Add ReplayGain analysis element (#357069).

Original commit message from CVS:
Patch by: René Stadler  <mail at renestadler de>
* configure.ac:
* docs/plugins/Makefile.am:
* docs/plugins/gst-plugins-bad-plugins-docs.sgml:
* docs/plugins/gst-plugins-bad-plugins-sections.txt:
* gst/replaygain/Makefile.am:
* gst/replaygain/gstrganalysis.c: (gst_rg_analysis_base_init),
(gst_rg_analysis_class_init), (gst_rg_analysis_init),
(gst_rg_analysis_set_property), (gst_rg_analysis_get_property),
(gst_rg_analysis_start), (gst_rg_analysis_set_caps),
(gst_rg_analysis_transform_ip), (gst_rg_analysis_event),
(gst_rg_analysis_stop), (gst_rg_analysis_handle_tags),
(gst_rg_analysis_handle_eos), (gst_rg_analysis_track_result),
(gst_rg_analysis_album_result), (plugin_init):
* gst/replaygain/gstrganalysis.h:
* gst/replaygain/rganalysis.c: (yule_filter), (butter_filter),
(apply_filters), (reset_filters), (accumulator_add),
(accumulator_clear), (accumulator_result), (rg_analysis_new),
(rg_analysis_set_sample_rate), (rg_analysis_destroy),
(rg_analysis_analyze_mono_float),
(rg_analysis_analyze_stereo_float),
(rg_analysis_analyze_mono_int16),
(rg_analysis_analyze_stereo_int16), (rg_analysis_analyze),
(rg_analysis_track_result), (rg_analysis_album_result),
(rg_analysis_reset_album), (rg_analysis_reset):
* gst/replaygain/rganalysis.h:
Add ReplayGain analysis element (#357069).
* tests/check/Makefile.am:
* tests/check/elements/.cvsignore:
* tests/check/elements/rganalysis.c: (get_expected_gain),
(setup_rganalysis), (cleanup_rganalysis), (set_playing_state),
(send_eos_event), (send_tag_event), (poll_eos), (poll_tags),
(fail_unless_track_gain), (fail_unless_track_peak),
(fail_unless_album_gain), (fail_unless_album_peak),
(fail_if_track_tags), (fail_if_album_tags),
(fail_unless_num_tracks), (test_buffer_const_float_mono),
(test_buffer_const_float_stereo), (test_buffer_const_int16_mono),
(test_buffer_const_int16_stereo), (test_buffer_square_float_mono),
(test_buffer_square_float_stereo), (test_buffer_square_int16_mono),
(test_buffer_square_int16_stereo), (push_buffer), (GST_START_TEST),
(rganalysis_suite), (main):
Unit tests for the new replaygain element.

1 files changed, 772 insertions, 0 deletions

diff --git a/gst/replaygain/rganalysis.c b/gst/replaygain/rganalysis.c
new file mode 100644
index 00000000..b20a08f5
--- /dev/null
+++ b/gst/replaygain/rganalysis.c
@@ -0,0 +1,772 @@
+/* GStreamer ReplayGain analysis
+ *
+ * Copyright (C) 2006 Rene Stadler <mail@renestadler.de>
+ * Copyright (C) 2001 David Robinson <David@Robinson.org>
+ *                    Glen Sawyer <glensawyer@hotmail.com>
+ *
+ * rganalysis.c: Analyze raw audio data in accordance with ReplayGain
+ *
+ * This library 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.
+ * 
+ * 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
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+/* Based on code with Copyright (C) 2001 David Robinson
+ * <David@Robinson.org> and Glen Sawyer <glensawyer@hotmail.com>,
+ * which is distributed under the LGPL as part of the vorbisgain
+ * program.  The original code also mentions Frank Klemm
+ * (http://www.uni-jena.de/~pfk/mpp/) for having contributed lots of
+ * good code.  Specifically, this is based on the file
+ * "gain_analysis.c" from vorbisgain version 0.34.
+ */
+
+/* Room for future improvement: Mono data is currently in fact copied
+ * to two channels which get processed normally.  This means that mono
+ * input data is processed twice.
+ */
+
+/* Helpful information for understanding this code: The two IIR
+ * filters depend on previous input _and_ previous output samples (up
+ * to the filter's order number of samples).  This explains the whole
+ * lot of memcpy'ing done in rg_analysis_analyze and why the context
+ * holds so many buffers.
+ */
+
+#include <math.h>
+#include <string.h>
+#include <glib.h>
+
+#include "rganalysis.h"
+
+#define YULE_ORDER         10
+#define BUTTER_ORDER        2
+/* Percentile which is louder than the proposed level: */
+#define RMS_PERCENTILE     95
+/* Duration of RMS window in milliseconds: */
+#define RMS_WINDOW_MSECS   50
+/* Histogram array elements per dB: */
+#define STEPS_PER_DB      100
+/* Histogram upper bound in dB (normal max. values in the wild are
+ * assumed to be around 70, 80 dB): */
+#define MAX_DB            120
+/* Calibration value: */
+#define PINK_REF           64.82        /* 298640883795 */
+
+#define MAX_ORDER         MAX (BUTTER_ORDER, YULE_ORDER)
+#define MAX_SAMPLE_RATE   48000
+/* The + 999 has the effect of ceil()ing: */
+#define MAX_SAMPLE_WINDOW (guint) \
+  ((MAX_SAMPLE_RATE * RMS_WINDOW_MSECS + 999) / 1000)
+
+/* Analysis result accumulator. */
+
+struct _RgAnalysisAcc
+{
+  guint32 histogram[STEPS_PER_DB * MAX_DB];
+  gdouble peak;
+};
+
+typedef struct _RgAnalysisAcc RgAnalysisAcc;
+
+/* Analysis context. */
+
+struct _RgAnalysisCtx
+{
+  /* Filter buffers for left channel. */
+  gfloat inprebuf_l[MAX_ORDER * 2];
+  gfloat *inpre_l;
+  gfloat stepbuf_l[MAX_SAMPLE_WINDOW + MAX_ORDER];
+  gfloat *step_l;
+  gfloat outbuf_l[MAX_SAMPLE_WINDOW + MAX_ORDER];
+  gfloat *out_l;
+  /* Filter buffers for right channel. */
+  gfloat inprebuf_r[MAX_ORDER * 2];
+  gfloat *inpre_r;
+  gfloat stepbuf_r[MAX_SAMPLE_WINDOW + MAX_ORDER];
+  gfloat *step_r;
+  gfloat outbuf_r[MAX_SAMPLE_WINDOW + MAX_ORDER];
+  gfloat *out_r;
+
+  /* Number of samples to reach duration of the RMS window: */
+  guint window_n_samples;
+  /* Progress of the running window: */
+  guint window_n_samples_done;
+  gdouble window_square_sum;
+
+  gint sample_rate;
+  gint sample_rate_index;
+
+  RgAnalysisAcc track;
+  RgAnalysisAcc album;
+};
+
+/* Filter coefficients for the IIR filters that form the equal
+ * loudness filter.  XFilter[ctx->sample_rate_index] gives the array
+ * of the X coefficients (A or B) for the configured sample rate. */
+
+#ifdef G_OS_WIN32
+/* Disable double-to-float warning: */
+#pragma warning ( disable : 4305 )
+#endif
+
+static const gfloat AYule[9][11] = {
+  {1., -3.84664617118067, 7.81501653005538, -11.34170355132042,
+        13.05504219327545, -12.28759895145294, 9.48293806319790,
+        -5.87257861775999, 2.75465861874613, -0.86984376593551,
+      0.13919314567432},
+  {1., -3.47845948550071, 6.36317777566148, -8.54751527471874, 9.47693607801280,
+        -8.81498681370155, 6.85401540936998, -4.39470996079559,
+      2.19611684890774, -0.75104302451432, 0.13149317958808},
+  {1., -2.37898834973084, 2.84868151156327, -2.64577170229825, 2.23697657451713,
+        -1.67148153367602, 1.00595954808547, -0.45953458054983,
+      0.16378164858596, -0.05032077717131, 0.02347897407020},
+  {1., -1.61273165137247, 1.07977492259970, -0.25656257754070,
+        -0.16276719120440, -0.22638893773906, 0.39120800788284,
+        -0.22138138954925, 0.04500235387352, 0.02005851806501,
+      0.00302439095741},
+  {1., -1.49858979367799, 0.87350271418188, 0.12205022308084, -0.80774944671438,
+        0.47854794562326, -0.12453458140019, -0.04067510197014,
+      0.08333755284107, -0.04237348025746, 0.02977207319925},
+  {1., -0.62820619233671, 0.29661783706366, -0.37256372942400, 0.00213767857124,
+        -0.42029820170918, 0.22199650564824, 0.00613424350682, 0.06747620744683,
+      0.05784820375801, 0.03222754072173},
+  {1., -1.04800335126349, 0.29156311971249, -0.26806001042947, 0.00819999645858,
+        0.45054734505008, -0.33032403314006, 0.06739368333110,
+      -0.04784254229033, 0.01639907836189, 0.01807364323573},
+  {1., -0.51035327095184, -0.31863563325245, -0.20256413484477,
+        0.14728154134330, 0.38952639978999, -0.23313271880868,
+        -0.05246019024463, -0.02505961724053, 0.02442357316099,
+      0.01818801111503},
+  {1., -0.25049871956020, -0.43193942311114, -0.03424681017675,
+        -0.04678328784242, 0.26408300200955, 0.15113130533216,
+        -0.17556493366449, -0.18823009262115, 0.05477720428674,
+      0.04704409688120}
+};
+
+static const gfloat BYule[9][11] = {
+  {0.03857599435200, -0.02160367184185, -0.00123395316851, -0.00009291677959,
+        -0.01655260341619, 0.02161526843274, -0.02074045215285,
+      0.00594298065125, 0.00306428023191, 0.00012025322027, 0.00288463683916},
+  {0.05418656406430, -0.02911007808948, -0.00848709379851, -0.00851165645469,
+        -0.00834990904936, 0.02245293253339, -0.02596338512915,
+        0.01624864962975, -0.00240879051584, 0.00674613682247,
+      -0.00187763777362},
+  {0.15457299681924, -0.09331049056315, -0.06247880153653, 0.02163541888798,
+        -0.05588393329856, 0.04781476674921, 0.00222312597743, 0.03174092540049,
+      -0.01390589421898, 0.00651420667831, -0.00881362733839},
+  {0.30296907319327, -0.22613988682123, -0.08587323730772, 0.03282930172664,
+        -0.00915702933434, -0.02364141202522, -0.00584456039913,
+        0.06276101321749, -0.00000828086748, 0.00205861885564,
+      -0.02950134983287},
+  {0.33642304856132, -0.25572241425570, -0.11828570177555, 0.11921148675203,
+        -0.07834489609479, -0.00469977914380, -0.00589500224440,
+        0.05724228140351, 0.00832043980773, -0.01635381384540,
+      -0.01760176568150},
+  {0.44915256608450, -0.14351757464547, -0.22784394429749, -0.01419140100551,
+        0.04078262797139, -0.12398163381748, 0.04097565135648, 0.10478503600251,
+      -0.01863887810927, -0.03193428438915, 0.00541907748707},
+  {0.56619470757641, -0.75464456939302, 0.16242137742230, 0.16744243493672,
+        -0.18901604199609, 0.30931782841830, -0.27562961986224,
+        0.00647310677246, 0.08647503780351, -0.03788984554840,
+      -0.00588215443421},
+  {0.58100494960553, -0.53174909058578, -0.14289799034253, 0.17520704835522,
+        0.02377945217615, 0.15558449135573, -0.25344790059353, 0.01628462406333,
+      0.06920467763959, -0.03721611395801, -0.00749618797172},
+  {0.53648789255105, -0.42163034350696, -0.00275953611929, 0.04267842219415,
+        -0.10214864179676, 0.14590772289388, -0.02459864859345,
+        -0.11202315195388, -0.04060034127000, 0.04788665548180,
+      -0.02217936801134}
+};
+
+static const gfloat AButter[9][3] = {
+  {1., -1.97223372919527, 0.97261396931306},
+  {1., -1.96977855582618, 0.97022847566350},
+  {1., -1.95835380975398, 0.95920349965459},
+  {1., -1.95002759149878, 0.95124613669835},
+  {1., -1.94561023566527, 0.94705070426118},
+  {1., -1.92783286977036, 0.93034775234268},
+  {1., -1.91858953033784, 0.92177618768381},
+  {1., -1.91542108074780, 0.91885558323625},
+  {1., -1.88903307939452, 0.89487434461664}
+};
+
+static const gfloat BButter[9][3] = {
+  {0.98621192462708, -1.97242384925416, 0.98621192462708},
+  {0.98500175787242, -1.97000351574484, 0.98500175787242},
+  {0.97938932735214, -1.95877865470428, 0.97938932735214},
+  {0.97531843204928, -1.95063686409857, 0.97531843204928},
+  {0.97316523498161, -1.94633046996323, 0.97316523498161},
+  {0.96454515552826, -1.92909031105652, 0.96454515552826},
+  {0.96009142950541, -1.92018285901082, 0.96009142950541},
+  {0.95856916599601, -1.91713833199203, 0.95856916599601},
+  {0.94597685600279, -1.89195371200558, 0.94597685600279}
+};
+
+#ifdef G_OS_WIN32
+#pragma warning ( default : 4305 )
+#endif
+
+/* Filter functions.  These access elements with negative indices of
+ * the input and output arrays (up to the filter's order). */
+
+/* For much better performance, the function below has been
+ * implemented by unrolling the inner loop for our two use cases. */
+
+/*
+ * static inline void
+ * apply_filter (const gfloat * input, gfloat * output, guint n_samples,
+ *     const gfloat * a, const gfloat * b, guint order)
+ * {
+ *   gfloat y;
+ *   gint i, k;
+ * 
+ *   for (i = 0; i < n_samples; i++) {
+ *     y = input[i] * b[0];
+ *     for (k = 1; k <= order; k++)
+ *       y += input[i - k] * b[k] - output[i - k] * a[k];
+ *     output[i] = y;
+ *   }
+ * }
+ */
+
+static inline void
+yule_filter (const gfloat * input, gfloat * output,
+    const gfloat * a, const gfloat * b)
+{
+  output[0] = input[0] * b[0]
+      + input[-1] * b[1] - output[-1] * a[1]
+      + input[-2] * b[2] - output[-2] * a[2]
+      + input[-3] * b[3] - output[-3] * a[3]
+      + input[-4] * b[4] - output[-4] * a[4]
+      + input[-5] * b[5] - output[-5] * a[5]
+      + input[-6] * b[6] - output[-6] * a[6]
+      + input[-7] * b[7] - output[-7] * a[7]
+      + input[-8] * b[8] - output[-8] * a[8]
+      + input[-9] * b[9] - output[-9] * a[9]
+      + input[-10] * b[10] - output[-10] * a[10];
+}
+
+static inline void
+butter_filter (const gfloat * input, gfloat * output,
+    const gfloat * a, const gfloat * b)
+{
+  output[0] = input[0] * b[0]
+      + input[-1] * b[1] - output[-1] * a[1]
+      + input[-2] * b[2] - output[-2] * a[2];
+}
+
+/* Because butter_filter and yule_filter are inlined, this function is
+ * a bit blown-up (code-size wise), but not inlining gives a ca. 40%
+ * performance penalty. */
+
+static inline void
+apply_filters (const RgAnalysisCtx * ctx, const gfloat * input_l,
+    const gfloat * input_r, guint n_samples)
+{
+  const gfloat *ayule = AYule[ctx->sample_rate_index];
+  const gfloat *byule = BYule[ctx->sample_rate_index];
+  const gfloat *abutter = AButter[ctx->sample_rate_index];
+  const gfloat *bbutter = BButter[ctx->sample_rate_index];
+  gint pos = ctx->window_n_samples_done;
+  gint i;
+
+  for (i = 0; i < n_samples; i++, pos++) {
+    yule_filter (input_l + i, ctx->step_l + pos, ayule, byule);
+    butter_filter (ctx->step_l + pos, ctx->out_l + pos, abutter, bbutter);
+
+    yule_filter (input_r + i, ctx->step_r + pos, ayule, byule);
+    butter_filter (ctx->step_r + pos, ctx->out_r + pos, abutter, bbutter);
+  }
+}
+
+/* Clear filter buffer state and current RMS window. */
+
+static void
+reset_filters (RgAnalysisCtx * ctx)
+{
+  gint i;
+
+  for (i = 0; i < MAX_ORDER; i++) {
+
+    ctx->inprebuf_l[i] = 0.;
+    ctx->stepbuf_l[i] = 0.;
+    ctx->outbuf_l[i] = 0.;
+
+    ctx->inprebuf_r[i] = 0.;
+    ctx->stepbuf_r[i] = 0.;
+    ctx->outbuf_r[i] = 0.;
+  }
+
+  ctx->window_square_sum = 0.;
+  ctx->window_n_samples_done = 0;
+}
+
+/* Accumulator functions. */
+
+/* Add two accumulators in-place.  The sum is defined as the result of
+ * the vector sum of the histogram array and the maximum value of the
+ * peak field.  Thus "adding" the accumulators for all tracks yields
+ * the correct result for obtaining the album gain and peak. */
+
+static void
+accumulator_add (RgAnalysisAcc * acc, const RgAnalysisAcc * acc_other)
+{
+  gint i;
+
+  for (i = 0; i < G_N_ELEMENTS (acc->histogram); i++)
+    acc->histogram[i] += acc_other->histogram[i];
+
+  acc->peak = MAX (acc->peak, acc_other->peak);
+}
+
+/* Reset an accumulator to zero. */
+
+static void
+accumulator_clear (RgAnalysisAcc * acc)
+{
+  memset (acc->histogram, 0, sizeof (acc->histogram));
+  acc->peak = 0.;
+}
+
+/* Obtain final analysis result from an accumulator.  Returns TRUE on
+ * success, FALSE on error (if accumulator is still zero). */
+
+static gboolean
+accumulator_result (const RgAnalysisAcc * acc, gdouble * result_gain,
+    gdouble * result_peak)
+{
+  guint32 sum = 0;
+  guint32 upper;
+  guint i;
+
+  for (i = 0; i < G_N_ELEMENTS (acc->histogram); i++)
+    sum += acc->histogram[i];
+
+  if (sum == 0)
+    /* All entries are 0: We got less than 50ms of data. */
+    return FALSE;
+
+  upper = (guint32) ceil (sum * (1. - (gdouble) (RMS_PERCENTILE / 100.)));
+
+  for (i = G_N_ELEMENTS (acc->histogram); i--;) {
+    if (upper <= acc->histogram[i])
+      break;
+    upper -= acc->histogram[i];
+  }
+
+  if (result_peak != NULL)
+    *result_peak = acc->peak;
+  if (result_gain != NULL)
+    *result_gain = PINK_REF - (gdouble) i / STEPS_PER_DB;
+
+  return TRUE;
+}
+
+/* Functions that operate on contexts, for external usage. */
+
+/* Create a new context.  Before it can be used, a sample rate must be
+ * configured using rg_analysis_set_sample_rate. */
+
+RgAnalysisCtx *
+rg_analysis_new (void)
+{
+  RgAnalysisCtx *ctx;
+
+  ctx = g_new (RgAnalysisCtx, 1);
+
+  ctx->inpre_l = ctx->inprebuf_l + MAX_ORDER;
+  ctx->step_l = ctx->stepbuf_l + MAX_ORDER;
+  ctx->out_l = ctx->outbuf_l + MAX_ORDER;
+
+  ctx->inpre_r = ctx->inprebuf_r + MAX_ORDER;
+  ctx->step_r = ctx->stepbuf_r + MAX_ORDER;
+  ctx->out_r = ctx->outbuf_r + MAX_ORDER;
+
+  ctx->sample_rate = 0;
+
+  accumulator_clear (&ctx->track);
+  accumulator_clear (&ctx->album);
+
+  return ctx;
+}
+
+/* Adapt to given sample rate.  Does nothing if already the current
+ * rate (returns TRUE then).  Returns FALSE only if given sample rate
+ * is not supported.  If the configured rate changes, the last
+ * unprocessed incomplete 50ms chunk of data is dropped because the
+ * filters are reset. */
+
+gboolean
+rg_analysis_set_sample_rate (RgAnalysisCtx * ctx, gint sample_rate)
+{
+  g_return_val_if_fail (ctx != NULL, FALSE);
+
+  if (ctx->sample_rate == sample_rate)
+    return TRUE;
+
+  switch (sample_rate) {
+    case 48000:
+      ctx->sample_rate_index = 0;
+      break;
+    case 44100:
+      ctx->sample_rate_index = 1;
+      break;
+    case 32000:
+      ctx->sample_rate_index = 2;
+      break;
+    case 24000:
+      ctx->sample_rate_index = 3;
+      break;
+    case 22050:
+      ctx->sample_rate_index = 4;
+      break;
+    case 16000:
+      ctx->sample_rate_index = 5;
+      break;
+    case 12000:
+      ctx->sample_rate_index = 6;
+      break;
+    case 11025:
+      ctx->sample_rate_index = 7;
+      break;
+    case 8000:
+      ctx->sample_rate_index = 8;
+      break;
+    default:
+      return FALSE;
+  }
+
+  ctx->sample_rate = sample_rate;
+  /* The + 999 has the effect of ceil()ing: */
+  ctx->window_n_samples = (guint) ((sample_rate * RMS_WINDOW_MSECS + 999)
+      / 1000);
+
+  reset_filters (ctx);
+
+  return TRUE;
+}
+
+void
+rg_analysis_destroy (RgAnalysisCtx * ctx)
+{
+  g_free (ctx);
+}
+
+/* Entry points for analyzing sample data in common raw data formats.
+ * The stereo format functions expect interleaved frames.  It is
+ * possible to pass data in different formats for the same context,
+ * there are no restrictions.  All functions have the same signature;
+ * the depth argument for the float functions is not variable and must
+ * be given the value 32. */
+
+void
+rg_analysis_analyze_mono_float (RgAnalysisCtx * ctx, gconstpointer data,
+    gsize size, guint depth)
+{
+  gfloat conv_samples[512];
+  const gfloat *samples = (gfloat *) data;
+  guint n_samples = size / sizeof (gfloat);
+  gint i;
+
+  g_return_if_fail (depth == 32);
+  g_return_if_fail (size % sizeof (gfloat) == 0);
+
+  while (n_samples) {
+    gint n = MIN (n_samples, G_N_ELEMENTS (conv_samples));
+
+    n_samples -= n;
+    memcpy (conv_samples, samples, n * sizeof (gfloat));
+    for (i = 0; i < n; i++) {
+      ctx->track.peak = MAX (ctx->track.peak, fabs (conv_samples[i]));
+      conv_samples[i] *= 32768.;
+    }
+    samples += n;
+    rg_analysis_analyze (ctx, conv_samples, NULL, n);
+  }
+}
+
+void
+rg_analysis_analyze_stereo_float (RgAnalysisCtx * ctx, gconstpointer data,
+    gsize size, guint depth)
+{
+  gfloat conv_samples_l[256];
+  gfloat conv_samples_r[256];
+  const gfloat *samples = (gfloat *) data;
+  guint n_frames = size / (sizeof (gfloat) * 2);
+  gint i;
+
+  g_return_if_fail (depth == 32);
+  g_return_if_fail (size % (sizeof (gfloat) * 2) == 0);
+
+  while (n_frames) {
+    gint n = MIN (n_frames, G_N_ELEMENTS (conv_samples_l));
+
+    n_frames -= n;
+    for (i = 0; i < n; i++) {
+      gfloat old_sample;
+
+      old_sample = samples[2 * i];
+      ctx->track.peak = MAX (ctx->track.peak, fabs (old_sample));
+      conv_samples_l[i] = old_sample * 32768.;
+
+      old_sample = samples[2 * i + 1];
+      ctx->track.peak = MAX (ctx->track.peak, fabs (old_sample));
+      conv_samples_r[i] = old_sample * 32768.;
+    }
+    samples += 2 * n;
+    rg_analysis_analyze (ctx, conv_samples_l, conv_samples_r, n);
+  }
+}
+
+void
+rg_analysis_analyze_mono_int16 (RgAnalysisCtx * ctx, gconstpointer data,
+    gsize size, guint depth)
+{
+  gfloat conv_samples[512];
+  gint32 peak_sample = 0;
+  const gint16 *samples = (gint16 *) data;
+  guint n_samples = size / sizeof (gint16);
+  gint shift = sizeof (gint16) * 8 - depth;
+  gint i;
+
+  g_return_if_fail (depth <= (sizeof (gint16) * 8));
+  g_return_if_fail (size % sizeof (gint16) == 0);
+
+  while (n_samples) {
+    gint n = MIN (n_samples, G_N_ELEMENTS (conv_samples));
+
+    n_samples -= n;
+    for (i = 0; i < n; i++) {
+      gint16 old_sample = samples[i] << shift;
+
+      peak_sample = MAX (peak_sample, ABS ((gint32) old_sample));
+      conv_samples[i] = (gfloat) old_sample;
+    }
+    samples += n;
+    rg_analysis_analyze (ctx, conv_samples, NULL, n);
+  }
+  ctx->track.peak = MAX (ctx->track.peak,
+      (gdouble) peak_sample / ((gdouble) (1u << 15)));
+}
+
+void
+rg_analysis_analyze_stereo_int16 (RgAnalysisCtx * ctx, gconstpointer data,
+    gsize size, guint depth)
+{
+  gfloat conv_samples_l[256];
+  gfloat conv_samples_r[256];
+  gint32 peak_sample = 0;
+  const gint16 *samples = (gint16 *) data;
+  guint n_frames = size / (sizeof (gint16) * 2);
+  gint shift = sizeof (gint16) * 8 - depth;
+  gint i;
+
+  g_return_if_fail (depth <= (sizeof (gint16) * 8));
+  g_return_if_fail (size % (sizeof (gint16) * 2) == 0);
+
+  while (n_frames) {
+    gint n = MIN (n_frames, G_N_ELEMENTS (conv_samples_l));
+
+    n_frames -= n;
+    for (i = 0; i < n; i++) {
+      gint16 old_sample;
+
+      old_sample = samples[2 * i] << shift;
+      peak_sample = MAX (peak_sample, ABS ((gint32) old_sample));
+      conv_samples_l[i] = (gfloat) old_sample;
+
+      old_sample = samples[2 * i + 1] << shift;
+      peak_sample = MAX (peak_sample, ABS ((gint32) old_sample));
+      conv_samples_r[i] = (gfloat) old_sample;
+    }
+    samples += 2 * n;
+    rg_analysis_analyze (ctx, conv_samples_l, conv_samples_r, n);
+  }
+  ctx->track.peak = MAX (ctx->track.peak,
+      (gdouble) peak_sample / ((gdouble) (1u << 15)));
+}
+
+/* Analyze the given chunk of samples.  The sample data is given in
+ * floating point format but should be scaled such that the values
+ * +/-32768.0 correspond to the -0dBFS reference amplitude.
+ *
+ * samples_l: Buffer with sample data for the left channel or of the
+ * mono channel.
+ *
+ * samples_r: Buffer with sample data for the right channel or NULL
+ * for mono.
+ *
+ * n_samples: Number of samples passed in each buffer.
+ */
+
+void
+rg_analysis_analyze (RgAnalysisCtx * ctx, const gfloat * samples_l,
+    const gfloat * samples_r, guint n_samples)
+{
+  const gfloat *input_l, *input_r;
+  guint n_samples_done;
+  gint i;
+
+  g_return_if_fail (ctx != NULL);
+  g_return_if_fail (samples_l != NULL);
+  g_return_if_fail (ctx->sample_rate != 0);
+
+  if (n_samples == 0)
+    return;
+
+  if (samples_r == NULL)
+    /* Mono. */
+    samples_r = samples_l;
+
+  memcpy (ctx->inpre_l, samples_l,
+      MIN (n_samples, MAX_ORDER) * sizeof (gfloat));
+  memcpy (ctx->inpre_r, samples_r,
+      MIN (n_samples, MAX_ORDER) * sizeof (gfloat));
+
+  n_samples_done = 0;
+  while (n_samples_done < n_samples) {
+    /* Limit number of samples to be processed in this iteration to
+     * the number needed to complete the next window: */
+    guint n_samples_current = MIN (n_samples - n_samples_done,
+        ctx->window_n_samples - ctx->window_n_samples_done);
+
+    if (n_samples_done < MAX_ORDER) {
+      input_l = ctx->inpre_l + n_samples_done;
+      input_r = ctx->inpre_r + n_samples_done;
+      n_samples_current = MIN (n_samples_current, MAX_ORDER - n_samples_done);
+    } else {
+      input_l = samples_l + n_samples_done;
+      input_r = samples_r + n_samples_done;
+    }
+
+    apply_filters (ctx, input_l, input_r, n_samples_current);
+
+    /* Update the square sum. */
+    for (i = 0; i < n_samples_current; i++)
+      ctx->window_square_sum += ctx->out_l[ctx->window_n_samples_done + i]
+          * ctx->out_l[ctx->window_n_samples_done + i]
+          + ctx->out_r[ctx->window_n_samples_done + i]
+          * ctx->out_r[ctx->window_n_samples_done + i];
+
+    ctx->window_n_samples_done += n_samples_current;
+
+    g_return_if_fail (ctx->window_n_samples_done <= ctx->window_n_samples);
+
+    if (ctx->window_n_samples_done == ctx->window_n_samples) {
+      /* Get the Root Mean Square (RMS) for this set of samples. */
+      gdouble val = STEPS_PER_DB * 10. * log10 (ctx->window_square_sum /
+          ctx->window_n_samples * 0.5 + 1.e-37);
+      gint ival = CLAMP ((gint) val, 0,
+          (gint) G_N_ELEMENTS (ctx->track.histogram) - 1);
+
+      ctx->track.histogram[ival]++;
+      ctx->window_square_sum = 0.;
+      ctx->window_n_samples_done = 0;
+
+      /* No need for memmove here, the areas never overlap: Even for
+       * the smallest sample rate, the number of samples needed for
+       * the window is greater than MAX_ORDER. */
+
+      memcpy (ctx->stepbuf_l, ctx->stepbuf_l + ctx->window_n_samples,
+          MAX_ORDER * sizeof (gfloat));
+      memcpy (ctx->outbuf_l, ctx->outbuf_l + ctx->window_n_samples,
+          MAX_ORDER * sizeof (gfloat));
+
+      memcpy (ctx->stepbuf_r, ctx->stepbuf_r + ctx->window_n_samples,
+          MAX_ORDER * sizeof (gfloat));
+      memcpy (ctx->outbuf_r, ctx->outbuf_r + ctx->window_n_samples,
+          MAX_ORDER * sizeof (gfloat));
+    }
+
+    n_samples_done += n_samples_current;
+  }
+
+  if (n_samples >= MAX_ORDER) {
+
+    memcpy (ctx->inprebuf_l, samples_l + n_samples - MAX_ORDER,
+        MAX_ORDER * sizeof (gfloat));
+
+    memcpy (ctx->inprebuf_r, samples_r + n_samples - MAX_ORDER,
+        MAX_ORDER * sizeof (gfloat));
+
+  } else {
+
+    memmove (ctx->inprebuf_l, ctx->inprebuf_l + n_samples,
+        (MAX_ORDER - n_samples) * sizeof (gfloat));
+    memcpy (ctx->inprebuf_l + MAX_ORDER - n_samples, samples_l,
+        n_samples * sizeof (gfloat));
+
+    memmove (ctx->inprebuf_r, ctx->inprebuf_r + n_samples,
+        (MAX_ORDER - n_samples) * sizeof (gfloat));
+    memcpy (ctx->inprebuf_r + MAX_ORDER - n_samples, samples_r,
+        n_samples * sizeof (gfloat));
+
+  }
+}
+
+/* Obtain track gain and peak.  Returns TRUE on success.  Can fail if
+ * not enough samples have been processed.  Updates album accumulator.
+ * Resets track accumulator. */
+
+gboolean
+rg_analysis_track_result (RgAnalysisCtx * ctx, gdouble * gain, gdouble * peak)
+{
+  gboolean result;
+
+  g_return_val_if_fail (ctx != NULL, FALSE);
+
+  accumulator_add (&ctx->album, &ctx->track);
+  result = accumulator_result (&ctx->track, gain, peak);
+  accumulator_clear (&ctx->track);
+
+  reset_filters (ctx);
+
+  return result;
+}
+
+/* Obtain album gain and peak.  Returns TRUE on success.  Can fail if
+ * not enough samples have been processed.  Resets album
+ * accumulator. */
+
+gboolean
+rg_analysis_album_result (RgAnalysisCtx * ctx, gdouble * gain, gdouble * peak)
+{
+  gboolean result;
+
+  g_return_val_if_fail (ctx != NULL, FALSE);
+
+  result = accumulator_result (&ctx->album, gain, peak);
+  accumulator_clear (&ctx->album);
+
+  return result;
+}
+
+void
+rg_analysis_reset_album (RgAnalysisCtx * ctx)
+{
+  accumulator_clear (&ctx->album);
+}
+
+/* Reset internal buffers as well as track and album accumulators.
+ * Configured sample rate is kept intact. */
+
+void
+rg_analysis_reset (RgAnalysisCtx * ctx)
+{
+  g_return_if_fail (ctx != NULL);
+
+  reset_filters (ctx);
+  accumulator_clear (&ctx->track);
+  accumulator_clear (&ctx->album);
+}