我正在开发一款 iOS 应用程序,它允许用户拍摄一系列照片 - 然后将照片放入动画中并导出为 MP4 和 GIF。
虽然 MP4 呈现源质量,但 GIF 颜色等级是可见的。
这是视觉比较:
GIF:
MP4
我用于导出为 GIF 的代码:
var dictFile = new NSMutableDictionary();
var gifDictionaryFile = new NSMutableDictionary();
gifDictionaryFile.Add(ImageIO.CGImageProperties.GIFLoopCount, NSNumber.FromFloat(0));
dictFile.Add(ImageIO.CGImageProperties.GIFDictionary, gifDictionaryFile);
var dictFrame = new NSMutableDictionary();
var gifDictionaryFrame = new NSMutableDictionary();
gifDictionaryFrame.Add(ImageIO.CGImageProperties.GIFDelayTime, NSNumber.FromFloat(0f));
dictFrame.Add(ImageIO.CGImageProperties.GIFDictionary, gifDictionaryFrame);
InvokeOnMainThread(() =>
{
var imageDestination = CGImageDestination.Create(fileURL, MobileCoreServices.UTType.GIF, _images.Length);
imageDestination.SetProperties(dictFile);
for (int i = 0; i < this._images.Length; i++)
{
imageDestination.AddImage(this._images[i].CGImage, dictFrame);
}
imageDestination.Close();
});
我用于导出为 MP4 的代码:
var videoSettings = new NSMutableDictionary();
videoSettings.Add(AVVideo.CodecKey, AVVideo.CodecH264);
videoSettings.Add(AVVideo.WidthKey, NSNumber.FromNFloat(images[0].Size.Width));
videoSettings.Add(AVVideo.HeightKey, NSNumber.FromNFloat(images[0].Size.Height));
var videoWriter = new AVAssetWriter(fileURL, AVFileType.Mpeg4, out nsError);
var writerInput = new AVAssetWriterInput(AVMediaType.Video, new AVVideoSettingsCompressed(videoSettings));
var sourcePixelBufferAttributes = new NSMutableDictionary();
sourcePixelBufferAttributes.Add(CVPixelBuffer.PixelFormatTypeKey, NSNumber.FromInt32((int)CVPixelFormatType.CV32ARGB));
var pixelBufferAdaptor = new AVAssetWriterInputPixelBufferAdaptor(writerInput, sourcePixelBufferAttributes);
videoWriter.AddInput(writerInput);
if (videoWriter.StartWriting())
{
videoWriter.StartSessionAtSourceTime(CMTime.Zero);
for (int i = 0; i < images.Length; i++)
{
while (true)
{
if (writerInput.ReadyForMoreMediaData)
{
var frameTime = new CMTime(1, 10);
var lastTime = new CMTime(1 * i, 10);
var presentTime = CMTime.Add(lastTime, frameTime);
var pixelBufferImage = PixelBufferFromCGImage(images[i].CGImage, pixelBufferAdaptor);
Console.WriteLine(pixelBufferAdaptor.AppendPixelBufferWithPresentationTime(pixelBufferImage, presentTime));
break;
}
}
}
writerInput.MarkAsFinished();
await videoWriter.FinishWritingAsync();
我将不胜感激您的帮助!
亲切的问候,
Andre