2014/10/15 下午 10:09:23

iphone Programming Glossary: frequencies

http://stackoverflow.com/questions/1002838/audio-on-the-iphone

on the RemoteIO AudioUnit. Audio Toolbox is fine for basic triggered sound effects but it wasn't able to change frequencies or loop samples. Audio Queue Services can loop samples but the only way I could find to adjust the playback frequency of..

AurioTouch & FFT for an instrument tuner

http://stackoverflow.com/questions/1447059/auriotouch-fft-for-an-instrument-tuner

at the frequency domain graph. I play a single note on an instrument and I don't see a nicely ordered small set of frequencies with one string peak at the appropriate frequency of the note. Has anyone used aurioTouch enough to know whether the underlying..

Determining the magnitude of a certain frequency on the iPhone

http://stackoverflow.com/questions/2921674/determining-the-magnitude-of-a-certain-frequency-on-the-iphone

magnitude of a given frequency in a sound. It's my understanding that a FFT function will return the magnitudes of all frequencies in a signal. I'm wondering if there is any shortcut I could use if I'm only concerned about a specific frequency. I'll be.. frequency of interest. k is just the indexing on the output of the DFT. Mapping k indexes of the DFT output into real frequencies Hz depends on two things Sampling frequency for example 44100 Hz for CD Audio FFT size Real frequencies are mapped to k.. into real frequencies Hz depends on two things Sampling frequency for example 44100 Hz for CD Audio FFT size Real frequencies are mapped to k as follows F k Fs N for k 0 ... N 2 1 N 1 2 for odd N or k F N Fs for F 0Hz ... Fs 2 Fs N where F is the..

Using the apple FFT and accelerate Framework

http://stackoverflow.com/questions/3398753/using-the-apple-fft-and-accelerate-framework

great pitch detector as it doesn't have nearly fine enough granularity. There is a cunning trick Extracting precise frequencies from FFT Bins using phase change between frames to get the precise frequency for a given bin. Ok Now onto the code Note..

How to reduce the size of an sqlite3 database for iphone?

http://stackoverflow.com/questions/401467/how-to-reduce-the-size-of-an-sqlite3-database-for-iphone

1 1 10002011000001210111010000 photoengraving 1 1 10001021100002210101010000 The last field represents the letter frequencies for anagram retrieval each position is in the range 0..9 . The two booleans represent sub dictionaries. I need to do queries.. by word asc select word from words where word 'foo' and sowpods '1' or twl '1' One idea I have is to encode the letter frequencies more efficiently e.g. binary encode them as a blob perhaps with RLE as there are many zeros . Any ideas for how best to..

iPhone FFT with Accelerate framework vDSP

http://stackoverflow.com/questions/6358764/iphone-fft-with-accelerate-framework-vdsp

magnitude re re im im . You would look at the magnitudes of the bin or bins see 2 that correspond to your frequency or frequencies of interest. If your sample rate is Fs and your FFT size is N then the corresponding frequency for output bin i is given..

update frequency set for deviceMotionUpdateInterval it's the actual frequency?

http://stackoverflow.com/questions/6777799/update-frequency-set-for-devicemotionupdateinterval-its-the-actual-frequency

but scales up with setting but there is still no answer. Surprisingly you are the first on to report higher actual frequencies. I did several tests on this and it makes no real difference which way you go. Push or pull i.e. handler callback or own..

Accelerometer Low Pass Filtering

http://stackoverflow.com/questions/6942626/accelerometer-low-pass-filtering

10 of any change to go through to the new accelX value. The KFilteringFactor of 0.1 makes this filter cut out all high frequencies. You will definitely want to experiment by changing this value to suit your particular application. share improve this..

FFT on iPhone to ignore background noise and find lower pitches

http://stackoverflow.com/questions/7181630/fft-on-iphone-to-ignore-background-noise-and-find-lower-pitches

the data returned from the vDSP functions. I'm also not sure how to improve the accuracy of the code in the lower frequencies. There seem to be other algorithms to determine the dominant frequency but again looking for a kick in the right direction..

iPhone headphone jack - read in data?

http://stackoverflow.com/questions/7192473/iphone-headphone-jack-read-in-data

powers the input device. The key as Dominik Selbold has pointed out is that the incoming data must be modulated at frequencies within the passband of the iPhone microphone input. Although many have suggested that this limits the data rate in fact.. of kilobits per second. For example in 2008 Jonti Olds demonstrated how using Quadrature Amplitude Modulation at audio frequencies could stream TV sound and picture between two computers using their audio cards. What would be needed on the iPhone would..