making act segmenter

1 files changed, 160 insertions, 0 deletions

diff --git a/ffmpeg/libavdevice/timefilter.c b/ffmpeg/libavdevice/timefilter.c
new file mode 100644
index 0000000..ba2e54e
--- /dev/null
+++ b/ffmpeg/libavdevice/timefilter.c
@@ -0,0 +1,160 @@
+/*
+ * Delay Locked Loop based time filter
+ * Copyright (c) 2009 Samalyse
+ * Copyright (c) 2009 Michael Niedermayer
+ * Author: Olivier Guilyardi <olivier samalyse com>
+ *         Michael Niedermayer <michaelni gmx at>
+ *
+ * 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/common.h"
+#include "libavutil/mem.h"
+#include "config.h"
+#include "timefilter.h"
+
+struct TimeFilter {
+    // Delay Locked Loop data. These variables refer to mathematical
+    // concepts described in: http://www.kokkinizita.net/papers/usingdll.pdf
+    double cycle_time;
+    double feedback2_factor;
+    double feedback3_factor;
+    double clock_period;
+    int count;
+};
+
+/* 1 - exp(-x) using a 3-order power series */
+static double qexpneg(double x)
+{
+    return 1 - 1 / (1 + x * (1 + x / 2 * (1 + x / 3)));
+}
+
+TimeFilter *ff_timefilter_new(double time_base,
+                              double period,
+                              double bandwidth)
+{
+    TimeFilter *self       = av_mallocz(sizeof(TimeFilter));
+    double o               = 2 * M_PI * bandwidth * period * time_base;
+    self->clock_period     = time_base;
+    self->feedback2_factor = qexpneg(M_SQRT2 * o);
+    self->feedback3_factor = qexpneg(o * o) / period;
+    return self;
+}
+
+void ff_timefilter_destroy(TimeFilter *self)
+{
+    av_freep(&self);
+}
+
+void ff_timefilter_reset(TimeFilter *self)
+{
+    self->count = 0;
+}
+
+double ff_timefilter_update(TimeFilter *self, double system_time, double period)
+{
+    self->count++;
+    if (self->count == 1) {
+        self->cycle_time = system_time;
+    } else {
+        double loop_error;
+        self->cycle_time += self->clock_period * period;
+        loop_error = system_time - self->cycle_time;
+
+        self->cycle_time   += FFMAX(self->feedback2_factor, 1.0 / self->count) * loop_error;
+        self->clock_period += self->feedback3_factor * loop_error;
+    }
+    return self->cycle_time;
+}
+
+double ff_timefilter_eval(TimeFilter *self, double delta)
+{
+    return self->cycle_time + self->clock_period * delta;
+}
+
+#ifdef TEST
+#include "libavutil/lfg.h"
+#define LFG_MAX ((1LL << 32) - 1)
+
+int main(void)
+{
+    AVLFG prng;
+    double n0, n1;
+#define SAMPLES 1000
+    double ideal[SAMPLES];
+    double samples[SAMPLES];
+    double samplet[SAMPLES];
+    for (n0 = 0; n0 < 40; n0 = 2 * n0 + 1) {
+        for (n1 = 0; n1 < 10; n1 = 2 * n1 + 1) {
+            double best_error = 1000000000;
+            double bestpar0   = 1;
+            double bestpar1   = 1;
+            int better, i;
+
+            av_lfg_init(&prng, 123);
+            for (i = 0; i < SAMPLES; i++) {
+                samplet[i] = 10 + i + (av_lfg_get(&prng) < LFG_MAX/2 ? 0 : 0.999);
+                ideal[i]   = samplet[i] + n1 * i / (1000);
+                samples[i] = ideal[i] + n0 * (av_lfg_get(&prng) - LFG_MAX / 2) / (LFG_MAX * 10LL);
+                if(i && samples[i]<samples[i-1])
+                    samples[i]=samples[i-1]+0.001;
+            }
+
+            do {
+                double par0, par1;
+                better = 0;
+                for (par0 = bestpar0 * 0.8; par0 <= bestpar0 * 1.21; par0 += bestpar0 * 0.05) {
+                    for (par1 = bestpar1 * 0.8; par1 <= bestpar1 * 1.21; par1 += bestpar1 * 0.05) {
+                        double error   = 0;
+                        TimeFilter *tf = ff_timefilter_new(1, par0, par1);
+                        for (i = 0; i < SAMPLES; i++) {
+                            double filtered;
+                            filtered = ff_timefilter_update(tf, samples[i], i ? (samplet[i] - samplet[i-1]) : 1);
+                            if(filtered < 0 || filtered > 1000000000)
+                                printf("filter is unstable\n");
+                            error   += (filtered - ideal[i]) * (filtered - ideal[i]);
+                        }
+                        ff_timefilter_destroy(tf);
+                        if (error < best_error) {
+                            best_error = error;
+                            bestpar0   = par0;
+                            bestpar1   = par1;
+                            better     = 1;
+                        }
+                    }
+                }
+            } while (better);
+#if 0
+            double lastfil = 9;
+            TimeFilter *tf = ff_timefilter_new(1, bestpar0, bestpar1);
+            for (i = 0; i < SAMPLES; i++) {
+                double filtered;
+                filtered = ff_timefilter_update(tf, samples[i], 1);
+                printf("%f %f %f %f\n", i - samples[i] + 10, filtered - samples[i],
+                       samples[FFMAX(i, 1)] - samples[FFMAX(i - 1, 0)], filtered - lastfil);
+                lastfil = filtered;
+            }
+            ff_timefilter_destroy(tf);
+#else
+            printf(" [%f %f %9f]", bestpar0, bestpar1, best_error);
+#endif
+        }
+        printf("\n");
+    }
+    return 0;
+}
+#endif