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This is my first question on dsp. I am looking for something very simple here and I am sure there are libraries that will do pitch recognition and FFT but my requirement is very simple.

I have a PC and I am using the audio input for analog signal feedback and output for controlling the device. I am using windows as the OS.

  1. I want to ensure that I have full control on the audio output and no other program or the OS will stream sounds into the same channel.

  2. I want to output precisely at a known time interval

  3. I want to check if the feedback matches with what is expected of the device.

Any snippet of code or an article to do the same will be useful. I can provide more details if there is something missing in my question.

Ram
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  • How precise is "precise"? Is a delay in the order of hundreds of ms acceptable to you? Can you please clarify your third question? What are the input and output of your system and your "device"? – A_A May 18 '18 at 13:47
  • 10ms is a reasonably precise in my world. But I would hope that I can get 1ms. – Ram May 18 '18 at 14:04
  • PC output: a wave signal that has encoded information using amplitude and frequency – Ram May 18 '18 at 14:05
  • PC Input: the device sends signal with information encoded as amplitude and frequency – Ram May 18 '18 at 14:06
  • #1 and #2 will be very hard and are operating-system dependent. For example, the sound samples will go through the sound card drivers and there's no easy way to tell what they do and how much latency they add. #3, you can connect an oscilloscope to the sound card's output and see the signal. – MBaz May 18 '18 at 14:37
  • Can I please ask if this was resolved? – A_A May 21 '18 at 08:15
  • Not really. Tried using Windows Media Timer Callbacks and I am still struggling to get them to play nicely. – Ram May 21 '18 at 21:37
  • @Ram That is not described in your question, can you please talk a little bit more on why you want to use the timers as opposed to simply scheduling the output via the buffers? – A_A May 23 '18 at 06:31
  • Yes, good point. Marking your answer as the correct one. – Ram May 23 '18 at 18:41

1 Answers1

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The best performance you will be able to squeeze out of a PC is with an audio interface that supports ASIO.

To be able to get near 10ms of total delay (input and output) you will also need a very fast machine. Not only in terms of CPU but more importantly in terms of memory performance.

On top of this delay, you are going to have to add the delay in processing your signal and generating the output signal.

1ms (total delay (?) ) on the hardware you are describing is unrealistic.

The way ASIO works will handle issues #1,#2. I am still not really sure what you mean by #3. If you want to use the PC to drive a device with some signal and collect the response of the device to that signal then that is relatively easily achievable with an ASIO enabled audio interface too.

Hope this helps.

A_A
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