Excerpts from JC Daniel's book, where this species is listed as Rana malabarica:
Medium sized frog, max. 8cm from snout to vent
Back bright orange to red, black flanks. Upper lip white, possibly extending on the sides along the line of glands. Ventrally white, often marbled with black. Legs brown or black with white barring.
Distributed throughout the western ghats, also known from Nilgiris and possibly occurring in suitable biotopes of the eastern ghats.
Semi arboreal. Colouration camouflages with bark fungi. Emits a powerful fungoid odour, also compared to burnt rubber, when excited. (I have never smelt this, despite seeing and even handling these frogs countless times.)

I might have an old image of this species (heard but didn't see it this time!), will look for it and post it soon. The call (posted here) is roughly similar to that of other Hylarana frogs, with the characteristic "tin rattle" sound.
Thanks Sabyasachi for the processing!