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I have just downloaded GNU Radio's installer for the windows environment and am having trouble with simple audio playback from a wav file.

The audio file will play but is 'choppy' and seems to be playing back at the wrong sample rate (difficult to tell for sure due to the intermittent audio). I am using the correct sample rate from the file (11.025kHz). I have also tried adding a throttle block between the file and the audio sink, although I know that is not recommended. I'm not sure if there are 'issues' with the port to Windows or if there is some additional hardware config needed (above what is typically done in Linux) Attached is a screen grab of the GNUradio flowgraph.

note: the same 'choppy' audio is heard when the wav file source block is replaced by a signal source block.

Simple GNUradio audio playback flowgraph

Image showing the internal data samples related to the second comment below:

enter image description here

Ed Coleman
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  • Hi Ed! Welcome to GNU Radio. Yep, things might still be a little rough around the edges on Windows. No, a Throttle should never help here (in fact, I'd expect you'd even get a warning in GRC when using it together with an Audio sink). Can you try a more directly supported sampling rate with a signal source block, preferably 44kHz or 48kHz? If that works, we'll know how to make the 11.025 kHz-sampled signal from the wav file source work with that rate (4x). – Marcus Müller Oct 17 '17 at 20:57
  • Marcus: Thank you for the feedback! Changing the sampling rate to 44kHz on the signal source seemed to work. I adjusted the sample rate from the file using the rational resampler block I'm still having an issue. When playing back a 7 second sample (5 secs of sound and 2 secs of silence), The sound plays back thru the speakers repeating in under 5 seconds instead of the expected 7 seconds. Looking at the date internal to gnuradio via a time and frequency sink the raw samples look correct (see image added to the original question) – Ed Coleman Oct 18 '17 at 15:10
  • Just to verify: you have a rational resampler, interpolation=4, decimation=1 between your Wav File Source and your audio Sink, sample rate=44100, right? – Marcus Müller Oct 18 '17 at 21:37
  • Marcus: yes, correct. – Ed Coleman Oct 19 '17 at 16:45

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