If all you want to do is string mpg1's together, use mpgtx. The version for X has more features than for 9.x, but I think there are still a few bugs. Rosetta can do this, too. But so far, QT 6 even has trouble with series of mpg1's that have been "edited" in QT 4/5. The difference is that in 4/5, they remain separate streams which you can later -- theoretically -- extract, while mpgtx and Rosetta merge the streams.