timeside/decoder/sink.py: add gst sink

diff --git a/timeside/decoder/sink.py b/timeside/decoder/sink.py
new file mode 100644 (file)
index 0000000..c91c2a0
--- /dev/null
+++ b/timeside/decoder/sink.py
@@ -0,0 +1,55 @@
+import pygst
+pygst.require('0.10')
+import gst
+import gobject
+gobject.threads_init()
+
+class TimesideSink(gst.BaseSink):
+    """
+    a simple sink element with a hopsize property to adjust the size of the buffer emitted
+    """
+    _caps = gst.caps_from_string('audio/x-raw-float, \
+                    rate=[ 1, 2147483647 ], \
+                    channels=[ 1, 2147483647 ], \
+                    endianness={ 1234, 4321 }, \
+                    width=32')
+
+    __gsttemplates__ = ( 
+            gst.PadTemplate ("sink",
+                gst.PAD_SINK,
+                gst.PAD_ALWAYS,
+                _caps),
+            )
+
+    def __init__(self, name):
+        self.__gobject_init__()
+        self.set_name(name)
+        self.adapter = gst.Adapter()
+        self.set_property('sync', False)
+
+    def set_property(self, name, value): 
+        if name == 'hopsize':
+            # blocksize is in byte, convert from hopsize 
+            from struct import calcsize
+            self.set_property('blocksize', value * calcsize('f'))
+        else:
+            super(gst.BaseSink, self).set_property(name, value)
+
+    def do_render(self, buffer):
+        self.adapter.push(buffer)
+        return gst.FLOW_OK
+
+    def pull(self):
+        # TODO use signals
+        blocksize = self.get_property('blocksize')
+        remaining = self.adapter.available()
+        if remaining == 0:
+            return None
+        if remaining >= blocksize:
+            return self.adapter.take_buffer(blocksize)
+        if remaining < blocksize and remaining > 0:
+            return self.adapter.take_buffer(remaining)
+
+gobject.type_register(TimesideSink)
+
+