Question

我使用AVAssetWriter与AVAssetWriterInputPixelBufferAdaptor一起制作UIImage数组中的视频。结果电影播放得很好，但整个画面都有蓝色调。我知道像素格式不正确，但不足以解决问题。

AVAssetWriterInputPixelBufferAdaptor代码：

NSDictionary *sourcePixelBufferAttributesDictionary = [NSDictionary dictionaryWithObjectsAndKeys:
                                                       [NSNumber numberWithInt:kCVPixelFormatType_32ARGB], kCVPixelBufferPixelFormatTypeKey, nil];

AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput
                                                                                                                 sourcePixelBufferAttributes:sourcePixelBufferAttributesDictionary];

从CVPixelBufferRef

生成CGImageRef

+ (CVPixelBufferRef)pixelBufferFromCGImage:(CGImageRef)image
{
    CGSize frameSize = CGSizeMake(CGImageGetWidth(image), CGImageGetHeight(image));
    NSDictionary *options = @{
                              (__bridge NSString *)kCVPixelBufferCGImageCompatibilityKey: @(NO),
                              (__bridge NSString *)kCVPixelBufferCGBitmapContextCompatibilityKey: @(NO)
                              };
    CVPixelBufferRef pixelBuffer;
    CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, frameSize.width,
                                          frameSize.height,  kCVPixelFormatType_32ARGB, (__bridge CFDictionaryRef) options,
                                          &pixelBuffer);
    if (status != kCVReturnSuccess) {
        return NULL;
    }

    CVPixelBufferLockBaseAddress(pixelBuffer, 0);
    void *data = CVPixelBufferGetBaseAddress(pixelBuffer);
    CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
    CGContextRef context = CGBitmapContextCreate(data, frameSize.width, frameSize.height,
                                                 8, CVPixelBufferGetBytesPerRow(pixelBuffer), rgbColorSpace,
                                                 (CGBitmapInfo) kCGImageAlphaNoneSkipLast);
    CGContextDrawImage(context, CGRectMake(0, 0, CGImageGetWidth(image),
                                           CGImageGetHeight(image)), image);
    CGColorSpaceRelease(rgbColorSpace);
    CGContextRelease(context);
    CVPixelBufferUnlockBaseAddress(pixelBuffer, 0);

    return pixelBuffer;
}

有什么建议吗？

Answer 1

致电CGBitmapContextCreate时，您应该通过kCGImageAlphaNoneSkipFirst而不是kCGImageAlphaNoneSkipLast。

这是因为您的位图布局为alpha然后是颜色，而不是颜色，而不是alpha。

这让你觉得蓝色的原因是你将ARG视为RGB。 A（alpha）为零，因此您的图像中没有红色。从图像中删除所有红色通常会给你一种蓝绿色调。

将UIImage数组导出为视频 - 蓝色结果

1 个答案: