Roku (NASDAQ: ROKU) reported first-quarter earnings results yesterday, and the company’s platform business continues to put up strong growth. Other operating metrics also marched higher as Roku grows its audience and engagement remains robust. In fact, the business is doing so well that Roku raised its full-year forecast. Shares have jumped to all-time highs following the release.Roku results: The raw numbers Metric Q1 2019 Q1 2018 Year-Over-Year Change Active accounts 29.1 million 20.8 million 40% Streaming hours 8.9 billion 5.1 billion 74% Average revenue per user (ARPU) $19.06 $15.07 27% Total revenue $206.7 million $136.6 million 51% Gross profit $100.9 million $63.1 million 60% Net loss ($9.7 million) ($6.6 million) N/A Data source: SEC filings.Roku interface displayed on a TVThird-party Roku TVs are helping to drive growth. Image source: Roku.What happened with Roku this quarter?Roku beat expectations and its own guidance on a number of fronts, and made progress on many critical strategic imperatives that it has been pursuing.The company added 2 million active accounts during the quarter.Roku expanded gross margin by 2.6 percentage points year over year, thanks to the ongoing shift to the highly profitable platform segment.Monetized video ad impressions more than doubled year over year.The company estimates that over a third of smart TVs sold in the U.S. in the first quarter were Roku TVs made by third-party manufacturers.Player unit sales increased 21% year over year.Player average selling prices (ASPs) declined 4% year over year due to aggressive pricing.Platform revenue jumped 79% to $134.2 million.Roku raised $98 million in net proceeds through an at-the-market secondary offering.Adjusted EBITDA was $10 million.What management had to sayDisney and Apple are launching high-profile over-the-top (OTT) streaming services this year, and Roku is on board with both of the giant companies. “In recent weeks, some of the world’s largest media publishers have announced massive new investments in streaming,” CEO Anthony Wood said on the conference call. “New services and customer acquisition campaigns from Disney, Apple, and others will help fuel Roku’s growth for years to come.”Roku launched premium third-party subscriptions during the quarter, and has grown its stable of available channels to 30, including AT&T’s HBO (which was not available initially at launch). CFO Steve Louden declined to elaborate on whether premium subscriptions were material in the quarter or give any specific figures regarding premium subscriptions, but did note that premium subscriptions may weigh on gross margin due to the way they are accounted for.”And then the other piece [regarding platform gross margin] , which again is early days, but has a very different margin structure because it’s the premium subscription business because it’s handled on a gross basis and then the payment to the content provider is considered [cost of goods sold] , that can have a potential effect as well,” Louden said.Looking forwardGuidance for the second quarter calls for $220 million to $225 million in revenue, which should result in $98 million to $103 million in gross profit. The company expects adjusted EBITDA to be negative $5 million to negative $10 million, with a net loss of $25 million to $30 million.Last quarter, Roku had forecast full-year 2019 revenue of over $1 billion, and the company is raising its outlook slightly. Roku now expects 2019 revenue to be $1.03 billion to $1.05 billion, up from the prior projection of $1 billion to $1.025 billion in sales. Gross profit for 2019 should be $465 million to $475 million, with adjusted EBITDA of $10 million to $20 million. Net loss for the year is expected to be $65 million to $75 million. More From The Motley Fool 10 Best Stocks to Buy Today The $16,728 Social Security Bonus You Cannot Afford to Miss 20 of the Top Stocks to Buy (Including the Two Every Investor Should Own) What Is an ETF? 5 Recession-Proof Stocks How to Beat the Market Evan Niu, CFA owns shares of AAPL and DIS. The Motley Fool owns shares of and recommends AAPL and DIS. The Motley Fool has the following options: short January 2020 $155 calls on AAPL and long January 2020 $150 calls on AAPL. The Motley Fool recommends Roku. The Motley Fool has a disclosure policy.