1

我在将音频文件从 wav 转换为 mp3 时遇到问题。我的应用程序录制语音并将音频流保存到 user_audio_raw.wav。之后我尝试将此文件转换为 mp3 格式：

var asset = AVAsset.FromUrl(NSUrl.FromFilename(Path.Combine(Path.GetTempPath(), "user_audio_raw.wav")));

var export = new AVAssetExportSession(asset, AVAssetExportSession.PresetLowQuality);

var u = Path.Combine(Path.GetTempPath(), "user_audio_rec.mp3");

if(File.Exists(u)) {
     File.Delete(u);
}

export.OutputUrl = NSUrl.FromFilename(Path.Combine(Path.GetTempPath(), "user_audio_rec.mp3"));
export.OutputFileType = AVFileType.MpegLayer3;
export.ShouldOptimizeForNetworkUse = true;

export.ExportAsynchronously(() =>
{
     if (export.Error != null)              
      System.Diagnostics.Debug.WriteLine(export.Error.LocalizedDescription);
     else {
         Console.Write("Converted success!");
}
};

当我使用下一条消息调用 export.ExportAsynchronously() 时应用程序崩溃：

Foundation.MonoTouchException has been thrown
Objective-C exception thrown.  Name: NSInvalidArgumentException Reason: *** -[AVAssetExportSession setOutputFileType:] Invalid output file type
Native stack trace:
    0   CoreFoundation                      0x0000000181fc9d1c <redacted> + 148
    1   libobjc.A.dylib                     0x0000000181218528 objc_exception_throw + 56
    2   AVFoundation                        0x000000018787fcc0 <redacted> + 0
    3   BattleSpeak.Platform                0x00000001012276d0 BattleSpeak.Platform + 13596368
..........................................

但是当我尝试转换为 mp4 或任何其他格式的应用程序时，它可以完美运行并且转换没有任何问题。有人知道为什么会发生吗？

4

1 回答 1

1

AVFileType.MpegLayer3是一种可以在 mpeg 视频容器中使用的图层类型，但您不能使用它来导出到仅音频.mp3文件。

注意：您可以导入mp3，但不能导出，我从未见过官方答案，但大多数人都提到了mp3许可问题......（？）

您可以测试资产与AVFoundation文件类型 (UTI) 和导出预设的组合是否是有效组合，以避免通过DetermineCompatibilityOfExportPreset/出现本机异常DetermineCompatibilityOfExportPresetAsync：

var ok = await AVAssetExportSession.DetermineCompatibilityOfExportPresetAsync(
    preset,
    asset,
    UTIConstant
);

根据所有可用的预设和导出类型测试.wav资产，您会发现 mp3 不是受支持的格式。可用选项之一是：

 AppleM4a : com.apple.m4a-audio : AVAssetExportPresetAppleM4A

如果.m4a格式是您的应用程序的选项。

我 NSLog 列出了针对wav资产的所有预设/文件类型：

  True:       QuickTimeMovie : com.apple.quicktime-movie : AVAssetExportPreset1920x1080
  True:       QuickTimeMovie : com.apple.quicktime-movie : AVAssetExportPresetLowQuality
 False:       QuickTimeMovie : com.apple.quicktime-movie : AVAssetExportPresetAppleM4A
  True:       QuickTimeMovie : com.apple.quicktime-movie : AVAssetExportPresetHEVCHighestQuality
  True:       QuickTimeMovie : com.apple.quicktime-movie : AVAssetExportPreset640x480
  True:       QuickTimeMovie : com.apple.quicktime-movie : AVAssetExportPreset3840x2160
  True:       QuickTimeMovie : com.apple.quicktime-movie : AVAssetExportPresetHEVC3840x2160
  True:       QuickTimeMovie : com.apple.quicktime-movie : AVAssetExportPresetHighestQuality
  True:       QuickTimeMovie : com.apple.quicktime-movie : AVAssetExportPreset1280x720
  True:       QuickTimeMovie : com.apple.quicktime-movie : AVAssetExportPresetMediumQuality
  True:       QuickTimeMovie : com.apple.quicktime-movie : AVAssetExportPreset960x540
  True:       QuickTimeMovie : com.apple.quicktime-movie : AVAssetExportPresetHEVC1920x1080
  True:                Mpeg4 : public.mpeg-4 : AVAssetExportPreset1920x1080
  True:                Mpeg4 : public.mpeg-4 : AVAssetExportPresetLowQuality
 False:                Mpeg4 : public.mpeg-4 : AVAssetExportPresetAppleM4A
  True:                Mpeg4 : public.mpeg-4 : AVAssetExportPresetHEVCHighestQuality
  True:                Mpeg4 : public.mpeg-4 : AVAssetExportPreset640x480
  True:                Mpeg4 : public.mpeg-4 : AVAssetExportPreset3840x2160
  True:                Mpeg4 : public.mpeg-4 : AVAssetExportPresetHEVC3840x2160
  True:                Mpeg4 : public.mpeg-4 : AVAssetExportPresetHighestQuality
  True:                Mpeg4 : public.mpeg-4 : AVAssetExportPreset1280x720
  True:                Mpeg4 : public.mpeg-4 : AVAssetExportPresetMediumQuality
  True:                Mpeg4 : public.mpeg-4 : AVAssetExportPreset960x540
  True:                Mpeg4 : public.mpeg-4 : AVAssetExportPresetHEVC1920x1080
  True:             AppleM4V : com.apple.m4v-video : AVAssetExportPreset1920x1080
  True:             AppleM4V : com.apple.m4v-video : AVAssetExportPresetLowQuality
 False:             AppleM4V : com.apple.m4v-video : AVAssetExportPresetAppleM4A
  True:             AppleM4V : com.apple.m4v-video : AVAssetExportPresetHEVCHighestQuality
  True:             AppleM4V : com.apple.m4v-video : AVAssetExportPreset640x480
  True:             AppleM4V : com.apple.m4v-video : AVAssetExportPreset3840x2160
  True:             AppleM4V : com.apple.m4v-video : AVAssetExportPresetHEVC3840x2160
  True:             AppleM4V : com.apple.m4v-video : AVAssetExportPresetHighestQuality
  True:             AppleM4V : com.apple.m4v-video : AVAssetExportPreset1280x720
  True:             AppleM4V : com.apple.m4v-video : AVAssetExportPresetMediumQuality
  True:             AppleM4V : com.apple.m4v-video : AVAssetExportPreset960x540
  True:             AppleM4V : com.apple.m4v-video : AVAssetExportPresetHEVC1920x1080
 False:             ThreeGpp : public.3gpp : AVAssetExportPreset1920x1080
 False:             ThreeGpp : public.3gpp : AVAssetExportPresetLowQuality
 False:             ThreeGpp : public.3gpp : AVAssetExportPresetAppleM4A
 False:             ThreeGpp : public.3gpp : AVAssetExportPresetHEVCHighestQuality
 False:             ThreeGpp : public.3gpp : AVAssetExportPreset640x480
 False:             ThreeGpp : public.3gpp : AVAssetExportPreset3840x2160
 False:             ThreeGpp : public.3gpp : AVAssetExportPresetHEVC3840x2160
 False:             ThreeGpp : public.3gpp : AVAssetExportPresetHighestQuality
 False:             ThreeGpp : public.3gpp : AVAssetExportPreset1280x720
 False:             ThreeGpp : public.3gpp : AVAssetExportPresetMediumQuality
 False:             ThreeGpp : public.3gpp : AVAssetExportPreset960x540
 False:             ThreeGpp : public.3gpp : AVAssetExportPresetHEVC1920x1080
 False:             AppleM4a : com.apple.m4a-audio : AVAssetExportPreset1920x1080
 False:             AppleM4a : com.apple.m4a-audio : AVAssetExportPresetLowQuality
  True:             AppleM4a : com.apple.m4a-audio : AVAssetExportPresetAppleM4A
 False:             AppleM4a : com.apple.m4a-audio : AVAssetExportPresetHEVCHighestQuality
 False:             AppleM4a : com.apple.m4a-audio : AVAssetExportPreset640x480
 False:             AppleM4a : com.apple.m4a-audio : AVAssetExportPreset3840x2160
 False:             AppleM4a : com.apple.m4a-audio : AVAssetExportPresetHEVC3840x2160
 False:             AppleM4a : com.apple.m4a-audio : AVAssetExportPresetHighestQuality
 False:             AppleM4a : com.apple.m4a-audio : AVAssetExportPreset1280x720
 False:             AppleM4a : com.apple.m4a-audio : AVAssetExportPresetMediumQuality
 False:             AppleM4a : com.apple.m4a-audio : AVAssetExportPreset960x540
 False:             AppleM4a : com.apple.m4a-audio : AVAssetExportPresetHEVC1920x1080
 False:      CoreAudioFormat : com.apple.coreaudio-format : AVAssetExportPreset1920x1080
 False:      CoreAudioFormat : com.apple.coreaudio-format : AVAssetExportPresetLowQuality
 False:      CoreAudioFormat : com.apple.coreaudio-format : AVAssetExportPresetAppleM4A
 False:      CoreAudioFormat : com.apple.coreaudio-format : AVAssetExportPresetHEVCHighestQuality
 False:      CoreAudioFormat : com.apple.coreaudio-format : AVAssetExportPreset640x480
 False:      CoreAudioFormat : com.apple.coreaudio-format : AVAssetExportPreset3840x2160
 False:      CoreAudioFormat : com.apple.coreaudio-format : AVAssetExportPresetHEVC3840x2160
 False:      CoreAudioFormat : com.apple.coreaudio-format : AVAssetExportPresetHighestQuality
 False:      CoreAudioFormat : com.apple.coreaudio-format : AVAssetExportPreset1280x720
 False:      CoreAudioFormat : com.apple.coreaudio-format : AVAssetExportPresetMediumQuality
 False:      CoreAudioFormat : com.apple.coreaudio-format : AVAssetExportPreset960x540
 False:      CoreAudioFormat : com.apple.coreaudio-format : AVAssetExportPresetHEVC1920x1080
 False:                 Wave : com.microsoft.waveform-audio : AVAssetExportPreset1920x1080
 False:                 Wave : com.microsoft.waveform-audio : AVAssetExportPresetLowQuality
 False:                 Wave : com.microsoft.waveform-audio : AVAssetExportPresetAppleM4A
 False:                 Wave : com.microsoft.waveform-audio : AVAssetExportPresetHEVCHighestQuality
 False:                 Wave : com.microsoft.waveform-audio : AVAssetExportPreset640x480
 False:                 Wave : com.microsoft.waveform-audio : AVAssetExportPreset3840x2160
 False:                 Wave : com.microsoft.waveform-audio : AVAssetExportPresetHEVC3840x2160
 False:                 Wave : com.microsoft.waveform-audio : AVAssetExportPresetHighestQuality
 False:                 Wave : com.microsoft.waveform-audio : AVAssetExportPreset1280x720
 False:                 Wave : com.microsoft.waveform-audio : AVAssetExportPresetMediumQuality
 False:                 Wave : com.microsoft.waveform-audio : AVAssetExportPreset960x540
 False:                 Wave : com.microsoft.waveform-audio : AVAssetExportPresetHEVC1920x1080
 False:                 Aiff : public.aiff-audio : AVAssetExportPreset1920x1080
 False:                 Aiff : public.aiff-audio : AVAssetExportPresetLowQuality
 False:                 Aiff : public.aiff-audio : AVAssetExportPresetAppleM4A
 False:                 Aiff : public.aiff-audio : AVAssetExportPresetHEVCHighestQuality
 False:                 Aiff : public.aiff-audio : AVAssetExportPreset640x480
 False:                 Aiff : public.aiff-audio : AVAssetExportPreset3840x2160
 False:                 Aiff : public.aiff-audio : AVAssetExportPresetHEVC3840x2160
 False:                 Aiff : public.aiff-audio : AVAssetExportPresetHighestQuality
 False:                 Aiff : public.aiff-audio : AVAssetExportPreset1280x720
 False:                 Aiff : public.aiff-audio : AVAssetExportPresetMediumQuality
 False:                 Aiff : public.aiff-audio : AVAssetExportPreset960x540
 False:                 Aiff : public.aiff-audio : AVAssetExportPresetHEVC1920x1080
 False:                 Aifc : public.aifc-audio : AVAssetExportPreset1920x1080
 False:                 Aifc : public.aifc-audio : AVAssetExportPresetLowQuality
 False:                 Aifc : public.aifc-audio : AVAssetExportPresetAppleM4A
 False:                 Aifc : public.aifc-audio : AVAssetExportPresetHEVCHighestQuality
 False:                 Aifc : public.aifc-audio : AVAssetExportPreset640x480
 False:                 Aifc : public.aifc-audio : AVAssetExportPreset3840x2160
 False:                 Aifc : public.aifc-audio : AVAssetExportPresetHEVC3840x2160
 False:                 Aifc : public.aifc-audio : AVAssetExportPresetHighestQuality
 False:                 Aifc : public.aifc-audio : AVAssetExportPreset1280x720
 False:                 Aifc : public.aifc-audio : AVAssetExportPresetMediumQuality
 False:                 Aifc : public.aifc-audio : AVAssetExportPreset960x540
 False:                 Aifc : public.aifc-audio : AVAssetExportPresetHEVC1920x1080
 False:                  Amr : org.3gpp.adaptive-multi-rate-audio : AVAssetExportPreset1920x1080
 False:                  Amr : org.3gpp.adaptive-multi-rate-audio : AVAssetExportPresetLowQuality
 False:                  Amr : org.3gpp.adaptive-multi-rate-audio : AVAssetExportPresetAppleM4A
 False:                  Amr : org.3gpp.adaptive-multi-rate-audio : AVAssetExportPresetHEVCHighestQuality
 False:                  Amr : org.3gpp.adaptive-multi-rate-audio : AVAssetExportPreset640x480
 False:                  Amr : org.3gpp.adaptive-multi-rate-audio : AVAssetExportPreset3840x2160
 False:                  Amr : org.3gpp.adaptive-multi-rate-audio : AVAssetExportPresetHEVC3840x2160
 False:                  Amr : org.3gpp.adaptive-multi-rate-audio : AVAssetExportPresetHighestQuality
 False:                  Amr : org.3gpp.adaptive-multi-rate-audio : AVAssetExportPreset1280x720
 False:                  Amr : org.3gpp.adaptive-multi-rate-audio : AVAssetExportPresetMediumQuality
 False:                  Amr : org.3gpp.adaptive-multi-rate-audio : AVAssetExportPreset960x540
 False:                  Amr : org.3gpp.adaptive-multi-rate-audio : AVAssetExportPresetHEVC1920x1080
 False:            ThreeGpp2 : public.3gpp2 : AVAssetExportPreset1920x1080
 False:            ThreeGpp2 : public.3gpp2 : AVAssetExportPresetLowQuality
 False:            ThreeGpp2 : public.3gpp2 : AVAssetExportPresetAppleM4A
 False:            ThreeGpp2 : public.3gpp2 : AVAssetExportPresetHEVCHighestQuality
 False:            ThreeGpp2 : public.3gpp2 : AVAssetExportPreset640x480
 False:            ThreeGpp2 : public.3gpp2 : AVAssetExportPreset3840x2160
 False:            ThreeGpp2 : public.3gpp2 : AVAssetExportPresetHEVC3840x2160
 False:            ThreeGpp2 : public.3gpp2 : AVAssetExportPresetHighestQuality
 False:            ThreeGpp2 : public.3gpp2 : AVAssetExportPreset1280x720
 False:            ThreeGpp2 : public.3gpp2 : AVAssetExportPresetMediumQuality
 False:            ThreeGpp2 : public.3gpp2 : AVAssetExportPreset960x540
 False:            ThreeGpp2 : public.3gpp2 : AVAssetExportPresetHEVC1920x1080
 False:           MpegLayer3 : public.mp3 : AVAssetExportPreset1920x1080
 False:           MpegLayer3 : public.mp3 : AVAssetExportPresetLowQuality
 False:           MpegLayer3 : public.mp3 : AVAssetExportPresetAppleM4A
 False:           MpegLayer3 : public.mp3 : AVAssetExportPresetHEVCHighestQuality
 False:           MpegLayer3 : public.mp3 : AVAssetExportPreset640x480
 False:           MpegLayer3 : public.mp3 : AVAssetExportPreset3840x2160
 False:           MpegLayer3 : public.mp3 : AVAssetExportPresetHEVC3840x2160
 False:           MpegLayer3 : public.mp3 : AVAssetExportPresetHighestQuality
 False:           MpegLayer3 : public.mp3 : AVAssetExportPreset1280x720
 False:           MpegLayer3 : public.mp3 : AVAssetExportPresetMediumQuality
 False:           MpegLayer3 : public.mp3 : AVAssetExportPreset960x540
 False:           MpegLayer3 : public.mp3 : AVAssetExportPresetHEVC1920x1080
 False:                SunAU : public.au-audio : AVAssetExportPreset1920x1080
 False:                SunAU : public.au-audio : AVAssetExportPresetLowQuality
 False:                SunAU : public.au-audio : AVAssetExportPresetAppleM4A
 False:                SunAU : public.au-audio : AVAssetExportPresetHEVCHighestQuality
 False:                SunAU : public.au-audio : AVAssetExportPreset640x480
 False:                SunAU : public.au-audio : AVAssetExportPreset3840x2160
 False:                SunAU : public.au-audio : AVAssetExportPresetHEVC3840x2160
 False:                SunAU : public.au-audio : AVAssetExportPresetHighestQuality
 False:                SunAU : public.au-audio : AVAssetExportPreset1280x720
 False:                SunAU : public.au-audio : AVAssetExportPresetMediumQuality
 False:                SunAU : public.au-audio : AVAssetExportPreset960x540
 False:                SunAU : public.au-audio : AVAssetExportPresetHEVC1920x1080
 False:                  AC3 : public.ac3-audio : AVAssetExportPreset1920x1080
 False:                  AC3 : public.ac3-audio : AVAssetExportPresetLowQuality
 False:                  AC3 : public.ac3-audio : AVAssetExportPresetAppleM4A
 False:                  AC3 : public.ac3-audio : AVAssetExportPresetHEVCHighestQuality
 False:                  AC3 : public.ac3-audio : AVAssetExportPreset640x480
 False:                  AC3 : public.ac3-audio : AVAssetExportPreset3840x2160
 False:                  AC3 : public.ac3-audio : AVAssetExportPresetHEVC3840x2160
 False:                  AC3 : public.ac3-audio : AVAssetExportPresetHighestQuality
 False:                  AC3 : public.ac3-audio : AVAssetExportPreset1280x720
 False:                  AC3 : public.ac3-audio : AVAssetExportPresetMediumQuality
 False:                  AC3 : public.ac3-audio : AVAssetExportPreset960x540
 False:                  AC3 : public.ac3-audio : AVAssetExportPresetHEVC1920x1080
 False:          EnhancedAC3 : public.enhanced-ac3-audio : AVAssetExportPreset1920x1080
 False:          EnhancedAC3 : public.enhanced-ac3-audio : AVAssetExportPresetLowQuality
 False:          EnhancedAC3 : public.enhanced-ac3-audio : AVAssetExportPresetAppleM4A
 False:          EnhancedAC3 : public.enhanced-ac3-audio : AVAssetExportPresetHEVCHighestQuality
 False:          EnhancedAC3 : public.enhanced-ac3-audio : AVAssetExportPreset640x480
 False:          EnhancedAC3 : public.enhanced-ac3-audio : AVAssetExportPreset3840x2160
 False:          EnhancedAC3 : public.enhanced-ac3-audio : AVAssetExportPresetHEVC3840x2160
 False:          EnhancedAC3 : public.enhanced-ac3-audio : AVAssetExportPresetHighestQuality
 False:          EnhancedAC3 : public.enhanced-ac3-audio : AVAssetExportPreset1280x720
 False:          EnhancedAC3 : public.enhanced-ac3-audio : AVAssetExportPresetMediumQuality
 False:          EnhancedAC3 : public.enhanced-ac3-audio : AVAssetExportPreset960x540
 False:          EnhancedAC3 : public.enhanced-ac3-audio : AVAssetExportPresetHEVC1920x1080
 False:                 Jpeg : public.jpeg : AVAssetExportPreset1920x1080
 False:                 Jpeg : public.jpeg : AVAssetExportPresetLowQuality
 False:                 Jpeg : public.jpeg : AVAssetExportPresetAppleM4A
 False:                 Jpeg : public.jpeg : AVAssetExportPresetHEVCHighestQuality
 False:                 Jpeg : public.jpeg : AVAssetExportPreset640x480
 False:                 Jpeg : public.jpeg : AVAssetExportPreset3840x2160
 False:                 Jpeg : public.jpeg : AVAssetExportPresetHEVC3840x2160
 False:                 Jpeg : public.jpeg : AVAssetExportPresetHighestQuality
 False:                 Jpeg : public.jpeg : AVAssetExportPreset1280x720
 False:                 Jpeg : public.jpeg : AVAssetExportPresetMediumQuality
 False:                 Jpeg : public.jpeg : AVAssetExportPreset960x540
 False:                 Jpeg : public.jpeg : AVAssetExportPresetHEVC1920x1080
 False:                  Dng : com.adobe.raw-image : AVAssetExportPreset1920x1080
 False:                  Dng : com.adobe.raw-image : AVAssetExportPresetLowQuality
 False:                  Dng : com.adobe.raw-image : AVAssetExportPresetAppleM4A
 False:                  Dng : com.adobe.raw-image : AVAssetExportPresetHEVCHighestQuality
 False:                  Dng : com.adobe.raw-image : AVAssetExportPreset640x480
 False:                  Dng : com.adobe.raw-image : AVAssetExportPreset3840x2160
 False:                  Dng : com.adobe.raw-image : AVAssetExportPresetHEVC3840x2160
 False:                  Dng : com.adobe.raw-image : AVAssetExportPresetHighestQuality
 False:                  Dng : com.adobe.raw-image : AVAssetExportPreset1280x720
 False:                  Dng : com.adobe.raw-image : AVAssetExportPresetMediumQuality
 False:                  Dng : com.adobe.raw-image : AVAssetExportPreset960x540
 False:                  Dng : com.adobe.raw-image : AVAssetExportPresetHEVC1920x1080
 False:                 Heic : public.heic : AVAssetExportPreset1920x1080
 False:                 Heic : public.heic : AVAssetExportPresetLowQuality
 False:                 Heic : public.heic : AVAssetExportPresetAppleM4A
 False:                 Heic : public.heic : AVAssetExportPresetHEVCHighestQuality
 False:                 Heic : public.heic : AVAssetExportPreset640x480
 False:                 Heic : public.heic : AVAssetExportPreset3840x2160
 False:                 Heic : public.heic : AVAssetExportPresetHEVC3840x2160
 False:                 Heic : public.heic : AVAssetExportPresetHighestQuality
 False:                 Heic : public.heic : AVAssetExportPreset1280x720
 False:                 Heic : public.heic : AVAssetExportPresetMediumQuality
 False:                 Heic : public.heic : AVAssetExportPreset960x540
 False:                 Heic : public.heic : AVAssetExportPresetHEVC1920x1080
 False:                 Avci : public.avci : AVAssetExportPreset1920x1080
 False:                 Avci : public.avci : AVAssetExportPresetLowQuality
 False:                 Avci : public.avci : AVAssetExportPresetAppleM4A
 False:                 Avci : public.avci : AVAssetExportPresetHEVCHighestQuality
 False:                 Avci : public.avci : AVAssetExportPreset640x480
 False:                 Avci : public.avci : AVAssetExportPreset3840x2160
 False:                 Avci : public.avci : AVAssetExportPresetHEVC3840x2160
 False:                 Avci : public.avci : AVAssetExportPresetHighestQuality
 False:                 Avci : public.avci : AVAssetExportPreset1280x720
 False:                 Avci : public.avci : AVAssetExportPresetMediumQuality
 False:                 Avci : public.avci : AVAssetExportPreset960x540
 False:                 Avci : public.avci : AVAssetExportPresetHEVC1920x1080
 False:                 Heif : public.heif : AVAssetExportPreset1920x1080
 False:                 Heif : public.heif : AVAssetExportPresetLowQuality
 False:                 Heif : public.heif : AVAssetExportPresetAppleM4A
 False:                 Heif : public.heif : AVAssetExportPresetHEVCHighestQuality
 False:                 Heif : public.heif : AVAssetExportPreset640x480
 False:                 Heif : public.heif : AVAssetExportPreset3840x2160
 False:                 Heif : public.heif : AVAssetExportPresetHEVC3840x2160
 False:                 Heif : public.heif : AVAssetExportPresetHighestQuality
 False:                 Heif : public.heif : AVAssetExportPreset1280x720
 False:                 Heif : public.heif : AVAssetExportPresetMediumQuality
 False:                 Heif : public.heif : AVAssetExportPreset960x540
 False:                 Heif : public.heif : AVAssetExportPresetHEVC1920x1080
 False:                 Tiff : public.tiff : AVAssetExportPreset1920x1080
 False:                 Tiff : public.tiff : AVAssetExportPresetLowQuality
 False:                 Tiff : public.tiff : AVAssetExportPresetAppleM4A
 False:                 Tiff : public.tiff : AVAssetExportPresetHEVCHighestQuality
 False:                 Tiff : public.tiff : AVAssetExportPreset640x480
 False:                 Tiff : public.tiff : AVAssetExportPreset3840x2160
 False:                 Tiff : public.tiff : AVAssetExportPresetHEVC3840x2160
 False:                 Tiff : public.tiff : AVAssetExportPresetHighestQuality
 False:                 Tiff : public.tiff : AVAssetExportPreset1280x720
 False:                 Tiff : public.tiff : AVAssetExportPresetMediumQuality
 False:                 Tiff : public.tiff : AVAssetExportPreset960x540
 False:                 Tiff : public.tiff : AVAssetExportPresetHEVC1920x1080
于 2017-11-04T20:16:38.133 回答