lavfi: add sine audio source.

Changelog

@@ -10,6 +10,7 @@ version <next>:
 - perms and aperms filters
 - audio filtering support in ffplay
 - 10% faster aac encoding on x86 and MIPS
+- sine audio filter source
 
 
 version 1.2:

doc/filters.texi

@@ -1653,6 +1653,57 @@ ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
 For more information about libflite, check:
 @url{http://www.speech.cs.cmu.edu/flite/}
 
+@section sine
+
+Generate an audio signal made of a sine wave with amplitude 1/8.
+
+The audio signal is bit-exact.
+
+It accepts a list of options in the form of @var{key}=@var{value} pairs
+separated by ":". If the option name is omitted, the first option is the
+frequency and the second option is the beep factor.
+
+The supported options are:
+
+@table @option
+
+@item frequency, f
+Set the carrier frequency. Default is 440 Hz.
+
+@item beep_factor, b
+Enable a periodic beep every second with frequency @var{beep_factor} times
+the carrier frequency. Default is 0, meaning the beep is disabled.
+
+@item sample_rate, s
+Specify the sample rate, default is 44100.
+
+@item duration, d
+Specify the duration of the generated audio stream.
+
+@item samples_per_frame
+Set the number of samples per output frame, default is 1024.
+@end table
+
+@subsection Examples
+
+@itemize
+
+@item
+Generate a simple 440 Hz sine wave:
+@example
+sine
+@end example
+
+@item
+Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
+@example
+sine=220:4:d=5
+sine=f=220:b=4:d=5
+sine=frequency=220:beep_factor=4:duration=5
+@end example
+
+@end itemize
+
 @c man end AUDIO SOURCES
 
 @chapter Audio Sinks

libavfilter/Makefile

@@ -90,6 +90,7 @@ OBJS-$(CONFIG_VOLUMEDETECT_FILTER)           += af_volumedetect.o
 OBJS-$(CONFIG_AEVALSRC_FILTER)               += asrc_aevalsrc.o
 OBJS-$(CONFIG_ANULLSRC_FILTER)               += asrc_anullsrc.o
 OBJS-$(CONFIG_FLITE_FILTER)                  += asrc_flite.o
+OBJS-$(CONFIG_SINE_FILTER)                   += asrc_sine.o
 
 OBJS-$(CONFIG_ANULLSINK_FILTER)              += asink_anullsink.o
 

libavfilter/allfilters.c

@@ -86,6 +86,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER(AEVALSRC,       aevalsrc,       asrc);
     REGISTER_FILTER(ANULLSRC,       anullsrc,       asrc);
     REGISTER_FILTER(FLITE,          flite,          asrc);
+    REGISTER_FILTER(SINE,           sine,           asrc);
 
     REGISTER_FILTER(ANULLSINK,      anullsink,      asink);
 

libavfilter/asrc_sine.c

@@ -0,0 +1,228 @@
+/*
+ * Copyright (c) 2013 Nicolas George
+ *
+ * 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 "audio.h"
+#include "avfilter.h"
+#include "internal.h"
+
+typedef struct {
+    const AVClass *class;
+    double frequency;
+    double beep_factor;
+    int samples_per_frame;
+    int sample_rate;
+    int64_t duration;
+    int16_t *sin;
+    int64_t pts;
+    uint32_t phi;  ///< current phase of the sine (2pi = 1<<32)
+    uint32_t dphi; ///< phase increment between two samples
+    unsigned beep_period;
+    unsigned beep_index;
+    unsigned beep_length;
+    uint32_t phi_beep;  ///< current phase of the beep
+    uint32_t dphi_beep; ///< phase increment of the beep
+} SineContext;
+
+#define CONTEXT SineContext
+#define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
+
+#define OPT_GENERIC(name, field, def, min, max, descr, type, deffield, ...) \
+    { name, descr, offsetof(CONTEXT, field), AV_OPT_TYPE_ ## type,          \
+      { .deffield = def }, min, max, FLAGS, __VA_ARGS__ }
+
+#define OPT_INT(name, field, def, min, max, descr, ...) \
+    OPT_GENERIC(name, field, def, min, max, descr, INT, i64, __VA_ARGS__)
+
+#define OPT_DBL(name, field, def, min, max, descr, ...) \
+    OPT_GENERIC(name, field, def, min, max, descr, DOUBLE, dbl, __VA_ARGS__)
+
+#define OPT_DUR(name, field, def, min, max, descr, ...) \
+    OPT_GENERIC(name, field, def, min, max, descr, DURATION, str, __VA_ARGS__)
+
+static const AVOption sine_options[] = {
+    OPT_DBL("frequency",         frequency,            440, 0, INFINITY,  "set the sine frequency"),
+    OPT_DBL("f",                 frequency,            440, 0, INFINITY,  "set the sine frequency"),
+    OPT_DBL("beep_factor",       beep_factor,            0, 0, INFINITY,  "set the beep fequency factor"),
+    OPT_DBL("b",                 beep_factor,            0, 0, INFINITY,  "set the beep fequency factor"),
+    OPT_INT("sample_rate",       sample_rate,        44100, 1, INT_MAX,   "set the sample rate"),
+    OPT_INT("r",                 sample_rate,        44100, 1, INT_MAX,   "set the sample rate"),
+    OPT_DUR("duration",          duration,               0, 0, INT64_MAX, "set the audio duration"),
+    OPT_DUR("d",                 duration,               0, 0, INT64_MAX, "set the audio duration"),
+    OPT_INT("samples_per_frame", samples_per_frame,   1024, 0, INT_MAX,   "set the number of samples per frame"),
+    {NULL},
+};
+
+AVFILTER_DEFINE_CLASS(sine);
+
+#define LOG_PERIOD 15
+#define AMPLITUDE 4095
+#define AMPLITUDE_SHIFT 3
+
+static void make_sin_table(int16_t *sin)
+{
+    unsigned half_pi = 1 << (LOG_PERIOD - 2);
+    unsigned ampls = AMPLITUDE << AMPLITUDE_SHIFT;
+    uint64_t unit2 = (uint64_t)(ampls * ampls) << 32;
+    unsigned step, i, c, s, k, new_k, n2;
+
+    /* Principle: if u = exp(i*a1) and v = exp(i*a2), then
+       exp(i*(a1+a2)/2) = (u+v) / length(u+v) */
+    sin[0] = 0;
+    sin[half_pi] = ampls;
+    for (step = half_pi; step > 1; step /= 2) {
+        /* k = (1 << 16) * amplitude / length(u+v)
+           In exact values, k is constant at a given step */
+        k = 0x10000;
+        for (i = 0; i < half_pi / 2; i += step) {
+            s = sin[i] + sin[i + step];
+            c = sin[half_pi - i] + sin[half_pi - i - step];
+            n2 = s * s + c * c;
+            /* Newton's method to solve n² * k² = unit² */
+            while (1) {
+                new_k = (k + unit2 / ((uint64_t)k * n2) + 1) >> 1;
+                if (k == new_k)
+                    break;
+                k = new_k;
+            }
+            sin[i + step / 2] = (k * s + 0x7FFF) >> 16;
+            sin[half_pi - i - step / 2] = (k * c + 0x8000) >> 16;
+        }
+    }
+    /* Unshift amplitude */
+    for (i = 0; i <= half_pi; i++)
+        sin[i] = (sin[i] + (1 << (AMPLITUDE_SHIFT - 1))) >> AMPLITUDE_SHIFT;
+    /* Use symmetries to fill the other three quarters */
+    for (i = 0; i < half_pi; i++)
+        sin[half_pi * 2 - i] = sin[i];
+    for (i = 0; i < 2 * half_pi; i++)
+        sin[i + 2 * half_pi] = -sin[i];
+}
+
+static av_cold int init(AVFilterContext *ctx, const char *args)
+{
+    SineContext *sine = ctx->priv;
+    static const char *shorthand[] = { "frequency", "beep_factor", NULL };
+    int ret;
+
+    sine->class = &sine_class;
+    av_opt_set_defaults(sine);
+
+    if ((ret = av_opt_set_from_string(sine, args, shorthand, "=", ":")) < 0)
+        return ret;
+    if (!(sine->sin = av_malloc(sizeof(*sine->sin) << LOG_PERIOD)))
+        return AVERROR(ENOMEM);
+    sine->dphi = ldexp(sine->frequency, 32) / sine->sample_rate + 0.5;
+    make_sin_table(sine->sin);
+
+    if (sine->beep_factor) {
+        sine->beep_period = sine->sample_rate;
+        sine->beep_length = sine->beep_period / 25;
+        sine->dphi_beep = ldexp(sine->beep_factor * sine->frequency, 32) /
+                          sine->sample_rate + 0.5;
+    }
+
+    return 0;
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    SineContext *sine = ctx->priv;
+
+    av_freep(&sine->sin);
+}
+
+static av_cold int query_formats(AVFilterContext *ctx)
+{
+    SineContext *sine = ctx->priv;
+    static const int64_t chlayouts[] = { AV_CH_LAYOUT_MONO, -1 };
+    int sample_rates[] = { sine->sample_rate, -1 };
+    static const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_S16,
+                                                       AV_SAMPLE_FMT_NONE };
+
+    ff_set_common_formats (ctx, ff_make_format_list(sample_fmts));
+    ff_set_common_channel_layouts(ctx, avfilter_make_format64_list(chlayouts));
+    ff_set_common_samplerates(ctx, ff_make_format_list(sample_rates));
+    return 0;
+}
+
+static av_cold int config_props(AVFilterLink *outlink)
+{
+    SineContext *sine = outlink->src->priv;
+    sine->duration = av_rescale(sine->duration, sine->sample_rate, AV_TIME_BASE);
+    return 0;
+}
+
+static int request_frame(AVFilterLink *outlink)
+{
+    SineContext *sine = outlink->src->priv;
+    AVFrame *frame;
+    int i, nb_samples = sine->samples_per_frame;
+    int16_t *samples;
+
+    if (sine->duration) {
+        nb_samples = FFMIN(nb_samples, sine->duration - sine->pts);
+        av_assert1(nb_samples >= 0);
+        if (!nb_samples)
+            return AVERROR_EOF;
+    }
+    if (!(frame = ff_get_audio_buffer(outlink, nb_samples)))
+        return AVERROR(ENOMEM);
+    samples = (int16_t *)frame->data[0];
+
+    for (i = 0; i < nb_samples; i++) {
+        samples[i] = sine->sin[sine->phi >> (32 - LOG_PERIOD)];
+        sine->phi += sine->dphi;
+        if (sine->beep_index < sine->beep_length) {
+            samples[i] += sine->sin[sine->phi_beep >> (32 - LOG_PERIOD)] << 1;
+            sine->phi_beep += sine->dphi_beep;
+        }
+        if (++sine->beep_index == sine->beep_period)
+            sine->beep_index = 0;
+    }
+
+    frame->pts = sine->pts;
+    sine->pts += nb_samples;
+    return ff_filter_frame(outlink, frame);
+}
+
+static const AVFilterPad sine_outputs[] = {
+    {
+        .name          = "default",
+        .type          = AVMEDIA_TYPE_AUDIO,
+        .request_frame = request_frame,
+        .config_props  = config_props,
+    },
+    { NULL }
+};
+
+AVFilter avfilter_asrc_sine = {
+    .name          = "sine",
+    .description   = NULL_IF_CONFIG_SMALL("Generate sine wave audio signal."),
+    .query_formats = query_formats,
+    .init          = init,
+    .uninit        = uninit,
+    .priv_size     = sizeof(SineContext),
+    .inputs        = NULL,
+    .outputs       = sine_outputs,
+    .priv_class    = &sine_class,
+};

libavfilter/version.h

@@ -29,8 +29,8 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  3
-#define LIBAVFILTER_VERSION_MINOR  47
-#define LIBAVFILTER_VERSION_MICRO 104
+#define LIBAVFILTER_VERSION_MINOR  48
+#define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
                                                LIBAVFILTER_VERSION_MINOR, \