[andraudio] Android audio recording and fft latency issues?

[Dan S]

If you know which small set of tones you want to recognise (e.g.
touchtones), the Goertzel algorithm is more efficient than running a
whole FFT.

Dan


2011/10/8 Rafael Aroca <rafaelaroca at gmail.com>:
> Hi guys,
>
> I've been playing with android and trying to recognize audio tones from the mic.
>
> I modified some ready to use FFT libs and got up to 5 audio tones per
> second recognition. My first guess is that this low performance was
> due to the FFT timing, so I started changing the FFT's number of
> points, sample rates, etc. I managed to decrease the FFT timing to 5ms
> (previous timing was about 45ms).
>
> But for my surprise this improvement did not change at all the audio
> frequencies recognition rate. After googleing, I noticed that seems
> like there are audio latencies issues in android.
>
> Those tests were made on a HTC G1 using Android 2.2 (nonofficial ROM).
> I decided to test on a PC, so I installed android-x86 on a laptop and
> had about the same timings! Then I rebooted the x86 computer and
> tested a ham radio tone recognizer (that uses FFT) and got about 60
> tones per second recognition!
>
> Does it make sense? Any hints/suggestions on improving the android appilcations?
>
> thanks
>
> --
> []s Rafael.
> Linux User #56352
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