Creating audio programmatically

[Vic320]

I want to create short audio clips (less than 5 seconds) programmatically (synthesized sound) and save it into an audio file on the iPhone. It is simple to do something like this with images (just a few lines of code) but I can't seem to find any simple way of doing this with audio. Does anyone have any ideas here? I looked at the "Speak Here" example code, which I have been told will allow me to do it, but that seems exceptionally complex for this. Sample code would be greatly appreciated!

[deepak_chrome]

Hi there,
as i understand u want to play a sound clip only for 5 sec, to do the same you need to do something like this:-
1. Add framework:- audioToolbox.framework
2 . #import <AudioToolbox/AudioServices.h>
3. Use method to play your sound
4. Call method [self play_Sound];

-(void) play_Sound
{
//Get the filename of the sound file:
NSString *path = [NSString stringWithFormat:@"%@%@",
[[NSBundle mainBundle] resourcePath],
@"/your_sound_file.wav"];

//declare a system sound id
SystemSoundID soundID;

//Get a URL for the sound file
NSURL *filePath = [NSURL fileURLWithPath: path is Directory:NO];

//Use audio sevices to create the sound
AudioServicesCreateSystemSoundID((CFURLRef)filePat h, &soundID);

//Use audio services to play the sound

AudioServicesPlaySystemSound(soundID);
sleep(5); //define length for your sound clip
AudioServicesDisposeSystemSoundID(soundID);
}

[Vic320]

Thanks for the reply. This is actually half the solution (the playback part). I have figured out the create an audio file part on my own. Since I searched the Internet high and low for a *simple* solution and didn't find anything, I will post my solution here as a community service. The simplest solution that I came up with to programmatically create a sound is as follows:

Create a wave file from scratch. Wave files have a pretty simple structure so it's fairly easy to generate the needed header info (see the wave spec here: https://ccrma.stanford.edu/courses/4...ts/WaveFormat/). Since all of the sound files I am going to be creating are all the same length and sample rate, I created a file with all the header data all ready in place but it would be a simple matter to do it programmatically. I load that data into a NSMutableData object then just append my sound data after that. Example:

NSString *path = [[NSBundle mainBundle] pathForResource:@"WavHeader" ofType:@"wav"];
	
NSMutableData *audioData = [[NSMutableData alloc] initWithContentsOfFile:path];

int samples = 22050;
	
uint8_t dataToRecord[samples];
	
int x;
	
for(x = 0; x < samples; x++) {
		
	// populate the "dataToRecord" array with audio data. //
		
}

[audioData appendBytes:(const void *)dataToRecord length:samples];

	// Get path to documents folder and set a file name  //

[audioData writeToFile:pathToFile atomically:YES];

[rahdu]

i created a wav file in the Documents directory called myFile.wav but when i tried to play it i get the original wav file witch i used to get the data. what am i doing wrong ? 1 month nub here so any help will be appreciated.

[sobie]

hi
first thank you very much for your solution. but i'm a little confused about the way to fill dataToRecord. I tried two way, and they aren't working:

dataToRecord[x] = (sin(x*(PI2*(8000/freq1))) + sin(x*(PI2*(8000/freq2)))) * 16383;

PI2 = 6,28..
8000- playback frequency

and

dataToRecord[x]  = amplitude * (sin(x * freq1) + sin(x * freq2))

amplitude = 64

please help, can you show me how did you do it?


edit
maybe the header isn't valid.. a took the one from the site you gave, and there was as an example..