I don't remember where I first learned about the bit reservior. I've seen it documented in a bunch of different places. And to my knowledge, the bit reservior is present on both CBR and VBR files.

I believe (not sure about this) that the nogap option in LAME requires that the bit reservior be disabled at the encoder level. I could be wrong about this. If that's the case, then the nogap option might cause the files to be less "efficient" in terms of trading quality for size, so you would need a bigger file to achieve the same quality. That is, if I understand how the bit reservior works.

By the way, an update on WMA gapless: Did not work when I tried it just now. I had a set of perfectly gapless WAV files that I double-checked to make sure they were gapless. Then I encoded them at 160kbps WMA and put them on the player. There was a distinct pause between each file.

I do not know if this pause was encoded into the files or if it was inserted by the player software. But the pause happened on both Windows Media Player as well as on the car player (less badly on the car player).

If it was caused by my encoder, then I would like to know. Those of you who say that WMA is gapless: What encoder was used to encode these allegedly-gapless files?