I am currently building a MythTV server using Fedora Core 5, and have learned a good deal in the past week about A/V, encoding hardware and broadcast standards. There are currently three main broadcast standards in existence, and of course none of them are compatible. If you live in the USA, Canada, or Mexico, you are most likely using the NTSC standard. If you live in the United Kingdom, Asia, or Africa, you are probably using the PAL standard. And finally, if you live in Russia or the northern half of Europe, you can probalby count on the fact that the SECAM standard is used. The following link explains the differences, and as always Wikipedia has tons of useful information on each standard. Neat stuff!