GobQ is a magazine of international focus. These links and pages provide guides to questions about copyright in both the United States and many other countries. Despite the real advance towards harmonization of rules applying to IP matters in general and copyright of written, audio-visual, and digital works in particular (most intensively undertaken via specifically-directed legislation in the years 1998-2003, and since 2003 as conditions laid down in Free Trade Agreements), copyright still extends differently, and is applied differently, throughout the world.
However, the answers here are only guides. They have no legal force. Contract disputes require legal clarification or negotiation, either through a writers' organization or a copyright/intellectual property lawyer.
Most copyright issues hinge on the doctrine of "fair use": the concept that for the purposes of education, discussion, criticism, and research, short quotes and excerpts from otherwise protected works are both acceptable and necessary.
Beyond these uses, the copyright holder retains the right to reproduce, distribute, perform, display, sell or license the work in question. "Fair use" is currently the most actively-disputed concept in copyright matters.
At its most extreme the attitude of large copyright holders seems to be that no unrecompensed use is fair and that none should be permitted. The means of enforcing this view are technological, contractual, and legislative.
Always check the copyright on music - most music copyrights are held by corporations.
The public domain chart may not apply to music.
A work falls into the public domain at a set time after the author's death. Corporations are legal entities with long lives and strange afterlives. Corporate ownership may not cease in readily discernible ways.