looking for avs filter advise

[12 gage]

Hello all, i'm having a problem with pixelation during black/dark scenes while encoding to xvid. I'm using degrain, remove grain, and undot at default modes. Bright scenes look great, but dark ones don't. Is there a better filter for the job? I tried using denoisers turning the modes up on my current ones, and increasing the bitrate, but nothing yet has fixed. Denoiser just make everything look like a pastel drawing. Any help would be appreciated. Thanks in advance.

[celtic_druid]

Something like blockbuster (think that was the name) might help as it doesn't sound like a noise problem rather the oposite, lack of noise.