Error in extracting audio from .m4v video file - ios

Question

I am trying to extract the audio file from .m4v video. It shows the error like,
Error Domain=AVFoundationErrorDomain Code=-11800 "The operation could not be completed" UserInfo=0x15e350d0 {NSLocalizedDescription=The operation could not be completed, NSUnderlyingError=0x15d1c6b0 "The operation couldn’t be completed. (OSStatus error -12124.)", NSLocalizedFailureReason=An unknown error occurred (-12124)}
This is my code:
-(void)extractAudioFromVideo{
//Create a audia composition and add audio track
AVMutableComposition *newAudioAsset = [AVMutableComposition composition];
AVMutableCompositionTrack *dstCompositionTrack = [newAudioAsset addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
//Get video asset from which the audio should be extracted
NSURL *url = [[NSBundle mainBundle] URLForResource:#"sample_iPod" withExtension:#"m4v"];
AVAsset *srcAsset = [AVAsset assetWithURL:url];
NSArray *trackArray = [srcAsset tracksWithMediaType:AVMediaTypeAudio];
if(!trackArray.count){
NSLog(#"Track returns empty array for mediatype AVMediaTypeAudio");
return;
}
AVAssetTrack *srcAssetTrack = [trackArray objectAtIndex:0];
//Extract time range
CMTimeRange timeRange = srcAssetTrack.timeRange;
//Insert audio from the video to mutable avcomposition track
NSError *err = nil;
if(NO == [dstCompositionTrack insertTimeRange:timeRange ofTrack:srcAssetTrack atTime:kCMTimeZero error:&err]){
NSLog(#"Failed to insert audio from the video to mutable avcomposition track");
return;
}
//Export the avcompostion track to destination path
NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex: 0];
NSString *dstPath = [documentsDirectory stringByAppendingString:#"sample_audio.mp4"];
NSURL *dstURL = [NSURL fileURLWithPath:dstPath];
//Remove if any file already exists
[[NSFileManager defaultManager] removeItemAtURL:dstURL error:nil];
AVAssetExportSession *exportSession = [[AVAssetExportSession alloc]initWithAsset:newAudioAsset presetName:AVAssetExportPresetPassthrough];
NSLog(#"support file types= %#", [exportSession supportedFileTypes]);
exportSession.outputFileType = #"public.mpeg-4";
exportSession.outputURL = dstURL;
[exportSession exportAsynchronouslyWithCompletionHandler:^{
AVAssetExportSessionStatus status = exportSession.status;
if(AVAssetExportSessionStatusCompleted != status){
NSLog(#"Export status not yet completed. Error: %#", exportSession.error.description);
}
}];
}
How can I resolve this error?

Answer 1

I've tested your code in simulator. It's working fine in simulator(IOS7). But When I run on iPodTouch-5, it shows error as like what you've mention. Spend more than 15 mins, found and silly mistake.
Getting path as below(Documentssample_audio.mp4) when I run in Device..
#"file:///var/mobile/Applications/A1E1D85F-0198-4A0C-80F8-222F0DA1C31A/Documentssample_audio.mp4"
so I've modified path as..
NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex: 0];
NSString *dstPath = [documentsDirectory stringByAppendingString:#"/sample_audio.mp4"];
Now I'm getting path as below(/Documents/sample_audio.mp4) and working fine. But I don't know, How it is happened
#"file:///var/mobile/Applications/A1E1D85F-0198-4A0C-80F8-222F0DA1C31A/Documents/sample_audio.mp4"