如何在ios中更改录制视频的饱和度、亮度、对比度

Question

我正在开发一个编辑视频的应用。录制视频时没有问题，因为最初我会设置所有设置，如饱和度、亮度、对比度等。

但问题在于录制的视频。我无法更改已录制视频的上述所有属性。

任何人请告诉我他的问题的解决方案。

任何好的解决方案，建议将不胜感激。

Answer 1

电影可以通过 GPUImageMovie 类加载到框架中，过滤，然后使用 GPUImageMovieWriter 写出。 GPUImageMovieWriter 的速度也足够快，可以从 iPhone 4 的摄像头实时录制 640x480 的视频，因此可以将直接过滤的视频源输入其中。

以下示例说明了如何加载示例影片，将其通过像素化和旋转过滤器，然后将结果作为 480 x 640 h.264 影片记录到磁盘：

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];

录制完成后，您需要从过滤器链中删除电影录制器并使用如下代码关闭录制：

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

电影在完成之前无法使用，因此如果在此之前中断，录制将会丢失。

这里有很好的教程：

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

请参阅“过滤和重新编码电影”部分。

Answer 2

这是对我有用的代码。我使用了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]];
    }
}