How to change saturation, brightness, contrast of a recorded video in ios

Question

I am developing an app which edit videos. There is no problem when I record video because, initially I will set all the settings like saturation, brightness, contrast etc.

But the problem is with recorded videos. I am unable to change all the above properties of videos which are recorded already.

Anyone please tell me the solution for he problem.

Any good solutions, suggestions will be appreciated.

Answer 1

Movies can be loaded into the framework via the GPUImageMovie class, filtered, and then written out using a GPUImageMovieWriter. GPUImageMovieWriter is also fast enough to record video in realtime from an iPhone 4's camera at 640x480, so a direct filtered video source can be fed into it.

The following is an example of how you would load a sample movie, pass it through a pixellation and rotation filter, then record the result to disk as a 480 x 640 h.264 movie:

movieFile = [[GPUImageMovie alloc] initWithURL:sampleURL];
pixellateFilter = [[GPUImagePixellateFilter alloc] init];
GPUImageRotationFilter *rotationFilter = [[GPUImageRotationFilter alloc] initWithRotation:kGPUImageRotateRight];

[movieFile addTarget:rotationFilter];
[rotationFilter addTarget:pixellateFilter];

NSString *pathToMovie = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/Movie.m4v"];
unlink([pathToMovie UTF8String]);
NSURL *movieURL = [NSURL fileURLWithPath:pathToMovie];

movieWriter = [[GPUImageMovieWriter alloc] initWithMovieURL:movieURL size:CGSizeMake(480.0, 640.0)];
[pixellateFilter addTarget:movieWriter];

[movieWriter startRecording];
[movieFile startProcessing];

Once recording is finished, you need to remove the movie recorder from the filter chain and close off the recording using code like the following:

[pixellateFilter removeTarget:movieWriter];
[movieWriter finishRecording];

A movie won't be usable until it has been finished off, so if this is interrupted before this point, the recording will be lost.

Here is good tutorial:

http://www.sunsetlakesoftware.com/2012/02/12/introducing-gpuimage-framework

See "Filtering and re-encoding a movie" section.

Answer 2

Here is the code which worked for me.I used GPUImage.

viewController.h

#import "GPUImage.h"

GPUImageMovie *movieFile;
GPUImageOutput<GPUImageInput> *filter;
GPUImageMovieWriter *movieWriter;

int ArrayIndex;
UISlider *mSlider;

ViewController.m

NSURL *sampleURL = [[NSBundle mainBundle] URLForResource:@"sample_iPod" withExtension:@"m4v"];

    mSlider=[[UISlider alloc]initWithFrame:CGRectMake(60,380,200, 30)];
    mSlider.continuous=YES;
    [mSlider addTarget:self action:@selector(updatePixelWidth:) forControlEvents:UIControlEventValueChanged];
    [self.view addSubview:mSlider];

    movieFile = [[GPUImageMovie alloc] initWithURL:sampleURL];
    movieFile.runBenchmark = YES;
    movieFile.playAtActualSpeed = YES;

    if(ArrayIndex==0)
    {
         filter=[[GPUImageBrightnessFilter alloc]init];

        mSlider.maximumValue=1.0;
        mSlider.minimumValue=-1.0;
        mSlider.value=0.0;
    }
    else if(ArrayIndex==1)
    {
         filter=[[GPUImageContrastFilter alloc]init];

        mSlider.minimumValue=0.0;
        mSlider.maximumValue=4.0;
        mSlider.value=1.0;

    }
    else if(ArrayIndex==2)
    {
         filter=[[GPUImageSaturationFilter alloc]init];

        mSlider.minimumValue=0.0;
        mSlider.maximumValue=2.0;
        mSlider.value=1.0;

    }

    [movieFile addTarget:filter];

    // Only rotate the video for display, leave orientation the same for recording
    GPUImageView *filterView = (GPUImageView *)self.view;
    [filter addTarget:filterView];

    // In addition to displaying to the screen, write out a processed version of the movie to disk
    NSString *pathToMovie = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/Movie.m4v"];
    unlink([pathToMovie UTF8String]); // If a file already exists, AVAssetWriter won't let you record new frames, so delete the old movie
    NSURL *movieURL = [NSURL fileURLWithPath:pathToMovie];

    movieWriter = [[GPUImageMovieWriter alloc] initWithMovieURL:movieURL size:CGSizeMake(640.0, 480.0)];
    [filter addTarget:movieWriter];

    // Configure this for video from the movie file, where we want to preserve all video frames and audio samples
    movieWriter.shouldPassthroughAudio = YES;
    movieFile.audioEncodingTarget = movieWriter;
    [movieFile enableSynchronizedEncodingUsingMovieWriter:movieWriter];

    [movieWriter startRecording];
    [movieFile startProcessing];

    [movieWriter setCompletionBlock:^{
        [filter removeTarget:movieWriter];
        [movieWriter finishRecording];

        if (UIVideoAtPathIsCompatibleWithSavedPhotosAlbum (pathToMovie)) {
            UISaveVideoAtPathToSavedPhotosAlbum (pathToMovie,self, @selector(video:didFinishSavingWithError:contextInfo:), nil);
        }

    }];



- (void)updatePixelWidth:(id)sender
{
    if(ArrayIndex==0)
    {
        [(GPUImageBrightnessFilter *)filter setBrightness:[(UISlider *)sender value]];
    }
    else if (ArrayIndex==1)
    {
          [(GPUImageContrastFilter *)filter setContrast:[(UISlider *)sender value]];
    }
    else if (ArrayIndex==2)
    {
        [(GPUImageSaturationFilter *)filter setSaturation:[(UISlider *)sender value]];
    }
}