AVAssetWriter 输出设置失败，720p @ 60fps

Question

我正在开发这个相机应用程序。在某些时候我正在尝试写入视频，所以我正在创建一个 assetWriter 并且我有这些行：

  CGFloat videoFrameWidth = size.width;
  CGFloat videoFrameHeight  = size.height;

  NSUInteger numPixels = videoFrameWidth * videoFrameHeight;
  NSUInteger bitsPerSecond;

  NSUInteger bitsPerPixel = 11.4; // This bitrate matches the quality produced by AVCaptureSessionPresetHigh... this was copied from a code from Apple

  bitsPerSecond = numPixels * bitsPerPixel;

  NSDictionary *videoCompressionSettings = @{AVVideoCodecKey                  : AVVideoCodecH264,
                                             AVVideoWidthKey                  : @(videoFrameWidth),
                                             AVVideoHeightKey                 : @(videoFrameHeight),
                                             AVVideoCompressionPropertiesKey  : @{ AVVideoAverageBitRateKey      : @(bitsPerSecond),
                                                                                   AVVideoMaxKeyFrameIntervalKey : @(fps)}
                                             };

  if ([_assetWriter canApplyOutputSettings:videoCompressionSettings forMediaType:AVMediaTypeVideo])

如果我以 1080p @30 fps 录制，此方法非常有效，但如果我切换到 720p @ 60 fps，最后一行将失败。

Answer 1

如果删除 AVVideoMaxKeyFrameIntervalKey 键会怎样？我想你说的是每 60 帧 1 个关键帧。

AVAssetWriter 输出设置失败，720p @ 60fps

AVAssetWriter failing output settings with 720p @ 60fps

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