opusenc: implement a psychoacoustic system

This commit implements a psychoacoustic system for the native Opus
encoder. Its unlike any other psychoacoustic system known since its
capable of using a lookahead to make better choices on how to treat the
current frame and how many bits to allocate for it (and future frames).

Also, whilst the main bulk of the analysis function has to run in a
single thread, the per-frame anaylsis functions does not modify the main
psychoacoustic context, so in the future it will be fairly trivial to
run those as slice threads.
Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>

libavcodec/Makefile

@@ -467,7 +467,8 @@ OBJS-$(CONFIG_NUV_DECODER)             += nuv.o rtjpeg.o
 OBJS-$(CONFIG_ON2AVC_DECODER)          += on2avc.o on2avcdata.o
 OBJS-$(CONFIG_OPUS_DECODER)            += opusdec.o opus.o opus_celt.o opus_rc.o \
                                           opus_pvq.o opus_silk.o opustab.o vorbis_data.o
-OBJS-$(CONFIG_OPUS_ENCODER)            += opusenc.o opus_rc.o opustab.o opus_pvq.o
+OBJS-$(CONFIG_OPUS_ENCODER)            += opusenc.o opus_rc.o opustab.o opus_pvq.o \
+                                          opusenc_psy.o
 OBJS-$(CONFIG_PAF_AUDIO_DECODER)       += pafaudio.o
 OBJS-$(CONFIG_PAF_VIDEO_DECODER)       += pafvideo.o
 OBJS-$(CONFIG_PAM_DECODER)             += pnmdec.o pnm.o

libavcodec/opus_celt.h

@@ -120,6 +120,12 @@ struct CeltFrame {
     uint32_t seed;
     enum CeltSpread spread;
 
+    /* Encoder PF coeffs */
+    int pf_octave;
+    int pf_period;
+    int pf_tapset;
+    float pf_gain;
+
     /* Bit allocation */
     int framebits;
     int remaining;

libavcodec/opusenc.h

+/*
+ * Opus encoder
+ * Copyright (c) 2017 Rostislav Pehlivanov <atomnuker@gmail.com>
+ *
+ * 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
+ */
+
+#ifndef AVCODEC_OPUSENC_H
+#define AVCODEC_OPUSENC_H
+
+#include "internal.h"
+#include "opus_celt.h"
+
+/* Determines the maximum delay the psychoacoustic system will use for lookahead */
+#define FF_BUFQUEUE_SIZE 145
+#include "libavfilter/bufferqueue.h"
+
+#define OPUS_MAX_LOOKAHEAD ((FF_BUFQUEUE_SIZE - 1)*2.5f)
+
+#define OPUS_MAX_CHANNELS 2
+
+/* 120 ms / 2.5 ms = 48 frames (extremely improbable, but the encoder'll work) */
+#define OPUS_MAX_FRAMES_PER_PACKET 48
+
+#define OPUS_BLOCK_SIZE(x) (2 * 15 * (1 << ((x) + 2)))
+
+#define OPUS_SAMPLES_TO_BLOCK_SIZE(x) (ff_log2((x) / (2 * 15)) - 2)
+
+typedef struct OpusEncOptions {
+    float max_delay_ms;
+} OpusEncOptions;
+
+typedef struct OpusPacketInfo {
+    enum OpusMode mode;
+    enum OpusBandwidth bandwidth;
+    int framesize;
+    int frames;
+} OpusPacketInfo;
+
+void ff_celt_enc_bitalloc(OpusRangeCoder *rc, CeltFrame *f);
+
+#endif /* AVCODEC_OPUSENC_H */

libavcodec/opusenc_psy.h

+/*
+ * Opus encoder
+ * Copyright (c) 2017 Rostislav Pehlivanov <atomnuker@gmail.com>
+ *
+ * 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
+ */
+
+#ifndef AVCODEC_OPUSENC_PSY_H
+#define AVCODEC_OPUSENC_PSY_H
+
+#include "opusenc.h"
+#include "opusenc_utils.h"
+#include "libavfilter/window_func.h"
+
+/* Each step is 2.5ms */
+typedef struct OpusPsyStep {
+    int   index; /* Current index */
+    int   silence;
+    float energy[OPUS_MAX_CHANNELS][CELT_MAX_BANDS]; /* Masking effects included */
+    float tone[OPUS_MAX_CHANNELS][CELT_MAX_BANDS];   /* Tonality */
+    float stereo[CELT_MAX_BANDS];                    /* IS/MS compatibility */
+    float change_amp[OPUS_MAX_CHANNELS][CELT_MAX_BANDS]; /* Jump over last frame */
+    float total_change; /* Total change */
+
+    float *bands[OPUS_MAX_CHANNELS][CELT_MAX_BANDS];
+    float coeffs[OPUS_MAX_CHANNELS][OPUS_BLOCK_SIZE(CELT_BLOCK_960)];
+} OpusPsyStep;
+
+typedef struct OpusBandExcitation {
+    float excitation;
+    float excitation_dist;
+    float excitation_init;
+} OpusBandExcitation;
+
+typedef struct PsyChain {
+    int start;
+    int end;
+} PsyChain;
+
+typedef struct OpusPsyContext {
+    AVCodecContext *avctx;
+    AVFloatDSPContext *dsp;
+    struct FFBufQueue *bufqueue;
+    OpusEncOptions *options;
+
+    PsyChain cs[128];
+    int cs_num;
+
+    OpusBandExcitation ex[OPUS_MAX_CHANNELS][CELT_MAX_BANDS];
+    FFBesselFilter bfilter_lo[OPUS_MAX_CHANNELS][CELT_MAX_BANDS];
+    FFBesselFilter bfilter_hi[OPUS_MAX_CHANNELS][CELT_MAX_BANDS];
+
+    OpusPsyStep *steps[FF_BUFQUEUE_SIZE + 1];
+    int max_steps;
+
+    float *window[CELT_BLOCK_NB];
+    MDCT15Context *mdct[CELT_BLOCK_NB];
+    int bsize_analysis;
+
+    DECLARE_ALIGNED(32, float, scratch)[2048];
+
+    /* Stats */
+    float rc_waste;
+    float avg_is_band;
+    int64_t dual_stereo_used;
+    int64_t total_packets_out;
+
+    /* State */
+    FFBesselFilter lambda_lp;
+    OpusPacketInfo p;
+    int redo_analysis;
+    int buffered_steps;
+    int steps_to_process;
+    int eof;
+    float lambda;
+    int *inflection_points;
+    int inflection_points_count;
+} OpusPsyContext;
+
+int  ff_opus_psy_process           (OpusPsyContext *s, OpusPacketInfo *p);
+void ff_opus_psy_celt_frame_init   (OpusPsyContext *s, CeltFrame *f, int index);
+int  ff_opus_psy_celt_frame_process(OpusPsyContext *s, CeltFrame *f, int index);
+void ff_opus_psy_postencode_update (OpusPsyContext *s, CeltFrame *f, OpusRangeCoder *rc);
+
+int  ff_opus_psy_init(OpusPsyContext *s, AVCodecContext *avctx,
+                      struct FFBufQueue *bufqueue, OpusEncOptions *options);
+void ff_opus_psy_signal_eof(OpusPsyContext *s);
+int  ff_opus_psy_end(OpusPsyContext *s);
+
+#endif /* AVCODEC_OPUSENC_PSY_H */

libavcodec/opusenc_utils.h

+/*
+ * Opus encoder
+ * Copyright (c) 2017 Rostislav Pehlivanov <atomnuker@gmail.com>
+ *
+ * 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
+ */
+
+#include "opus.h"
+
+typedef struct FFBesselFilter {
+    float a[3];
+    float b[2];
+    float x[3];
+    float y[3];
+} FFBesselFilter;
+
+/* Fills the coefficients, returns 1 if filter will be unstable */
+static inline int bessel_reinit(FFBesselFilter *s, float n, float f0, float fs,
+                                int highpass)
+{
+    int unstable;
+    float c, cfreq, w0, k1, k2;
+
+    if (!highpass) {
+        c = (1.0f/sqrtf(sqrtf(pow(2.0f, 1.0f/n) - 3.0f/4.0f) - 0.5f))/sqrtf(3.0f);
+        cfreq = c*f0/fs;
+        unstable = (cfreq <= 0.0f || cfreq >= 1.0f/4.0f);
+    } else {
+        c = sqrtf(3.0f)*sqrtf(sqrtf(pow(2.0f, 1.0f/n) - 3.0f/4.0f) - 0.5f);
+        cfreq = 0.5f - c*f0/fs;
+        unstable = (cfreq <= 3.0f/8.0f || cfreq >= 1.0f/2.0f);
+    }
+
+    w0 = tanf(M_PI*cfreq);
+    k1 = 3.0f * w0;
+    k2 = 3.0f * w0;
+
+    s->a[0] = k2/(1.0f + k1 + k2);
+    s->a[1] = 2.0f * s->a[0];
+    s->a[2] = s->a[0];
+    s->b[0] = 2.0f * s->a[0] * (1.0f/k2 - 1.0f);
+    s->b[1] = 1.0f - (s->a[0] + s->a[1] + s->a[2] + s->b[0]);
+
+    if (highpass) {
+        s->a[1] *= -1;
+        s->b[0] *= -1;
+    }
+
+    return unstable;
+}
+
+static inline int bessel_init(FFBesselFilter *s, float n, float f0, float fs,
+                              int highpass)
+{
+    memset(s, 0, sizeof(FFBesselFilter));
+    return bessel_reinit(s, n, f0, fs, highpass);
+}
+
+static inline float bessel_filter(FFBesselFilter *s, float x)
+{
+    s->x[2] = s->x[1];
+    s->x[1] = s->x[0];
+    s->x[0] = x;
+    s->y[2] = s->y[1];
+    s->y[1] = s->y[0];
+    s->y[0] = s->a[0]*s->x[0] + s->a[1]*s->x[1] + s->a[2]*s->x[2] + s->b[0]*s->y[1] + s->b[1]*s->y[2];
+    return s->y[0];
+}