Add LongCat T2V (Base, Distillation and Refinement) Support to FastVideo (#883)

Co-authored-by: Shao Duan <shaoxiongduan@gmail.com>

scripts/inference/v1_inference_longcat.sh

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+#!/bin/bash
+
+num_gpus=2
+
+export FASTVIDEO_ATTENTION_BACKEND=
+
+# For longcat, we must first convert the official weights to FastVideo native format
+# conversion method: python scripts/checkpoint_conversion/longcat_to_fastvideo.py
+# --source /path/to/LongCat-Video/weights/LongCat-Video
+# --output weights/longcat-native
+export MODEL_BASE=weights/longcat-native
+
+fastvideo generate \
+    --model-path $MODEL_BASE \
+    --sp-size $num_gpus \
+    --tp-size 1 \
+    --num-gpus $num_gpus \
+    --dit-cpu-offload False \
+    --vae-cpu-offload False \
+    --text-encoder-cpu-offload False \
+    --pin-cpu-memory False \
+    --enable-bsa False \
+    --height 480 \
+    --width 832 \
+    --num-frames 93 \
+    --num-inference-steps 50 \
+    --fps 15 \
+    --guidance-scale 4.0 \
+    --prompt-txt assets/prompt.txt \
+    --negative-prompt "Bright tones, overexposed, static, blurred details, subtitles, style, works, paintings, images, static, overall gray, worst quality, low quality, JPEG compression residue, ugly, incomplete, extra fingers, poorly drawn hands, poorly drawn faces, deformed, disfigured, misshapen limbs, fused fingers, still picture, messy background, three legs, many people in the background, walking backwards" \
+    --seed 42 \
+    --output-path outputs_video/longcat_480p

scripts/inference/v1_inference_longcat_distill.sh

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+#!/bin/bash
+
+num_gpus=1
+export FASTVIDEO_ATTENTION_BACKEND=
+# For longcat, we must first convert the official weights to FastVideo native format
+# conversion method: python scripts/checkpoint_conversion/longcat_to_fastvideo.py
+# --source /path/to/LongCat-Video/weights/LongCat-Video
+# --output weights/longcat-native
+export MODEL_BASE=weights/longcat-native
+
+fastvideo generate \
+    --model-path $MODEL_BASE \
+    --sp-size $num_gpus \
+    --tp-size 1 \
+    --num-gpus $num_gpus \
+    --dit-cpu-offload False \
+    --vae-cpu-offload False \
+    --text-encoder-cpu-offload False \
+    --pin-cpu-memory False \
+    --enable-bsa False \
+    --lora-path "$MODEL_BASE/lora/distilled" \
+    --lora-nickname "distilled" \
+    --height 480 \
+    --width 832 \
+    --num-frames 93 \
+    --num-inference-steps 16 \
+    --fps 15 \
+    --guidance-scale 1.0 \
+    --prompt "In a realistic photography style, an asian boy around seven or eight years old sits on a park bench, wearing a light yellow T-shirt, denim shorts, and white sneakers. He holds an ice cream cone with vanilla and chocolate flavors, and beside him is a medium-sized golden Labrador. Smiling, the boy offers the ice cream to the dog, who eagerly licks it with its tongue. The sun is shining brightly, and the background features a green lawn and several tall trees, creating a warm and loving scene." \
+    --seed 42 \
+    --output-path outputs_video/longcat_distill

scripts/inference/v1_inference_longcat_refine_fromvideo.sh

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+#!/bin/bash
+
+num_gpus=1
+export FASTVIDEO_ATTENTION_BACKEND=
+# For longcat, we must first convert the official weights to FastVideo native format
+# conversion method: python scripts/checkpoint_conversion/longcat_to_fastvideo.py
+# --source /path/to/LongCat-Video/weights/LongCat-Video
+# --output weights/longcat-native
+export MODEL_BASE=weights/longcat-native
+
+INPUT_VIDEO="outputs_video/longcat_distill/In a realistic photography style, an asian boy around seven or eight years old sits on a park bench,.mp4"
+REFINE_OUTPUT="outputs_video/longcat_refine_720p"
+
+# Prompt used for base generation
+PROMPT="In a realistic photography style, an asian boy around seven or eight years old sits on a park bench, wearing a light yellow T-shirt, denim shorts, and white sneakers. He holds an ice cream cone with vanilla and chocolate flavors, and beside him is a medium-sized golden Labrador. Smiling, the boy offers the ice cream to the dog, who eagerly licks it with its tongue. The sun is shining brightly, and the background features a green lawn and several tall trees, creating a warm and loving scene."
+
+echo "=========================================="
+echo "LongCat 480p -> 720p Refinement"
+echo "=========================================="
+echo ""
+echo "Input:  $INPUT_VIDEO"
+echo "Output: $REFINE_OUTPUT"
+echo ""
+
+# Check if input video exists
+if [ ! -f "$INPUT_VIDEO" ]; then
+    echo "Error: Input video not found: $INPUT_VIDEO"
+    echo "Please set INPUT_VIDEO to your 480p video path"
+    exit 1
+fi
+
+echo "🔧 Configuring refinement (BSA enabled, refinement LoRA)..."
+echo "✅ Input video: $INPUT_VIDEO"
+echo "✅ BSA enabled with sparsity=0.875"
+echo "✅ Refinement LoRA loaded"
+echo ""
+
+fastvideo generate \
+    --model-path $MODEL_BASE \
+    --sp-size $num_gpus \
+    --tp-size 1 \
+    --num-gpus $num_gpus \
+    --dit-cpu-offload True \
+    --vae-cpu-offload False \
+    --text-encoder-cpu-offload True \
+    --pin-cpu-memory False \
+    --enable-bsa True \
+    --bsa-sparsity 0.875 \
+    --bsa-chunk-q 4 4 8 \
+    --bsa-chunk-k 4 4 8 \
+    --lora-path "$MODEL_BASE/lora/refinement" \
+    --lora-nickname "refinement" \
+    --refine-from "$INPUT_VIDEO" \
+    --t-thresh 0.5 \
+    --spatial-refine-only False \
+    --num-cond-frames 0 \
+    --height 720 \
+    --width 1280 \
+    --num-inference-steps 50 \
+    --fps 30 \
+    --guidance-scale 1.0 \
+    --prompt "$PROMPT" \
+    --seed 42 \
+    --output-path "$REFINE_OUTPUT"
+
+echo ""
+echo "=========================================="
+echo "✓ Refinement Complete!"
+echo "=========================================="
+echo ""
+echo "Output directory: $REFINE_OUTPUT"
+echo ""
+