MediaPlayer cannot render to TextureView after ima

问题:

I have a MediaPlayer rendering videos to a TextureView. This is working.

Now, I want to display a still image on this TextureView for a given time, then get the MediaPlayer to render a video to the same TextureView.

Here's my code to render the bitmap:

Canvas canvas = mTextureView.lockCanvas();
canvas.drawBitmap(sourceBitmap, matrix, new Paint());
mTextureView.unlockCanvasAndPost(canvas);

After this, any attempts to play videos result in ERROR_INVALID_OPERATION (-38) being triggered from the video player.

I tried commenting out the call to drawBitmap, and the error still happened. It seems that the simple act of calling lockCanvas followed by unlockCanvasAndPost results in the TextureView being unsuitable for the MediaPlayer to use.

Is there some way that I can reset the TextureView to a state that allows the MediaPlayer to use it?

I'm working on Android 4.2.2.

回答1:

You can't do this, due to a limitation of the Android app framework (as of Android 4.4 at least).

The SurfaceTexture that underlies the TextureView is a buffer consumer. The MediaPlayer is one example of a buffer producer, Canvas is another. Once you attach a producer, you have to detach it before you can attach a second producer.

The trouble is that there is no way to detach a software-based (Canvas) buffer producer. There could be, but isn't. So once you draw with Canvas, you're stuck. (There's a note to that effect here.)

You can detach a GLES producer. For example, in one of Grafika's video player classes you can find a clearSurface() method that clears the surface to black using GLES. Note the EGL context and window are created and explicitly released within the scope of the method. You could expand the method to show an image instead.

回答2:

I have encountered similar problems recently. My intention was to show video thumbnail directly into TextureView and then use the same TextureView to play video, without using another ImageView to display video thumbnail.

I implemented the second approach in @fadden's comments, use EGL to draw video thumbnail into the same TextureView.

In addition, we can also use two textures in GLSurfaceView to achieve the same goal. One external OES texture to play continuous video, and another 2D texture to display video thumbnail.

The full demo can be found in this github project EGLPoster.

Hopefully it will be helpful for anyone reaches here.