Error in extracting audio from .m4v video file

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"