Re: Detecting a beep in a movie file audio track
Re: Detecting a beep in a movie file audio track
- Subject: Re: Detecting a beep in a movie file audio track
- From: Pi <email@hidden>
- Date: Tue, 23 Nov 2010 11:41:11 +0700
Are you in control of the beep? ie do you put in the beep, and then you want to locate it again? Also can you guarantee the beep will exclude all other sounds while it is playing?
if yes, it makes things a bit easier. You can use a pitch detection algorithm.
If you can make the beep to be a pure sine wave of a particular frequency, it isn't that hard to detect it. you might run the risk of false positives (maybe the movie contains a similar sound). you could get round this by compositing say three unique sine waves and then listening for them.
you could do this by performing a Fourier transform 50 times a second on the most recent 1024 bytes of audio, and checking to see whether certain bins get hit. If you want to farm this work out, feel free to drop me a line (sunfish7|gmail|com): I have just spent the last fortnight figuring out the math and code for pitch detection, which is really speedy thanks to Apple's accelerate framework.
Sam
On 23 November 2010 11:11, Neal, Doug
<email@hidden> wrote:
I'm looking for advice on how to construct a piece of code that will search for and identify a particular sound (a beep for example) that occurs within a given movie file audio track and return the point at which that sound occurs in the timeline of the file/movie.
Any suggestions on which API's would be the best to use for this?
-Doug
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