[FFmpeg-devel] [PATCH][TESTERS WANTED] avfilter: add apitch filter

Paul B Mahol onemda at gmail.com
Sat May 11 21:25:29 EEST 2019


Signed-off-by: Paul B Mahol <onemda at gmail.com>
---

This filter can dynamically change both tempo and pitch of audio.
Also scale range is bigger, from 0.01 to 100.

---
 libavfilter/Makefile     |   1 +
 libavfilter/af_apitch.c  | 764 +++++++++++++++++++++++++++++++++++++++
 libavfilter/allfilters.c |   1 +
 3 files changed, 766 insertions(+)
 create mode 100644 libavfilter/af_apitch.c

diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index b41304d480..3662d50ae0 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -68,6 +68,7 @@ OBJS-$(CONFIG_ANULL_FILTER)                  += af_anull.o
 OBJS-$(CONFIG_APAD_FILTER)                   += af_apad.o
 OBJS-$(CONFIG_APERMS_FILTER)                 += f_perms.o
 OBJS-$(CONFIG_APHASER_FILTER)                += af_aphaser.o generate_wave_table.o
+OBJS-$(CONFIG_APITCH_FILTER)                 += af_apitch.o
 OBJS-$(CONFIG_APULSATOR_FILTER)              += af_apulsator.o
 OBJS-$(CONFIG_AREALTIME_FILTER)              += f_realtime.o
 OBJS-$(CONFIG_ARESAMPLE_FILTER)              += af_aresample.o
diff --git a/libavfilter/af_apitch.c b/libavfilter/af_apitch.c
new file mode 100644
index 0000000000..406951576b
--- /dev/null
+++ b/libavfilter/af_apitch.c
@@ -0,0 +1,764 @@
+/*
+ * Copyright (c) 2019 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 "libswresample/swresample.h"
+#include "libavutil/avassert.h"
+#include "libavutil/avstring.h"
+#include "libavutil/audio_fifo.h"
+#include "libavfilter/internal.h"
+#include "libavutil/common.h"
+#include "libavutil/opt.h"
+#include "libavcodec/avfft.h"
+#include "filters.h"
+#include "audio.h"
+
+typedef struct APitchContext {
+    const AVClass *class;
+
+    float pitch;
+    float tempo;
+    int window_size;
+    int ratio;
+
+    int power_change;
+    int fft_bits;
+    int nb_channels;
+
+    FFTContext *fft, *ifft;
+    AVAudioFifo *ififo;
+    int64_t pts;
+    int eof;
+    float *window_func_lut;
+
+    AVFrame *buffer;
+    AVFrame *magnitude;
+    AVFrame *phase;
+    AVFrame *acc;
+    AVFrame *new_phase;
+    AVFrame *last_phase;
+    AVFrame *osamples;
+    AVFrame *peaks;
+    AVFrame *map;
+
+    int   input_overlap;
+    int   output_overlap;
+    int   samples_to_drain;
+    float last_power;
+
+    int    flushed;
+    int    pitch_changed;
+    struct SwrContext *swr;
+} APitchContext;
+
+#define OFFSET(x) offsetof(APitchContext, x)
+#define AF AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
+
+static const AVOption apitch_options[] = {
+    { "pitch",    "set pitch scale factor", OFFSET(pitch),       AV_OPT_TYPE_FLOAT, {.dbl=1},    .01,   100, AF },
+    { "tempo",    "set tempo scale factor", OFFSET(tempo),       AV_OPT_TYPE_FLOAT, {.dbl=1},    .01,   100, AF },
+    { "oratio",   "set overlap ratio",      OFFSET(ratio),       AV_OPT_TYPE_INT,   {.i64=4},     1,     64, AF },
+    { NULL },
+};
+
+AVFILTER_DEFINE_CLASS(apitch);
+
+static int set_input_overlap(APitchContext *s, float rate)
+{
+    s->input_overlap = s->output_overlap * rate;
+    if (s->input_overlap <= 0)
+        return AVERROR(EINVAL);
+    return 0;
+}
+
+static int config_output(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    AVFilterLink *inlink = ctx->inputs[0];
+    APitchContext *s = ctx->priv;
+    int ret;
+
+    s->swr = swr_alloc();
+    if (!s->swr)
+        return AVERROR(ENOMEM);
+
+    s->swr = swr_alloc_set_opts(s->swr,
+                                inlink->channel_layout, inlink->format, inlink->sample_rate,
+                                inlink->channel_layout, inlink->format, inlink->sample_rate * s->pitch,
+                                0, ctx);
+    if (!s->swr)
+        return AVERROR(ENOMEM);
+
+    ret = swr_init(s->swr);
+    if (ret < 0)
+        return ret;
+
+    s->window_size = inlink->sample_rate / 10;
+    s->power_change = 1;
+    s->pts  = AV_NOPTS_VALUE;
+    s->fft_bits = av_log2(s->window_size);
+    s->fft  = av_fft_init(s->fft_bits, 0);
+    s->ifft = av_fft_init(s->fft_bits, 1);
+    if (!s->fft || !s->ifft)
+        return AVERROR(ENOMEM);
+
+    s->window_size = 1 << s->fft_bits;
+
+    s->ratio = FFMIN(1 << av_log2(s->ratio), s->window_size >> 1);
+    s->nb_channels = outlink->channels;
+
+    s->ififo = av_audio_fifo_alloc(outlink->format, outlink->channels, s->window_size);
+    if (!s->ififo)
+        return AVERROR(ENOMEM);
+
+    s->window_func_lut = av_realloc_f(s->window_func_lut, s->window_size,
+                                      sizeof(*s->window_func_lut));
+    if (!s->window_func_lut)
+        return AVERROR(ENOMEM);
+
+    for (int i = 0; i < s->window_size; i++) {
+        float t = (float)i / (float)(s->window_size - 1);
+        float h = 0.5 * (1.0 - cosf(2.0 * M_PI * t));
+        s->window_func_lut[i] = h;
+    }
+
+    s->output_overlap = s->window_size / s->ratio;
+    if (s->output_overlap <= 0)
+        return AVERROR(EINVAL);
+
+    return set_input_overlap(s, s->tempo / s->pitch);
+}
+
+static float get_power(const float *in, const int size)
+{
+    float sum = 0.f;
+
+    for (int n = 0; n < size; n++)
+        sum += in[n] * in[n];
+
+    return sqrtf(sum / size);
+}
+
+static void normalize(float *new, const float num, const int size)
+{
+    float den = get_power(new, size);
+    float f = den > 0.f ? num / den : 0.f;
+
+    for (int i = 0; i < size; i++)
+        new[i] *= f;
+}
+
+static void complex2polar(const FFTComplex *in,
+                          float *magn, float *phase, const int size)
+{
+    for (int i = 0; i < size; i++) {
+        const float re = in[i + 1].re;
+        const float im = in[i + 1].im;
+
+        magn[i]  = hypotf(re, im);
+        phase[i] = atan2f(im, re);
+    }
+}
+
+static void polar2complex(FFTComplex *out,
+                          const float *magn, const float *phase,
+                          const int size)
+{
+    for (int i = 0; i < size; i++) {
+        const float m = magn[i];
+        const float p = phase[i];
+
+        out[i + 1].re = cosf(p) * m;
+        out[i + 1].im = sinf(p) * m;
+    }
+}
+
+static void update_phase(const float *phase, float *last_phase,
+                         float *new_phase, const int size)
+{
+    for (int i = 0; i < size; i++) {
+        new_phase[i] = last_phase[i];
+        last_phase[i] = phase[i];
+    }
+}
+
+static void restore_symmetry(FFTComplex *win, const int size)
+{
+    for (int i = 1; i < size / 2; i++) {
+        int pos = size - i;
+
+        win[pos].re =  win[i].re;
+        win[pos].im = -win[i].im;
+    }
+}
+
+static float principal_angle(const float a)
+{
+    float b = fmodf(a + M_PI, 2 * M_PI);
+
+    if (b < 0.f)
+        b = 2 * M_PI + b;
+    b -= M_PI;
+
+    return b;
+}
+
+static void make_phase(const float *phase, const float *last_phase,
+                       float *new_phase,
+                       int io, int oo, int size)
+{
+    const float size2 = 2 * size;
+
+    for (int i = 0; i < size; i++) {
+        float h = 2 * M_PI * (i + 1.f) / size2;
+        float ii = phase[i] - last_phase[i] - io * h;
+        float j = h + principal_angle(ii) / io;
+
+        new_phase[i] += oo * j;
+    }
+}
+
+static int is_peak(const float *magnitude, const int pos, const int search)
+{
+    const float cmag = magnitude[pos];
+
+    for (int i = 0; i <= search; i++)
+        if (!(i > pos) && magnitude[pos - i] > cmag)
+            return 0;
+    for (int i = 0; i <= search; i++)
+        if (magnitude[pos + i] > cmag)
+            return 0;
+
+    return 1;
+}
+
+static int find_peaks(const float *magnitude, float *peaks, const int search, const int size)
+{
+    int count = 0;
+
+    for (int i = 0; i < size - search; i++) {
+        if (is_peak(magnitude, i, search))
+            peaks[count++] = i;
+    }
+
+    return count;
+}
+
+static void interp_phase(const float *map, const float *peaks, const int nb_peaks,
+                         const float *phase, const float *last_phase,
+                         float *new_phase, const float io, const float oo, const int size)
+{
+    const float size2 = 2 * size;
+
+    for (int i = 0; i < nb_peaks; i++) {
+        int peak = peaks[i];
+        int l = map[peak];
+        float m, n, o;
+
+        if (FFABS(peak - l) > FFMIN(1, av_log2(i)) - 3)
+            l = peak;
+        m = 2.f * M_PI * (peak + 1.f) / size2;
+        n = phase[peak] - last_phase[l] - io * m;
+        o = m + principal_angle(n) / io;
+
+        new_phase[peak] = new_phase[l] + oo * o;
+    }
+}
+
+static void get_new_phase(const float *map, const float *phase,
+                          float *new_phase, const float I, const int size)
+{
+    for (int i = 0; i < size; i++) {
+        int f = map[i];
+
+        new_phase[i] = new_phase[f] + I * (phase[i] - phase[f]);
+    }
+}
+
+static int lowest_valley(const float *magnitude,
+                         const int start, const int size)
+{
+    float lowest_magn = magnitude[start];
+    int lowest = start;
+
+    for (int i = start + 1; i < size; i++) {
+        if (magnitude[i] < lowest_magn) {
+            lowest = i;
+            lowest_magn = magnitude[i];
+        }
+    }
+
+    return lowest;
+}
+
+static void map_peaks(const float *peaks, const int nb_peaks,
+                      const float *magnitude, float *map, const int size)
+{
+    int e = 0, f;
+
+    for (f = 0; f < nb_peaks - 1; f++) {
+        int peak = peaks[f];
+        int next_peak = peaks[f+1];
+
+        for (int j = lowest_valley(magnitude, peak, next_peak); e <= j; e++)
+            map[e] = peak;
+    }
+
+    for (; e < size; e++)
+        map[e] = peaks[f];
+}
+
+static void stretch(APitchContext *s, int nb_samples,
+                    int window_size, float sample_rate,
+                    const float *indata, float *outdata, int ch)
+{
+    FFTComplex *window_buffer = (FFTComplex *)s->buffer->extended_data[ch];
+    float *phase = (float *)s->phase->extended_data[ch];
+    float *magnitude = (float *)s->magnitude->extended_data[ch];
+    float *acc = (float *)s->acc->extended_data[ch];
+    float *new_phase = (float *)s->new_phase->extended_data[ch];
+    float *last_phase = (float *)s->last_phase->extended_data[ch];
+    float *osamples = (float *)s->osamples->extended_data[ch];
+    float *peaks = (float *)s->peaks->extended_data[ch];
+    float *map = (float *)s->map->extended_data[ch];
+    const int output_overlap = s->output_overlap;
+    const int input_overlap = s->input_overlap;
+    const int half_window_size = window_size / 2;
+    const float ratio = output_overlap / (float)input_overlap;
+    const float wscale = 1.f / window_size;
+    float power;
+
+    if (s->pitch == s->tempo && s->tempo == 1.f) {
+        for (int k = 0; k < window_size; k++)
+            osamples[k] = indata[k];
+
+        goto copy;
+    }
+
+    for (int k = 0; k < window_size; k++) {
+        const float window = s->window_func_lut[k];
+
+        window_buffer[k].re = indata[k] * window;
+        window_buffer[k].im = 0.f;
+    }
+
+    power = get_power(indata, window_size);
+    if (power > 2.f * s->last_power)
+        s->power_change = 1;
+
+    av_fft_permute(s->fft, window_buffer);
+    av_fft_calc(s->fft, window_buffer);
+
+    complex2polar(window_buffer, magnitude, phase, half_window_size);
+
+    if (s->power_change)
+        update_phase(phase, last_phase, new_phase, half_window_size);
+    s->power_change = 0;
+
+    if (ratio < 2.f) {
+        int nb_peaks = find_peaks(magnitude, peaks, 1, half_window_size);
+        float I = 2.f / 3.f + fminf(1.5, ratio) / 3.f;
+
+        av_assert0(nb_peaks > 0);
+        map_peaks(peaks, nb_peaks, magnitude, map, half_window_size);
+        interp_phase(map, peaks, nb_peaks, phase, last_phase, new_phase,
+                     input_overlap, output_overlap, half_window_size);
+        get_new_phase(map, phase, new_phase, I, half_window_size);
+    } else {
+        make_phase(phase, last_phase, new_phase, input_overlap, output_overlap, half_window_size);
+    }
+
+    polar2complex(window_buffer, magnitude, new_phase, half_window_size);
+    restore_symmetry(window_buffer, window_size);
+
+    av_fft_permute(s->ifft, window_buffer);
+    av_fft_calc(s->ifft, window_buffer);
+
+    for (int k = 0; k < window_size; k++)
+        osamples[k] = window_buffer[k].re * wscale;
+
+    normalize(osamples, power, window_size);
+
+copy:
+    for (int k = 0; k < window_size; k++) {
+        const float window = s->window_func_lut[k];
+        osamples[k] *= window * .5f;
+    }
+
+    for (int k = 0; k < window_size; k++) {
+        acc[k] += osamples[k];
+    }
+
+    for (int k = 0; k < output_overlap; k++)
+        outdata[k] = acc[k];
+
+    memmove(acc, acc + output_overlap, (window_size * 2 - output_overlap) * sizeof(float));
+    FFSWAP(uint8_t *, s->last_phase->extended_data[ch], s->phase->extended_data[ch]);
+
+    s->last_power = power;
+}
+
+static int filter_frame(AVFilterLink *inlink)
+{
+    AVFilterContext *ctx = inlink->dst;
+    AVFilterLink *outlink = ctx->outputs[0];
+    APitchContext *s = ctx->priv;
+    AVFrame *out = NULL, *in = NULL, *new_out = NULL;
+    int ret, drain, available = 0;
+
+    if (s->pitch_changed) {
+        out = ff_get_audio_buffer(outlink, s->output_overlap);
+        if (!out) {
+            return AVERROR(ENOMEM);
+        }
+
+        ret = swr_convert_frame(s->swr, out, NULL);
+        if (ret < 0) {
+            av_frame_free(&out);
+            return ret;
+        }
+
+        if (out->nb_samples > 0) {
+            out->pts = s->pts;
+            s->pts += out->nb_samples;
+
+            return ff_filter_frame(outlink, out);
+        } else {
+            s->pitch_changed = 0;
+            av_frame_free(&out);
+        }
+
+        s->swr = swr_alloc_set_opts(s->swr,
+                                    inlink->channel_layout, inlink->format, inlink->sample_rate,
+                                    inlink->channel_layout, inlink->format, inlink->sample_rate * s->pitch,
+                                    0, ctx);
+        if (!s->swr)
+            return AVERROR(ENOMEM);
+
+        ret = swr_init(s->swr);
+        if (ret < 0)
+            return ret;
+    }
+
+    in = ff_get_audio_buffer(outlink, s->window_size);
+    if (!in)
+        return AVERROR(ENOMEM);
+
+    ret = av_audio_fifo_peek(s->ififo, (void **)in->extended_data, s->window_size);
+    if (ret < 0) {
+        ret = AVERROR(ENOMEM);
+        goto end;
+    }
+    available = av_audio_fifo_size(s->ififo) > 0;
+
+    if (available > 0) {
+        out = ff_get_audio_buffer(outlink, s->output_overlap);
+        if (!out) {
+            ret = AVERROR(ENOMEM);
+            goto end;
+        }
+
+        for (int ch = 0; ch < inlink->channels; ch++) {
+            stretch(s, in->nb_samples,
+                    s->window_size,
+                    inlink->sample_rate,
+                    (const float *)in->extended_data[ch],
+                    (float *)out->extended_data[ch], ch);
+        }
+    }
+
+    if (s->pitch != 1.f) {
+        new_out = ff_get_audio_buffer(outlink, s->output_overlap);
+        if (!new_out) {
+            av_frame_free(&out);
+            ret = AVERROR(ENOMEM);
+            goto end;
+        }
+
+        if (out)
+            out->sample_rate *= s->pitch;
+        ret = swr_convert_frame(s->swr, new_out, out);
+        av_frame_free(&out);
+        if (ret < 0)
+            goto end;
+        out = new_out;
+        new_out = NULL;
+    }
+
+    if (!out) {
+        ret = 1;
+        goto end;
+    }
+
+    out->pts = s->pts;
+    s->pts += s->output_overlap;
+
+    s->flushed = out->nb_samples == 0;
+    if (s->flushed) {
+        ret = 1;
+        av_frame_free(&out);
+        goto end;
+    }
+
+    ret = ff_filter_frame(outlink, out);
+    if (ret < 0)
+        goto end;
+
+    s->samples_to_drain = s->input_overlap;
+    drain = FFMIN(s->samples_to_drain, av_audio_fifo_size(s->ififo));
+    av_audio_fifo_drain(s->ififo, drain);
+    s->samples_to_drain -= drain;
+
+end:
+    av_frame_free(&in);
+    av_frame_free(&new_out);
+    return ret;
+}
+
+static int activate(AVFilterContext *ctx)
+{
+    AVFilterLink *inlink = ctx->inputs[0];
+    AVFilterLink *outlink = ctx->outputs[0];
+    APitchContext *s = ctx->priv;
+    AVFrame *in = NULL;
+    int ret = 0, status;
+    int64_t pts;
+
+    if (!s->magnitude) {
+        s->magnitude = ff_get_audio_buffer(outlink, s->window_size / 2);
+        if (!s->magnitude)
+            return AVERROR(ENOMEM);
+    }
+
+    if (!s->phase) {
+        s->phase = ff_get_audio_buffer(outlink, s->window_size / 2);
+        if (!s->phase)
+            return AVERROR(ENOMEM);
+    }
+
+    if (!s->acc) {
+        s->acc = ff_get_audio_buffer(outlink, s->window_size * 2);
+        if (!s->acc)
+            return AVERROR(ENOMEM);
+    }
+
+    if (!s->new_phase) {
+        s->new_phase = ff_get_audio_buffer(outlink, s->window_size / 2);
+        if (!s->new_phase)
+            return AVERROR(ENOMEM);
+    }
+
+    if (!s->last_phase) {
+        s->last_phase = ff_get_audio_buffer(outlink, s->window_size / 2);
+        if (!s->last_phase)
+            return AVERROR(ENOMEM);
+    }
+
+    if (!s->osamples) {
+        s->osamples = ff_get_audio_buffer(outlink, s->window_size);
+        if (!s->osamples)
+            return AVERROR(ENOMEM);
+    }
+
+    if (!s->peaks) {
+        s->peaks = ff_get_audio_buffer(outlink, s->window_size / 2);
+        if (!s->peaks)
+            return AVERROR(ENOMEM);
+    }
+
+    if (!s->map) {
+        s->map = ff_get_audio_buffer(outlink, s->window_size / 2);
+        if (!s->map)
+            return AVERROR(ENOMEM);
+    }
+
+    if (!s->buffer) {
+        s->buffer = ff_get_audio_buffer(outlink, s->window_size * 2);
+        if (!s->buffer)
+            return AVERROR(ENOMEM);
+    }
+
+    FF_FILTER_FORWARD_STATUS_BACK(outlink, inlink);
+
+    if (!s->eof && av_audio_fifo_size(s->ififo) < s->window_size) {
+        ret = ff_inlink_consume_frame(inlink, &in);
+        if (ret < 0)
+            return ret;
+
+        if (ret > 0) {
+            ret = av_audio_fifo_write(s->ififo, (void **)in->extended_data,
+                                      in->nb_samples);
+            if (ret >= 0 && s->pts == AV_NOPTS_VALUE)
+                s->pts = in->pts;
+
+            if (s->samples_to_drain > 0) {
+                int drain = FFMIN(s->samples_to_drain, av_audio_fifo_size(s->ififo));
+                av_audio_fifo_drain(s->ififo, drain);
+                s->samples_to_drain -= drain;
+            }
+
+            av_frame_free(&in);
+            if (ret < 0)
+                return ret;
+        }
+    }
+
+    if ((av_audio_fifo_size(s->ififo) >= s->window_size) ||
+        ((av_audio_fifo_size(s->ififo) > 0 || !s->flushed) && s->eof)) {
+        ret = filter_frame(inlink);
+        if (av_audio_fifo_size(s->ififo) >= s->window_size)
+            ff_filter_set_ready(ctx, 100);
+        if (ret != 1)
+            return ret;
+    }
+
+    if (!s->eof && ff_inlink_acknowledge_status(inlink, &status, &pts)) {
+        if (status == AVERROR_EOF) {
+            s->eof = 1;
+            if (av_audio_fifo_size(s->ififo) >= 0 && !s->flushed) {
+                ff_filter_set_ready(ctx, 100);
+                return 0;
+            }
+        }
+    }
+
+    if (s->eof && (av_audio_fifo_size(s->ififo) <= 0 || s->flushed)) {
+        ff_outlink_set_status(outlink, AVERROR_EOF, s->pts);
+        return 0;
+    }
+
+    if (!s->eof)
+        FF_FILTER_FORWARD_WANTED(outlink, inlink);
+
+    return FFERROR_NOT_READY;
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+    AVFilterFormats *formats;
+    AVFilterChannelLayouts *layouts;
+    static const enum AVSampleFormat sample_fmts[] = {
+        AV_SAMPLE_FMT_FLTP,
+        AV_SAMPLE_FMT_NONE
+    };
+    int ret;
+
+    layouts = ff_all_channel_counts();
+    if (!layouts)
+        return AVERROR(ENOMEM);
+    ret = ff_set_common_channel_layouts(ctx, layouts);
+    if (ret < 0)
+        return ret;
+
+    formats = ff_make_format_list(sample_fmts);
+    if (!formats)
+        return AVERROR(ENOMEM);
+    ret = ff_set_common_formats(ctx, formats);
+    if (ret < 0)
+        return ret;
+
+    formats = ff_all_samplerates();
+    if (!formats)
+        return AVERROR(ENOMEM);
+    return ff_set_common_samplerates(ctx, formats);
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    APitchContext *s = ctx->priv;
+
+    av_fft_end(s->fft);
+    s->fft = NULL;
+    av_fft_end(s->ifft);
+    s->ifft = NULL;
+
+    av_frame_free(&s->acc);
+    av_frame_free(&s->magnitude);
+    av_frame_free(&s->phase);
+    av_frame_free(&s->peaks);
+    av_frame_free(&s->new_phase);
+    av_frame_free(&s->last_phase);
+    av_frame_free(&s->osamples);
+    av_frame_free(&s->map);
+    av_frame_free(&s->buffer);
+
+    av_freep(&s->window_func_lut);
+
+    av_audio_fifo_free(s->ififo);
+    s->ififo = NULL;
+
+    swr_free(&s->swr);
+}
+
+static int process_command(AVFilterContext *ctx,
+                           const char *cmd,
+                           const char *arg,
+                           char *res,
+                           int res_len,
+                           int flags)
+{
+    APitchContext *s = ctx->priv;
+    float tempo;
+    float pitch;
+    int ret = 0;
+
+    if (!strcmp(cmd, "tempo") && av_sscanf(arg, "%f", &tempo) == 1) {
+        s->tempo = av_clipf(tempo, 0.01f, 100.f);
+        ret = set_input_overlap(s, s->tempo / s->pitch);
+    } else if (!strcmp(cmd, "pitch") && av_sscanf(arg, "%f", &pitch) == 1) {
+        pitch = av_clipf(pitch, 0.01f, 100.f);
+        s->pitch_changed = pitch != s->pitch;
+        s->pitch = pitch;
+        ret = set_input_overlap(s, s->tempo / s->pitch);
+    } else {
+        ret = AVERROR(ENOSYS);
+    }
+
+    return ret;
+}
+
+static const AVFilterPad inputs[] = {
+    {
+        .name = "default",
+        .type = AVMEDIA_TYPE_AUDIO,
+    },
+    { NULL }
+};
+
+static const AVFilterPad outputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_AUDIO,
+        .config_props = config_output,
+    },
+    { NULL }
+};
+
+AVFilter ff_af_apitch = {
+    .name            = "apitch",
+    .description     = NULL_IF_CONFIG_SMALL("Adjust audio pitch and tempo."),
+    .priv_size       = sizeof(APitchContext),
+    .priv_class      = &apitch_class,
+    .inputs          = inputs,
+    .outputs         = outputs,
+    .activate        = activate,
+    .query_formats   = query_formats,
+    .process_command = process_command,
+    .uninit          = uninit,
+};
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 9bdfa7d1bc..e3ea0e8214 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -60,6 +60,7 @@ extern AVFilter ff_af_anull;
 extern AVFilter ff_af_apad;
 extern AVFilter ff_af_aperms;
 extern AVFilter ff_af_aphaser;
+extern AVFilter ff_af_apitch;
 extern AVFilter ff_af_apulsator;
 extern AVFilter ff_af_arealtime;
 extern AVFilter ff_af_aresample;
-- 
2.17.1



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