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hao-ai-lab-FastVideo/examples/inference/basic/V2_PORTING_STATUS.md
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SolitaryThinker 7ac2ff0d1c [refactor] v2: shared model registry (HF-id primary + arch fallback) for all entrypoints
Per review: dispatch should be a directly-mapped HF-string -> card registry (like fastvideo), shared
by every entrypoint (VideoGenerator + a future CLI / server), not buried in the generator.

- New v2/registry.py mirrors fastvideo's fastvideo/registry.py hybrid resolution: (1) exact HF repo id
  in an explicit ModelEntry registry [PRIMARY — correct per-model card/capabilities, and the only way to
  split same-architecture capability variants like Wan2.1 T2V vs the i2v 'InP' 1.3B], (2) short repo-name
  match, (3) architecture inference [FALLBACK — local paths / unregistered repos]. resolve(model_path[,
  root]) is the single shared entry point.
- video_generator.py: moved _read_arch_signature/_select_builders into the registry; from_config now
  calls resolve() — registered ids resolve with no config read, else arch inference on a cheap *.json
  snapshot. Reconciles the earlier 'no brittle table' refactor with the 'map hf string -> card' ask: one
  clean registry + a fallback, not three coupled structures.
- Verified: registry resolves exact-id / short-name / arch-fallback / unregistered correctly; CPU suite
  green (202+2); wan21 GPU smoke generates via the new resolve path.
2026-07-04 17:15:34 +00:00

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v2 porting status — fastvideo models → the v2 (recipe, runtime) substrate

Goal: drive each examples/inference/basic/ model through the v2 VideoGenerator (typed fastvideo.api configs + the real torch backend) and generate video, with a matching v2_* example.

Active scope (per request): the Wan family + LTX-2 only. The Cosmos/Hunyuan/SD3.5/LongCat/Flux2/ audio/interactive families below are kept as an upstream reference map but are out of the current scope.

Dispatch is architecture-driven (v2/video_generator.py): from_config reads the checkpoint's pipeline / transformer / VAE class names (+ z_dim, transformer_2) and picks the v2 card — mirroring fastvideo's get_pipeline_config_cls_from_name, with no hardcoded repo-id table.

The v2 mini implements a small set of loops/samplers (flow-match Euler, causal chunk_rollout, FlowGRPO SDE) and adapters (Wan DiT/VAE/UMT5, causal Wan, LTX-2 DiT/VAE/Gemma/spatial upsampler). A model ports cleanly only when its architecture and sampler match what v2 implements; otherwise it needs new per-model work (a card, an adapter for the DiT/VAE/encoder forward, and/or a new sampler), and some are blocked by the environment (gated weights, local-only weights, non-video modality, no VSA).

The v2 bring-up runs single-GPU, resident, on the TORCH_SDPA backend (no fastvideo-kernel / VSA / FP4), so distilled models that depend on VSA/SLA/FP4 kernels or non-flow-match samplers won't match. (Wan2.2-A14B MoE is the exception to "resident": its two 14B experts are CPU-offloaded and swapped onto the GPU one at a time at the boundary-timestep transition, so it fits a single 80GB GPU.)

Environment status: the box was rescheduled from an aarch64 host to an x86_64 host mid-session (ipp1a1… → ipp2-0493). The aarch64 .venv couldn't execute on x86, so the venv was rebuilt for x86 (torch 2.11.0+cu128 x86 + numpy 2.5.0rc1 x86 + fastvideo[dev]) and re-validated: the v2 CPU suite is green and wan21 + LTX-2 base both generate real video on the x86 stack. (If the box flips arch again, rebuild the venv for the current arch — system python /usr/bin/python3.12, reinstall the matching uv, uv pip install -e ".[dev]" with fastvideo-kernel commented out.)

Working today (verified, real video) — committed on v2

Official example(s) Model v2 card v2 example
basic.py, basic_mps.py, basic_ray.py Wan-AI/Wan2.1-T2V-1.3B-Diffusers wan21 v2_basic.py, v2_basic_new_api.py
basic_self_forcing_causal.py wlsaidhi/SFWan2.1-T2V-1.3B-Diffusers wan_causal v2_basic_self_forcing_causal.py, v2_basic_new_api.py
basic_ltx2_distilled.py, basic_ltx2_distilled_fast_profile.py FastVideo/LTX2-Distilled-Diffusers ltx2 — real LTX2LatentUpsampler between base/refine (un_normalize→learned 2× upsample→normalize) v2_basic_new_api.py
basic_wan2_2_ti2v.py (T2V branch) Wan-AI/Wan2.2-TI2V-5B-Diffusers wan2.2-ti2v v2_basic_wan2_2_ti2v.py
basic_wan2_2.py Wan-AI/Wan2.2-T2V-A14B-Diffusers (MoE) wan2.2-a14b + CPU expert offload (one 14B expert resident at a time, swapped at the boundary → 60GB peak) v2_basic_wan2_2.py
basic_ltx2.py Davids048/LTX2-Base-Diffusers ltx2 base (single-stage, request-driven many-step) v2_basic_ltx2.py
basic_ltx2_3_distilled.py FastVideo/LTX-2.3-Distilled-Diffusers (18.99B) ltx2 base card (single-stage; few-step) v2_basic_ltx2_3_distilled.py

All seven rows GPU-verified to generate real video (LTX-2 base / 2.3 show inter-frame motion 4.5 / 6.6 on the rebuilt x86 stack). * basic_mps.py (Apple MPS) and basic_ray.py (ray executor) are device/executor variants of the same Wan2.1 model — covered by wan21; those runtime modes are out of scope.

Needs per-model work (architecture/sampler matches partially)

Official example(s) Model What v2 needs
basic_dmd.py, basic_dmd_new_api.py FastWan2.1-T2V-1.3B (WanDMDPipeline) Blocked (env): loading needs a non-strict load to skip the VSA-only to_gate_compress (root cause: the checkpoint key mis-maps under the generic Wan path, and TransformerLoader is strict except Cosmos2.5 — component_loader.py:1005). Even loaded, the DMD model is trained for VSA, which is not built here (no nvcc), so SDPA output would be degraded. Needs the fastvideo-kernel VSA build + a non-strict WanDMD load.
basic_turbodiffusion*.py TurboWan2.1/2.2 (RCM) New sampler: Reparameterized Consistency Model (fastvideo/models/schedulers/scheduling_rcm.py:RCMScheduler) — v2 has only flow-match/chunk/SDE loops; needs a new RCM consistency loop.
basic_wan2_2_i2v.py, basic_wan2_2_Fun.py Wan2.2-I2V / Fun I2V mechanism (identified, pipelines/stages/image_encoding.py): SigLIP image_encoder+image_processor → image_embeds (the DiT's encoder_hidden_states_image, already accepted) and VAE-encode the first frame, concat [noisy_latent, image_latent, mask] (first-frame mask=1) → an i2v DiT (larger in_channels). v2 needs: image_encoder/image_processor components+adapters, a VAE-encode-image node, the concat-mask conditioning in the wan loop, the i2v DiT in_channels, image_path handling (reuse A14B offload). Fun adds a control input.
basic_lucy_edit.py decart-ai/Lucy-Edit-Dev (Wan v2v) V2V mechanism (identified): WanVideoToVideoPipeline + VideoVAEEncodingStage — VAE-encode the input video to a conditioning latent. v2 needs input-video loading + a VAE-encode-video node + the v2v conditioning (no image_encoder).
basic_ltx2_3_distilled_i2v*.py LTX-2.3-Distilled I2V Image conditioning on the ltx2 single-stage program (encode the input image + condition the denoise).

Out of current scope — new families (kept as an upstream reference map only)

Each would need a new card + adapters (DiT/VAE/encoder forwards) + maybe a sampler: basic_cosmos2_5_* (Cosmos-Predict2.5), basic_gen3c.py (GEN3C — local converted_weights/ only), basic_hy15*.py / basic_gamecraft.py / basic_hyworld.py (Hunyuan family), basic_longcat_*.py (LongCat + LoRA), basic_lingbotworld_base_cam.py, basic_sd35_t2i.py (SD3.5 image), basic_flux2*.py (gated black-forest-labs).

Different modality / interactive (out of the t2v VideoGenerator surface)

basic_stable_audio*.py (audio), basic_matrixgame2*.py / basic_matrixgame3.py (interactive mouse/keyboard-conditioned world models).

How to add a model to the v2 VideoGenerator

  1. Ensure a v2 card exists (v2/models/<family>/) whose load_ids resolve to real fastvideo.models.*.
  2. Register it in the shared v2/registry.py (used by every entrypoint — VideoGenerator, CLI, server): add a ModelEntry mapping its HF id(s) → builders (the explicit PRIMARY path — the only way to split same-architecture capability variants, e.g. T2V vs the i2v "InP"), and/or a branch in select_by_architecture for the arch-inference FALLBACK (local paths / unregistered repos).
  3. If a DiT/VAE/encoder/upsampler forward differs, add an adapter + class-detection in torch_adapters.py and register the component kind in torch_cuda.py.
  4. Add examples/inference/basic/v2_<name>.py mirroring the official example; generate to confirm.