Which AWS service transforms video and audio files into formats that will play on smartphones?

Amazon Elastic Transcoder is a media transcoding service in the cloud. It converts media files from their source format into versions that will play back on devices like smartphones, tablets, and PCs, or be stored in services like Amazon S3. This service is specifically designed for changing the format of video and audio files. Amazon Comprehend is a natural language processing (NLP) service. Amazon Rekognition is an image and video analysis service. Amazon Polly is a text-to-speech service. These services do not perform media format transformations.