AVFoundation，如何在captureStillImageAsynchronouslyFromConnection 时关闭快门声? [英] AVFoundation, how to turn off the shutter sound when captureStillImageAsynchronouslyFromConnection?

问题描述

我正在尝试通过 AVFoundation 在实时预览期间从相机捕获图像

I am trying to capture an image during a live preview from the camera, by AVFoundation captureStillImageAsynchronouslyFromConnection. So far the program works as expected. However, how can I mute the shutter sound?

解决方案

I used this code once to capture iOS default shutter sound (here is list of sound file names https://github.com/TUNER88/iOSSystemSoundsLibrary):

NSString *path = @"/System/Library/Audio/UISounds/photoShutter.caf";
NSString *docs = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
NSData *data = [NSData dataWithContentsOfFile:path];
[data writeToFile:[docs stringByAppendingPathComponent:@"photoShutter.caf"] atomically:YES];

Then I used third-party app to extract photoShutter.caf from Documents directory (DiskAid for Mac). Next step I opened photoShutter.caf in Audacity audio editor and applied inversion effect, it looks like this on high zoom:

Then I saved this sound as photoShutter2.caf and tried to play this sound right before captureStillImageAsynchronouslyFromConnection:

static SystemSoundID soundID = 0;
if (soundID == 0) {
    NSString *path = [[NSBundle mainBundle] pathForResource:@"photoShutter2" ofType:@"caf"];
    NSURL *filePath = [NSURL fileURLWithPath:path isDirectory:NO];
    AudioServicesCreateSystemSoundID((__bridge CFURLRef)filePath, &soundID);
}
AudioServicesPlaySystemSound(soundID);

[self.stillImageOutput captureStillImageAsynchronouslyFromConnection:
...

And this really works! I runs test several times, every time I hear no shutter sound :)

You can get already inverted sound, captured on iPhone 5S iOS 7.1.1 from this link: https://www.dropbox.com/s/1echsi6ivbb85bv/photoShutter2.caf

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