[content] sample.py (python)
from flax.training.train_state import TrainState
import numpy as np
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 = ""
    # 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
    tokenizer_ffn_dim: int = 2048
    latent_patch_dim: int = 32
    num_patch_latents: int = 1024
    patch_size: int = 4
    tokenizer_num_blocks: int = 4
    tokenizer_num_heads: int = 8
    # LAM checkpoint
    lam_dim: int = 512
    lam_ffn_dim: int = 2048
    latent_action_dim: int = 32
    num_latent_actions: int = 6
    lam_patch_size: int = 16
    lam_num_blocks: int = 4
    lam_num_heads: int = 8
    # Dynamics checkpoint
    dyna_dim: int = 512
    dyna_ffn_dim: int = 2048
    dyna_num_blocks: int = 6
    dyna_num_heads: int = 8
    param_dtype = jnp.float32
    dtype = jnp.bfloat16
    use_flash_attention: bool = True


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,
    tokenizer_ffn_dim=args.tokenizer_ffn_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,
    lam_ffn_dim=args.lam_ffn_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=False,
    # Dynamics
    dyna_dim=args.dyna_dim,
    dyna_ffn_dim=args.dyna_ffn_dim,
    dyna_num_blocks=args.dyna_num_blocks,
    dyna_num_heads=args.dyna_num_heads,
    param_dtype=args.param_dtype,
    dtype=args.dtype,
    use_flash_attention=args.use_flash_attention,
)
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(
    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


# --- Get video + latent actions ---
array_record_files = [
    os.path.join(args.data_dir, x)
    for x in os.listdir(args.data_dir)
    if x.endswith(".array_record")
]
dataloader = get_dataloader(
    array_record_files,
    args.seq_len,
    args.batch_size,
    args.image_height,
    args.image_width,
    args.image_channels,
    num_workers=0,
    prefetch_buffer_size=1,
    seed=args.seed,
)
video_batch = next(iter(dataloader))
video_batch = jnp.array(video_batch)
print(video_batch.dtype)
video_batch = video_batch.astype(args.dtype) # / 255.0
print(video_batch.dtype)
video_batch = video_batch / 255.0
print(video_batch.dtype)
# 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 ---
print("Autoregressively sampling...")
vid = _autoreg_sample(rng, video_batch, action_batch)
print("Sampling done. Calculating ssim and saving video.")
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 ---