Add moodbar

2019-04-18 15:03:01 +02:00
parent 37b923bea3
commit 907d18a83a
49 changed files with 3347 additions and 5 deletions
--- a/ext/gstmoodbar/CMakeLists.txt
+++ b/ext/gstmoodbar/CMakeLists.txt
@@ -0,0 +1,27 @@
+cmake_minimum_required(VERSION 2.8.11)
+
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall")
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} --std=c++11 -U__STRICT_ANSI__ -Wall -Woverloaded-virtual -Wno-sign-compare -Wno-deprecated-declarations -Wno-unused-local-typedefs -fpermissive")
+
+include_directories(${CMAKE_CURRENT_BINARY_DIR} ${CMAKE_CURRENT_SOURCE_DIR})
+
+include_directories(${GLIB_INCLUDE_DIRS})
+include_directories(${GOBJECT_INCLUDE_DIRS})
+include_directories(${GSTREAMER_INCLUDE_DIRS})
+include_directories(${FFTW3_INCLUDE_DIR})
+
+set(SOURCES gstfastspectrum.cpp gstmoodbarplugin.cpp)
+
+add_library(gstmoodbar STATIC ${SOURCES})
+
+target_link_libraries(gstmoodbar
+  ${GOBJECT_LIBRARIES}
+  ${GLIB_LIBRARIES}
+  ${GSTREAMER_LIBRARIES}
+  ${GSTREAMER_AUDIO_LIBRARIES}
+  ${GSTREAMER_BASE_LIBRARIES}
+  ${FFTW3_FFTW_LIBRARY}
+)
+
+target_link_libraries(gstmoodbar Qt5::Core)
--- a/ext/gstmoodbar/gstfastspectrum.cpp
+++ b/ext/gstmoodbar/gstfastspectrum.cpp
@@ -0,0 +1,525 @@
+/* GStreamer
+ * Copyright (C) <1999> Erik Walthinsen <omega@cse.ogi.edu>
+ *               <2006,2011> Stefan Kost <ensonic@users.sf.net>
+ *               <2007-2009> Sebastian Dröge <sebastian.droege@collabora.co.uk>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#include <cstring>
+#include <cmath>
+
+#include <QMutex>
+#include <QMutexLocker>
+
+#include "gstfastspectrum.h"
+
+GST_DEBUG_CATEGORY_STATIC (gst_fastspectrum_debug);
+#define GST_CAT_DEFAULT gst_fastspectrum_debug
+
+/* elementfactory information */
+#if G_BYTE_ORDER == G_LITTLE_ENDIAN
+# define FORMATS "{ S16LE, S24LE, S32LE, F32LE, F64LE }"
+#else
+# define FORMATS "{ S16BE, S24BE, S32BE, F32BE, F64BE }"
+#endif
+
+#define ALLOWED_CAPS \
+  GST_AUDIO_CAPS_MAKE (FORMATS) ", " \
+  "layout = (string) interleaved, " \
+  "channels = 1"
+
+/* Spectrum properties */
+#define DEFAULT_INTERVAL		(GST_SECOND / 10)
+#define DEFAULT_BANDS			128
+
+enum {
+  PROP_0,
+  PROP_INTERVAL,
+  PROP_BANDS
+};
+
+#define gst_fastspectrum_parent_class parent_class
+G_DEFINE_TYPE (GstFastSpectrum, gst_fastspectrum, GST_TYPE_AUDIO_FILTER);
+
+static void gst_fastspectrum_finalize (GObject * object);
+static void gst_fastspectrum_set_property (GObject * object, guint prop_id, const GValue * value, GParamSpec * pspec);
+static void gst_fastspectrum_get_property (GObject * object, guint prop_id, GValue * value, GParamSpec * pspec);
+static gboolean gst_fastspectrum_start (GstBaseTransform * trans);
+static gboolean gst_fastspectrum_stop (GstBaseTransform * trans);
+static GstFlowReturn gst_fastspectrum_transform_ip (GstBaseTransform * trans, GstBuffer * in);
+static gboolean gst_fastspectrum_setup (GstAudioFilter * base, const GstAudioInfo * info);
+
+static void
+gst_fastspectrum_class_init (GstFastSpectrumClass * klass)
+{
+  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
+  GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
+  GstBaseTransformClass *trans_class = GST_BASE_TRANSFORM_CLASS (klass);
+  GstAudioFilterClass *filter_class = GST_AUDIO_FILTER_CLASS (klass);
+  GstCaps *caps;
+
+  gobject_class->set_property = gst_fastspectrum_set_property;
+  gobject_class->get_property = gst_fastspectrum_get_property;
+  gobject_class->finalize = gst_fastspectrum_finalize;
+
+  trans_class->start = GST_DEBUG_FUNCPTR (gst_fastspectrum_start);
+  trans_class->stop = GST_DEBUG_FUNCPTR (gst_fastspectrum_stop);
+  trans_class->transform_ip = GST_DEBUG_FUNCPTR (gst_fastspectrum_transform_ip);
+  trans_class->passthrough_on_same_caps = TRUE;
+
+  filter_class->setup = GST_DEBUG_FUNCPTR (gst_fastspectrum_setup);
+
+  g_object_class_install_property (gobject_class, PROP_INTERVAL,
+      g_param_spec_uint64 ("interval", "Interval", "Interval of time between message posts (in nanoseconds)", 1, G_MAXUINT64, DEFAULT_INTERVAL, GParamFlags(G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS)));
+
+  g_object_class_install_property (gobject_class, PROP_BANDS, g_param_spec_uint ("bands", "Bands", "Number of frequency bands", 0, G_MAXUINT, DEFAULT_BANDS, GParamFlags(G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS)));
+
+  GST_DEBUG_CATEGORY_INIT (gst_fastspectrum_debug, "spectrum", 0,
+      "audio spectrum analyser element");
+
+  gst_element_class_set_static_metadata (element_class, "Spectrum analyzer",
+      "Filter/Analyzer/Audio",
+      "Run an FFT on the audio signal, output spectrum data",
+      "Erik Walthinsen <omega@cse.ogi.edu>, "
+      "Stefan Kost <ensonic@users.sf.net>, "
+      "Sebastian Dröge <sebastian.droege@collabora.co.uk>");
+
+  caps = gst_caps_from_string (ALLOWED_CAPS);
+  gst_audio_filter_class_add_pad_templates (filter_class, caps);
+  gst_caps_unref (caps);
+
+  klass->fftw_lock = new QMutex;
+}
+
+static void gst_fastspectrum_init (GstFastSpectrum * spectrum) {
+
+  spectrum->interval = DEFAULT_INTERVAL;
+  spectrum->bands = DEFAULT_BANDS;
+
+  spectrum->channel_data_initialised = false;
+
+  g_mutex_init (&spectrum->lock);
+
+}
+
+static void gst_fastspectrum_alloc_channel_data (GstFastSpectrum * spectrum) {
+
+  guint bands = spectrum->bands;
+  guint nfft = 2 * bands - 2;
+
+  spectrum->input_ring_buffer = new double[nfft];
+  spectrum->fft_input = reinterpret_cast<double*>( fftw_malloc(sizeof(double) * nfft));
+  spectrum->fft_output =reinterpret_cast<fftw_complex*>( fftw_malloc(sizeof(fftw_complex) * (nfft/2+1)));
+
+  spectrum->spect_magnitude = new double[bands]{};
+
+  GstFastSpectrumClass* klass = reinterpret_cast<GstFastSpectrumClass*>(G_OBJECT_GET_CLASS(spectrum));
+  {
+    QMutexLocker l(klass->fftw_lock);
+    spectrum->plan = fftw_plan_dft_r2c_1d(nfft, spectrum->fft_input, spectrum->fft_output, FFTW_ESTIMATE);
+  }
+  spectrum->channel_data_initialised = true;
+
+}
+
+static void gst_fastspectrum_free_channel_data (GstFastSpectrum * spectrum) {
+
+  GstFastSpectrumClass* klass = reinterpret_cast<GstFastSpectrumClass*>(G_OBJECT_GET_CLASS(spectrum));
+  if (spectrum->channel_data_initialised) {
+    {
+      QMutexLocker l(klass->fftw_lock);
+      fftw_destroy_plan(spectrum->plan);
+    }
+    fftw_free(spectrum->fft_input);
+    fftw_free(spectrum->fft_output);
+    delete[] spectrum->input_ring_buffer;
+    delete[] spectrum->spect_magnitude;
+
+    spectrum->channel_data_initialised = false;
+  }
+
+}
+
+static void gst_fastspectrum_flush (GstFastSpectrum * spectrum) {
+
+  spectrum->num_frames = 0;
+  spectrum->num_fft = 0;
+
+  spectrum->accumulated_error = 0;
+
+}
+
+static void gst_fastspectrum_reset_state (GstFastSpectrum * spectrum) {
+
+  GST_DEBUG_OBJECT (spectrum, "resetting state");
+
+  gst_fastspectrum_free_channel_data (spectrum);
+  gst_fastspectrum_flush (spectrum);
+
+}
+
+static void gst_fastspectrum_finalize (GObject * object) {
+
+  GstFastSpectrum *spectrum = GST_FASTSPECTRUM (object);
+
+  gst_fastspectrum_reset_state (spectrum);
+  g_mutex_clear (&spectrum->lock);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+
+}
+
+static void gst_fastspectrum_set_property (GObject * object, guint prop_id, const GValue * value, GParamSpec * pspec) {
+
+  GstFastSpectrum *filter = GST_FASTSPECTRUM (object);
+
+  switch (prop_id) {
+    case PROP_INTERVAL:{
+      guint64 interval = g_value_get_uint64 (value);
+      g_mutex_lock (&filter->lock);
+      if (filter->interval != interval) {
+        filter->interval = interval;
+        gst_fastspectrum_reset_state (filter);
+      }
+      g_mutex_unlock (&filter->lock);
+      break;
+    }
+    case PROP_BANDS:{
+      guint bands = g_value_get_uint (value);
+      g_mutex_lock (&filter->lock);
+      if (filter->bands != bands) {
+        filter->bands = bands;
+        gst_fastspectrum_reset_state (filter);
+      }
+      g_mutex_unlock (&filter->lock);
+      break;
+    }
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+  }
+
+}
+
+static void gst_fastspectrum_get_property (GObject * object, guint prop_id, GValue * value, GParamSpec * pspec) {
+
+  GstFastSpectrum *filter = GST_FASTSPECTRUM (object);
+
+  switch (prop_id) {
+    case PROP_INTERVAL:
+      g_value_set_uint64 (value, filter->interval);
+      break;
+    case PROP_BANDS:
+      g_value_set_uint (value, filter->bands);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+  }
+
+}
+
+static gboolean gst_fastspectrum_start (GstBaseTransform * trans) {
+
+  GstFastSpectrum *spectrum = GST_FASTSPECTRUM (trans);
+
+  gst_fastspectrum_reset_state (spectrum);
+
+  return TRUE;
+
+}
+
+static gboolean gst_fastspectrum_stop (GstBaseTransform * trans) {
+
+  GstFastSpectrum *spectrum = GST_FASTSPECTRUM (trans);
+
+  gst_fastspectrum_reset_state (spectrum);
+
+  return TRUE;
+
+}
+
+/* mixing data readers */
+
+static void input_data_mixed_float(const guint8* _in, double* out, guint len, double max_value, guint op, guint nfft) {
+
+  guint j, ip = 0;
+  gfloat *in = (gfloat *) _in;
+
+  for (j = 0; j < len; j++) {
+    out[op] = in[ip++];
+    op = (op + 1) % nfft;
+  }
+
+}
+
+static void input_data_mixed_double (const guint8 * _in, double* out, guint len, double max_value, guint op, guint nfft) {
+
+  guint j, ip = 0;
+  gdouble *in = (gdouble *) _in;
+
+  for (j = 0; j < len; j++) {
+    out[op] = in[ip++];
+    op = (op + 1) % nfft;
+  }
+
+}
+
+static void input_data_mixed_int32_max (const guint8 * _in, double* out, guint len, double max_value, guint op, guint nfft) {
+
+  guint j, ip = 0;
+  gint32 *in = (gint32 *) _in;
+
+  for (j = 0; j < len; j++) {
+    out[op] = in[ip++] / max_value;
+    op = (op + 1) % nfft;
+  }
+
+}
+
+static void input_data_mixed_int24_max (const guint8 * _in, double* out, guint len, double max_value, guint op, guint nfft) {
+
+  guint j;
+
+  for (j = 0; j < len; j++) {
+#if G_BYTE_ORDER == G_BIG_ENDIAN
+    gint32 value = GST_READ_UINT24_BE (_in);
+#else
+    gint32 value = GST_READ_UINT24_LE (_in);
+#endif
+    if (value & 0x00800000)
+      value |= 0xff000000;
+
+    out[op] = value / max_value;
+    op = (op + 1) % nfft;
+    _in += 3;
+  }
+
+}
+
+static void input_data_mixed_int16_max (const guint8 * _in, double * out, guint len, double max_value, guint op, guint nfft) {
+
+  guint j, ip = 0;
+  gint16 *in = (gint16 *) _in;
+
+  for (j = 0; j < len; j++) {
+    out[op] = in[ip++] / max_value;
+    op = (op + 1) % nfft;
+  }
+
+}
+
+static gboolean gst_fastspectrum_setup (GstAudioFilter * base, const GstAudioInfo * info) {
+
+  GstFastSpectrum *spectrum = GST_FASTSPECTRUM (base);
+  GstFastSpectrumInputData input_data = NULL;
+
+  g_mutex_lock (&spectrum->lock);
+  switch (GST_AUDIO_INFO_FORMAT (info)) {
+    case GST_AUDIO_FORMAT_S16:
+      input_data = input_data_mixed_int16_max;
+      break;
+    case GST_AUDIO_FORMAT_S24:
+      input_data = input_data_mixed_int24_max;
+      break;
+    case GST_AUDIO_FORMAT_S32:
+      input_data = input_data_mixed_int32_max;
+      break;
+    case GST_AUDIO_FORMAT_F32:
+      input_data = input_data_mixed_float;
+      break;
+    case GST_AUDIO_FORMAT_F64:
+      input_data = input_data_mixed_double;
+      break;
+    default:
+      g_assert_not_reached ();
+      break;
+  }
+  spectrum->input_data = input_data;
+
+  gst_fastspectrum_reset_state (spectrum);
+  g_mutex_unlock (&spectrum->lock);
+
+  return TRUE;
+
+}
+
+static void gst_fastspectrum_run_fft (GstFastSpectrum * spectrum, guint input_pos) {
+
+  guint i;
+  guint bands = spectrum->bands;
+  guint nfft = 2 * bands - 2;
+
+  for (i = 0; i < nfft; i++)
+    spectrum->fft_input[i] =
+        spectrum->input_ring_buffer[(input_pos + i) % nfft];
+
+  // Should be safe to execute the same plan multiple times in parallel.
+  fftw_execute(spectrum->plan);
+
+  gdouble val;
+  /* Calculate magnitude in db */
+  for (i = 0; i < bands; i++) {
+    val = spectrum->fft_output[i][0] * spectrum->fft_output[i][0];
+    val += spectrum->fft_output[i][1] * spectrum->fft_output[i][1];
+    val /= nfft * nfft;
+    spectrum->spect_magnitude[i] += val;
+  }
+
+}
+
+static GstFlowReturn gst_fastspectrum_transform_ip (GstBaseTransform * trans, GstBuffer * buffer) {
+
+  GstFastSpectrum *spectrum = GST_FASTSPECTRUM (trans);
+  guint rate = GST_AUDIO_FILTER_RATE (spectrum);
+  guint bps = GST_AUDIO_FILTER_BPS (spectrum);
+  guint bpf = GST_AUDIO_FILTER_BPF (spectrum);
+  double max_value = (1UL << ((bps << 3) - 1)) - 1;
+  guint bands = spectrum->bands;
+  guint nfft = 2 * bands - 2;
+  guint input_pos;
+  GstMapInfo map;
+  const guint8 *data;
+  gsize size;
+  guint fft_todo, msg_todo, block_size;
+  gboolean have_full_interval;
+  GstFastSpectrumInputData input_data;
+
+  g_mutex_lock (&spectrum->lock);
+  gst_buffer_map (buffer, &map, GST_MAP_READ);
+  data = map.data;
+  size = map.size;
+
+  GST_LOG_OBJECT (spectrum, "input size: %" G_GSIZE_FORMAT " bytes", size);
+
+  if (GST_BUFFER_IS_DISCONT (buffer)) {
+    GST_DEBUG_OBJECT (spectrum, "Discontinuity detected -- flushing");
+    gst_fastspectrum_flush (spectrum);
+  }
+
+  /* If we don't have a FFT context yet (or it was reset due to parameter
+   * changes) get one and allocate memory for everything
+   */
+  if (!spectrum->channel_data_initialised) {
+    GST_DEBUG_OBJECT (spectrum, "allocating for bands %u", bands);
+
+    gst_fastspectrum_alloc_channel_data (spectrum);
+
+    /* number of sample frames we process before posting a message
+     * interval is in ns */
+    spectrum->frames_per_interval = gst_util_uint64_scale (spectrum->interval, rate, GST_SECOND);
+    spectrum->frames_todo = spectrum->frames_per_interval;
+    /* rounding error for frames_per_interval in ns,
+     * aggregated it in accumulated_error */
+    spectrum->error_per_interval = (spectrum->interval * rate) % GST_SECOND;
+    if (spectrum->frames_per_interval == 0)
+      spectrum->frames_per_interval = 1;
+
+    GST_INFO_OBJECT (spectrum, "interval %" GST_TIME_FORMAT ", fpi %"
+        G_GUINT64_FORMAT ", error %" GST_TIME_FORMAT,
+        GST_TIME_ARGS (spectrum->interval), spectrum->frames_per_interval,
+        GST_TIME_ARGS (spectrum->error_per_interval));
+
+    spectrum->input_pos = 0;
+
+    gst_fastspectrum_flush (spectrum);
+  }
+
+  if (spectrum->num_frames == 0)
+    spectrum->message_ts = GST_BUFFER_TIMESTAMP (buffer);
+
+  input_pos = spectrum->input_pos;
+  input_data = spectrum->input_data;
+
+  while (size >= bpf) {
+    /* run input_data for a chunk of data */
+    fft_todo = nfft - (spectrum->num_frames % nfft);
+    msg_todo = spectrum->frames_todo - spectrum->num_frames;
+    GST_LOG_OBJECT (spectrum,
+        "message frames todo: %u, fft frames todo: %u, input frames %"
+        G_GSIZE_FORMAT, msg_todo, fft_todo, (size / bpf));
+    block_size = msg_todo;
+    if (block_size > (size / bpf))
+      block_size = (size / bpf);
+    if (block_size > fft_todo)
+      block_size = fft_todo;
+
+    /* Move the current frames into our ringbuffers */
+    input_data(data, spectrum->input_ring_buffer, block_size, max_value, input_pos, nfft);
+
+    data += block_size * bpf;
+    size -= block_size * bpf;
+    input_pos = (input_pos + block_size) % nfft;
+    spectrum->num_frames += block_size;
+
+    have_full_interval = (spectrum->num_frames == spectrum->frames_todo);
+
+    GST_LOG_OBJECT (spectrum,
+        "size: %" G_GSIZE_FORMAT ", do-fft = %d, do-message = %d", size,
+        (spectrum->num_frames % nfft == 0), have_full_interval);
+
+    /* If we have enough frames for an FFT or we have all frames required for
+     * the interval and we haven't run a FFT, then run an FFT */
+    if ((spectrum->num_frames % nfft == 0) || (have_full_interval && !spectrum->num_fft)) {
+      gst_fastspectrum_run_fft (spectrum, input_pos);
+      spectrum->num_fft++;
+    }
+
+    /* Do we have the FFTs for one interval? */
+    if (have_full_interval) {
+      GST_DEBUG_OBJECT (spectrum, "nfft: %u frames: %" G_GUINT64_FORMAT
+          " fpi: %" G_GUINT64_FORMAT " error: %" GST_TIME_FORMAT, nfft,
+          spectrum->num_frames, spectrum->frames_per_interval,
+          GST_TIME_ARGS (spectrum->accumulated_error));
+
+      spectrum->frames_todo = spectrum->frames_per_interval;
+      if (spectrum->accumulated_error >= GST_SECOND) {
+        spectrum->accumulated_error -= GST_SECOND;
+        spectrum->frames_todo++;
+      }
+      spectrum->accumulated_error += spectrum->error_per_interval;
+
+      if (spectrum->output_callback) {
+        // Calculate average
+        for (guint i = 0; i < spectrum->bands; i++) {
+          spectrum->spect_magnitude[i] /= spectrum->num_fft;
+        }
+
+        spectrum->output_callback(spectrum->spect_magnitude, spectrum->bands);
+
+        // Reset spectrum accumulators
+        memset(spectrum->spect_magnitude, 0, spectrum->bands * sizeof(double));
+      }
+
+      if (GST_CLOCK_TIME_IS_VALID (spectrum->message_ts))
+        spectrum->message_ts += gst_util_uint64_scale (spectrum->num_frames, GST_SECOND, rate);
+
+      spectrum->num_frames = 0;
+      spectrum->num_fft = 0;
+    }
+  }
+
+  spectrum->input_pos = input_pos;
+
+  gst_buffer_unmap (buffer, &map);
+  g_mutex_unlock (&spectrum->lock);
+
+  g_assert (size == 0);
+
+  return GST_FLOW_OK;
+
+}
--- a/ext/gstmoodbar/gstfastspectrum.h
+++ b/ext/gstmoodbar/gstfastspectrum.h
@@ -0,0 +1,98 @@
+/* GStreamer
+ * Copyright (C) <1999> Erik Walthinsen <omega@cse.ogi.edu>
+ * Copyright (C) <2009> Sebastian Dröge <sebastian.droege@collabora.co.uk>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+// Adapted from gstspectrum for Clementine with the following changes:
+//   - Uses fftw instead of kiss fft (2x faster).
+//   - Hardcoded to 1 channel (use an audioconvert element to do the work
+//     instead, simplifies this code a lot).
+//   - Send output via a callback instead of GST messages (less overhead).
+//   - Removed all properties except interval and band.
+
+
+#ifndef GST_MOODBAR_FASTSPECTRUM_H_
+#define GST_MOODBAR_FASTSPECTRUM_H_
+
+#include <functional>
+
+#include <gst/gst.h>
+#include <gst/audio/gstaudiofilter.h>
+#include <fftw3.h>
+
+G_BEGIN_DECLS
+
+#define GST_TYPE_FASTSPECTRUM            (gst_fastspectrum_get_type())
+#define GST_FASTSPECTRUM(obj)            (G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_FASTSPECTRUM,GstFastSpectrum))
+#define GST_IS_FASTSPECTRUM(obj)         (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_FASTSPECTRUM))
+#define GST_FASTSPECTRUM_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST((klass), GST_TYPE_FASTSPECTRUM,GstFastSpectrumClass))
+#define GST_IS_FASTSPECTRUM_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE((klass), GST_TYPE_FASTSPECTRUM))
+
+class QMutex;
+
+typedef void (*GstFastSpectrumInputData)(const guint8* in, double* out,
+    guint len, double max_value, guint op, guint nfft);
+
+typedef std::function<void(double* magnitudes, int size)> OutputCallback;
+
+struct GstFastSpectrum {
+  GstAudioFilter parent;
+
+  /* properties */
+  guint64 interval;             /* how many nanoseconds between emits */
+  guint64 frames_per_interval;  /* how many frames per interval */
+  guint64 frames_todo;
+  guint bands;                  /* number of spectrum bands */
+  gboolean multi_channel;       /* send separate channel results */
+
+  guint64 num_frames;           /* frame count (1 sample per channel)
+                                 * since last emit */
+  guint64 num_fft;              /* number of FFTs since last emit */
+  GstClockTime message_ts;      /* starttime for next message */
+
+  /* <private> */
+  bool channel_data_initialised;
+  double* input_ring_buffer;
+  double* fft_input;
+  fftw_complex* fft_output;
+  double* spect_magnitude;
+  fftw_plan plan;
+
+  guint input_pos;
+  guint64 error_per_interval;
+  guint64 accumulated_error;
+
+  GMutex lock;
+
+  GstFastSpectrumInputData input_data;
+
+  OutputCallback output_callback;
+};
+
+struct GstFastSpectrumClass {
+  GstAudioFilterClass parent_class;
+
+  // Static lock for creating & destroying FFTW plans.
+  QMutex* fftw_lock;
+};
+
+GType gst_fastspectrum_get_type (void);
+
+G_END_DECLS
+
+#endif // GST_MOODBAR_FASTSPECTRUM_H_
--- a/ext/gstmoodbar/gstmoodbarplugin.cpp
+++ b/ext/gstmoodbar/gstmoodbarplugin.cpp
@@ -0,0 +1,50 @@
+/* This file was part of Clementine.
+   Copyright 2014, David Sansome <me@davidsansome.com>
+
+   Strawberry is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   Strawberry 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with Strawberry.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <gst/gst.h>
+
+#include "gstfastspectrum.h"
+#include "gstmoodbarplugin.h"
+
+namespace {
+
+static gboolean gst_moodbar_plugin_init(GstPlugin* plugin) {
+
+  if (!gst_element_register(plugin, "fastspectrum", GST_RANK_NONE, GST_TYPE_FASTSPECTRUM)) {
+    return FALSE;
+  }
+
+  return TRUE;
+
+}
+
+}  // namespace
+
+int gstfastspectrum_register_static() {
+
+  return gst_plugin_register_static(
+    GST_VERSION_MAJOR,
+    GST_VERSION_MINOR,
+    "fastspectrum",
+    "Fast spectrum analyzer for generating Moodbars",
+    gst_moodbar_plugin_init,
+    "0.1",
+    "GPL",
+    "FastSpectrum",
+    "FastSpectrum",
+    "https://www.strawbs.org");
+}
--- a/ext/gstmoodbar/gstmoodbarplugin.h
+++ b/ext/gstmoodbar/gstmoodbarplugin.h
@@ -0,0 +1,25 @@
+/* This file was part of Clementine.
+   Copyright 2014, David Sansome <me@davidsansome.com>
+
+   Strawberry is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   Strawberry 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with Strawberry.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef GST_MOODBAR_PLUGIN_H
+#define GST_MOODBAR_PLUGIN_H
+
+extern "C" {
+  int gstfastspectrum_register_static();
+}
+
+#endif  // GST_MOODBAR_PLUGIN_H