A basclass for scopes. Takes care of re-fitting the audio-rate to video-rate.

It receives audio-data at the sampling-rate. I needs to render video-frames at
frame-rate. The rendering needs n audio samples (depends on subclass). The
baseclass takes care of that.

= API =

* should we add some basic drawing helpers to the baseclass
  draw_point (x,y,color);
  draw_hline (x1,x2,y,color);
  draw_vline (x,y1,y2,color);
  draw_rect (x1,x2,y1,y2,color);
  draw_box (x1,x2,y1,y2,color); // filled

* have background processing in baseclass
  - enum property to select from several shade-and-move variants
    shade-only, up, down, left, right, v-in, v-out, h-in, h-out

= Elements to port =
gst-plugin-ugly/gst/synaestesia -> synaescope
gst-plugin-good/gst/monoscope ->

= TODO =
- element maker template
- test for baseclass

= Test it =

GST_DEBUG="*:2,*scope*:4"

GST_PLUGIN_PATH=$GST_PLUGIN_PATH:$PWD gst-inspect scopes

GST_PLUGIN_PATH=$GST_PLUGIN_PATH:$PWD gst-launch audiotestsrc ! audioconvert ! wavescope ! colorspace ! ximagesink
GST_PLUGIN_PATH=$GST_PLUGIN_PATH:$PWD gst-launch filesrc location=/home/ensonic/Musik/xotox-hypnocat.mp3 ! decodebin2 ! audioconvert ! wavescope ! colorspace ! ximagesink
GST_PLUGIN_PATH=$GST_PLUGIN_PATH:$PWD gst-launch filesrc location=/home/ensonic/Musik/xotox-hypnocat.mp3 ! decodebin2 ! audioconvert ! spectrascope ! colorspace ! ximagesink

GST_PLUGIN_PATH=$GST_PLUGIN_PATH:$PWD gst-launch filesrc location=/home/ensonic/Musik/Gridlock/Trace/04\ Uh4.17.mp3 ! decodebin2 ! audioconvert ! spectrascope ! colorspace ! ximagesink
GST_PLUGIN_PATH=$GST_PLUGIN_PATH:$PWD gst-launch filesrc location=/home/ensonic/Musik/Gridlock/Trace/04\ Uh4.17.mp3 ! decodebin2 ! audioconvert ! spectrascope shader=fade-and-move-up shade-amount=0x00040302 ! colorspace ! ximagesink

GST_PLUGIN_PATH=$GST_PLUGIN_PATH:$PWD gst-launch filesrc location=/home/ensonic/Musik/Gridlock/Trace/04\ Uh4.17.mp3 ! decodebin2 ! tee name=t ! queue ! audioconvert ! synaesthesia ! ximagesink t. ! queue ! synaescope shade-amount=0x00040404 ! colorspace ! ximagesink

