From e10f73d363d0313774bcb132b3b1f2417fcfba11 Mon Sep 17 00:00:00 2001
From: Atana <atana@openmailbox.org>
Date: Thu, 3 Nov 2016 01:05:51 +0530
Subject: [PATCH] avfilter: added peakpoints filter

---
 libavfilter/af_peakpoints.c | 226 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 226 insertions(+)
 create mode 100644 libavfilter/af_peakpoints.c

diff --git a/libavfilter/af_peakpoints.c b/libavfilter/af_peakpoints.c
new file mode 100644
index 0000000..9265c47
--- /dev/null
+++ b/libavfilter/af_peakpoints.c
@@ -0,0 +1,226 @@
+/*
+ * Copyright (c) 2016 Atana
+ *
+ * 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 "libavcodec/avcodec.h"
+#include "libavcodec/avfft.h"
+#include "libavformat/avformat.h"
+#include "libswscale/swscale.h"
+#include "avfilter.h"
+#include "audio.h"
+#include "libavutil/opt.h"
+
+
+/* Structure to contain peak points context */
+typedef struct {
+    const AVClass *class;
+    double *data;
+    int nsamples;
+    int index;
+    double *peaks;
+    int size; // number of peaks
+    int windowSize;
+    //char *inputFile;
+} PeakPointsContext;
+
+/* returns maximum value from an array conditioned on start and end index */
+static double getMax(double *res_arr, int startIndex, int endIndex) {
+    int i;
+    double max = res_arr[startIndex];
+    for (i = startIndex; i <= endIndex; i++) {
+	    if (res_arr[i] > max) {
+	        max = res_arr[i];
+	    }
+    }
+    return max;
+}
+
+/* Stores peak frequency for each window(of chunkSize) in peaks array */
+static void getPeakPointInChunk(int chunkSize, double *res_arr, int size, double *peaks) {
+    int i = 0, peakIndex = 0;
+    int startIndex = 0;
+    double max;
+    // get a chunk and find max value in it
+    while (i < size) {
+	    if (i % chunkSize-1 == 0) {
+            max = getMax(res_arr, startIndex, i);
+	        peaks[peakIndex++] = max;
+	        startIndex = startIndex + chunkSize;
+	    }
+        i += 1;
+    }
+}
+
+/* Get peaks points from windowed frequency domain data*/
+static int getPeakPoints(PeakPointsContext *ppc) {
+    int i, m, k, size, chunkSize, pSize, chunkSampleSize, resSize;
+    double *fft_res;
+    void *avc;
+    RDFTContext *rdftC;
+    FFTSample *data;
+
+    size = ppc->index;
+    m = log2(ppc->windowSize);
+    chunkSize = ppc->windowSize;
+    chunkSampleSize = size/chunkSize;
+    resSize = chunkSize * chunkSampleSize;
+
+    fft_res = av_malloc(sizeof(double) * resSize);
+
+    if (!fft_res) {
+        av_log(avc, AV_LOG_ERROR, "Cann't allocate memmory for storing fft data\n");
+        return 0;
+    }
+
+
+    rdftC = av_rdft_init(m, DFT_R2C);
+    data = av_malloc(sizeof(FFTSample)*chunkSize);
+
+    if (!data) {
+        av_log(avc, AV_LOG_ERROR, "Cann't allocate memmory for chunk fft data\n");
+        return 0;
+    }
+    // FFT transform for windowed time domain data
+    // window is of size chunkSize
+    k = 0;
+    while (k < resSize) {
+        //copy data
+        for (i = 0; i < chunkSize; i++) {
+            data[i] = ppc->data[i+k];
+        }
+        //calculate FFT
+        av_rdft_calc(rdftC, data);
+        for (i = 0; i < chunkSize; i++) {
+	    fft_res[i+k] = data[i];
+        }
+        k = k + chunkSize;
+    }
+
+    av_rdft_end(rdftC);
+    pSize = resSize/chunkSize;
+    ppc->size = pSize;
+    ppc->peaks = av_malloc(sizeof(double)*pSize);
+
+    if (!ppc->peaks) {
+        av_log(avc, AV_LOG_ERROR, "Cann't allocate memory for peak storage\n");
+        return 0;
+    }
+
+    getPeakPointInChunk(chunkSize, fft_res, resSize, ppc->peaks);
+    return 1;
+}
+
+
+#define OFFSET(x) offsetof(PeakPointsContext, x)
+
+static const AVOption peakpoints_options[] = {
+    { "wsize",  "set window size", OFFSET(windowSize),  AV_OPT_TYPE_INT,    {.i64=16},    0, INT_MAX},
+    { NULL },
+};
+
+AVFILTER_DEFINE_CLASS(peakpoints);
+
+static av_cold int init(AVFilterContext *ctx)
+{
+    PeakPointsContext *p = ctx->priv;
+
+    if (p->windowSize < 16) {
+	    av_log(ctx, AV_LOG_ERROR, "window size must be greater than or equal to 16\n");
+        return AVERROR(EINVAL);
+    }
+
+    p->index = 0;
+    p->size = 0;
+    p->data = av_malloc(sizeof(double)*10000);
+
+    if (!p->data) {
+        av_log(ctx, AV_LOG_ERROR, "Cann't allocate memmory for audio data\n");
+        return AVERROR(EINVAL);
+    }
+
+    return 0;
+}
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *samples)
+{
+    AVFilterContext *ctx = inlink->dst;
+    PeakPointsContext *p = ctx->priv;
+
+    // store audio data
+    p->data[p->index] = (double)*samples->data[0];
+    p->index = p->index + 1;
+
+    return ff_filter_frame(inlink->dst->outputs[0], samples);
+}
+
+static void ppointsStats(AVFilterContext *ctx, PeakPointsContext *p) {
+    int i, ret;
+    ret = getPeakPoints(p);
+
+    if (ret && p->size) {
+    	// print peaks
+        av_log(ctx, AV_LOG_INFO, "######## Peak points are ########\n");
+        for (i = 0; i < p->size; i++) {
+	        av_log(ctx, AV_LOG_INFO, "%f\n", p->peaks[i]);
+        }
+    } else if (p->size || !ret) {
+        av_log(ctx, AV_LOG_ERROR, "Peak points not retrieved\n");
+        return;
+    }
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    PeakPointsContext *p = ctx->priv;
+
+    ppointsStats(ctx, p);
+
+    // free allocated memories
+    av_freep(&p->data);
+    av_freep(&p->peaks);
+}
+
+static const AVFilterPad peakpoints_inputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_AUDIO,
+        .filter_frame = filter_frame,
+    },
+    { NULL }
+};
+
+static const AVFilterPad peakpoints_outputs[] = {
+    {
+        .name = "default",
+        .type = AVMEDIA_TYPE_AUDIO,
+    },
+    { NULL }
+};
+
+AVFilter ff_af_peakpoints = {
+    .name          = "peakpoints",
+    .description   = NULL_IF_CONFIG_SMALL("peak points from frequency domain windowed data."),
+    .init          = init,
+    .uninit        = uninit,
+    //.query_formats = query_formats,
+    .priv_size     = sizeof(PeakPointsContext),
+    .inputs        = peakpoints_inputs,
+    .outputs       = peakpoints_outputs,
+    .priv_class    = &peakpoints_class,
+};
-- 
1.9.1

