[tab] sample.py (python)
from dataclasses import dataclass
from typing import Optional
import time
import os

import dm_pix as pix
import einops
import jax
import jax.numpy as jnp
import flax.linen as nn
import numpy as np
from flax.training.train_state import TrainState
import grain
import orbax.checkpoint as ocp
import optax
from PIL import Image, ImageDraw
import tyro

from genie import Genie
from utils.dataloader import get_dataloader


@dataclass
class Args:
    # Experiment
    seed: int = 0
    seq_len: int = 16
    image_channels: int = 3
    image_height: int = 90
    image_width: int = 160
    data_dir: str = "data/coinrun_episodes"
    checkpoint: str = ""
    checkpoint_step: Optional[int] = None
    # Sampling
    batch_size: int = 1
    maskgit_steps: int = 25
    temperature: float = 1.0
    sample_argmax: bool = True
    start_frame: int = 0
    # Tokenizer checkpoint
    tokenizer_dim: int = 512
    latent_patch_dim: int = 32
    num_patch_latents: int = 1024
    patch_size: int = 4
    tokenizer_num_blocks: int = 8
    tokenizer_num_heads: int = 8
    # LAM checkpoint
    lam_dim: int = 512
    latent_action_dim: int = 32
    num_latent_actions: int = 6
    lam_patch_size: int = 16
    lam_num_blocks: int = 8
    lam_num_heads: int = 8
    lam_co_train: bool = True
    # Dynamics checkpoint
    dyna_dim: int = 512
    dyna_num_blocks: int = 12
    dyna_num_heads: int = 8


args = tyro.cli(Args)
rng = jax.random.PRNGKey(args.seed)

# --- Load Genie checkpoint ---
genie = Genie(
    # Tokenizer
    in_dim=args.image_channels,
    tokenizer_dim=args.tokenizer_dim,
    latent_patch_dim=args.latent_patch_dim,
    num_patch_latents=args.num_patch_latents,
    patch_size=args.patch_size,
    tokenizer_num_blocks=args.tokenizer_num_blocks,
    tokenizer_num_heads=args.tokenizer_num_heads,
    # LAM
    lam_dim=args.lam_dim,
    latent_action_dim=args.latent_action_dim,
    num_latent_actions=args.num_latent_actions,
    lam_patch_size=args.lam_patch_size,
    lam_num_blocks=args.lam_num_blocks,
    lam_num_heads=args.lam_num_heads,
    lam_co_train=args.lam_co_train,
    # Dynamics
    dyna_dim=args.dyna_dim,
    dyna_num_blocks=args.dyna_num_blocks,
    dyna_num_heads=args.dyna_num_heads,
)
rng, _rng = jax.random.split(rng)
image_shape = (args.image_height, args.image_width, args.image_channels)
dummy_inputs = dict(
    videos=jnp.zeros((args.batch_size, args.seq_len, *image_shape), dtype=jnp.float32),
    mask_rng=_rng,
)
rng, _rng = jax.random.split(rng)
params = genie.init(_rng, dummy_inputs)

dummy_train_state = TrainState.create(
    apply_fn=genie.apply,
    params=params,
    tx=optax.adamw(
        optax.warmup_cosine_decay_schedule(
            0, 0, 1, 2 # dummy values
        )
    ), 
)
handler_registry = ocp.handlers.DefaultCheckpointHandlerRegistry()
handler_registry.add('model_state', ocp.args.StandardRestore, ocp.handlers.StandardCheckpointHandler)
checkpoint_manager = ocp.CheckpointManager(
    args.checkpoint,
    options=ocp.CheckpointManagerOptions(step_format_fixed_length=6),
    handler_registry=handler_registry
)
abstract_train_state = jax.tree_util.tree_map(
    ocp.utils.to_shape_dtype_struct, dummy_train_state
)

restored = checkpoint_manager.restore(
    args.checkpoint_step or checkpoint_manager.latest_step(),
    args=ocp.args.Composite(
        model_state=ocp.args.StandardRestore(abstract_train_state),
    ),
)
restored_train_state = restored["model_state"]
params = restored_train_state.params


def _sampling_wrapper(module, batch):
    return module.sample(batch, args.seq_len, args.maskgit_steps, args.temperature, args.sample_argmax)

# --- Define autoregressive sampling loop ---
def _autoreg_sample(rng, video_batch, action_batch):
    vid = video_batch[:, : args.start_frame + 1]
    sampling_fn = jax.jit(nn.apply(_sampling_wrapper, genie)) 
    rng, _rng = jax.random.split(rng)
    batch = dict(videos=vid, latent_actions=action_batch, rng=_rng)
    generated_vid = sampling_fn(
        params,
        batch
    )
    return generated_vid

def _get_dataloader_iterator():
    array_record_files = [
        os.path.join(args.data_dir, x)
        for x in os.listdir(args.data_dir)
        if x.endswith(".array_record")
    ]
    grain_dataloader = get_dataloader(
        array_record_files,
        args.seq_len,
        # NOTE: We deliberately pass the global batch size
        # The dataloader shards the dataset across all processes
        args.batch_size,
        *image_shape,
        num_workers=0,
        prefetch_buffer_size=1,
        seed=args.seed,
    )
    initial_state = grain_dataloader._create_initial_state()
    grain_iterator = grain.DataLoaderIterator(grain_dataloader, initial_state)
    return grain_iterator

# --- Get video + latent actions ---
grain_iterator = _get_dataloader_iterator()
video_batch = next(grain_iterator)

# Get latent actions for all videos in the batch
batch = dict(videos=video_batch)
action_batch = genie.apply(params, batch, False, method=Genie.vq_encode)
action_batch = action_batch.reshape(video_batch.shape[0], args.seq_len - 1, 1)

# --- Sample + evaluate video ---
vid = _autoreg_sample(rng, video_batch, action_batch)
gt = video_batch[:, : vid.shape[1]].clip(0, 1).reshape(-1, *video_batch.shape[2:])
recon = vid.clip(0, 1).reshape(-1, *vid.shape[2:])
ssim = pix.ssim(gt[:, args.start_frame + 1 :], recon[:, args.start_frame + 1 :]).mean()
print(f"SSIM: {ssim}")

# --- Construct video ---
true_videos = (video_batch * 255).astype(np.uint8)
pred_videos = (vid * 255).astype(np.uint8)
video_comparison = np.zeros((2, *vid.shape), dtype=np.uint8)
video_comparison[0] = true_videos[:, :args.seq_len]
video_comparison[1] = pred_videos
frames = einops.rearrange(video_comparison, "n b t h w c -> t (b h) (n w) c")

# --- Save video --- 
imgs = [Image.fromarray(img) for img in frames]
# Write actions on each frame, on each row (i.e., for each video in the batch, on the GT row)
for t, img in enumerate(imgs[1:]):
    d = ImageDraw.Draw(img)
    for row in range(action_batch.shape[0]):
        action = action_batch[row, t, 0]
        y_offset = row * video_batch.shape[2] + 2
        d.text((2, y_offset), f"{action}", fill=255)
imgs[0].save(
    f"generation_{time.time()}.gif",
    save_all=True,
    append_images=imgs[1:],
    duration=250,
    loop=0,
)