The world's biggest record labels are suing a website that allows users to download the audio from YouTube videos.
Universal, Sony, Warner Bros and other labels launched legal action against the German operator of YouTube-mp3.org in a federal court in Los Angeles.
They are seeking damages from the company and its owner that include $150,000 (£115,000) for every alleged instance of piracy.
The defendants have yet to respond to the claims.
According to the legal papers, users can turn YouTube videos into permanent audio files and store them on their computer with a few simple mouse clicks.
The record labels claim that "tens, or even hundreds, of millions of tracks are illegally copied and distributed by stream-ripping services each month" and that YouTube-mp3.org is the "chief offender", with more than 60 million users per month.
As part of their evidence, the labels submitted the names of more than 300 songs that, they allege, have been converted and downloaded by users of the service.
They include Meghan Trainor's All About That Bass, One Direction's Story Of My Life and Sia's Chandelier.
"Stream ripping has become a major threat to the music industry, functioning as an unlawful substitute for the purchase of recorded music and the purchase of subscriptions to authorised streaming services," the labels said.
As well as suing for damages, the music industry is asking for a court order that would forbid web hosts, advertisers and other third parties from facilitating access to youtube-mp3.org.
"This site is raking in millions on the backs of artists, songwriters and labels," said the Recording Industry Association of America's president, Cary Sherman, in a statement.
"It should not be so easy to engage in this activity in the first place, and no stream ripping site should appear at the top of any search result or app chart."
The BPI, which represents UK record labels, has also put YouTube-mp3.org on formal notice of intended legal action in the UK if it does not cease infringing copyright.
"It's time to stop illegal sites like this building huge fortunes by ripping off artists and labels," said the BPI's chief executive, Geoff Taylor.
"Fans have access now to a fantastic range of legal music streaming services, but they can only exist if we take action to tackle the online black market.
"We hope that responsible advertisers, search engines and hosting providers will also reflect on the ethics of supporting sites that enrich themselves by defrauding creators."