如何使用AVAssetWriter将视频裁剪为iOS正方形？

Question

我正在使用AVAssetWriter录制视频，并希望能够将视频裁剪为一个带有顶部偏移的正方形。以下是我的代码 -

NSDictionary *videoCleanApertureSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                            @320, AVVideoCleanApertureWidthKey,
                                            @320, AVVideoCleanApertureHeightKey,
                                            @10, AVVideoCleanApertureHorizontalOffsetKey,
                                            @10, AVVideoCleanApertureVerticalOffsetKey,
                                            nil];


NSDictionary *videoAspectRatioSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                          @3, AVVideoPixelAspectRatioHorizontalSpacingKey,
                                          @3,AVVideoPixelAspectRatioVerticalSpacingKey,
                                          nil];



NSDictionary *codecSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                               [NSNumber numberWithInteger:bitsPerSecond], AVVideoAverageBitRateKey,
                               @1,AVVideoMaxKeyFrameIntervalKey,
                               videoCleanApertureSettings, AVVideoCleanApertureKey,
                               //AVVideoScalingModeFit,AVVideoScalingModeKey,
                               videoAspectRatioSettings, AVVideoPixelAspectRatioKey,
                               nil];

NSDictionary *videoCompressionSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                               AVVideoCodecH264, AVVideoCodecKey,
                               codecSettings,AVVideoCompressionPropertiesKey,
                               @320, AVVideoWidthKey,
                               @320, AVVideoHeightKey,
                               nil];

每当我取消注释AVVideoScalingModeKey时，我的assetWriter就会报错，称无法应用videoCompressionSettings。我尝试使用如何使用AVAssetWriter制作缩小尺寸的视频？，但对我来说仍然不起作用。

- MichaelScaria

Answer 1

我将AVVideoScalingModeFit,AVVideoScalingModeKey添加到我的videoCompressionSettings中，以使其正常工作。

- MichaelScaria

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我尝试过，但出现了“AVAssetWriterInput目前不支持AVVideoScalingModeFit”错误。有新的解决方案来修复这个问题吗？ - jgvb

AVAssetWriter比AVAssetExportSession更快吗？ - brian Scroggins