Roku (NASDAQ: ROKU) lists Amazon (NASDAQ: AMZN) as one of its biggest competitors in its quarterly filings with the Securities and Exchange Commission. And its competition with Amazon just got a bit bigger, after the online retailer announced a partnership with Best Buy (NYSE: BBY) to sell several new Fire TV Edition smart TVs.Roku is putting a greater focus on licensing its software to television manufacturers in 2018, as it looks to expand the reach of its platform.