Function to Convert Video to Grayscale using Media Transaformer

TransformerActivity.kt

private fun convertToGrayScale() {
        val effect = arrayListOf<Effect>()
        effect.add(RgbFilter.createGrayscaleFilter())
        val transformer = with(Transformer.Builder(this)) {
            addListener(object : Transformer.Listener {
                override fun onCompleted(composition: Composition, exportResult: ExportResult) {
                    //Play the video from the path you specified below
                }

                override fun onError(
                    composition: Composition,
                    exportResult: ExportResult,
                    exportException: ExportException
                ) {
                    //Handle error scenarios
                }
            })
            build()
        }
        val inputMediaItem = MediaItem.Builder().apply {
            setUri("<videoUrl>")
        }.build()
        val editedMediaItem = EditedMediaItem.Builder(inputMediaItem).apply {
            setEffects(Effects(mutableListOf(), effect))
        }
        transformer.start(editedMediaItem.build(), "file://<path>")
}