BEIJING — A new type of DVD, called HDVD, has appeared on China’s black market, further aggravating the DVD piracy problem.A single HDVD can contain about four full-length feature films. A standard DVD can generally hold one film. HDVD discs play on standard DVD players and sell for the same price as standard pirated DVDs — about $1 per disc. The Ministry of Culture has launched a nationwide campaign to combat the sale of illegal HDVDs. The crackdown will run until the end of February.