gstreamer/gst/audiovisualizers/gstwavescope.c

/* GStreamer
 * Copyright (C) <2011> Stefan Kost <ensonic@users.sf.net>
 *
 * gstwavescope.c: simple oscilloscope
 *
 * This program 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 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */
/**
 * SECTION:element-wavescope
 * @see_also: goom
 *
 * Wavescope is a simple audio visualisation element. It renders the waveforms
 * like on an oscilloscope.
 *
 * <refsect2>
 * <title>Example launch line</title>
 * |[
 * gst-launch audiotestsrc ! audioconvert ! wavescope ! ximagesink
 * ]|
 * </refsect2>
 */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "gstwavescope.h"

static GstStaticPadTemplate gst_wave_scope_src_template =
GST_STATIC_PAD_TEMPLATE ("src",
    GST_PAD_SRC,
    GST_PAD_ALWAYS,
#if G_BYTE_ORDER == G_BIG_ENDIAN
    GST_STATIC_CAPS (GST_VIDEO_CAPS_MAKE ("xRGB"))
#else
    GST_STATIC_CAPS (GST_VIDEO_CAPS_MAKE ("BGRx"))
#endif
    );

static GstStaticPadTemplate gst_wave_scope_sink_template =
GST_STATIC_PAD_TEMPLATE ("sink",
    GST_PAD_SINK,
    GST_PAD_ALWAYS,
    GST_STATIC_CAPS ("audio/x-raw, "
        "format = (string) " GST_AUDIO_NE (S16) ", "
        "rate = (int) [ 8000, 96000 ], " "channels = (int) 2")
    );


GST_DEBUG_CATEGORY_STATIC (wave_scope_debug);
#define GST_CAT_DEFAULT wave_scope_debug

static gboolean gst_wave_scope_render (GstBaseAudioVisualizer * scope,
    GstBuffer * audio, GstBuffer * video);


G_DEFINE_TYPE (GstWaveScope, gst_wave_scope, GST_TYPE_BASE_AUDIO_VISUALIZER);

static void
gst_wave_scope_class_init (GstWaveScopeClass * g_class)
{
  GstElementClass *element_class = (GstElementClass *) g_class;
  GstBaseAudioVisualizerClass *scope_class =
      (GstBaseAudioVisualizerClass *) g_class;

  gst_element_class_set_details_simple (element_class, "Waveform oscilloscope",
      "Visualization",
      "Simple waveform oscilloscope", "Stefan Kost <ensonic@users.sf.net>");

  gst_element_class_add_pad_template (element_class,
      gst_static_pad_template_get (&gst_wave_scope_src_template));
  gst_element_class_add_pad_template (element_class,
      gst_static_pad_template_get (&gst_wave_scope_sink_template));

  scope_class->render = GST_DEBUG_FUNCPTR (gst_wave_scope_render);
}

static void
gst_wave_scope_init (GstWaveScope * scope)
{
  /* do nothing */
}

static gboolean
gst_wave_scope_render (GstBaseAudioVisualizer * scope, GstBuffer * audio,
    GstBuffer * video)
{
  gsize asize;
  guint32 *vdata =
      (guint32 *) gst_buffer_map (video, NULL, NULL, GST_MAP_WRITE);
  gint16 *adata = (gint16 *) gst_buffer_map (audio, &asize, NULL, GST_MAP_READ);
  guint i, c, s, x, y, off, oy;
  guint num_samples;
  gfloat dx, dy;
  guint w = scope->width;

  /* draw dots */
  num_samples = asize / (scope->channels * sizeof (gint16));
  dx = (gfloat) scope->width / (gfloat) num_samples;
  dy = scope->height / 65536.0;
  oy = scope->height / 2;
  s = 0;
  for (i = 0; i < num_samples; i++) {
    x = (guint) ((gfloat) i * dx);
    for (c = 0; c < scope->channels; c++) {
      y = (guint) (oy + (gfloat) adata[s++] * dy);
      off = (y * w) + x;
      vdata[off] = 0x00FFFFFF;
    }
  }
  gst_buffer_unmap (video, vdata, -1);
  gst_buffer_unmap (audio, adata, -1);
  return TRUE;
}

gboolean
gst_wave_scope_plugin_init (GstPlugin * plugin)
{
  GST_DEBUG_CATEGORY_INIT (wave_scope_debug, "wavescope", 0, "wavescope");

  return gst_element_register (plugin, "wavescope", GST_RANK_NONE,
      GST_TYPE_WAVE_SCOPE);
}