Chris Kelly -- Tragic LAST VIDEO ... Drugged Out Rap Session

Hours before his death, a drugged out Chris Kelly attempted to rap ... and spit out lyrics about a room full of dead bodies ... and TMZ has the sad footage.

The video -- shot in Kelly's Atlanta home around 7:00 AM on May 1 -- is a window into the life of a drug addict. There's crap strewn all over the house ... and several seemingly drugged out people just hanging out.

One of Kelly's guests -- who also seems inebriated -- pulls out a camera and begins to record as a discombobulated Kelly struggles to rap along with music pumping through the speakers.

We're told the song is a track Kelly had been working on recently -- and includes the lyric, "We don’t stop, for nothing or nobody … look around you it's full of dead bodies."

Hours after the video was shot, someone in Kelly's home called 911 and told officials the Kris Kross rapper passed out and wouldn't wake up. He was pronounced dead around 5:00 PM.

According to the police report obtained by TMZ, Kelly's mother told cops Kelly had been mixing cocaine and heroin the night before he died.