Video decoders are usually fixed function blocks, separate from the SMs (which I believe the parent is referring to by "GPU") but are still usually on the same

Video decoders are usually fixed function blocks, separate from the SMs (which I believe the parent is referring to by "GPU") but are still usually on the same physical silicon as the GPU (in case of SoCs, also shared with CPU). They're exposed as an independent engine on the GPU/SoC and can operate with most of the chip power gated.