How to fit video in Live wallpaper, by center-crop and by fitting to width/height?

Background

I'm making a live wallpaper that can show a video. In the beginning I thought this is going to be very hard, so some people suggested using OpenGL solutions or other, very complex solutions (such as this one).
Anyway, for this, I've found various places talking about it, and based on this github library (which has some bugs), I finally got it to work.

The problem

While I've succeeded showing a video, I can't find the way to control how it's shown compared to the screen resolution.
Currently it always gets to be stretched to the screen size, meaning that this (video taken from here) :

gets to show as this:

Reason is the different aspect ratio : 560x320 (video resolution) vs 1080x1920 (device resolution).

What I've tried

I tried to play with various fields and functions of the SurfaceHolder, but with no luck so far.
Here's the current code I've made (full project available here) :

class MovieLiveWallpaperService : WallpaperService() {
    override fun onCreateEngine(): WallpaperService.Engine {
        return VideoLiveWallpaperEngine()
    }

    private enum class PlayerState {
        NONE, PREPARING, READY, PLAYING
    }

    inner class VideoLiveWallpaperEngine : WallpaperService.Engine() {
        private var mp: MediaPlayer? = null
        private var playerState: PlayerState = PlayerState.NONE

        override fun onSurfaceCreated(holder: SurfaceHolder) {
            super.onSurfaceCreated(holder)
            Log.d("AppLog", "onSurfaceCreated")
            mp = MediaPlayer()
            val mySurfaceHolder = MySurfaceHolder(holder)
            mp!!.setDisplay(mySurfaceHolder)
            mp!!.isLooping = true
            mp!!.setVolume(0.0f, 0.0f)
            mp!!.setOnPreparedListener { mp ->
                playerState = PlayerState.READY
                setPlay(true)
            }
            try {
                //mp!!.setDataSource(this@MovieLiveWallpaperService, Uri.parse("http://techslides.com/demos/sample-videos/small.mp4"))
                mp!!.setDataSource(this@MovieLiveWallpaperService, Uri.parse("android.resource://" + packageName + "/" + R.raw.small))
            } catch (e: Exception) {
            }
        }

        override fun onDestroy() {
            super.onDestroy()
            Log.d("AppLog", "onDestroy")
            if (mp == null)
                return
            mp!!.stop()
            mp!!.release()
            playerState = PlayerState.NONE
        }

        private fun setPlay(play: Boolean) {
            if (mp == null)
                return
            if (play == mp!!.isPlaying)
                return
            when {
                !play -> {
                    mp!!.pause()
                    playerState = PlayerState.READY
                }
                mp!!.isPlaying -> return
                playerState == PlayerState.READY -> {
                    Log.d("AppLog", "ready, so starting to play")
                    mp!!.start()
                    playerState = PlayerState.PLAYING
                }
                playerState == PlayerState.NONE -> {
                    Log.d("AppLog", "not ready, so preparing")
                    mp!!.prepareAsync()
                    playerState = PlayerState.PREPARING
                }
            }
        }

        override fun onVisibilityChanged(visible: Boolean) {
            super.onVisibilityChanged(visible)
            Log.d("AppLog", "onVisibilityChanged:" + visible + " " + playerState)
            if (mp == null)
                return
            setPlay(visible)
        }

    }

    class MySurfaceHolder(private val surfaceHolder: SurfaceHolder) : SurfaceHolder {
        override fun addCallback(callback: SurfaceHolder.Callback) = surfaceHolder.addCallback(callback)

        override fun getSurface() = surfaceHolder.surface!!

        override fun getSurfaceFrame() = surfaceHolder.surfaceFrame

        override fun isCreating(): Boolean = surfaceHolder.isCreating

        override fun lockCanvas(): Canvas = surfaceHolder.lockCanvas()

        override fun lockCanvas(dirty: Rect): Canvas = surfaceHolder.lockCanvas(dirty)

        override fun removeCallback(callback: SurfaceHolder.Callback) = surfaceHolder.removeCallback(callback)

        override fun setFixedSize(width: Int, height: Int) = surfaceHolder.setFixedSize(width, height)

        override fun setFormat(format: Int) = surfaceHolder.setFormat(format)

        override fun setKeepScreenOn(screenOn: Boolean) {}

        override fun setSizeFromLayout() = surfaceHolder.setSizeFromLayout()

        override fun setType(type: Int) = surfaceHolder.setType(type)

        override fun unlockCanvasAndPost(canvas: Canvas) = surfaceHolder.unlockCanvasAndPost(canvas)
    }
}

The questions

1. How can I make the content fit the screen, without losing aspect ratio and without cropping (meaning there will be margins) ?
2. How can I make it fill entire screen, without losing aspect ratio, and allowing content to crop (meaning like center-crop) ?

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