Audio streaming

[charles0601]

Hi everyone,

i have to build a streaming audio application in LabV. Does anyone have experience with this matter? If so could you please point me in the right direction.

Thx

[shrekt]

Hi,

Can you explain your application a little more and have a look at ni examples for sound.

Regards,

Shrenik

[charles0601]

The application need play the audio continously without clipping when the incoming audio signal is delayed.

[Coq_Rouge]

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charles0601 wrote:
The application need play the audio continously without clipping when the incoming audio signal is delayed.

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It is hard to play anything then the data is missing 🙂 But in order to play audio whithout any clipping you have to implement a buffer scheme. Post your code, it is much simpler to take it from there

[charles0601]

This is a vi that simulate my target.   The producer loop take longer time to produce audio data. The consumer loop need take the audio data from the producer loop and continously(repeatly) loop back the audio data obtained before until producer has delayed new audio signal pass to without clip. 

I have not come out a good way to do this. Any help would cout. Thank you very much.

[huyu]

A little modification, can this be helpful?

[RavensFan]

Try this.  Don't put a delay in the loop.

Set a timeout on your dequeue with minimal to no timeout value.  If it times out (meaning another item sound wasn't added), it will play the wave stored in the shift register.  If a new queue element is available, it will play that.

Message Edited by Ravens Fan on 02-04-2010 10:59 PM

[charles0601]

This is the latest vi I have got taking.   There is a clip sound when a new audio signal coming from producer loop to consumer loop.    This is caused by the incontinous between the looping signal and new coming signal.

Is there any way to eliminate it? thank you. 

[charles0601]

To correct the argument in my previous post. The waveform in consumer loop seems like contious when the new wave from the producer loop. But there is a clip.

How this happen?

[RavensFan]

I would take the metronome (Wait for Next ms multiple) out of the loop. I think it could complicate the timing. You are relying on that taking precisely as long as your waveform takes to play. If you have a slight error in timing, it will cause the loop to wait until another whole iteration before playing the waveform again. I think you are also getting artifacts in your sound when you have a waveform where it does not finish a complete phase of the sinewave. So when the sinewave does not finish at zero, but the next one starts at zero, you have a discontinuity that is going to sound like another frequency clicking in the sound output. If you set your frequency to be evenly divisible into your number of samples, the resulting sinewave is continuous, and you don't hear the extra clicking. You'll have to play around with some of the other parameters (# of samples, waveform bandwidth, ...) if you need to output a frequency that is not evenly divisible into the settings as you currently have them.