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)