VideoTransformEffectDefinition ends with Error: Video could not be decoded

Question

I am trying to use VideoTransformEffectDefinition .

        var clip = await MediaClip.CreateFromFileAsync(pickedFile);//creating clip from storage file
        MediaComposition composition = new MediaComposition();
        composition.Clips.Add(clip);
        VideoTransformEffectDefinition videoEffect1 = new VideoTransformEffectDefinition();
        videoEffect1.PaddingColor = Colors.Blue;//this line is not necessary, does not matter how videoEffect is changed 
        clip.VideoEffectDefinitions.Add(videoEffect1);//adding videoEffect
        this.mediaElement.SetMediaStreamSource(composition.GenerateMediaStreamSource());//setting source to MediaElement

This is not going to throw exception but it show me

"Error: Video could not be decoded"

on media element.

It is strange, because code is working well with VideoStabilizationEffectDefinition:

        var clip = await MediaClip.CreateFromFileAsync(pickedFile);//creating clip from storage file
        MediaComposition composition = new MediaComposition();
        composition.Clips.Add(clip);
        VideoStabilizationEffectDefinition videoEffect = new VideoStabilizationEffectDefinition();
        clip.VideoEffectDefinitions.Add(videoEffect);//adding videoEffect
        this.mediaElement.SetMediaStreamSource(composition.GenerateMediaStreamSource());//setting source to MediaElement

What am I doing wrong?

Answer 1

The VideoTransformEffectDefinition only works with MediaTranscoder. It has no effect over MediaComposition. And it throw an NullReferenceException when you set the MediaElement by MediaElement.SetMediaStreamSource(MediaComposition .GenerateMediaStreamSource()).

There is an official sample from GitHub that uses the MediaTranscoder. And in Scenario1, it creates the MediaTranscoder by private MediaTranscoder _Transcoder = new MediaTranscoder(); You can add the VideoTransformEffectDefinition to MediaTranscoder by AddAudioEffect(System.String activatableClassId, System.Boolean effectRequired, IPropertySet configuration).

You can add the following code to TranscodePreset event in Scenario1_Default.xaml.cs.

For example:

VideoTransformEffectDefinition videoEffect = new VideoTransformEffectDefinition();
_Transcoder.ClearEffects();
var activatableClassId = videoEffect.ActivatableClassId;
_Transcoder.AddVideoEffect(activatableClassId, true, videoEffect.Properties);
videoEffect.PaddingColor = Colors.Blue;
videoEffect.Rotation = MediaRotation.Clockwise90Degrees;