sinf(stream, codecs) {
    const Mp4Generator = shaka.util.Mp4Generator;
    return Mp4Generator.box('sinf',
        this.frma_(codecs),
        this.schm_(stream),
        this.schi_(stream));
  }
Generate a SINF box

@param {!shaka.extern.Stream} stream
@param {string} codecs
@return {!Uint8Array}