only got a video in black frames in 1070Ti

In order to run this project in win10 with 1070Ti(8G RAM), Modified some code in 'demo_gradio.py' and 'k_diffusion_hunyuan.py' by chage torch_dtype from 'torch.bfloat16' to 'torch float16. and run it without Xformers, Flash Attn and Sage Attn.
The relult is a video in black frames, and there is a warning shows when running the code:
\FramePack\demo_gradio.py:223: RuntimeWarning: invalid value encountered in cast preview = (preview * 255.0).detach().cpu().numpy().clip(0, 255).astype(np.uint8)

Reproduce the report on Windows 10 with a GTX 1070 Ti using the reported changes in demo_gradio.py and k_diffusion_hunyuan.py, without Xformers, Flash Attn, or Sage Attn. Start at demo_gradio.py:223 and inspect the warning during preview conversion. Done means the generated video no longer consists of black frames and the invalid-value warning is understood.

Written by the indexing model from the issue text.