/* * Copyright (c) 2008-2009 Rob Sykes <robs@users.sourceforge.net> * Copyright (c) 2017 Paul B Mahol * * 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 "libavutil/avassert.h" #include "libavutil/channel_layout.h" #include "libavutil/opt.h" #include "libavcodec/avfft.h" #include "audio.h" #include "avfilter.h" #include "filters.h" #include "internal.h" typedef struct SincContext { const AVClass *class; int sample_rate, nb_samples; float att, beta, phase, Fc0, Fc1, tbw0, tbw1; int num_taps[2]; int round; int n, rdft_len; float *coeffs; int64_t pts; RDFTContext *rdft, *irdft; } SincContext; static int activate(AVFilterContext *ctx) { AVFilterLink *outlink = ctx->outputs[0]; SincContext *s = ctx->priv; const float *coeffs = s->coeffs; AVFrame *frame = NULL; int nb_samples; if (!ff_outlink_frame_wanted(outlink)) return FFERROR_NOT_READY; nb_samples = FFMIN(s->nb_samples, s->n - s->pts); if (nb_samples <= 0) { ff_outlink_set_status(outlink, AVERROR_EOF, s->pts); return 0; } if (!(frame = ff_get_audio_buffer(outlink, nb_samples))) return AVERROR(ENOMEM); memcpy(frame->data[0], coeffs + s->pts, nb_samples * sizeof(float)); frame->pts = s->pts; s->pts += nb_samples; return ff_filter_frame(outlink, frame); } static int query_formats(AVFilterContext *ctx) { SincContext *s = ctx->priv; static const int64_t chlayouts[] = { AV_CH_LAYOUT_MONO, -1 }; int sample_rates[] = { s->sample_rate, -1 }; static const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_FLT, AV_SAMPLE_FMT_NONE }; int ret = ff_set_common_formats_from_list(ctx, sample_fmts); if (ret < 0) return ret; ret = ff_set_common_channel_layouts_from_list(ctx, chlayouts); if (ret < 0) return ret; return ff_set_common_samplerates_from_list(ctx, sample_rates); } static float bessel_I_0(float x) { float term = 1, sum = 1, last_sum, x2 = x / 2; int i = 1; do { float y = x2 / i++; last_sum = sum; sum += term *= y * y; } while (sum != last_sum); return sum; } static float *make_lpf(int num_taps, float Fc, float beta, float rho, float scale, int dc_norm) { int i, m = num_taps - 1; float *h = av_calloc(num_taps, sizeof(*h)), sum = 0; float mult = scale / bessel_I_0(beta), mult1 = 1.f / (.5f * m + rho); av_assert0(Fc >= 0 && Fc <= 1); for (i = 0; i <= m / 2; i++) { float z = i - .5f * m, x = z * M_PI, y = z * mult1; h[i] = x ? sinf(Fc * x) / x : Fc; sum += h[i] *= bessel_I_0(beta * sqrtf(1.f - y * y)) * mult; if (m - i != i) { h[m - i] = h[i]; sum += h[i]; } } for (i = 0; dc_norm && i < num_taps; i++) h[i] *= scale / sum; return h; } static float kaiser_beta(float att, float tr_bw) { if (att >= 60.f) { static const float coefs[][4] = { {-6.784957e-10, 1.02856e-05, 0.1087556, -0.8988365 + .001}, {-6.897885e-10, 1.027433e-05, 0.10876, -0.8994658 + .002}, {-1.000683e-09, 1.030092e-05, 0.1087677, -0.9007898 + .003}, {-3.654474e-10, 1.040631e-05, 0.1087085, -0.8977766 + .006}, {8.106988e-09, 6.983091e-06, 0.1091387, -0.9172048 + .015}, {9.519571e-09, 7.272678e-06, 0.1090068, -0.9140768 + .025}, {-5.626821e-09, 1.342186e-05, 0.1083999, -0.9065452 + .05}, {-9.965946e-08, 5.073548e-05, 0.1040967, -0.7672778 + .085}, {1.604808e-07, -5.856462e-05, 0.1185998, -1.34824 + .1}, {-1.511964e-07, 6.363034e-05, 0.1064627, -0.9876665 + .18}, }; float realm = logf(tr_bw / .0005f) / logf(2.f); float const *c0 = coefs[av_clip((int)realm, 0, FF_ARRAY_ELEMS(coefs) - 1)]; float const *c1 = coefs[av_clip(1 + (int)realm, 0, FF_ARRAY_ELEMS(coefs) - 1)]; float b0 = ((c0[0] * att + c0[1]) * att + c0[2]) * att + c0[3]; float b1 = ((c1[0] * att + c1[1]) * att + c1[2]) * att + c1[3]; return b0 + (b1 - b0) * (realm - (int)realm); } if (att > 50.f) return .1102f * (att - 8.7f); if (att > 20.96f) return .58417f * powf(att - 20.96f, .4f) + .07886f * (att - 20.96f); return 0; } static void kaiser_params(float att, float Fc, float tr_bw, float *beta, int *num_taps) { *beta = *beta < 0.f ? kaiser_beta(att, tr_bw * .5f / Fc): *beta; att = att < 60.f ? (att - 7.95f) / (2.285f * M_PI * 2.f) : ((.0007528358f-1.577737e-05 * *beta) * *beta + 0.6248022f) * *beta + .06186902f; *num_taps = !*num_taps ? ceilf(att/tr_bw + 1) : *num_taps; } static float *lpf(float Fn, float Fc, float tbw, int *num_taps, float att, float *beta, int round) { int n = *num_taps; if ((Fc /= Fn) <= 0.f || Fc >= 1.f) { *num_taps = 0; return NULL; } att = att ? att : 120.f; kaiser_params(att, Fc, (tbw ? tbw / Fn : .05f) * .5f, beta, num_taps); if (!n) { n = *num_taps; *num_taps = av_clip(n, 11, 32767); if (round) *num_taps = 1 + 2 * (int)((int)((*num_taps / 2) * Fc + .5f) / Fc + .5f); } return make_lpf(*num_taps |= 1, Fc, *beta, 0.f, 1.f, 0); } static void invert(float *h, int n) { for (int i = 0; i < n; i++) h[i] = -h[i]; h[(n - 1) / 2] += 1; } #define PACK(h, n) h[1] = h[n] #define UNPACK(h, n) h[n] = h[1], h[n + 1] = h[1] = 0; #define SQR(a) ((a) * (a)) static float safe_log(float x) { av_assert0(x >= 0); if (x) return logf(x); return -26; } static int fir_to_phase(SincContext *s, float **h, int *len, int *post_len, float phase) { float *pi_wraps, *work, phase1 = (phase > 50.f ? 100.f - phase : phase) / 50.f; int i, work_len, begin, end, imp_peak = 0, peak = 0; float imp_sum = 0, peak_imp_sum = 0; float prev_angle2 = 0, cum_2pi = 0, prev_angle1 = 0, cum_1pi = 0; for (i = *len, work_len = 2 * 2 * 8; i > 1; work_len <<= 1, i >>= 1); /* The first part is for work (+2 for (UN)PACK), the latter for pi_wraps. */ work = av_calloc((work_len + 2) + (work_len / 2 + 1), sizeof(float)); if (!work) return AVERROR(ENOMEM); pi_wraps = &work[work_len + 2]; memcpy(work, *h, *len * sizeof(*work)); av_rdft_end(s->rdft); av_rdft_end(s->irdft); s->rdft = s->irdft = NULL; s->rdft = av_rdft_init(av_log2(work_len), DFT_R2C); s->irdft = av_rdft_init(av_log2(work_len), IDFT_C2R); if (!s->rdft || !s->irdft) { av_free(work); return AVERROR(ENOMEM); } av_rdft_calc(s->rdft, work); /* Cepstral: */ UNPACK(work, work_len); for (i = 0; i <= work_len; i += 2) { float angle = atan2f(work[i + 1], work[i]); float detect = 2 * M_PI; float delta = angle - prev_angle2; float adjust = detect * ((delta < -detect * .7f) - (delta > detect * .7f)); prev_angle2 = angle; cum_2pi += adjust; angle += cum_2pi; detect = M_PI; delta = angle - prev_angle1; adjust = detect * ((delta < -detect * .7f) - (delta > detect * .7f)); prev_angle1 = angle; cum_1pi += fabsf(adjust); /* fabs for when 2pi and 1pi have combined */ pi_wraps[i >> 1] = cum_1pi; work[i] = safe_log(sqrtf(SQR(work[i]) + SQR(work[i + 1]))); work[i + 1] = 0; } PACK(work, work_len); av_rdft_calc(s->irdft, work); for (i = 0; i < work_len; i++) work[i] *= 2.f / work_len; for (i = 1; i < work_len / 2; i++) { /* Window to reject acausal components */ work[i] *= 2; work[i + work_len / 2] = 0; } av_rdft_calc(s->rdft, work); for (i = 2; i < work_len; i += 2) /* Interpolate between linear & min phase */ work[i + 1] = phase1 * i / work_len * pi_wraps[work_len >> 1] + (1 - phase1) * (work[i + 1] + pi_wraps[i >> 1]) - pi_wraps[i >> 1]; work[0] = exp(work[0]); work[1] = exp(work[1]); for (i = 2; i < work_len; i += 2) { float x = expf(work[i]); work[i ] = x * cosf(work[i + 1]); work[i + 1] = x * sinf(work[i + 1]); } av_rdft_calc(s->irdft, work); for (i = 0; i < work_len; i++) work[i] *= 2.f / work_len; /* Find peak pos. */ for (i = 0; i <= (int) (pi_wraps[work_len >> 1] / M_PI + .5f); i++) { imp_sum += work[i]; if (fabs(imp_sum) > fabs(peak_imp_sum)) { peak_imp_sum = imp_sum; peak = i; } if (work[i] > work[imp_peak]) /* For debug check only */ imp_peak = i; } while (peak && fabsf(work[peak - 1]) > fabsf(work[peak]) && (work[peak - 1] * work[peak] > 0)) { peak--; } if (!phase1) { begin = 0; } else if (phase1 == 1) { begin = peak - *len / 2; } else { begin = (.997f - (2 - phase1) * .22f) * *len + .5f; end = (.997f + (0 - phase1) * .22f) * *len + .5f; begin = peak - (begin & ~3); end = peak + 1 + ((end + 3) & ~3); *len = end - begin; *h = av_realloc_f(*h, *len, sizeof(**h)); if (!*h) { av_free(work); return AVERROR(ENOMEM); } } for (i = 0; i < *len; i++) { (*h)[i] = work[(begin + (phase > 50.f ? *len - 1 - i : i) + work_len) & (work_len - 1)]; } *post_len = phase > 50 ? peak - begin : begin + *len - (peak + 1); av_log(s, AV_LOG_DEBUG, "%d nPI=%g peak-sum@%i=%g (val@%i=%g); len=%i post=%i (%g%%)\n", work_len, pi_wraps[work_len >> 1] / M_PI, peak, peak_imp_sum, imp_peak, work[imp_peak], *len, *post_len, 100.f - 100.f * *post_len / (*len - 1)); av_free(work); return 0; } static int config_output(AVFilterLink *outlink) { AVFilterContext *ctx = outlink->src; SincContext *s = ctx->priv; float Fn = s->sample_rate * .5f; float *h[2]; int i, n, post_peak, longer; outlink->sample_rate = s->sample_rate; s->pts = 0; if (s->Fc0 >= Fn || s->Fc1 >= Fn) { av_log(ctx, AV_LOG_ERROR, "filter frequency must be less than %d/2.\n", s->sample_rate); return AVERROR(EINVAL); } h[0] = lpf(Fn, s->Fc0, s->tbw0, &s->num_taps[0], s->att, &s->beta, s->round); h[1] = lpf(Fn, s->Fc1, s->tbw1, &s->num_taps[1], s->att, &s->beta, s->round); if (h[0]) invert(h[0], s->num_taps[0]); longer = s->num_taps[1] > s->num_taps[0]; n = s->num_taps[longer]; if (h[0] && h[1]) { for (i = 0; i < s->num_taps[!longer]; i++) h[longer][i + (n - s->num_taps[!longer]) / 2] += h[!longer][i]; if (s->Fc0 < s->Fc1) invert(h[longer], n); av_free(h[!longer]); } if (s->phase != 50.f) { int ret = fir_to_phase(s, &h[longer], &n, &post_peak, s->phase); if (ret < 0) return ret; } else { post_peak = n >> 1; } s->n = 1 << (av_log2(n) + 1); s->rdft_len = 1 << av_log2(n); s->coeffs = av_calloc(s->n, sizeof(*s->coeffs)); if (!s->coeffs) return AVERROR(ENOMEM); for (i = 0; i < n; i++) s->coeffs[i] = h[longer][i]; av_free(h[longer]); av_rdft_end(s->rdft); av_rdft_end(s->irdft); s->rdft = s->irdft = NULL; return 0; } static av_cold void uninit(AVFilterContext *ctx) { SincContext *s = ctx->priv; av_freep(&s->coeffs); av_rdft_end(s->rdft); av_rdft_end(s->irdft); s->rdft = s->irdft = NULL; } static const AVFilterPad sinc_outputs[] = { { .name = "default", .type = AVMEDIA_TYPE_AUDIO, .config_props = config_output, }, }; #define AF AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM #define OFFSET(x) offsetof(SincContext, x) static const AVOption sinc_options[] = { { "sample_rate", "set sample rate", OFFSET(sample_rate), AV_OPT_TYPE_INT, {.i64=44100}, 1, INT_MAX, AF }, { "r", "set sample rate", OFFSET(sample_rate), AV_OPT_TYPE_INT, {.i64=44100}, 1, INT_MAX, AF }, { "nb_samples", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64=1024}, 1, INT_MAX, AF }, { "n", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64=1024}, 1, INT_MAX, AF }, { "hp", "set high-pass filter frequency", OFFSET(Fc0), AV_OPT_TYPE_FLOAT, {.dbl=0}, 0, INT_MAX, AF }, { "lp", "set low-pass filter frequency", OFFSET(Fc1), AV_OPT_TYPE_FLOAT, {.dbl=0}, 0, INT_MAX, AF }, { "phase", "set filter phase response", OFFSET(phase), AV_OPT_TYPE_FLOAT, {.dbl=50}, 0, 100, AF }, { "beta", "set kaiser window beta", OFFSET(beta), AV_OPT_TYPE_FLOAT, {.dbl=-1}, -1, 256, AF }, { "att", "set stop-band attenuation", OFFSET(att), AV_OPT_TYPE_FLOAT, {.dbl=120}, 40, 180, AF }, { "round", "enable rounding", OFFSET(round), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, AF }, { "hptaps", "set number of taps for high-pass filter", OFFSET(num_taps[0]), AV_OPT_TYPE_INT, {.i64=0}, 0, 32768, AF }, { "lptaps", "set number of taps for low-pass filter", OFFSET(num_taps[1]), AV_OPT_TYPE_INT, {.i64=0}, 0, 32768, AF }, { NULL } }; AVFILTER_DEFINE_CLASS(sinc); const AVFilter ff_asrc_sinc = { .name = "sinc", .description = NULL_IF_CONFIG_SMALL("Generate a sinc kaiser-windowed low-pass, high-pass, band-pass, or band-reject FIR coefficients."), .priv_size = sizeof(SincContext), .priv_class = &sinc_class, .uninit = uninit, .activate = activate, .inputs = NULL, FILTER_OUTPUTS(sinc_outputs), FILTER_QUERY_FUNC(query_formats), };