def create_expression(inbuf, outbuf, caps, expression):
rate = caps[0]["rate"]
dt = 1.0/float(rate)
t_start = float(inbuf.timestamp) / float(gst.SECOND)
dur = float(inbuf.duration) / float(gst.SECOND)
t_end = t_start + dur
t = numpy.arange(t_start, t_end, dt)
y = eval(expression, numpy.__dict__, {'t': t})
unitsize = pipeio.get_unit_size(caps)
bufsize = unitsize * len(t)
outbuf[0:bufsize] = y.flatten().astype(pipeio.numpy_dtype_from_caps(caps)).data
def do_get_unit_size(self, caps):
return pipeio.get_unit_size(caps)