who's responsibility is it?

[Pot Odds RAC]

[ QUOTE ]
Is it a players responsibility to know exaclty how many chips the other player in the hand has before he says "all-in" or should all players have their biggest denominations in plain view out in front?

[/ QUOTE ]

Both.

It is considered to be angle shooting to "hide" chips and cash from plain view. Many card rooms have a rule board that explicitly forbids this. The local casinos here have recently stopped letting Cash play at the tables because people can more easily hide $100, add to their stack of $100, or "go south" with cash.

However it is also the player's responsibility to confirm the other player's stack before acting.