iOS Audio Trimming - ios

Question

I searched a lot and couldn't find anything relevant... I am working on iOS audio files and here is what I want to do...
Record Audio and Save Clip (Checked, I did this using AVAudioRecorder)
Change the pitch (Checked, Did this using Dirac)
Trimming :(
I have two markers i.e. starting & ending offset and using this info I want to trim recorded file and want to save it back. I don't want to use "seek" because later on I want to play all recorded files in sync (just like flash movie clips in timeline) and then finally I want to export as one audio file.

Answer 1

Here's the code that I've used to trim audio from a pre-existing file. You'll need to change the M4A related constants if you've saved or are saving to another format.
- (BOOL)trimAudio
{
float vocalStartMarker = <starting time>;
float vocalEndMarker = <ending time>;
NSURL *audioFileInput = <your pre-existing file>;
NSURL *audioFileOutput = <the file you want to create>;
if (!audioFileInput || !audioFileOutput)
{
return NO;
}
[[NSFileManager defaultManager] removeItemAtURL:audioFileOutput error:NULL];
AVAsset *asset = [AVAsset assetWithURL:audioFileInput];
AVAssetExportSession *exportSession = [AVAssetExportSession exportSessionWithAsset:asset
presetName:AVAssetExportPresetAppleM4A];
if (exportSession == nil)
{
return NO;
}
CMTime startTime = CMTimeMake((int)(floor(vocalStartMarker * 100)), 100);
CMTime stopTime = CMTimeMake((int)(ceil(vocalEndMarker * 100)), 100);
CMTimeRange exportTimeRange = CMTimeRangeFromTimeToTime(startTime, stopTime);
exportSession.outputURL = audioFileOutput;
exportSession.outputFileType = AVFileTypeAppleM4A;
exportSession.timeRange = exportTimeRange;
[exportSession exportAsynchronouslyWithCompletionHandler:^
{
if (AVAssetExportSessionStatusCompleted == exportSession.status)
{
// It worked!
}
else if (AVAssetExportSessionStatusFailed == exportSession.status)
{
// It failed...
}
}];
return YES;
}
There's also Technical Q&A 1730, which gives a slightly more detailed approach.

Answer 2

import following two libraries in .m
#import "BJRangeSliderWithProgress.h"
#import < AVFoundation/AVFoundation.h >
and after that paste following code you will be able to trim an audio file with the help of two thumbs.
- (void) viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
mySlider = [[BJRangeSliderWithProgress alloc] initWithFrame:CGRectMake(20, 100, 300, 50)];
[mySlider setDisplayMode:BJRSWPAudioSetTrimMode];
[mySlider addTarget:self action:#selector(valueChanged) forControlEvents:UIControlEventValueChanged];
[mySlider setMinValue:0.0];
NSString *strInputFilePath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:#"saewill.mp3"];
NSURL *audioFileInput = [NSURL fileURLWithPath:strInputFilePath];
audioPlayer=[[AVAudioPlayer alloc]initWithContentsOfURL:audioFileInput error:nil];
[mySlider setMaxValue:audioPlayer.duration];
[self.view addSubview:mySlider];
}
-(void)valueChanged {
NSLog(#"%f %f", mySlider.leftValue, mySlider.rightValue);
}
-(IBAction)playTheSong
{
// Path of your source audio file
NSString *strInputFilePath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:#"saewill.mp3"];
NSURL *audioFileInput = [NSURL fileURLWithPath:strInputFilePath];
// Path of your destination save audio file
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES);
NSString *libraryCachesDirectory = [paths objectAtIndex:0];
//libraryCachesDirectory = [libraryCachesDirectory stringByAppendingPathComponent:#"Caches"];
NSString *strOutputFilePath = [libraryCachesDirectory stringByAppendingPathComponent:#"output.mov"];
NSString *requiredOutputPath = [libraryCachesDirectory stringByAppendingPathComponent:#"output.m4a"];
NSURL *audioFileOutput = [NSURL fileURLWithPath:requiredOutputPath];
[[NSFileManager defaultManager] removeItemAtURL:audioFileOutput error:NULL];
AVAsset *asset = [AVAsset assetWithURL:audioFileInput];
AVAssetExportSession *exportSession = [AVAssetExportSession exportSessionWithAsset:asset
presetName:AVAssetExportPresetAppleM4A];
float startTrimTime = mySlider.leftValue;
float endTrimTime = mySlider.rightValue;
CMTime startTime = CMTimeMake((int)(floor(startTrimTime * 100)), 100);
CMTime stopTime = CMTimeMake((int)(ceil(endTrimTime * 100)), 100);
CMTimeRange exportTimeRange = CMTimeRangeFromTimeToTime(startTime, stopTime);
exportSession.outputURL = audioFileOutput;
exportSession.outputFileType = AVFileTypeAppleM4A;
exportSession.timeRange = exportTimeRange;
[exportSession exportAsynchronouslyWithCompletionHandler:^
{
if (AVAssetExportSessionStatusCompleted == exportSession.status)
{
NSLog(#"Success!");
NSLog(#" OUtput path is \n %#", requiredOutputPath);
NSFileManager * fm = [[NSFileManager alloc] init];
[fm moveItemAtPath:strOutputFilePath toPath:requiredOutputPath error:nil];
//[[NSFileManager defaultManager] removeItemAtURL:audioFileOutput error:NULL];
NSURL *url=[NSURL fileURLWithPath:requiredOutputPath];
NSError *error;
audioPlayer=[[AVAudioPlayer alloc]initWithContentsOfURL:url error:&error];
audioPlayer.numberOfLoops=0;
[audioPlayer play];
}
else if (AVAssetExportSessionStatusFailed == exportSession.status)
{
NSLog(#"failed with error: %#", exportSession.error.localizedDescription);
}
}];
}

Answer 3

// Swift 4.2
If anybody is still looking for answer in swift here it is.
//Audio Trimming
func trimAudio(asset: AVAsset, startTime: Double, stopTime: Double, finished:#escaping (URL) -> ())
{
let compatiblePresets = AVAssetExportSession.exportPresets(compatibleWith:asset)
if compatiblePresets.contains(AVAssetExportPresetMediumQuality) {
guard let exportSession = AVAssetExportSession(asset: asset,
presetName: AVAssetExportPresetAppleM4A) else{return}
// Creating new output File url and removing it if already exists.
let furl = createUrlInAppDD("trimmedAudio.m4a") //Custom Function
removeFileIfExists(fileURL: furl) //Custom Function
exportSession.outputURL = furl
exportSession.outputFileType = AVFileType.m4a
let start: CMTime = CMTimeMakeWithSeconds(startTime, preferredTimescale: asset.duration.timescale)
let stop: CMTime = CMTimeMakeWithSeconds(stopTime, preferredTimescale: asset.duration.timescale)
let range: CMTimeRange = CMTimeRangeFromTimeToTime(start: start, end: stop)
exportSession.timeRange = range
exportSession.exportAsynchronously(completionHandler: {
switch exportSession.status {
case .failed:
print("Export failed: \(exportSession.error!.localizedDescription)")
case .cancelled:
print("Export canceled")
default:
print("Successfully trimmed audio")
DispatchQueue.main.async(execute: {
finished(furl)
})
}
})
}
}
You can use it for video trimming as well. For Video trimming replace the value of export session as bellow:
guard let exportSession = AVAssetExportSession(asset: asset,
presetName: AVAssetExportPresetPassthrough) else{return}
and filetype to mp4
exportSession.outputFileType = AVFileType.mp4

Answer 4

Here is a sample code which trim audio file from starting & ending offset and save it back.
Please check this iOS Audio Trimming.
// Path of your source audio file
NSString *strInputFilePath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:#"abc.mp3"];
NSURL *audioFileInput = [NSURL fileURLWithPath:strInputFilePath];
// Path of your destination save audio file
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES);
NSString *libraryCachesDirectory = [paths objectAtIndex:0];
libraryCachesDirectory = [libraryCachesDirectory stringByAppendingPathComponent:#"Caches"];
NSString *strOutputFilePath = [NSString stringWithFormat:#"%#%#",libraryCachesDirectory,#"/abc.mp4"];
NSURL *audioFileOutput = [NSURL fileURLWithPath:strOutputFilePath];
if (!audioFileInput || !audioFileOutput)
{
return NO;
}
[[NSFileManager defaultManager] removeItemAtURL:audioFileOutput error:NULL];
AVAsset *asset = [AVAsset assetWithURL:audioFileInput];
AVAssetExportSession *exportSession = [AVAssetExportSession exportSessionWithAsset:asset presetName:AVAssetExportPresetAppleM4A];
if (exportSession == nil)
{
return NO;
}
float startTrimTime = 0;
float endTrimTime = 5;
CMTime startTime = CMTimeMake((int)(floor(startTrimTime * 100)), 100);
CMTime stopTime = CMTimeMake((int)(ceil(endTrimTime * 100)), 100);
CMTimeRange exportTimeRange = CMTimeRangeFromTimeToTime(startTime, stopTime);
exportSession.outputURL = audioFileOutput;
exportSession.outputFileType = AVFileTypeAppleM4A;
exportSession.timeRange = exportTimeRange;
[exportSession exportAsynchronouslyWithCompletionHandler:^
{
if (AVAssetExportSessionStatusCompleted == exportSession.status)
{
NSLog(#"Success!");
}
else if (AVAssetExportSessionStatusFailed == exportSession.status)
{
NSLog(#"failed");
}
}];