Why are my mp3s out of synch?

When I publish my movie at 32kb per second, the animation is perfectly in synch with the sound.

But when I lower the quality to 16kb per secont, the sound goes out of shynch and progressivly plays quicker.

I need to lower the quality to 16kb to reduce the file size of my animation (to meet a criteria in my brief).

Is there an easy way or sorting it out, or do I have to space my sound files differently to accomodate for the un-synching?

Thanks :slight_smile: