[Discuss-gnuradio] Help Needed: ValueError: itemsize mismatch: audio_alsa_source(1):0 using 4, flex_demod(2):0 using 8

[Darryl Ross]

(Apologies is this is a duplicate, I think I sent the first one before 
my subscription activated)


Hi All,

I'm having a problem trying to use the flex_demod() method of
gnuradio.pager:

> address@hidden bin]# ./alsa_flex.py 
> > > > gr_fir_fff: using SSE
> Traceback (most recent call last):
>   File "./alsa_flex.py", line 22, in ?
>     tb = top_block(queue)
>   File "./alsa_flex.py", line 17, in __init__
>     self.connect(src, dst)
>   File "/opt/gnuradio/lib/python2.4/site-packages/gnuradio/gr/top_block.py", 
> line 70, in connect
>     self._connect(points[i-1], points[i])
>   File "/opt/gnuradio/lib/python2.4/site-packages/gnuradio/gr/top_block.py", 
> line 76, in _connect
>     dst_block.basic_block(), dst_port)
>   File 
> "/opt/gnuradio/lib/python2.4/site-packages/gnuradio/gr/gnuradio_swig_py_runtime.py",
>  line 1493, in connect
>     return _gnuradio_swig_py_runtime.gr_top_block_sptr_connect(*args)
> ValueError: itemsize mismatch: audio_alsa_source(1):0 using 4, flex_demod(2):0 
> using 8

Reading through some of the documentation, it looks to me like the
itemsize variable is the size of the samples?

I'm guessing that I need to process (resample?) the signal from the
sound card before passing it to the flex decoder, but I'm not sure what
that processing would be. I'm very new to signal processing, so don't
know what search terms I should be using.

Can anyone give me a pointer?

My (very simple) program so far is:

> #!/usr/bin/python
>
> from gnuradio import audio, gr, pager
>
>
> sample_rate = 48000
> audio_device = 'hw:0'
>
>
> class top_block(gr.top_block):
>     def __init__(self, queue):
>         gr.top_block.__init__(self)
>
>         src = audio.source(sample_rate, audio_device)
>         dst = pager.flex_demod(queue)
>
>         self.connect(src, dst)
>
>
> if __name__ == '__main__':
>     queue = gr.msg_queue()
>     tb = top_block(queue)
>     tb.start()
>     while True:
>         if not queue.empty_p():
>             msg = queue.delete_head()
>             print msg.to_string()

Thanks
-Darryl

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