cut audio file with iPhone SDK

Question

Hi!

Is it possible to cut audio file with iPhone SDK? (file has .caf extension) I just need to cut off the silence at the beginning.

(Also, maybe it's possible to write new file from the existing one with specified start and end time.)

Thanks in advance!

Answer 1

Its not hard, its just fiddly, you can use Extended Audio File Services. have a look at the reference for ExtAudioFileRead & ExtAudioFileWrite (they have sample code) then you can open one audio file read it, trim it and then write the new one.

Answer 2

There is no trim function. You have to write some code that opens a file for reading and creates and opens another file for writing. Then write a loop that reads the audio sample or packet data, discards the silence at the beginning, and writes the audio data to the output file.

Answer 3

See example 6 here:

http://www.modejong.com/iPhone/

The example shows how to use ExtAudioFile to fade an audio clip out after truncating it, but you could easily adapt the logic to support a starting point as well as an ending point. The main thing is that the example provides a code sample that works on the iPhone and also works as a Mac OS X command line app.