How many years was the copyright of a film or television work valid?

The duration of the copyright of a film or television work was usually determined by the copyright agreement signed by the producer, director, scriptwriter, actor, producer, and other parties. Some countries have laws that specify the duration of copyright while others don't. For example, in the United States, the copyright of movies and television programs is valid for 20 years, but the producer can renew the copyright 12 months before the copyright expired. Each time the copyright is renewed, it will be valid for 20 years. This meant that if the producer renewed the copyright before it expired, the copyright could be extended by 20 years. If the producer didn't want to renew the contract, the copyright would be terminated after it expired. In other countries, copyrights may be effective for a longer period of time. For example, in Germany, France, the United Kingdom and other countries, copyrights are usually effective for 50 or 70 years. It should be noted that the copyright period was not the only factor that determined whether a film or television work could be legally disseminated. In addition, the broadcast of film and television works also involves the transfer of copyright, authorization and other issues. Therefore, before playing the film and television works, you need to obtain the authorization of the copyright owner.