-(void)convertimagetoVideo
{
    ///////////// setup OR function def if we move this to a separate function ////////////
    // this should be moved to its own function,that can take an imageArray,videoOutputPath,etc...


NSError *error = nil;


// set up file manager,and file videoOutputPath,remove "test_output.mp4" if it exists...
//NSString *videoOutputPath = @"/Users/someuser/Desktop/test_output.mp4";
NSFileManager *fileMgr = [NSFileManager defaultManager];
NSString *documentsDirectory = [NSHomeDirectory()
                                stringByAppendingPathComponent:@"Documents"];
NSString *videoOutputPath = [documentsDirectory stringByAppendingPathComponent:@"test_output.mp4"];
//NSLog(@"-->videoOutputPath= %@",videoOutputPath);
// get rid of existing mp4 if exists...
if ([fileMgr removeItemAtPath:videoOutputPath error:&error] != YES)
    NSLog(@"Unable to delete file: %@",[error localizedDescription]);


CGSize imageSize = CGSizeMake(400,200);
//    NSUInteger fps = 30;
    NSUInteger fps = 30;

//NSMutableArray *imageArray;
//imageArray = [[NSMutableArray alloc] initWithObjects:@"download.jpeg",@"download2.jpeg",nil];
NSMutableArray *imageArray;
NSArray* imagePaths = [[NSBundle mainBundle] pathsForResourcesOfType:@"png" inDirectory:nil];
imageArray = [[NSMutableArray alloc] initWithCapacity:imagePaths.count];
NSLog(@"-->imageArray.count= %i",imageArray.count);
for (NSString* path in imagePaths)
{
    [imageArray addObject:[UIImage imageWithContentsOfFile:path]];
    //NSLog(@"-->image path= %@",path);
}

//////////////     end setup    ///////////////////////////////////

NSLog(@"Start building video from defined frames.");

AVAssetWriter *videoWriter = [[AVAssetWriter alloc] initWithURL:
                              [NSURL fileURLWithPath:videoOutputPath] fileType:AVFileTypeQuickTimeMovie
                                                          error:&error];
NSParameterAssert(videoWriter);

NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                               AVVideoCodecH264,[NSNumber numberWithInt:imageSize.width],[NSNumber numberWithInt:imageSize.height],nil];

AVAssetWriterInput* videoWriterInput = [AVAssetWriterInput
                                        assetWriterInputWithMediaType:AVMediaTypeVideo
                                        outputSettings:videoSettings];


AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor
                                                 assetWriterInputPixelBufferAdaptorWithAssetWriterInput:videoWriterInput
                                                 sourcePixelBufferAttributes:nil];

NSParameterAssert(videoWriterInput);
NSParameterAssert([videoWriter canAddInput:videoWriterInput]);
videoWriterInput.expectsMediaDataInRealTime = YES;
[videoWriter addInput:videoWriterInput];

//Start a session:
[videoWriter startWriting];
[videoWriter startSessionAtSourceTime:kCMTimeZero];

CVPixelBufferRef buffer = NULL;

//convert uiimage to CGImage.
int frameCount = 0;
double numberOfSecondsPerFrame = 6;
double frameDuration = fps * numberOfSecondsPerFrame;

//for(VideoFrame * frm in imageArray)
NSLog(@"**************************************************");
for(UIImage * img in imageArray)
{
    //UIImage * img = frm._imageFrame;
    buffer = [self pixelBufferFromCGImage:[img CGImage]];

    BOOL append_ok = NO;
    int j = 0;
    while (!append_ok && j < 30) {
        if (adaptor.assetWriterInput.readyForMoreMediaData)  {
            //print out status:
            NSLog(@"Processing video frame (%d,%d)",frameCount,[imageArray count]);

            //CMTime frameTime = CMTimeMake((int64_t),(int32_t)2);

            CMTime frameTime = CMTimeMake(frameCount*frameDuration,(int32_t) fps);
            NSLog(@"seconds = %f,%u,%d",CMTimeGetSeconds(frameTime),fps,j);
            append_ok = [adaptor appendPixelBuffer:buffer withPresentationTime:frameTime];
            if(!append_ok){
                NSError *error = videoWriter.error;
                if(error!=nil) {
                    NSLog(@"Unresolved error %@,%@.",error,[error userInfo]);
                }
            }
        }
        else {
            printf("adaptor not ready %d,%d\n",j);
            [NSThread sleepForTimeInterval:0.1];
        }
        j++;
    }
    if (!append_ok) {
        printf("error appending image %d times %d\n,with error.",j);
    }
    frameCount++;
}
NSLog(@"**************************************************");

//Finish the session:
[videoWriterInput markAsFinished];
[videoWriter finishWriting];
NSLog(@"Write Ended");

}


-(void)CompileFilestomakeVideo
{

    // set up file manager,remove "test_output.mp4" if it exists...
    //NSString *videoOutputPath = @"/Users/someuser/Desktop/test_output.mp4";
    NSString *documentsDirectory = [NSHomeDirectory()
                                    stringByAppendingPathComponent:@"Documents"];
    NSString *videoOutputPath = [documentsDirectory stringByAppendingPathComponent:@"test_output.mp4"];
    //NSLog(@"-->videoOutputPath= %@",videoOutputPath);
    // get rid of existing mp4 if exists...

    AVMutableComposition* mixComposition = [AVMutableComposition composition];

    NSString *bundleDirectory = [[NSBundle mainBundle] bundlePath];
    // audio input file...
    NSString *audio_inputFilePath = [bundleDirectory stringByAppendingPathComponent:@"30secs.mp3"];
    NSURL    *audio_inputFileUrl = [NSURL fileURLWithPath:audio_inputFilePath];

    // this is the video file that was just written above,full path to file is in --> videoOutputPath
    NSURL    *video_inputFileUrl = [NSURL fileURLWithPath:videoOutputPath];

    // create the final video output file as MOV file - may need to be MP4,but this works so far...
    NSString *outputFilePath = [documentsDirectory stringByAppendingPathComponent:@"final_video.mp4"];
    NSURL    *outputFileUrl = [NSURL fileURLWithPath:outputFilePath];

    if ([[NSFileManager defaultManager] fileExistsAtPath:outputFilePath])
        [[NSFileManager defaultManager] removeItemAtPath:outputFilePath error:nil];

    CMTime nextClipStartTime = kCMTimeZero;

    AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL:video_inputFileUrl options:nil];
    CMTimeRange video_timeRange = CMTimeRangeMake(kCMTimeZero,videoAsset.duration);
    AVMutableCompositionTrack *a_compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
    [a_compositionVideoTrack insertTimeRange:video_timeRange ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] atTime:nextClipStartTime error:nil];

    //nextClipStartTime = CMTimeAdd(nextClipStartTime,a_timeRange.duration);

    AVURLAsset* audioAsset = [[AVURLAsset alloc]initWithURL:audio_inputFileUrl options:nil];
    CMTimeRange audio_timeRange = CMTimeRangeMake(kCMTimeZero,audioAsset.duration);
    AVMutableCompositionTrack *b_compositionAudioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
    [b_compositionAudioTrack insertTimeRange:audio_timeRange ofTrack:[[audioAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:nextClipStartTime error:nil];



    AVAssetExportSession* _assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetHighestQuality];
    _assetExport.outputFileType = @"com.apple.quicktime-movie";
    //_assetExport.outputFileType = @"public.mpeg-4";
    //NSLog(@"support file types= %@",[_assetExport supportedFileTypes]);
    _assetExport.outputURL = outputFileUrl;

    [_assetExport exportAsynchronouslyWithCompletionHandler:
     ^(void ) {
         [self saveVideoToAlbum:outputFilePath];
     }
     ];

    ///// THAT IS IT DONE... the final video file will be written here...
    NSLog(@"DONE.....outputFilePath--->%@",outputFilePath);

    // the final video file will be located somewhere like here:
    // /Users/caferrara/Library/Application Support/iPhone Simulator/6.0/Applications/D4B12FEE-E09C-4B12-B772-7F1BD6011BE1/Documents/outputFile.mov


    ////////////////////////////////////////////////////////////////////////////
    ////////////////////////////////////////////////////////////////////////////
}
- (void) saveVideoToAlbum:(NSString*)path {

    NSLog(@"saveVideoToAlbum");

    if(UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(path)){
        UISaveVideoAtPathToSavedPhotosAlbum (path,nil);
    }
}

-(void) video:(NSString *)videoPath didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo {
    if(error)
        NSLog(@"error: %@",error);
    else
        NSLog(@" OK");
}



////////////////////////
- (CVPixelBufferRef) pixelBufferFromCGImage: (CGImageRef) image {

    CGSize size = CGSizeMake(400,200);

    NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
                             [NSNumber numberWithBool:YES],size.width,size.height,(__bridge CFDictionaryRef) options,&pxbuffer);
    if (status != kCVReturnSuccess){
        NSLog(@"Failed to create pixel buffer");
    }

    CVPixelBufferLockBaseAddress(pxbuffer,0);
    void *pxdata = CVPixelBufferGetBaseAddress(pxbuffer);

    CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
    CGContextRef context = CGBitmapContextCreate(pxdata,4*size.width,kCGImageAlphaPremultipliedFirst);
    //kCGImageAlphaNoneSkipFirst);
    CGContextConcatCTM(context,0);

    return pxbuffer;
}