/*

 * audio resampling

 * Copyright (c) 2004-2012 Michael Niedermayer <michaelni@gmx.at>

 * bessel function: Copyright (c) 2006 Xiaogang Zhang

 *

 * 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

 * audio resampling

 * @author Michael Niedermayer <michaelni@gmx.at>

 */

#include "libavutil/avassert.h"

#include "libavutil/mem.h"

#include "resample.h"

/**

 * builds a polyphase filterbank.

 * @param factor resampling factor

 * @param scale wanted sum of coefficients for each filter

 * @param filter_type  filter type

 * @param kaiser_beta  kaiser window beta

 * @return 0 on success, negative on error

 */

static int build_filter(ResampleContext *c, void *filter, double factor, int tap_count, int alloc, int phase_count, int scale,

                        int filter_type, double kaiser_beta){

    int ph, i;

    int ph_nb = phase_count % 2 ? phase_count : phase_count / 2 + 1;

    double x, y, w, t, s;

    double *tab = av_malloc_array(tap_count+1,  sizeof(*tab));

    double *sin_lut = av_malloc_array(ph_nb, sizeof(*sin_lut));

    const int center= (tap_count-1)/2;

    double norm = 0;

    int ret = AVERROR(ENOMEM);

    if (!tab || !sin_lut)

        goto fail;

    av_assert0(tap_count == 1 || tap_count % 2 == 0);

    /* if upsampling, only need to interpolate, no filter */

    if (factor > 1.0)

        factor = 1.0;

    if (factor == 1.0) {

        for (ph = 0; ph < ph_nb; ph++)

            sin_lut[ph] = sin(M_PI * ph / phase_count) * (center & 1 ? 1 : -1);

    }

    for(ph = 0; ph < ph_nb; ph++) {

        s = sin_lut[ph];

        for(i=0;i<tap_count;i++) {

            x = M_PI * ((double)(i - center) - (double)ph / phase_count) * factor;

            if (x == 0) y = 1.0;

            else if (factor == 1.0)

                y = s / x;

            else

                y = sin(x) / x;

            switch(filter_type){

            case SWR_FILTER_TYPE_CUBIC:{

                const float d= -0.5; //first order derivative = -0.5

                x = fabs(((double)(i - center) - (double)ph / phase_count) * factor);

                if(x<1.0) y= 1 - 3*x*x + 2*x*x*x + d*(            -x*x + x*x*x);

                else      y=                       d*(-4 + 8*x - 5*x*x + x*x*x);

                break;}

            case SWR_FILTER_TYPE_BLACKMAN_NUTTALL:

                w = 2.0*x / (factor*tap_count);

                t = -cos(w);

                y *= 0.3635819 - 0.4891775 * t + 0.1365995 * (2*t*t-1) - 0.0106411 * (4*t*t*t - 3*t);

                break;

            case SWR_FILTER_TYPE_KAISER:

                w = 2.0*x / (factor*tap_count*M_PI);

                y *= av_bessel_i0(kaiser_beta*sqrt(FFMAX(1-w*w, 0)));

                break;

            default:

                av_assert0(0);

            }

            tab[i] = y;

            s = -s;

            if (!ph)

                norm += y;

        }

        /* normalize so that an uniform color remains the same */

        switch(c->format){

        case AV_SAMPLE_FMT_S16P:

            for(i=0;i<tap_count;i++)

                ((int16_t*)filter)[ph * alloc + i] = av_clip_int16(lrintf(tab[i] * scale / norm));

            if (phase_count % 2) break;

            for (i = 0; i < tap_count; i++)

                ((int16_t*)filter)[(phase_count-ph) * alloc + tap_count-1-i] = ((int16_t*)filter)[ph * alloc + i];

            break;

        case AV_SAMPLE_FMT_S32P:

            for(i=0;i<tap_count;i++)

                ((int32_t*)filter)[ph * alloc + i] = av_clipl_int32(llrint(tab[i] * scale / norm));

            if (phase_count % 2) break;

            for (i = 0; i < tap_count; i++)

                ((int32_t*)filter)[(phase_count-ph) * alloc + tap_count-1-i] = ((int32_t*)filter)[ph * alloc + i];

            break;

        case AV_SAMPLE_FMT_FLTP:

            for(i=0;i<tap_count;i++)

                ((float*)filter)[ph * alloc + i] = tab[i] * scale / norm;

            if (phase_count % 2) break;

            for (i = 0; i < tap_count; i++)

                ((float*)filter)[(phase_count-ph) * alloc + tap_count-1-i] = ((float*)filter)[ph * alloc + i];

            break;

        case AV_SAMPLE_FMT_DBLP:

            for(i=0;i<tap_count;i++)

                ((double*)filter)[ph * alloc + i] = tab[i] * scale / norm;

            if (phase_count % 2) break;

            for (i = 0; i < tap_count; i++)

                ((double*)filter)[(phase_count-ph) * alloc + tap_count-1-i] = ((double*)filter)[ph * alloc + i];

            break;

        }

    }

#if 0

    {

#define LEN 1024

        int j,k;

        double sine[LEN + tap_count];

        double filtered[LEN];

        double maxff=-2, minff=2, maxsf=-2, minsf=2;

        for(i=0; i<LEN; i++){

            double ss=0, sf=0, ff=0;

            for(j=0; j<LEN+tap_count; j++)

                sine[j]= cos(i*j*M_PI/LEN);

            for(j=0; j<LEN; j++){

                double sum=0;

                ph=0;

                for(k=0; k<tap_count; k++)

                    sum += filter[ph * tap_count + k] * sine[k+j];

                filtered[j]= sum / (1<<FILTER_SHIFT);

                ss+= sine[j + center] * sine[j + center];

                ff+= filtered[j] * filtered[j];

                sf+= sine[j + center] * filtered[j];

            }

            ss= sqrt(2*ss/LEN);

            ff= sqrt(2*ff/LEN);

            sf= 2*sf/LEN;

            maxff= FFMAX(maxff, ff);

            minff= FFMIN(minff, ff);

            maxsf= FFMAX(maxsf, sf);

            minsf= FFMIN(minsf, sf);

            if(i%11==0){

                av_log(NULL, AV_LOG_ERROR, "i:%4d ss:%f ff:%13.6e-%13.6e sf:%13.6e-%13.6e\n", i, ss, maxff, minff, maxsf, minsf);

                minff=minsf= 2;

                maxff=maxsf= -2;

            }

        }

    }

#endif

    ret = 0;

fail:

    av_free(tab);

    av_free(sin_lut);

    return ret;

}

static void resample_free(ResampleContext **cc){

    ResampleContext *c = *cc;

    if(!c)

        return;

    av_freep(&c->filter_bank);

    av_freep(cc);

}

static ResampleContext *resample_init(ResampleContext *c, int out_rate, int in_rate, int filter_size, int phase_shift, int linear,

                                    double cutoff0, enum AVSampleFormat format, enum SwrFilterType filter_type, double kaiser_beta,

                                    double precision, int cheby, int exact_rational)

{

    double cutoff = cutoff0? cutoff0 : 0.97;

    double factor= FFMIN(out_rate * cutoff / in_rate, 1.0);

    int phase_count= 1<<phase_shift;

    int phase_count_compensation = phase_count;

    int filter_length = FFMAX((int)ceil(filter_size/factor), 1);

    if (filter_length > 1)

        filter_length = FFALIGN(filter_length, 2);

    if (exact_rational) {

        int phase_count_exact, phase_count_exact_den;

        av_reduce(&phase_count_exact, &phase_count_exact_den, out_rate, in_rate, INT_MAX);

        if (phase_count_exact <= phase_count) {

            phase_count_compensation = phase_count_exact * (phase_count / phase_count_exact);

            phase_count = phase_count_exact;

        }

    }

    if (!c || c->phase_count != phase_count || c->linear!=linear || c->factor != factor

           || c->filter_length != filter_length || c->format != format

           || c->filter_type != filter_type || c->kaiser_beta != kaiser_beta) {

        resample_free(&c);

        c = av_mallocz(sizeof(*c));

        if (!c)

            return NULL;

        c->format= format;

        c->felem_size= av_get_bytes_per_sample(c->format);

        switch(c->format){

        case AV_SAMPLE_FMT_S16P:

            c->filter_shift = 15;

            break;

        case AV_SAMPLE_FMT_S32P:

            c->filter_shift = 30;

            break;

        case AV_SAMPLE_FMT_FLTP:

        case AV_SAMPLE_FMT_DBLP:

            c->filter_shift = 0;

            break;

        default:

            av_log(NULL, AV_LOG_ERROR, "Unsupported sample format\n");

            av_assert0(0);

        }

        if (filter_size/factor > INT32_MAX/256) {

            av_log(NULL, AV_LOG_ERROR, "Filter length too large\n");

            goto error;

        }

        c->phase_count   = phase_count;

        c->linear        = linear;

        c->factor        = factor;

        c->filter_length = filter_length;

        c->filter_alloc  = FFALIGN(c->filter_length, 8);

        c->filter_bank   = av_calloc(c->filter_alloc, (phase_count+1)*c->felem_size);

        c->filter_type   = filter_type;

        c->kaiser_beta   = kaiser_beta;

        c->phase_count_compensation = phase_count_compensation;

        if (!c->filter_bank)

            goto error;

        if (build_filter(c, (void*)c->filter_bank, factor, c->filter_length, c->filter_alloc, phase_count, 1<<c->filter_shift, filter_type, kaiser_beta))

            goto error;

        memcpy(c->filter_bank + (c->filter_alloc*phase_count+1)*c->felem_size, c->filter_bank, (c->filter_alloc-1)*c->felem_size);

        memcpy(c->filter_bank + (c->filter_alloc*phase_count  )*c->felem_size, c->filter_bank + (c->filter_alloc - 1)*c->felem_size, c->felem_size);

    }

    c->compensation_distance= 0;

    if(!av_reduce(&c->src_incr, &c->dst_incr, out_rate, in_rate * (int64_t)phase_count, INT32_MAX/2))

        goto error;

    while (c->dst_incr < (1<<20) && c->src_incr < (1<<20)) {

        c->dst_incr *= 2;

        c->src_incr *= 2;

    }

    c->ideal_dst_incr = c->dst_incr;

    c->dst_incr_div   = c->dst_incr / c->src_incr;

    c->dst_incr_mod   = c->dst_incr % c->src_incr;

    c->index= -phase_count*((c->filter_length-1)/2);

    c->frac= 0;

    swri_resample_dsp_init(c);

    return c;

error:

    av_freep(&c->filter_bank);

    av_free(c);

    return NULL;

}

static int rebuild_filter_bank_with_compensation(ResampleContext *c)

{

    uint8_t *new_filter_bank;

    int new_src_incr, new_dst_incr;

    int phase_count = c->phase_count_compensation;

    int ret;

    if (phase_count == c->phase_count)

        return 0;

    av_assert0(!c->frac && !c->dst_incr_mod);

    new_filter_bank = av_calloc(c->filter_alloc, (phase_count + 1) * c->felem_size);

    if (!new_filter_bank)

        return AVERROR(ENOMEM);

    ret = build_filter(c, new_filter_bank, c->factor, c->filter_length, c->filter_alloc,

                       phase_count, 1 << c->filter_shift, c->filter_type, c->kaiser_beta);

    if (ret < 0) {

        av_freep(&new_filter_bank);

        return ret;

    }

    memcpy(new_filter_bank + (c->filter_alloc*phase_count+1)*c->felem_size, new_filter_bank, (c->filter_alloc-1)*c->felem_size);

    memcpy(new_filter_bank + (c->filter_alloc*phase_count  )*c->felem_size, new_filter_bank + (c->filter_alloc - 1)*c->felem_size, c->felem_size);

    if (!av_reduce(&new_src_incr, &new_dst_incr, c->src_incr,

                   c->dst_incr * (int64_t)(phase_count/c->phase_count), INT32_MAX/2))

    {

        av_freep(&new_filter_bank);

        return AVERROR(EINVAL);

    }

    c->src_incr = new_src_incr;

    c->dst_incr = new_dst_incr;

    while (c->dst_incr < (1<<20) && c->src_incr < (1<<20)) {

        c->dst_incr *= 2;

        c->src_incr *= 2;

    }

    c->ideal_dst_incr = c->dst_incr;

    c->dst_incr_div   = c->dst_incr / c->src_incr;

    c->dst_incr_mod   = c->dst_incr % c->src_incr;

    c->index         *= phase_count / c->phase_count;

    c->phase_count    = phase_count;

    av_freep(&c->filter_bank);

    c->filter_bank = new_filter_bank;

    return 0;

}

static int set_compensation(ResampleContext *c, int sample_delta, int compensation_distance){

    int ret;

    if (compensation_distance && sample_delta) {

        ret = rebuild_filter_bank_with_compensation(c);

        if (ret < 0)

            return ret;

    }

    c->compensation_distance= compensation_distance;

    if (compensation_distance)

        c->dst_incr = c->ideal_dst_incr - c->ideal_dst_incr * (int64_t)sample_delta / compensation_distance;

    else

        c->dst_incr = c->ideal_dst_incr;

    c->dst_incr_div   = c->dst_incr / c->src_incr;

    c->dst_incr_mod   = c->dst_incr % c->src_incr;

    return 0;

}

static int multiple_resample(ResampleContext *c, AudioData *dst, int dst_size, AudioData *src, int src_size, int *consumed){

    int i;

    int64_t max_src_size = (INT64_MAX/2 / c->phase_count) / c->src_incr;

    if (c->compensation_distance)

        dst_size = FFMIN(dst_size, c->compensation_distance);

    src_size = FFMIN(src_size, max_src_size);

    *consumed = 0;

    if (c->filter_length == 1 && c->phase_count == 1) {

        int64_t index2= (1LL<<32)*c->frac/c->src_incr + (1LL<<32)*c->index + 1;

        int64_t incr= (1LL<<32) * c->dst_incr / c->src_incr + 1;

        int new_size = (src_size * (int64_t)c->src_incr - c->frac + c->dst_incr - 1) / c->dst_incr;

        dst_size = FFMAX(FFMIN(dst_size, new_size), 0);

        if (dst_size > 0) {

            for (i = 0; i < dst->ch_count; i++) {

                c->dsp.resample_one(dst->ch[i], src->ch[i], dst_size, index2, incr);

                if (i+1 == dst->ch_count) {

                    c->index += dst_size * c->dst_incr_div;

                    c->index += (c->frac + dst_size * (int64_t)c->dst_incr_mod) / c->src_incr;

                    av_assert2(c->index >= 0);

                    *consumed = c->index;

                    c->frac   = (c->frac + dst_size * (int64_t)c->dst_incr_mod) % c->src_incr;

                    c->index = 0;

                }

            }

        }

    } else {

        int64_t end_index = (1LL + src_size - c->filter_length) * c->phase_count;

        int64_t delta_frac = (end_index - c->index) * c->src_incr - c->frac;

        int delta_n = (delta_frac + c->dst_incr - 1) / c->dst_incr;

        int (*resample_func)(struct ResampleContext *c, void *dst,

                             const void *src, int n, int update_ctx);

        dst_size = FFMAX(FFMIN(dst_size, delta_n), 0);

        if (dst_size > 0) {

            /* resample_linear and resample_common should have same behavior

             * when frac and dst_incr_mod are zero */

            resample_func = (c->linear && (c->frac || c->dst_incr_mod)) ?

                            c->dsp.resample_linear : c->dsp.resample_common;

            for (i = 0; i < dst->ch_count; i++)

                *consumed = resample_func(c, dst->ch[i], src->ch[i], dst_size, i+1 == dst->ch_count);

        }

    }

    if (c->compensation_distance) {

        c->compensation_distance -= dst_size;

        if (!c->compensation_distance) {

            c->dst_incr     = c->ideal_dst_incr;

            c->dst_incr_div = c->dst_incr / c->src_incr;

            c->dst_incr_mod = c->dst_incr % c->src_incr;

        }

    }

    return dst_size;

}

static int64_t get_delay(struct SwrContext *s, int64_t base){

    ResampleContext *c = s->resample;

    int64_t num = s->in_buffer_count - (c->filter_length-1)/2;

    num *= c->phase_count;

    num -= c->index;

    num *= c->src_incr;

    num -= c->frac;

    return av_rescale(num, base, s->in_sample_rate*(int64_t)c->src_incr * c->phase_count);

}

static int64_t get_out_samples(struct SwrContext *s, int in_samples) {

    ResampleContext *c = s->resample;

    // The + 2 are added to allow implementations to be slightly inaccurate, they should not be needed currently.

    // They also make it easier to proof that changes and optimizations do not

    // break the upper bound.

    int64_t num = s->in_buffer_count + 2LL + in_samples;

    num *= c->phase_count;

    num -= c->index;

    num = av_rescale_rnd(num, s->out_sample_rate, ((int64_t)s->in_sample_rate) * c->phase_count, AV_ROUND_UP) + 2;

    if (c->compensation_distance) {

        if (num > INT_MAX)

            return AVERROR(EINVAL);

        num = FFMAX(num, (num * c->ideal_dst_incr - 1) / c->dst_incr + 1);

    }

    return num;

}

static int resample_flush(struct SwrContext *s) {

    ResampleContext *c = s->resample;

    AudioData *a= &s->in_buffer;

    int i, j, ret;

    int reflection = (FFMIN(s->in_buffer_count, c->filter_length) + 1) / 2;

    if((ret = swri_realloc_audio(a, s->in_buffer_index + s->in_buffer_count + reflection)) < 0)

        return ret;

    av_assert0(a->planar);

    for(i=0; i<a->ch_count; i++){

        for(j=0; j<reflection; j++){

            memcpy(a->ch[i] + (s->in_buffer_index+s->in_buffer_count+j  )*a->bps,

                a->ch[i] + (s->in_buffer_index+s->in_buffer_count-j-1)*a->bps, a->bps);

        }

    }

    s->in_buffer_count += reflection;

    return 0;

}

// in fact the whole handle multiple ridiculously small buffers might need more thinking...

static int invert_initial_buffer(ResampleContext *c, AudioData *dst, const AudioData *src,

                                 int in_count, int *out_idx, int *out_sz)

{

    int n, ch, num = FFMIN(in_count + *out_sz, c->filter_length + 1), res;

    if (c->index >= 0)

        return 0;

    if ((res = swri_realloc_audio(dst, c->filter_length * 2 + 1)) < 0)

        return res;

    // copy

    for (n = *out_sz; n < num; n++) {

        for (ch = 0; ch < src->ch_count; ch++) {

            memcpy(dst->ch[ch] + ((c->filter_length + n) * c->felem_size),

                   src->ch[ch] + ((n - *out_sz) * c->felem_size), c->felem_size);

        }

    }

    // if not enough data is in, return and wait for more

    if (num < c->filter_length + 1) {

        *out_sz = num;

        *out_idx = c->filter_length;

        return INT_MAX;

    }

    // else invert

    for (n = 1; n <= c->filter_length; n++) {

        for (ch = 0; ch < src->ch_count; ch++) {

            memcpy(dst->ch[ch] + ((c->filter_length - n) * c->felem_size),

                   dst->ch[ch] + ((c->filter_length + n) * c->felem_size),

                   c->felem_size);

        }

    }

    res = num - *out_sz;

    *out_idx = c->filter_length;

    while (c->index < 0) {

        --*out_idx;

        c->index += c->phase_count;

    }

    *out_sz = FFMAX(*out_sz + c->filter_length,

                    1 + c->filter_length * 2) - *out_idx;

    return FFMAX(res, 0);

}

const struct Resampler swri_resampler = {

    .init                  = resample_init,

    .free                  = resample_free,

    .multiple_resample     = multiple_resample,

    .flush                 = resample_flush,

    .set_compensation      = set_compensation,

    .get_delay             = get_delay,

    .invert_initial_buffer = invert_initial_buffer,

    .get_out_samples       = get_out_samples,

};