iphone - AVCaptureSession 仅在 iPhone 3G 上返回空白图像

Question

我正在使用 Apple 的 AVCaptureSession 示例代码，并且创建的 UIImage 完全是空白的。这种情况仅发生在 iPhone 3G 上，并在控制台上显示一个独特的错误，显示 -

Error: CGDataProviderCreateWithCopyOfData: vm_copy failed: status 2.

我在线研究了该错误并发现了这个 StackOverflow answer ，它消除了错误...但图像仍然是空白的。

还有其他人经历过这种情况并知道如何解决吗？

提前致谢。

我的代码 -

CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer); 
CVPixelBufferLockBaseAddress(imageBuffer, 0); 

void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer); 
size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer); 
size_t width = CVPixelBufferGetWidth(imageBuffer); 
size_t height = CVPixelBufferGetHeight(imageBuffer); 

CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); 

CGContextRef context = CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst); 
CGImageRef quartzImage = CGBitmapContextCreateImage(context); 
CVPixelBufferUnlockBaseAddress(imageBuffer,0);

CGContextRelease(context); 
CGColorSpaceRelease(colorSpace);

UIImage *image = [UIImage imageWithCGImage:quartzImage];

CGImageRelease(quartzImage);

return image;

Answer 1

API 中有一些奇怪的东西，所以我使用的解决方法是:

//void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer);     
size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);     
size_t width = CVPixelBufferGetWidth(imageBuffer);     
size_t height = CVPixelBufferGetHeight(imageBuffer);     

// vm_copy fails on older model phones...    
//    
uint8_t *baseAddress = malloc( bytesPerRow * height );    
memcpy( baseAddress, CVPixelBufferGetBaseAddress(imageBuffer), bytesPerRow * height );

CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();     

// NO ALPHA CHANNEL ON OLDER MODELS    
// CGContextRef context = CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);     
CGContextRef context = CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipFirst);     
CGImageRef quartzImage = CGBitmapContextCreateImage(context);     

CVPixelBufferUnlockBaseAddress(imageBuffer,0);    
CGContextRelease(context);     
CGColorSpaceRelease(colorSpace);    
free( baseAddress );

UIImage *image = [UIImage imageWithCGImage:quartzImage];    
CGImageRelease(quartzImage);

return image;