If you’re using Hunyuan AI Video but frustrated by slow render times, I found a game-changer: AC Video. This new method cuts generation time by 8.5X while keeping—or even improving—quality. Here’s how I made it work in ComfyUI, even on my 8GB VRAM GPU, using GGUF quantization and LoRA models.
Why This Matters
Hunyuan Video is powerful but slow. Traditional methods like reducing sampling steps (e.g., LCM) often sacrifice quality. AC Video uses a fusion model and synthetic datasets to speed up rendering without compromising results. In my tests:
- A 3-second video took 3 minutes (15 steps).
- A 5-second clip finished in 1 minute 55 seconds (5 steps).
What You’ll Need
- ComfyUI (latest version).
- AC Video Models:
- GGUF Quantized (Q8 for best quality). :- hunyuan_video_accvid_t2v-5-steps_Q8_0.gguf
- FP8 Safetensors (~13GB, full quality).:- hunyuan_video_accvid-t2v-5-steps_fp8_e4m3fn.safetensors
- LoRA Adapters (tiny 174MB files for quick testing).:- hunyuan_video_accvid_5_steps_lora_rank16_fp8_e4m3fn.safetensors
- Hunyuan Video Base Model (720p).
Step 1: Setting Up AC Video in ComfyUI
AC Video works two ways:
Option A: LoRA Adapters
- Load your Hunyuan Video workflow in ComfyUI.
- Add the AC Video LoRA (e.g.,
5-step rank 16 FP8). - Use double blocks if combining with other LoRAs (like Hunyuan’s reward model for stability).
Option B: GGUF Quantization
- Replace the default model loader with a GGUF loader.
- Load the AC Video FStep GGUF file (Q8 recommended).
- Bypass the diffusion loader—this alone cuts render time.
Step 2: Testing Speed vs. Quality
I compared:
- 15 steps: 3-minute render (near-original quality).
- 5 steps: Under 2 minutes (slightly less detail but great for drafts).
Pro Tip: For character consistency, pair AC Video with Hunyuan LoRAs (e.g., fantasy elves, cinematic portraits).
Step 3: Real-World Examples
Here’s what I generated:
- Cinematic Fashion Model: 4-second clip, 97 frames, 1:56 render time.
- Fantasy Elf Scene: “A beautiful elf near a river” (2-minute render).
- Action Shot: “Hero raising hands” (motion stayed smooth at 10 steps).
Optimizations for Low VRAM
- Use GGUF Q4 or Q5 if Q8 is too heavy.
- Enable torch attention patches for extra speed.
- Reduce frame count: 72 frames ≈ 3 seconds (good for testing).
