I’m sure it is no surprise to anyone that copyright is not a simple thing. When you deal in international law, things get even worse.
As base, there are compositions that are under copyright protection, and there are compositions in the Public Domain (no copyright protection).
If you were to record Bach’s Brandenburg Concertos (written around 1715) – the compositions are in the Public Domain, and you can release your recording with no worries about paying licenses to anyone.
Copyright in Effect
On the other side – if you record Regina Spektor’s (who is still alive – and also quite good) compositions – you would certainly need a license.
And then there’s people in Limbo. “Also sprach Zarathustra” was written by Richard Strauss in 1896. That means the work is in the Public Domain in the US (and many other countries). Strauss died in 1949 – which means the work is not in the Public Domain in Spain (and many other countries).
So, if I record and release “Also sprach Zarathustra” in the US – I’m all good… until you watch it in Spain.
Let’s go to the map…
Image by Balfour Smith at Duke University
For every new color, there are some composers in a different kind of limbo.
Argentina-Canada limbo (e.g. Prokoviev) is different from Spain-Australia limbo (e.g. Gershwin).
While trying to figure out a good rule of thumb for worst-case worldwide copyright to Public Domain timelines, it becomes evident that there is not one.
You can be reasonably certain that if a piece of music was written before 1833 – it is in the Public Domain pretty much everywhere. There are certainly pieces of music written in 1910 that are in the Public Domain pretty much everywhere. There may be pieces written in 1828 that are still under copyright somewhere (I have yet to find an example, though).
I hope that I have cleared up one thing… international copyright is insane. Check with the laws in each country you plan to distribute your media.
Some or all of the information in this post may be highly wrong… I did the best I could.