Trimming audio file in iOS 7 using AVAssetExportSession gives wrong duration

Question

I have a requirement where user will be allowed to trim a audio file before submitting to server. The trimming function works fine in iOS 6 and not in iOS 7.

This happens in iOS 7 when user chooses a song from iTunes library and start trimming. It appears as trimmed. The new file which is created after trimming plays upto trimmed and rest will be blank. Also the duration shows the original song duration. This doesn't happen for all files. It happens only for some files. Also I did check the exportable and hasProtectedContent . Both have correct values (exportable - yes, hasProtectedContent - no). Can I know what could be issue in iOS 7.

I am pasting the trimming audio file code for reference

  - (void)trimAndExportAudio:(AVAsset *)avAsset withDuration:(NSInteger)durationInSeconds withStartTime:(NSInteger)startTime endTime:(NSInteger)endTime toFileName:(NSString *)filename withTrimCompleteBlock:(TrimCompleteBlock)trimCompleteBlock
{
    if (startTime < 0 || startTime > durationInSeconds || startTime >= endTime)
    {
        CGLog(@"start time = %d endTime %d durationInSeconds %d", startTime, endTime, durationInSeconds);

        trimCompleteBlock(NO, @"Invalid Start Time");
        return;
    }
    if (endTime > durationInSeconds)
    {
        CGLog(@"start time = %d endTime %d durationInSeconds %d", startTime, endTime, durationInSeconds);

        trimCompleteBlock(NO, @"Invalid End Time");
        return;
    }

    // create the export session
    AVAssetExportSession *exportSession = [AVAssetExportSession exportSessionWithAsset:avAsset presetName:AVAssetExportPresetAppleM4A];
    if (exportSession == nil)
    {
        trimCompleteBlock(NO, @"Could not create an Export Session.");
        return;
    }

    //export file path
    NSError *removeError = nil;
    NSString *filePath = [[CGUtilities applicationLibraryMyRecordingsDirectory] stringByAppendingPathComponent:filename];
    if ([[NSFileManager defaultManager] fileExistsAtPath:filePath])
    {
        [[NSFileManager defaultManager] removeItemAtPath:filePath error:&removeError];
    }
    if (removeError)
    {
        CGLog(@"Error removing existing file = %@", removeError);
    }

    // create trim time range
    CMTime exportStartTime = CMTimeMake(startTime, 1);
    CMTime exportStopTime = CMTimeMake(endTime, 1);
    CMTimeRange exportTimeRange = CMTimeRangeFromTimeToTime(exportStartTime, exportStopTime);

    // configure export session  output with all our parameters
    exportSession.outputURL = [NSURL fileURLWithPath:filePath];     // output path
    exportSession.outputFileType = AVFileTypeAppleM4A;              // output file type
    exportSession.timeRange = exportTimeRange;                      // trim time range

    //perform the export
    __weak AVAssetExportSession *weakExportSession = exportSession;
    [exportSession exportAsynchronouslyWithCompletionHandler:^{
        if (AVAssetExportSessionStatusCompleted == exportSession.status)
        {
            if (![filename isEqualToString:kLibraryTempFileName])
            {
                //created a new recording
            }

            trimCompleteBlock(YES, nil);
        }
        else if (AVAssetExportSessionStatusFailed == exportSession.status)
        {
            // a failure may happen because of an event out of your control
            // for example, an interruption like a phone call comming in
            // make sure and handle this case appropriately
            trimCompleteBlock(NO, weakExportSession.error.description);
        }
        else
        {
            trimCompleteBlock(NO, weakExportSession.error.description);
        }
    }];
}

Thanks

Answer 1

We can import AVFoundation/AVFoundation.h

-(BOOL)trimAudiofile{

    float audioStartTime;//define start time of audio
    float audioEndTime;//define end time of audio
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
   [dateFormatter setDateFormat:@"yyyy-MM-dd_HH-mm-ss"];
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES);
    NSString *libraryCachesDirectory = [paths objectAtIndex:0];
   libraryCachesDirectory = [libraryCachesDirectory stringByAppendingPathComponent:@"Caches"];
    NSString *OutputFilePath = [libraryCachesDirectory stringByAppendingFormat:@"/output_%@.mp4", [dateFormatter stringFromDate:[NSDate date]]];
   NSURL *audioFileOutput = [NSURL fileURLWithPath:OutputFilePath];
   NSURL *audioFileInput;//<Path of orignal audio file>

   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(audioStartTime * 100)), 100);
   CMTime stopTime = CMTimeMake((int)(ceil(audioEndTime * 100)), 100);
   CMTimeRange exportTimeRange = CMTimeRangeFromTimeToTime(startTime, stopTime);

   exportSession.outputURL = audioFileOutput;
   exportSession.timeRange = exportTimeRange;
   exportSession.outputFileType = AVFileTypeAppleM4A;

   [exportSession exportAsynchronouslyWithCompletionHandler:^
   {
       if (AVAssetExportSessionStatusCompleted == exportSession.status)
       {
           NSLog(@"Export OK");
       }
       else if (AVAssetExportSessionStatusFailed == exportSession.status)
       {
           NSLog(@"Export failed: %@", [[exportSession error] localizedDescription]);
       }
   }];
  return YES;
}