sfb, i, count = 0, cost_coeffs = 0, cost_pred = 0;
-    const int pmax = FFMIN(sce->ics.max_sfb, ff_aac_pred_sfb_max[s->samplerate_index]);
-    float *O34  = &s->scoefs[128*0], *P34 = &s->scoefs[128*1];
-    float *SENT = &s->scoefs[128*2], *S34 = &s->scoefs[128*3];
-    float *QERR = &s->scoefs[128*4];
-
-    if (sce->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE) {
-        sce->ics.predictor_present = 0;
-        return;
-    }
-
-    if (!sce->ics.predictor_initialized) {
-        reset_all_predictors(sce->predictor_state);
-        sce->ics.predictor_initialized = 1;
-        memcpy(sce->prcoeffs, sce->coeffs, 1024*sizeof(float));
-        for (i = 1; i < 31; i++)
-            sce->ics.predictor_reset_count[i] = i;
-    }
-
-    update_pred_resets(sce);
-    memcpy(sce->band_alt, sce->band_type, sizeof(sce->band_type));
-
-    for (sfb = PRED_SFB_START; sfb < pmax; sfb++) {
-        int cost1, cost2, cb_p;
-        float dist1, dist2, dist_spec_err = 0.0f;
-        const int cb_n = sce->zeroes[sfb] ? 0 : sce->band_type[sfb];
-        const int cb_min = sce->zeroes[sfb] ? 0 : 1;
-        const int cb_max = sce->zeroes[sfb] ? 0 : RESERVED_BT;
-        const int start_coef = sce->ics.swb_offset[sfb];
-        const int num_coeffs = sce->ics.swb_offset[sfb + 1] - start_coef;
-        const FFPsyBand *band = &s->psy.ch[s->cur_channel].psy_bands[sfb];
-
-        if (start_coef + num_coeffs > MAX_PREDICTORS ||
-            (s->cur_channel && sce->band_type[sfb] >= INTENSITY_BT2) ||
-            sce->band_type[sfb] == NOISE_BT)
-            continue;
-
-        /* Normal coefficients */
-        s->aacdsp.abs_pow34(O34, &sce->coeffs[start_coef], num_coeffs);
-        dist1 = ff_quantize_and_encode_band_cost(s, NULL, &sce->coeffs[start_coef], NULL,
-                                                 O34, num_coeffs, sce->sf_idx[sfb],
-                                                 cb_n, s->lambda / band->threshold, INFINITY, &cost1, NULL);
-        cost_coeffs += cost1;
-
-        /* Encoded coefficients - needed for #bits, band type and quant. error */
-        for (i = 0; i < num_coeffs; i++)
-            SENT[i] = sce->coeffs[start_coef + i] - sce->prcoeffs[start_coef + i];
-        s->aacdsp.abs_pow34(S34, SENT, num_coeffs);
-        if (cb_n < RESERVED_BT)
-            cb_p = av_clip(find_min_book(find_max_val(1, num_coeffs, S34), sce->sf_idx[sfb]), cb_min, cb_max);
-        else
-            cb_p = cb_n;
-        ff_quantize_and_encode_band_cost(s, NULL, SENT, QERR, S34, num_coeffs,
-                                         sce->sf_idx[sfb], cb_p, s->lambda / band->threshold, INFINITY,
-                                         &cost2, NULL);
-
-        /* Reconstructed coefficients - needed for distortion measurements */
-        for (i = 0; i < num_coeffs; i++)
-            sce->prcoeffs[start_coef + i] += QERR[i] != 0.0f ? (sce->prcoeffs[start_coef + i] - QERR[i]) : 0.0f;
-        s->aacdsp.abs_pow34(P34, &sce->prcoeffs[start_coef], num_coeffs);
-        if (cb_n < RESERVED_BT)
-            cb_p = av_clip(find_min_book(find_max_val(1, num_coeffs, P34), sce->sf_idx[sfb]), cb_min, cb_max);
-        else
-            cb_p = cb_n;
-        dist2 = ff_quantize_and_encode_band_cost(s, NULL, &sce->prcoeffs[start_coef], NULL,
-                                                 P34, num_coeffs, sce->sf_idx[sfb],
-                                                 cb_p, s->lambda / band->threshold, INFINITY, NULL, NULL);
-        for (i = 0; i < num_coeffs; i++)
-            dist_spec_err += (O34[i] - P34[i])*(O34[i] - P34[i]);
-        dist_spec_err *= s->lambda / band->threshold;
-        dist2 += dist_spec_err;
-
-        if (dist2 <= dist1 && cb_p <= cb_n) {
-            cost_pred += cost2;
-            sce->ics.prediction_used[sfb] = 1;
-            sce->band_alt[sfb]  = cb_n;
-            sce->band_type[sfb] = cb_p;
-            count++;
-        } else {
-            cost_pred += cost1;
-            sce->band_alt[sfb] = cb_p;
-        }
-    }
-
-    if (count && cost_coeffs < cost_pred) {
-        count = 0;
-        for (sfb = PRED_SFB_START; sfb < pmax; sfb++)
-            RESTORE_PRED(sce, sfb);
-        memset(&sce->ics.prediction_used, 0, sizeof(sce->ics.prediction_used));
-    }
-
-    sce->ics.predictor_present = !!count;
-}
-
-/**
- * Encoder predictors data.
- */
-void ff_aac_encode_main_pred(AACEncContext *s, SingleChannelElement *sce)
-{
-    int sfb;
-    IndividualChannelStream *ics = &sce->ics;
-    const int pmax = FFMIN(ics->max_sfb, ff_aac_pred_sfb_max[s->samplerate_index]);
-
-    if (s->profile != AV_PROFILE_AAC_MAIN ||
-        !ics->predictor_present)
-        return;
-
-    put_bits(&s->pb, 1, !!ics->predictor_reset_group);
-    if (ics->predictor_reset_group)
-        put_bits(&s->pb, 5, ics->predictor_reset_group);
-    for (sfb = 0; sfb < pmax; sfb++)
-        put_bits(&s->pb, 1, ics->prediction_used[sfb]);
-}