图片合成视频

https://github.com/czboosj/HJImagesToVideo 自己修复了这个库的内存泄漏

https://github.com/Willib/ImagesToVideo
swift 版本的图片处理

https://stackoverflow.com/questions/3741323/how-do-i-export-uiimage-array-as-a-movie?noredirect=1&lq=1
图片合成详解

From: http://www.itqls.com/index.php?m=Home&c=Article&a=index&id=63

最近做一个无线设备相关的项目,

需要把扫描得到的图像,合成视频.

由于扫描得到的图像 是通过 drawRect 绘图画出来的,不是一个 Image

而图片转视频的方法是需要用 CGImage去实现的.

方法如下:

由于我需要得到 Image 数组, 就需要把我绘制出来的图片转换一下,

截屏: (正确姿势)

- (UIImage*)screenCap

{

    CGSize size=  CGSizeMake((int)self.bounds.size.width, (int)self.bounds.size.height);

    

//  size 为尺寸, YES 为不透明,第三个参数是缩放比例,直接根据屏幕设置保持清晰度

//  关于这个不透明好多博客都说错了,opaque 的意思是不透明...

    UIGraphicsBeginImageContextWithOptions(size, YES, [UIScreen mainScreen].scale);  

    // 遇到这个没拆分出来直接写,后发现内存泄漏,所以提出来 然后Relese
    CGContextRef context = UIGraphicsGetCurrentContext();

    [self.layer renderInContext:context];

    UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
    CGContextRelease(context);
    UIGraphicsEndImageContext();

  


    return viewImage;

}

通过这个方法可以拿到当前屏幕的图像转换成的 Image

但是,如果需要拿到大量的图,比如100张,他就相当于去截图100张,

内存消耗会非常恐怖.

所以 调用 以上方法 screenCap 的时候, 在外面包一层 autoRelease 去解决.

图片转视频:

- (void)saveVideo:(NSMutableArray *)imageArr withPaths:(NSString *)paths andCallBack:(void(^)(void))callBack 

{ 

    if (!imageArr.count) { 

        return; 

    } 

     

    UIImage *image = self.screenCap; 

     

    CGSize sizeImage = image.size; 

  


    int width = ((int) (sizeImage.width / 16) * 16); 

    int height = ((int) (sizeImage.height / 16) * 16); 

  


    NSLog(@"%d,%d",width,height); 

     

    CGSize size = CGSizeMake(width, height); 

     

    NSError *error = nil; 

  


    unlink([paths UTF8String]); 


     

    AVAssetWriter *videoWriter = [[AVAssetWriter alloc] initWithURL: 

                                  [NSURL fileURLWithPath:paths] 

                                fileType:AVFileTypeQuickTimeMovie 

                                error:&error]; 

     

    NSParameterAssert(videoWriter); 

     

    if(error) 

         

        NSLog(@"error = %@", [error localizedDescription]); 

     

    NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:AVVideoCodecH264, AVVideoCodecKey, 

                                   [NSNumber numberWithInt:size.width], AVVideoWidthKey, 

                                   [NSNumber numberWithInt:size.height], AVVideoHeightKey, nil]; 

     

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

     

     

    NSDictionary *sourcePixelBufferAttributesDictionary = [NSDictionary dictionaryWithObjectsAndKeys: 

                                                            

                                                           [NSNumber numberWithInt:kCVPixelFormatType_32ARGB], kCVPixelBufferPixelFormatTypeKey, nil]; 

     

     

     

    AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput 

                                                            sourcePixelBufferAttributes:sourcePixelBufferAttributesDictionary]; 

     

    NSParameterAssert(writerInput); 

     

    NSParameterAssert([videoWriter canAddInput:writerInput]); 

     

    if ([videoWriter canAddInput:writerInput]) 

        NSLog(@"I can add this input"); 

    else 

        NSLog(@"i can't add this input"); 

     

    [videoWriter addInput:writerInput]; 

     

    [videoWriter startWriting]; 

     

    [videoWriter startSessionAtSourceTime:kCMTimeZero]; 

  


    dispatch_queue_t    dispatchQueue = dispatch_queue_create("mediaInputQueue", NULL); 

     

    [writerInput requestMediaDataWhenReadyOnQueue:dispatchQueue usingBlock:^{ 

             

        CVPixelBufferRef buffer = NULL; 

        NSUInteger fps = 10; 

  


        int frameCount = 0; 

        double numberOfSecondsPerFrame = 0.1; 

        double frameDuration = fps * numberOfSecondsPerFrame; 

         

        for (UIImage *img in imageArr) 

        { 

            //convert uiimage to CGImage. 

            buffer = [self pixelBufferFromCGImage:[img CGImage] size:size]; 

             

            BOOL append_ok = NO; 

            int j = 0; 

            while (!append_ok && j < 30) 

            { 

                if (adaptor.assetWriterInput.readyForMoreMediaData) 

                { 

                    CMTime frameTime = CMTimeMake(frameCount * frameDuration, (int32_t) fps); 

                    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", frameCount, j); 

                    [NSThread sleepForTimeInterval:0.1]; 

                } 

                j++; 

            } 

            if (!append_ok) 

            { 

                printf("error appending image %d times %d\n, with error.", frameCount, j); 

            } 

            frameCount++; 

             

            CVPixelBufferRelease(buffer); 

  


        } 

        //Finish the session: 

        [writerInput markAsFinished]; 

        [videoWriter finishWriting]; 

         

        callBack(); 

    }]; 

     

    NSLog(@"outside for loop"); 

     

}

下面这个方法是拿到 一个 buffer 的 , 通过它去拼接视频.

- (CVPixelBufferRef)pixelBufferFromCGImage:(CGImageRef)image size:(CGSize)size

{

    NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:

                             [NSNumber numberWithBool:YES], kCVPixelBufferCGImageCompatibilityKey,

                             [NSNumber numberWithBool:YES], kCVPixelBufferCGBitmapContextCompatibilityKey, nil];

    CVPixelBufferRef pxbuffer = NULL;

    CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, size.width, size.height, kCVPixelFormatType_32ARGB, (__bridge CFDictionaryRef) options, &pxbuffer);

    

    NSParameterAssert(status == kCVReturnSuccess && pxbuffer != NULL);

    

    CVPixelBufferLockBaseAddress(pxbuffer, 0);

    void *pxdata = CVPixelBufferGetBaseAddress(pxbuffer);

    NSParameterAssert(pxdata != NULL);

    

    CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();

    CGContextRef context = CGBitmapContextCreate(pxdata, size.width, size.height, 8, 4 * size.width, rgbColorSpace, kCGImageAlphaPremultipliedFirst);

    NSParameterAssert(context);

    

    CGContextDrawImage(context, CGRectMake(0, 0, CGImageGetWidth(image), CGImageGetHeight(image)), image);

    

    CGColorSpaceRelease(rgbColorSpace);

    CGContextRelease(context);

    CVPixelBufferUnlockBaseAddress(pxbuffer, 0);

    return pxbuffer;

}

这里会有一个内存飙升的问题,所以要注意 release.