def build_graph():
sample_rate = 8000
scale_factor = 32000
tb = gr.top_block()
src = audio.source(sample_rate, "plughw:0,0")
src_scale = gr.multiply_const_ff(scale_factor)
interp = blks2.rational_resampler_fff(8, 1)
f2s = gr.float_to_short ()
enc = cvsd_vocoder.encode_sb()
dec = cvsd_vocoder.decode_bs()
s2f = gr.short_to_float ()
decim = blks2.rational_resampler_fff(1, 8)
sink_scale = gr.multiply_const_ff(1.0/scale_factor)
sink = audio.sink(sample_rate, "plughw:0,0")
tb.connect(src, src_scale, interp, f2s, enc)
tb.connect(enc, dec, s2f, decim, sink_scale, sink)
if 0: # debug
tb.conect(src, gr.file_sink(gr.sizeof_float, "source.dat"))
tb.conect(src_scale, gr.file_sink(gr.sizeof_float, "src_scale.dat"))
tb.conect(interp, gr.file_sink(gr.sizeof_float, "interp.dat"))
tb.conect(f2s, gr.file_sink(gr.sizeof_short, "f2s.dat"))
tb.conect(enc, gr.file_sink(gr.sizeof_char, "enc.dat"))
tb.conect(dec, gr.file_sink(gr.sizeof_short, "dec.dat"))
tb.conect(s2f, gr.file_sink(gr.sizeof_float, "s2f.dat"))
tb.conect(decim, gr.file_sink(gr.sizeof_float, "decim.dat"))
tb.conect(sink_scale, gr.file_sink(gr.sizeof_float, "sink_scale.dat"))
return tb
def build_graph():
sample_rate = 8000
scale_factor = 32000
tb = gr.top_block()
src = audio.source(sample_rate, "plughw:0,0")
src_scale = gr.multiply_const_ff(scale_factor)
interp = blks2.rational_resampler_fff(8, 1)
f2s = gr.float_to_short()
enc = cvsd_vocoder.encode_sb()
dec = cvsd_vocoder.decode_bs()
s2f = gr.short_to_float()
decim = blks2.rational_resampler_fff(1, 8)
sink_scale = gr.multiply_const_ff(1.0 / scale_factor)
sink = audio.sink(sample_rate, "plughw:0,0")
tb.connect(src, src_scale, interp, f2s, enc)
tb.connect(enc, dec, s2f, decim, sink_scale, sink)
if 0: # debug
tb.conect(src, gr.file_sink(gr.sizeof_float, "source.dat"))
tb.conect(src_scale, gr.file_sink(gr.sizeof_float, "src_scale.dat"))
tb.conect(interp, gr.file_sink(gr.sizeof_float, "interp.dat"))
tb.conect(f2s, gr.file_sink(gr.sizeof_short, "f2s.dat"))
tb.conect(enc, gr.file_sink(gr.sizeof_char, "enc.dat"))
tb.conect(dec, gr.file_sink(gr.sizeof_short, "dec.dat"))
tb.conect(s2f, gr.file_sink(gr.sizeof_float, "s2f.dat"))
tb.conect(decim, gr.file_sink(gr.sizeof_float, "decim.dat"))
tb.conect(sink_scale, gr.file_sink(gr.sizeof_float, "sink_scale.dat"))
return tb
def __init__(self, resample=8, bw=0.5):
'''
When using the CVSD vocoder, appropriate sampling rates are from 8k to 64k with resampling rates
from 1 to 8. A rate of 8k with a resampling rate of 8 provides a good quality signal.
'''
gr.hier_block2.__init__(self, "cvsd_encode",
gr.io_signature(1, 1, gr.sizeof_float), # Input signature
gr.io_signature(1, 1, gr.sizeof_char)) # Output signature
scale_factor = 32000.0
self.interp = resample
src_scale = gr.multiply_const_ff(scale_factor)
taps = gr.firdes.low_pass(self.interp, self.interp, bw, 2*bw)
interp = gr.interp_fir_filter_fff(self.interp, taps)
f2s = gr.float_to_short()
enc = cvsd_vocoder.encode_sb()
self.connect(self, src_scale, interp, f2s, enc, self)