I'm not sure about dsd but becouse of the ratio of symbol rate to sample
rate, some digital decoders will take a variable number of inputs per
output, this could without a sizable buffer under-run your sound card, some
sound servers handle these gaps in the sample stream for you.

Also have you tried just playing the .wav's in a music player? I have had
issues with the wavfile_sink messing up the format. Also check that you are
feeding the wavfile_sink in the format, could you just post your .grc file
here?

Andrew


On Fri, Aug 30, 2013 at 8:23 PM, Luke Berndt <[email protected]> wrote:

> Thanks Andrew! - I am actually able to play the sound fine through sound
> card using the audio_sink block. It was is when I try recording it to a
> .wav file using the wavfile_sink block that the sounds becomes distorted. I
> have tired using a resampler and also tried a variety of different sample
> rate on the wavfile_sink, but none of them sounded normal.
>
> gr-dsd is a vocoder block and its decoding is sort of bursty. Sometimes it
> seems to only take 4 input packets to equal 1 output, others it is 8 or 11.
> Any wise, I am wondering I am getting some form of under run. I am not
> getting 'aUaU' on the screen. Sometimes the sound from audio sink initially
> sound garbled but then becomes normal, so I wonder if it is an issue of
> needing to buffer up. I have tried adding in a Forecast, but it didn't help.
>
> Any other tips would be great!
>
>  - Luke
>
> On Aug 30, 2013, at 5:03 PM, Andrew Davis <[email protected]> wrote:
>
> I'm not sure exactly what you are doing, but some sound cards don't
> support very many rates, windows always re-samples to some rate supported
> by the card, in linux you get more direct access to sound hardware and so
> you can send it rates it may not like, you could add a re-sampler/sound
> manager like pulse to handle all this for you, worked for me with similar
> issues.
>
> Andrew
>
>
> On Fri, Aug 30, 2013 at 10:53 AM, Luke Berndt <[email protected]> wrote:
>
>> So I clearly have a sample rate mis-match. I am trying to record the
>> audio from the gr-dsd block. I don't seem to have an issue doing it using
>> GRC. However when I try doing using C++ the audio sounds extra slow and
>> choppy and the playing time is much longer than I was actually recording
>> for. I gr-dsd block is supposed to output audio at 8khz. I have the
>> wavfile_sink set at 8000 for the samples per sec parameter. I use the same
>> setting in GRC and it works fine. I have also tried passing this through a
>> resampler to get the audio rate up to 44.1khz and I still have the same
>> problem. If I use an audio_sink set to a sample rate of 44100 instead, I am
>> able to listen to the audio with no problem.
>>
>> Any idea what is going on or what I can try?
>>
>> Here is a sample of the output:
>> https://soundcloud.com/hackrfsounds/moto-smartnet-recording
>>
>> Thanks!
>>
>>
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>>
>>
>
>
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