的Windows Phone 8.1 MediaComposition - 音频过快当拼接视频 [英] Windows Phone 8.1 MediaComposition - Audio Too Fast When Stitching Videos

问题描述

我试图连接多个视频在一起的时候有问题。每当我结合2个或更多的视频，音频以双倍速度播放，而视频正常播放了。

下面是代码。我缺少的东西吗？

我得到相同的结果测试，但克隆一个视频或选择多个视频时使用。

我比较的代码示例这里（我不切边）。

 公共静态IAsyncOperation< ; IStorageFile> ConcatenateVideoRT（[ReadOnlyArray] IStorageFile [] videoFiles，IStorageFolder outputFolder，串outputfileName）
 {
返回Task.Run< IStorageFile>（异步（）=> 
 {
 IStorageFile _OutputFile =等待outputFolder.CreateFileAsync（outputfileName，CreationCollisionOption.GenerateUniqueName）; 
 
 MediaComposition _MediaComposition =新MediaComposition（）; 
的foreach（IStorageFile _VideoFile在videoFiles）
 {
 MediaClip _MediaClip =等待MediaClip.CreateFromFileAsync（_VideoFile）; 
 _MediaComposition.Clips.Add（_MediaClip）; 
 _MediaComposition.Clips.Add（_MediaClip.Clone（））; 
} 
 
 TranscodeFailureReason _TranscodeFailureReason =等待_MediaComposition.RenderToFileAsync（_OutputFile）; 
如果（_TranscodeFailureReason = TranscodeFailureReason.None！）
 {
抛出新的异常（视频级联失败：+ _TranscodeFailureReason.ToString （））; 
} 
 
返回_OutputFile; 
}）AsAsyncOperation（）; 
} 
  

解决方案

它看起来像有两个的问题。我通过添加以下行得到了这个工作：

  MediaEncodingProfile _MediaEncodingProfile = MediaEncodingProfile.CreateMp4（VideoEncodingQuality.Vga）; 
  

和更改以下行：

  TranscodeFailureReason _TranscodeFailureReason =等待_MediaComposition.RenderToFileAsync（_OutputFile）; 
  

要：

  TranscodeFailureReason _TranscodeFailureReason =等待_MediaComposition.RenderToFileAsync（_OutputFile，MediaTrimmingPreference.Fast，_MediaEncodingProfile）; 
  

这个问题似乎是用VideoEncodingQuality.HD720p或VideoEncodingQuality时RenderToFileAsync似乎没有正常工作.HD1080p，这两个设置中重新创建快速的音频问题。此外，使用VideoEncodingQuality.Auto似乎导致编码失败（虽然我觉得它的目的是使用从相机默认设置）。

此外，我张贴的在微软合作伙伴社区论坛，他们的反应的问题是，编码可以在特定的设备，如失败在他们的测试上的Lumia视频记录638无法被编码/级联甚至在其它设备上，而是从一个HTC 8倍，的Lumia 920和的Lumia 930视频可以在所有装置甚至可编码的638

他们认为这是一个设备故障（固件）不是Windows.Media.Editing API的问题。

I am having a problem when trying to concatenate multiple videos together. Whenever I combine 2 or more videos, the audio is played at double speed, while the video plays out normally.

Below is the code. Am I missing something?

I get the same results when testing but cloning a single video or selecting multiple videos.

I have compared to the code example here (I am not trimming).

public static IAsyncOperation<IStorageFile> ConcatenateVideoRT([ReadOnlyArray]IStorageFile[] videoFiles, IStorageFolder outputFolder, string outputfileName)
    {
        return Task.Run<IStorageFile>(async () =>
        {
            IStorageFile _OutputFile = await outputFolder.CreateFileAsync(outputfileName, CreationCollisionOption.GenerateUniqueName);

            MediaComposition _MediaComposition = new MediaComposition();
            foreach (IStorageFile _VideoFile in videoFiles)
            {
                MediaClip _MediaClip = await MediaClip.CreateFromFileAsync(_VideoFile);
                _MediaComposition.Clips.Add(_MediaClip);
                _MediaComposition.Clips.Add(_MediaClip.Clone());
            }

            TranscodeFailureReason _TranscodeFailureReason = await _MediaComposition.RenderToFileAsync(_OutputFile);
            if (_TranscodeFailureReason != TranscodeFailureReason.None)
            {
                throw new Exception("Video Concatenation Failed: " + _TranscodeFailureReason.ToString());
            }

            return _OutputFile;
        }).AsAsyncOperation();
    }

解决方案

It looks like there are two issues. I have got this working by adding the following line:

MediaEncodingProfile _MediaEncodingProfile = MediaEncodingProfile.CreateMp4(VideoEncodingQuality.Vga);

And changing the following line:

TranscodeFailureReason _TranscodeFailureReason = await _MediaComposition.RenderToFileAsync(_OutputFile);

To:

TranscodeFailureReason _TranscodeFailureReason = await _MediaComposition.RenderToFileAsync(_OutputFile, MediaTrimmingPreference.Fast, _MediaEncodingProfile);

The problem seems to be that RenderToFileAsync doesn't appear to work properly when using VideoEncodingQuality.HD720p or VideoEncodingQuality.HD1080p, both of these settings recreate the fast audio issue. Also, using VideoEncodingQuality.Auto seems to cause the encode to fail (although I think it is meant to use the default settings from the camera).

Additionally, I posted the problem on the Microsoft Partner Community Forums and their response was that encoding can fail on specific devices, e.g. in their tests video recorded on a Lumia 638 could not be encoded/concatenated even on other devices, but video from a HTC 8x, Lumia 920 and Lumia 930 could be encoded on all devices even the 638.

They suggested this was a device problem (firmware) not a Windows.Media.Editing API problem.

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