intermediate_device() controls where large output tensors (decoded video
frames) are accumulated. On unified memory, cpu and cuda:0 share the same
physical RAM, but the CUDA allocator has different fragmentation behavior.
With intermediate_device=cuda:0, LTX video VAE decode hung because
tiled_scale_multidim allocates the full output tensor on cuda:0 upfront,
and the CUDA allocator can't efficiently reclaim space during tiled
decode. Reverting to cpu fixes the hang.
vae_offload_device() and text_encoder_offload_device() remain cuda:0
since those model-loading paths benefit from GPU allocation.
Evan Carmen
31939a9710