Refactor weight loading and sanitization processes for audio models

mlx_video/models/ltx/audio_vae/__init__.py

@@ -3,7 +3,7 @@
 from .attention import AttentionType, AttnBlock, make_attn
 from .audio_vae import AudioDecoder, decode_audio
 from .causal_conv_2d import CausalConv2d, make_conv2d
-from .causality_axis import CausalityAxis
+from ..config import CausalityAxis
 from .downsample import Downsample, build_downsampling_path
 from .normalization import NormType, PixelNorm, build_normalization_layer
 from .ops import AudioLatentShape, AudioPatchifier, PerChannelStatistics

mlx_video/models/ltx/audio_vae/audio_vae.py

@@ -1,14 +1,15 @@
 """Audio VAE encoder and decoder for LTX-2."""
 
-from typing import Set, Tuple
+from typing import Dict
+from pathlib import Path
 
 import mlx.core as mx
 import mlx.nn as nn
-
+from mlx_vlm.models.base import check_array_shape
+from ..config import AudioDecoderModelConfig
 from .attention import AttentionType, make_attn
 from .causal_conv_2d import make_conv2d
-from .causality_axis import CausalityAxis
-from .downsample import build_downsampling_path
+from ..config import CausalityAxis
 from .normalization import NormType, build_normalization_layer
 from .ops import AudioLatentShape, AudioPatchifier, PerChannelStatistics
 from .resnet import ResnetBlock
@@ -67,22 +68,7 @@ class AudioDecoder(nn.Module):
 
     def __init__(
         self,
-        *,
-        ch: int = 128,
-        out_ch: int = 2,
-        ch_mult: Tuple[int, ...] = (1, 2, 4),
-        num_res_blocks: int = 2,
-        attn_resolutions: Set[int] = None,
-        resolution: int = 256,
-        z_channels: int = 8,
-        norm_type: NormType = NormType.PIXEL,
-        causality_axis: CausalityAxis = CausalityAxis.HEIGHT,
-        dropout: float = 0.0,
-        mid_block_add_attention: bool = True,
-        sample_rate: int = 16000,
-        mel_hop_length: int = 160,
-        is_causal: bool = True,
-        mel_bins: int | None = None,
+        config: AudioDecoderModelConfig,
     ) -> None:
         """
         Initialize the AudioDecoder.
@@ -105,86 +91,132 @@ class AudioDecoder(nn.Module):
         """
         super().__init__()
 
-        if attn_resolutions is None:
-            attn_resolutions = {8, 16, 32}
-
-        # Internal behavioral defaults
-        resamp_with_conv = True
-        attn_type = AttentionType.VANILLA
 
         # Per-channel statistics for denormalizing latents
         # Uses ch (base channel count) to match the patchified latent dimension
         # Input latent shape: (B, z_channels, T, latent_mel_bins) = (B, 8, T, 16)
         # After patchify: (B, T, z_channels * latent_mel_bins) = (B, T, 128)
         # ch=128 matches this dimension, so use ch for per_channel_statistics
-        self.per_channel_statistics = PerChannelStatistics(latent_channels=ch)
-        self.sample_rate = sample_rate
-        self.mel_hop_length = mel_hop_length
-        self.is_causal = is_causal
-        self.mel_bins = mel_bins
+        self.per_channel_statistics = PerChannelStatistics(latent_channels=config.ch)
+        self.sample_rate = config.sample_rate
+        self.mel_hop_length = config.mel_hop_length
+        self.is_causal = config.is_causal
+        self.mel_bins = config.mel_bins
 
         self.patchifier = AudioPatchifier(
             patch_size=1,
             audio_latent_downsample_factor=LATENT_DOWNSAMPLE_FACTOR,
-            sample_rate=sample_rate,
-            hop_length=mel_hop_length,
-            is_causal=is_causal,
+            sample_rate=config.sample_rate,
+            hop_length=config.mel_hop_length,
+            is_causal=config.is_causal,
         )
 
-        self.ch = ch
+        self.ch = config.ch
         self.temb_ch = 0
-        self.num_resolutions = len(ch_mult)
-        self.num_res_blocks = num_res_blocks
-        self.resolution = resolution
-        self.out_ch = out_ch
-        self.give_pre_end = False
-        self.tanh_out = False
-        self.norm_type = norm_type
-        self.z_channels = z_channels
-        self.channel_multipliers = ch_mult
-        self.attn_resolutions = attn_resolutions
-        self.causality_axis = causality_axis
-        self.attn_type = attn_type
+        self.num_resolutions = len(config.ch_mult)
+        self.num_res_blocks = config.num_res_blocks
+        self.resolution = config.resolution
+        self.out_ch = config.out_ch
+        self.give_pre_end = config.give_pre_end
+        self.tanh_out = config.tanh_out
+        self.norm_type = config.norm_type
+        self.z_channels = config.z_channels
+        self.channel_multipliers = config.ch_mult
+        self.attn_resolutions = config.attn_resolutions
+        self.causality_axis = config.causality_axis
+        self.attn_type = config.attn_type
 
-        base_block_channels = ch * self.channel_multipliers[-1]
-        base_resolution = resolution // (2 ** (self.num_resolutions - 1))
-        self.z_shape = (1, z_channels, base_resolution, base_resolution)
+        base_block_channels = config.ch * self.channel_multipliers[-1]
+        base_resolution = config.resolution // (2 ** (self.num_resolutions - 1))
+        self.z_shape = (1, config.z_channels, base_resolution, base_resolution)
 
         self.conv_in = make_conv2d(
-            z_channels, base_block_channels, kernel_size=3, stride=1, causality_axis=self.causality_axis
+            config.z_channels, base_block_channels, kernel_size=3, stride=1, causality_axis=self.causality_axis
         )
 
         self.mid = build_mid_block(
             channels=base_block_channels,
             temb_channels=self.temb_ch,
-            dropout=dropout,
+            dropout=config.dropout,
             norm_type=self.norm_type,
             causality_axis=self.causality_axis,
             attn_type=self.attn_type,
-            add_attention=mid_block_add_attention,
+            add_attention=config.mid_block_add_attention,
         )
 
         self.up, final_block_channels = build_upsampling_path(
-            ch=ch,
-            ch_mult=ch_mult,
+            ch=config.ch,
+            ch_mult=config.ch_mult,
             num_resolutions=self.num_resolutions,
-            num_res_blocks=num_res_blocks,
-            resolution=resolution,
+            num_res_blocks=config.num_res_blocks,
+            resolution=config.resolution,
             temb_channels=self.temb_ch,
-            dropout=dropout,
+            dropout=config.dropout,
             norm_type=self.norm_type,
             causality_axis=self.causality_axis,
             attn_type=self.attn_type,
-            attn_resolutions=attn_resolutions,
-            resamp_with_conv=resamp_with_conv,
+            attn_resolutions=config.attn_resolutions,
+            resamp_with_conv=config.resamp_with_conv,
             initial_block_channels=base_block_channels,
         )
 
         self.norm_out = build_normalization_layer(final_block_channels, normtype=self.norm_type)
         self.conv_out = make_conv2d(
-            final_block_channels, out_ch, kernel_size=3, stride=1, causality_axis=self.causality_axis
+            final_block_channels, config.out_ch, kernel_size=3, stride=1, causality_axis=self.causality_axis
         )
 
+    def sanitize(self, weights: Dict[str, mx.array]) -> Dict[str, mx.array]:
+        """Sanitize audio VAE weight names from PyTorch format to MLX format.
+
+        Args:
+            weights: Dictionary of weights with PyTorch naming
+
+        Returns:
+            Dictionary with MLX-compatible naming for audio VAE decoder
+        """
+        sanitized = {}
+
+        for key, value in weights.items():
+            new_key = key
+
+            # Handle audio_vae.decoder weights
+            if key.startswith("audio_vae.decoder."):
+                new_key = key.replace("audio_vae.decoder.", "")
+            elif key.startswith("audio_vae.per_channel_statistics."):
+                # Map per-channel statistics
+                if "mean-of-means" in key:
+                    new_key = "per_channel_statistics.mean_of_means"
+                elif "std-of-means" in key:
+                    new_key = "per_channel_statistics.std_of_means"
+                else:
+                    continue  # Skip other statistics keys
+            else:
+                continue  # Skip non-decoder keys
+
+            # Handle Conv2d weight shape conversion
+            # PyTorch: (out_channels, in_channels, H, W)
+            # MLX: (out_channels, H, W, in_channels)
+            if "conv" in new_key.lower() and "weight" in new_key and value.ndim == 4:
+                value = value if check_array_shape(value) else mx.transpose(value, (0, 2, 3, 1))
+
+            sanitized[new_key] = value
+
+        return sanitized
+
+    @classmethod
+    def from_pretrained(cls, model_path: Path) -> "AudioDecoder":
+        """Load audio VAE decoder from pretrained model."""
+        from mlx_video.models.ltx.config import AudioDecoderModelConfig
+        import json
+
+        config = AudioDecoderModelConfig.from_dict(json.load(open(model_path / "config.json")))
+        decoder = cls(config)
+        weights = mx.load(str(model_path / "model.safetensors"))
+        # weights = decoder.sanitize(weights)
+        decoder.load_weights(list(weights.items()), strict=True)
+        return decoder
+
+
     def __call__(self, sample: mx.array) -> mx.array:
         """
         Decode latent features back to audio spectrograms.

mlx_video/models/ltx/audio_vae/causal_conv_2d.py

@@ -5,7 +5,7 @@ from typing import Tuple, Union
 import mlx.core as mx
 import mlx.nn as nn
 
-from .causality_axis import CausalityAxis
+from ..config import CausalityAxis
 
 
 def _pair(x: Union[int, Tuple[int, int]]) -> Tuple[int, int]:

mlx_video/models/ltx/audio_vae/causality_axis.py

@@ -1,12 +0,0 @@
-"""Causality axis enum for specifying causal convolution dimensions."""
-
-from enum import Enum
-
-
-class CausalityAxis(Enum):
-    """Enum for specifying the causality axis in causal convolutions."""
-
-    NONE = None
-    WIDTH = "width"
-    HEIGHT = "height"
-    WIDTH_COMPATIBILITY = "width-compatibility"

mlx_video/models/ltx/audio_vae/downsample.py

@@ -6,7 +6,7 @@ import mlx.core as mx
 import mlx.nn as nn
 
 from .attention import AttentionType, make_attn
-from .causality_axis import CausalityAxis
+from ..config import CausalityAxis
 from .normalization import NormType
 from .resnet import ResnetBlock
 

mlx_video/models/ltx/audio_vae/ops.py

@@ -27,21 +27,21 @@ class PerChannelStatistics(nn.Module):
         self.latent_channels = latent_channels
         # Initialize buffers - will be loaded from weights
         # Using underscores for MLX compatibility with weight loading
-        self._std_of_means = mx.ones((latent_channels,))
-        self._mean_of_means = mx.zeros((latent_channels,))
+        self.std_of_means = mx.ones((latent_channels,))
+        self.mean_of_means = mx.zeros((latent_channels,))
 
     def un_normalize(self, x: mx.array) -> mx.array:
         """Denormalize latent representation."""
         # Broadcast statistics to match x shape
         # x shape: (B, C, ...) or (B, ..., C)
-        std = self._std_of_means.astype(x.dtype)
-        mean = self._mean_of_means.astype(x.dtype)
+        std = self.std_of_means.astype(x.dtype)
+        mean = self.mean_of_means.astype(x.dtype)
         return (x * std) + mean
 
     def normalize(self, x: mx.array) -> mx.array:
         """Normalize latent representation."""
-        std = self._std_of_means.astype(x.dtype)
-        mean = self._mean_of_means.astype(x.dtype)
+        std = self.std_of_means.astype(x.dtype)
+        mean = self.mean_of_means.astype(x.dtype)
         return (x - mean) / std
 
 

mlx_video/models/ltx/audio_vae/resnet.py

@@ -6,7 +6,7 @@ import mlx.core as mx
 import mlx.nn as nn
 
 from .causal_conv_2d import make_conv2d
-from .causality_axis import CausalityAxis
+from ..config import CausalityAxis
 from .normalization import NormType, build_normalization_layer
 
 LRELU_SLOPE = 0.1

mlx_video/models/ltx/audio_vae/upsample.py

@@ -7,7 +7,7 @@ import mlx.nn as nn
 
 from .attention import AttentionType, make_attn
 from .causal_conv_2d import make_conv2d
-from .causality_axis import CausalityAxis
+from ..config import CausalityAxis
 from .normalization import NormType
 from .resnet import ResnetBlock
 

mlx_video/models/ltx/audio_vae/vocoder.py

@@ -1,11 +1,12 @@
 """Vocoder for converting mel spectrograms to audio waveforms."""
 
 import math
-from typing import List
-
+from typing import Dict
+from pathlib import Path
 import mlx.core as mx
 import mlx.nn as nn
-
+from mlx_vlm.models.base import check_array_shape
+from ..config import VocoderModelConfig
 from .resnet import LRELU_SLOPE, ResBlock1, ResBlock2, leaky_relu
 
 
@@ -27,44 +28,29 @@ class Vocoder(nn.Module):
 
     def __init__(
         self,
-        resblock_kernel_sizes: List[int] | None = None,
-        upsample_rates: List[int] | None = None,
-        upsample_kernel_sizes: List[int] | None = None,
-        resblock_dilation_sizes: List[List[int]] | None = None,
-        upsample_initial_channel: int = 1024,
-        stereo: bool = True,
-        resblock: str = "1",
-        output_sample_rate: int = 24000,
+        config: VocoderModelConfig
     ):
         super().__init__()
 
-        # Initialize default values if not provided
-        if resblock_kernel_sizes is None:
-            resblock_kernel_sizes = [3, 7, 11]
-        if upsample_rates is None:
-            upsample_rates = [6, 5, 2, 2, 2]
-        if upsample_kernel_sizes is None:
-            upsample_kernel_sizes = [16, 15, 8, 4, 4]
-        if resblock_dilation_sizes is None:
-            resblock_dilation_sizes = [[1, 3, 5], [1, 3, 5], [1, 3, 5]]
 
-        self.output_sample_rate = output_sample_rate
-        self.num_kernels = len(resblock_kernel_sizes)
-        self.num_upsamples = len(upsample_rates)
-        self.upsample_rates = upsample_rates
-        self.upsample_kernel_sizes = upsample_kernel_sizes
-        self.upsample_initial_channel = upsample_initial_channel
+        
+        self.output_sample_rate = config.output_sample_rate
+        self.num_kernels = len(config.resblock_kernel_sizes)
+        self.num_upsamples = len(config.upsample_rates)
+        self.upsample_rates = config.upsample_rates
+        self.upsample_kernel_sizes = config.upsample_kernel_sizes
+        self.upsample_initial_channel = config.upsample_initial_channel
 
-        in_channels = 128 if stereo else 64
-        self.conv_pre = nn.Conv1d(in_channels, upsample_initial_channel, kernel_size=7, stride=1, padding=3)
+        in_channels = 128 if config.stereo else 64
+        self.conv_pre = nn.Conv1d(in_channels, config.upsample_initial_channel, kernel_size=7, stride=1, padding=3)
 
-        resblock_class = ResBlock1 if resblock == "1" else ResBlock2
+        resblock_class = ResBlock1 if config.resblock == "1" else ResBlock2
 
         # Upsampling layers using ConvTranspose1d
         self.ups = {}
-        for i, (stride, kernel_size) in enumerate(zip(upsample_rates, upsample_kernel_sizes)):
-            in_ch = upsample_initial_channel // (2**i)
-            out_ch = upsample_initial_channel // (2 ** (i + 1))
+        for i, (stride, kernel_size) in enumerate(zip(config.upsample_rates, config.upsample_kernel_sizes)):
+            in_ch = config.upsample_initial_channel // (2**i)
+            out_ch = config.upsample_initial_channel // (2 ** (i + 1))
             self.ups[i] = nn.ConvTranspose1d(
                 in_ch,
                 out_ch,
@@ -77,16 +63,67 @@ class Vocoder(nn.Module):
         self.resblocks = {}
         block_idx = 0
         for i in range(len(self.ups)):
-            ch = upsample_initial_channel // (2 ** (i + 1))
-            for kernel_size, dilations in zip(resblock_kernel_sizes, resblock_dilation_sizes):
+            ch = config.upsample_initial_channel // (2 ** (i + 1))
+            for kernel_size, dilations in zip(config.resblock_kernel_sizes, config.resblock_dilation_sizes):
                 self.resblocks[block_idx] = resblock_class(ch, kernel_size, tuple(dilations))
                 block_idx += 1
 
-        out_channels = 2 if stereo else 1
-        final_channels = upsample_initial_channel // (2**self.num_upsamples)
+        out_channels = 2 if config.stereo else 1
+        final_channels = config.upsample_initial_channel // (2**self.num_upsamples)
         self.conv_post = nn.Conv1d(final_channels, out_channels, kernel_size=7, stride=1, padding=3)
 
-        self.upsample_factor = math.prod(upsample_rates)
+        self.upsample_factor = math.prod(config.upsample_rates)
+
+    def sanitize(self, weights: Dict[str, mx.array]) -> Dict[str, mx.array]:
+        sanitized = {}
+
+        if "vocoder." not in weights:
+            return weights
+
+        for key, value in weights.items():
+            new_key = key
+
+            # Handle vocoder weights
+            if key.startswith("vocoder."):
+                new_key = key.replace("vocoder.", "")
+
+                # Handle ModuleList indices -> dict keys
+                # PyTorch: ups.0, ups.1, ... -> ups.0, ups.1, ...
+                # PyTorch: resblocks.0, resblocks.1, ... -> resblocks.0, resblocks.1, ...
+
+                # Handle Conv1d weight shape conversion
+                # PyTorch: (out_channels, in_channels, kernel)
+                # MLX: (out_channels, kernel, in_channels)
+                if "weight" in new_key and value.ndim == 3:
+                    if "ups" in new_key:
+                        # ConvTranspose1d: PyTorch (in_ch, out_ch, kernel) -> MLX (out_ch, kernel, in_ch)
+                        value = value if check_array_shape(value) else mx.transpose(value, (1, 2, 0))
+                    else:
+                        # Conv1d: PyTorch (out_ch, in_ch, kernel) -> MLX (out_ch, kernel, in_ch)
+                        value = value if check_array_shape(value) else mx.transpose(value, (0, 2, 1))
+
+                sanitized[new_key] = value
+
+        return sanitized
+
+    @classmethod
+    def from_pretrained(cls, model_path: Path, strict: bool = True) -> "Vocoder":
+        """Load vocoder from pretrained model."""
+        from mlx_video.models.ltx.config import VocoderModelConfig
+        import json
+
+        config_dict = {}
+        with open(model_path / "config.json", "r") as f:
+            config_dict = json.load(f)
+
+        config = VocoderModelConfig.from_dict(config_dict)
+        model = cls(config)
+        weights = mx.load(str(model_path / "model.safetensors"))
+
+        # weights = vocoder.sanitize(weights)
+        model.load_weights(list(weights.items()), strict=strict)
+        return model
+
 
     def __call__(self, x: mx.array) -> mx.array:
         """

mlx_video/models/ltx/config.py

@@ -2,7 +2,7 @@
 import inspect
 from dataclasses import dataclass, field
 from enum import Enum
-from typing import Any, List, Optional
+from typing import Any, List, Optional, Tuple, Set
 
 
 class LTXModelType(Enum):
@@ -180,3 +180,141 @@ class LTXModelConfig(BaseModelConfig):
             d_head=self.audio_attention_head_dim,
             context_dim=self.audio_cross_attention_dim,
         )
+
+
+
+class CausalityAxis(Enum):
+    """Enum for specifying the causality axis in causal convolutions."""
+
+    NONE = None
+    WIDTH = "width"
+    HEIGHT = "height"
+    WIDTH_COMPATIBILITY = "width-compatibility"
+
+
+@dataclass
+class AudioDecoderModelConfig(BaseModelConfig):
+    ch: int = 128
+    out_ch: int = 2
+    ch_mult: Tuple[int, ...] = (1, 2, 4)
+    num_res_blocks: int = 2
+    attn_resolutions: Optional[List[int]] = None
+    resolution: int = 256
+    z_channels: int = 8
+    norm_type: Enum = None
+    causality_axis: Enum = None
+    dropout: float = 0.0
+    mid_block_add_attention: bool = True
+    sample_rate: int = 16000
+    mel_hop_length: int = 160
+    is_causal: bool = True
+    mel_bins: int | None = None
+    resamp_with_conv: bool = True
+    attn_type: str = None
+    give_pre_end: bool = False
+    tanh_out: bool = False
+
+    def to_dict(self) -> dict[str, Any]:
+        result = super().to_dict()
+        if self.attn_resolutions is not None:
+            result["attn_resolutions"] = list(self.attn_resolutions)
+        return result
+
+    def __post_init__(self):
+        """Convert string enum values to proper enum types."""
+        # Import here to avoid circular imports
+        from .audio_vae.normalization import NormType
+        from .audio_vae.attention import AttentionType
+        
+        # Convert causality_axis string to enum
+        if isinstance(self.causality_axis, str):
+            self.causality_axis = CausalityAxis(self.causality_axis)
+        
+        # Convert norm_type string to enum
+        if isinstance(self.norm_type, str):
+            self.norm_type = NormType(self.norm_type)
+        
+        # Convert attn_type string to enum
+        if isinstance(self.attn_type, str):
+            self.attn_type = AttentionType(self.attn_type)
+
+@dataclass
+class VocoderModelConfig(BaseModelConfig):
+    resblock_kernel_sizes: Optional[List[int]] = None
+    upsample_rates: Optional[List[int]] = None
+    upsample_kernel_sizes: Optional[List[int]] = None
+    resblock_dilation_sizes: Optional[List[List[int]]] = None
+    upsample_initial_channel: int = 1024
+    stereo: bool = True
+    resblock: str = "1"
+    output_sample_rate: int = 24000
+
+    def __post_init__(self):
+                
+        if self.resblock_kernel_sizes is None:
+            self.resblock_kernel_sizes = [3, 7, 11]
+        if self.upsample_rates is None:
+            self.upsample_rates = [6, 5, 2, 2, 2]
+        if self.upsample_kernel_sizes is None:
+            self.upsample_kernel_sizes = [16, 15, 8, 4, 4]
+        if self.resblock_dilation_sizes is None:
+            self.resblock_dilation_sizes = [[1, 3, 5], [1, 3, 5], [1, 3, 5]]
+
+
+@dataclass
+class VideoDecoderModelConfig(BaseModelConfig):
+    ch: int = 128
+    out_ch: int = 2
+    ch_mult: Tuple[int, ...] = (1, 2, 4)
+    num_res_blocks: int = 2
+    attn_resolutions: Optional[List[int]] = None
+    resolution: int = 256
+    z_channels: int = 8
+    norm_type: Enum = None
+    causality_axis: Enum = None
+    dropout: float = 0.0
+
+@dataclass
+class VideoEncoderModelConfig(BaseModelConfig):
+    convolution_dimensions: int = 3
+    in_channels : int = 3,
+    out_channels: int = 128,
+    patch_size: int = 4,
+    norm_layer: Enum = None,
+    latent_log_var: Enum = None,
+    encoder_spatial_padding_mode: Enum = None,
+    encoder_blocks: List[tuple] = field(default_factory=lambda: [("res_x", {"num_layers": 4}),
+        ("compress_space_res", {"multiplier": 2}),
+        ("res_x", {"num_layers": 6}),
+        ("compress_time_res", {"multiplier": 2}),
+        ("res_x", {"num_layers": 6}),
+        ("compress_all_res", {"multiplier": 2}),
+        ("res_x", {"num_layers": 2}),
+        ("compress_all_res", {"multiplier": 2}),
+        ("res_x", {"num_layers": 2})
+    ])
+
+    def __post_init__(self):
+        from mlx_video.models.ltx.video_vae.resnet import NormLayerType
+        from mlx_video.models.ltx.video_vae.video_vae import LogVarianceType
+        from mlx_video.models.ltx.video_vae.convolution import PaddingModeType
+
+        if self.norm_layer is None:
+            self.norm_layer = NormLayerType.PIXEL_NORM
+        if self.latent_log_var is None:
+            self.latent_log_var = LogVarianceType.UNIFORM
+        if self.encoder_spatial_padding_mode is None:
+            self.encoder_spatial_padding_mode = PaddingModeType.ZEROS
+
+        if isinstance(self.norm_layer, str):
+            self.norm_layer = NormLayerType(self.norm_layer)
+        if isinstance(self.latent_log_var, str):
+            self.latent_log_var = LogVarianceType(self.latent_log_var)
+        if isinstance(self.encoder_spatial_padding_mode, str):
+            self.encoder_spatial_padding_mode = PaddingModeType(self.encoder_spatial_padding_mode)
+
+    def to_dict(self) -> dict[str, Any]:
+        result = super().to_dict()
+        if self.encoder_blocks is not None:
+            result["encoder_blocks"] = [list(block) for block in self.encoder_blocks]
+        return result   

mlx_video/models/ltx/ltx.py

@@ -2,7 +2,7 @@ from typing import List, Optional, Tuple
 
 import mlx.core as mx
 import mlx.nn as nn
-from pathlib import Path    
+
 from mlx_video.models.ltx.config import (
     LTXModelConfig,
     LTXModelType,
@@ -52,11 +52,10 @@ class TransformerArgsPreprocessor:
         self,
         timestep: mx.array,
         batch_size: int,
-        hidden_dtype: mx.Dtype = None,
     ) -> Tuple[mx.array, mx.array]:
 
         timestep = timestep * self.timestep_scale_multiplier
-        timestep_emb, embedded_timestep = self.adaln(timestep.reshape(-1), hidden_dtype=hidden_dtype)
+        timestep_emb, embedded_timestep = self.adaln(timestep.reshape(-1))
 
         # Reshape to (batch, tokens, dim)
         timestep_emb = mx.reshape(timestep_emb, (batch_size, -1, timestep_emb.shape[-1]))
@@ -71,9 +70,6 @@ class TransformerArgsPreprocessor:
         attention_mask: Optional[mx.array] = None,
     ) -> Tuple[mx.array, Optional[mx.array]]:
         batch_size = x.shape[0]
-
-        # Context is already processed through embeddings connector in text encoder
-        # Here we just apply the caption projection
         context = self.caption_projection(context)
         context = mx.reshape(context, (batch_size, -1, x.shape[-1]))
         return context, attention_mask
@@ -118,21 +114,16 @@ class TransformerArgsPreprocessor:
 
     def prepare(self, modality: Modality) -> TransformerArgs:
         x = self.patchify_proj(modality.latent)
-        timestep, embedded_timestep = self._prepare_timestep(modality.timesteps, x.shape[0], hidden_dtype=x.dtype)
+        timestep, embedded_timestep = self._prepare_timestep(modality.timesteps, x.shape[0])
         context, attention_mask = self._prepare_context(modality.context, x, modality.context_mask)
         attention_mask = self._prepare_attention_mask(attention_mask, modality.latent.dtype)
-
-        # Use precomputed positional embeddings if provided (avoids expensive RoPE recomputation)
-        if modality.positional_embeddings is not None:
-            pe = modality.positional_embeddings
-        else:
-            pe = self._prepare_positional_embeddings(
-                positions=modality.positions,
-                inner_dim=self.inner_dim,
-                max_pos=self.max_pos,
-                use_middle_indices_grid=self.use_middle_indices_grid,
-                num_attention_heads=self.num_attention_heads,
-            )
+        pe = self._prepare_positional_embeddings(
+            positions=modality.positions,
+            inner_dim=self.inner_dim,
+            max_pos=self.max_pos,
+            use_middle_indices_grid=self.use_middle_indices_grid,
+            num_attention_heads=self.num_attention_heads,
+        )
 
         return TransformerArgs(
             x=x,
@@ -207,7 +198,6 @@ class MultiModalTransformerArgsPreprocessor:
             timestep=modality.timesteps,
             timestep_scale_multiplier=self.simple_preprocessor.timestep_scale_multiplier,
             batch_size=transformer_args.x.shape[0],
-            hidden_dtype=transformer_args.x.dtype,
         )
 
         return replace(
@@ -222,16 +212,15 @@ class MultiModalTransformerArgsPreprocessor:
         timestep: mx.array,
         timestep_scale_multiplier: int,
         batch_size: int,
-        hidden_dtype: mx.Dtype = None,
     ) -> Tuple[mx.array, mx.array]:
         timestep = timestep * timestep_scale_multiplier
 
         av_ca_factor = self.av_ca_timestep_scale_multiplier / timestep_scale_multiplier
 
-        scale_shift_timestep, _ = self.cross_scale_shift_adaln(timestep.reshape(-1), hidden_dtype=hidden_dtype)
+        scale_shift_timestep, _ = self.cross_scale_shift_adaln(timestep.reshape(-1))
         scale_shift_timestep = mx.reshape(scale_shift_timestep, (batch_size, -1, scale_shift_timestep.shape[-1]))
 
-        gate_timestep, _ = self.cross_gate_adaln(timestep.reshape(-1) * av_ca_factor, hidden_dtype=hidden_dtype)
+        gate_timestep, _ = self.cross_gate_adaln(timestep.reshape(-1) * av_ca_factor)
         gate_timestep = mx.reshape(gate_timestep, (batch_size, -1, gate_timestep.shape[-1]))
 
         return scale_shift_timestep, gate_timestep
@@ -293,8 +282,6 @@ class LTXModel(nn.Module):
     def _init_audio(self, config: LTXModelConfig) -> None:
         self.audio_patchify_proj = nn.Linear(config.audio_in_channels, self.audio_inner_dim, bias=True)
         self.audio_adaln_single = AdaLayerNormSingle(self.audio_inner_dim)
-
-        # Audio caption projection: receives pre-processed embeddings from text encoder's audio_embeddings_connector
         self.audio_caption_projection = PixArtAlphaTextProjection(
             in_features=config.audio_caption_channels,
             hidden_size=self.audio_inner_dim,
@@ -397,9 +384,8 @@ class LTXModel(nn.Module):
         video_config = config.get_video_config()
         audio_config = config.get_audio_config()
 
-
-        self.transformer_blocks = {
-            idx: BasicAVTransformerBlock(
+        self.transformer_blocks = [
+            BasicAVTransformerBlock(
                 idx=idx,
                 video=video_config,
                 audio=audio_config,
@@ -407,7 +393,7 @@ class LTXModel(nn.Module):
                 norm_eps=config.norm_eps,
             )
             for idx in range(config.num_layers)
-        }
+        ]
 
     def _process_transformer_blocks(
         self,
@@ -415,7 +401,7 @@ class LTXModel(nn.Module):
         audio: Optional[TransformerArgs],
     ) -> Tuple[Optional[TransformerArgs], Optional[TransformerArgs]]:
         """Process through all transformer blocks."""
-        for block in self.transformer_blocks.values():
+        for block in self.transformer_blocks:
             video, audio = block(video=video, audio=audio)
         return video, audio
 
@@ -497,50 +483,19 @@ class LTXModel(nn.Module):
 
     def sanitize(self, weights: dict) -> dict:
         sanitized = {}
-
         for key, value in weights.items():
             new_key = key
-            # Skip non-transformer weights (VAE, vocoder, audio_vae, connectors)
-            if not key.startswith("model.diffusion_model.") or "audio_embeddings_connector" in key or "video_embeddings_connector" in key:
-                continue
-
-            # Remove 'model.diffusion_model.' prefix
-            new_key = new_key.replace("model.diffusion_model.", "")
-
-            new_key = new_key.replace(".to_out.0.", ".to_out.")
-
-            new_key = new_key.replace(".ff.net.0.proj.", ".ff.proj_in.")
-            new_key = new_key.replace(".ff.net.2.", ".ff.proj_out.")
-            new_key = new_key.replace(".audio_ff.net.0.proj.", ".audio_ff.proj_in.")
-            new_key = new_key.replace(".audio_ff.net.2.", ".audio_ff.proj_out.")
-
-            new_key = new_key.replace(".linear_1.", ".linear1.")
-            new_key = new_key.replace(".linear_2.", ".linear2.")
 
+            # Handle common remappings
+            # transformer_blocks.X -> transformer_blocks[X]
+            if "transformer_blocks." in new_key:
+                # Keep as-is for now, MLX handles this
+                pass
 
             sanitized[new_key] = value
 
         return sanitized
 
-    @classmethod
-    def from_pretrained(cls, model_path: [Path, List[Path]], config: LTXModelConfig, strict: bool = True) -> None:
-        model = cls(config)
-
-        weights = {}
-        if isinstance(model_path, Path):
-            model_path = [model_path]
-        for weight_file in model_path:
-            weights.update(mx.load(str(weight_file)))
-
-
-        sanitized = model.sanitize(weights)
-        sanitized = {k: v.astype(mx.bfloat16) if v.dtype == mx.float32 else v for k, v in sanitized.items()}
-
-        model.load_weights(list(sanitized.items()), strict=strict)
-        mx.eval(model.parameters())
-        model.eval()
-        return model
-
 
 class X0Model(nn.Module):
 

mlx_video/models/ltx/rope.py

@@ -428,11 +428,14 @@ def _precompute_freqs_cis_double_precision(
     num_attention_heads: int,
     rope_type: LTXRopeType,
 ) -> Tuple[mx.array, mx.array]:
-    """Compute RoPE frequencies with higher precision using float32.
+    """Compute RoPE frequencies with higher precision using float64 for frequency grid.
 
-    This version stays entirely in MLX/GPU, avoiding expensive NumPy round-trips.
-    Uses float32 for computation precision (sufficient for RoPE).
+    Matches PyTorch's approach: uses NumPy float64 for the critical frequency grid
+    computation (log-spaced values), then converts to float32 for the final tensor.
+    This provides better numerical precision in the frequency generation phase.
     """
+    import numpy as np
+
     # Warn if positions are bfloat16 - this causes quality degradation
     if indices_grid.dtype == mx.bfloat16:
         import warnings
@@ -443,21 +446,27 @@ def _precompute_freqs_cis_double_precision(
             stacklevel=2
         )
 
-    # Cast to float32 for computation (stay on GPU, no NumPy/CPU conversion)
+    # Cast to float32 for position computation
     indices_grid_f32 = indices_grid.astype(mx.float32)
 
     n_pos_dims = indices_grid_f32.shape[1]
     n_elem = 2 * n_pos_dims
 
-    # Compute log-spaced frequencies in float32
-    log_start = math.log(1.0) / math.log(theta)
-    log_end = math.log(theta) / math.log(theta)
+    # Compute log-spaced frequencies in float64 (matching PyTorch's generate_freq_grid_np)
+    # This is the critical precision step - PyTorch uses np.float64 here
+    log_start = np.log(1.0) / np.log(theta)
+    log_end = np.log(theta) / np.log(theta)  # = 1.0
     num_indices = dim // n_elem
     if num_indices == 0:
         num_indices = 1
 
-    lin_space = mx.linspace(log_start, log_end, num_indices)
-    freq_indices = mx.power(mx.array(theta, dtype=mx.float32), lin_space) * (math.pi / 2)
+    # Use numpy float64 for the linspace computation (matches PyTorch)
+    pow_indices = np.power(
+        theta,
+        np.linspace(log_start, log_end, num_indices, dtype=np.float64),
+    )
+    # Convert to float32 tensor (matches PyTorch: torch.tensor(..., dtype=torch.float32))
+    freq_indices = mx.array(pow_indices * (math.pi / 2), dtype=mx.float32)
 
     # Handle middle indices grid
     # Input shape: (B, n_dims, T, 2) for middle indices or (B, n_dims, T, 1) otherwise

mlx_video/models/ltx/video_vae/__init__.py

@@ -1,6 +1,6 @@
 from mlx_video.models.ltx.video_vae.video_vae import VideoEncoder, VideoDecoder
-from mlx_video.models.ltx.video_vae.encoder import load_vae_encoder, encode_image
-from mlx_video.models.ltx.video_vae.decoder import load_vae_decoder, LTX2VideoDecoder
+from mlx_video.models.ltx.video_vae.encoder import encode_image
+from mlx_video.models.ltx.video_vae.decoder import LTX2VideoDecoder
 from mlx_video.models.ltx.video_vae.tiling import (
     TilingConfig,
     SpatialTilingConfig,

mlx_video/models/ltx/video_vae/decoder.py

@@ -15,13 +15,14 @@ Architecture (from PyTorch weights):
 """
 
 import math
-from typing import Optional
+from typing import Optional, Dict
+from pathlib import Path
 
 import mlx.core as mx
 import mlx.nn as nn
 
 from mlx_video.models.ltx.video_vae.convolution import CausalConv3d, PaddingModeType
-from mlx_video.models.ltx.video_vae.ops import unpatchify
+from mlx_video.models.ltx.video_vae.ops import unpatchify, PerChannelStatistics
 from mlx_video.models.ltx.video_vae.sampling import DepthToSpaceUpsample
 from mlx_video.models.ltx.video_vae.tiling import TilingConfig, decode_with_tiling
 
@@ -269,8 +270,7 @@ class LTX2VideoDecoder(nn.Module):
         self.decode_timestep = 0.05
 
         # Per-channel statistics for denormalization (loaded from weights)
-        self.latents_mean = mx.zeros((in_channels,))
-        self.latents_std = mx.ones((in_channels,))
+        self.per_channel_statistics = PerChannelStatistics(latent_channels=in_channels)
 
         # Initial conv: 128 -> 1024
         class ConvInWrapper(nn.Module):
@@ -346,13 +346,72 @@ class LTX2VideoDecoder(nn.Module):
             )
             self.last_scale_shift_table = mx.zeros((2, 128))
 
-    def denormalize(self, x: mx.array) -> mx.array:
-        """Denormalize latents using per-channel statistics."""
-        dtype = x.dtype
-        # Cast to float32 for precision (statistics may be in bfloat16)
-        mean = self.latents_mean.astype(mx.float32).reshape(1, -1, 1, 1, 1)
-        std = self.latents_std.astype(mx.float32).reshape(1, -1, 1, 1, 1)
-        return (x * std + mean).astype(dtype)
+    def sanitize(self, weights: Dict[str, mx.array]) -> Dict[str, mx.array]:
+        # Build decoder weights dict with key remapping
+        sanitized = {}
+        for key, value in weights.items():
+            new_key = key
+            
+            if not key.startswith("vae.") or key.startswith("vae.encoder."):
+                continue
+
+            if key.startswith("vae.per_channel_statistics."):
+                # Map per-channel statistics (use exact key matching)
+                if key == "vae.per_channel_statistics.mean-of-means":
+                    new_key = "per_channel_statistics.mean"
+                elif key == "vae.per_channel_statistics.std-of-means":
+                    new_key = "per_channel_statistics.std"
+                else:
+                    continue  # Skip other statistics keys
+
+            if key.startswith("vae.decoder."):
+                new_key = key.replace("vae.decoder.", "")
+
+
+            # Handle Conv3d weight transpose: (O, I, D, H, W) -> (O, D, H, W, I)
+            if ".conv.weight" in key and value.ndim == 5:
+                value = mx.transpose(value, (0, 2, 3, 4, 1))
+
+            if ".conv.bias" in key:
+                pass  # bias doesn't need transpose
+
+            if ".conv.weight" in new_key or ".conv.bias" in new_key:
+
+                if ".conv.conv.weight" not in new_key and ".conv.conv.bias" not in new_key:
+                    new_key = new_key.replace(".conv.weight", ".conv.conv.weight")
+                    new_key = new_key.replace(".conv.bias", ".conv.conv.bias")
+
+            sanitized[new_key] = value
+        return sanitized
+
+    @classmethod
+    def from_pretrained(cls, model_path: Path, timestep_conditioning: Optional[bool] = None, strict: bool = True) -> "LTX2VideoDecoder":
+        from safetensors import safe_open
+        import json
+        weights = mx.load(str(model_path))
+
+        # Read config from safetensors metadata to auto-detect timestep_conditioning
+        if timestep_conditioning is None:
+            try:
+                with safe_open(str(model_path), framework="numpy") as f:
+                    metadata = f.metadata()
+                    if metadata and "config" in metadata:
+                        configs = json.loads(metadata["config"])
+                        vae_config = configs.get("vae", {})
+                        timestep_conditioning = vae_config.get("timestep_conditioning", False)
+                        print(f"  Auto-detected timestep_conditioning={timestep_conditioning} from weights")
+                    else:
+                        timestep_conditioning = False
+            except Exception as e:
+                print(f"  Could not read config from metadata: {e}, defaulting to timestep_conditioning=False")
+                timestep_conditioning = False
+
+        model = cls(timestep_conditioning=timestep_conditioning)
+        weights = model.sanitize(weights)
+        model.load_weights(list(weights.items()), strict=strict)
+        return model
+
+  
 
     def pixel_norm(self, x: mx.array, eps: float = 1e-8) -> mx.array:
         """Apply pixel normalization."""
@@ -367,28 +426,19 @@ class LTX2VideoDecoder(nn.Module):
         chunked_conv: bool = False,
     ) -> mx.array:
        
-        def debug_stats(name, t):
-            if debug:
-                mx.eval(t)
-                print(f"  [VAE] {name}: shape={t.shape}, min={t.min().item():.4f}, max={t.max().item():.4f}, mean={t.mean().item():.4f}")
 
         batch_size = sample.shape[0]
 
-        if debug:
-            debug_stats("Input", sample)
+   
 
         # Add noise if timestep conditioning is enabled
         if self.timestep_conditioning:
             noise = mx.random.normal(sample.shape) * self.decode_noise_scale
             sample = noise + (1.0 - self.decode_noise_scale) * sample
-            if debug:
-                debug_stats("After noise", sample)
+            
 
-        if debug:
-            print(f"  [VAE] Denorm stats - mean: [{self.latents_mean.min().item():.4f}, {self.latents_mean.max().item():.4f}], std: [{self.latents_std.min().item():.4f}, {self.latents_std.max().item():.4f}]")
-        sample = self.denormalize(sample)
-        if debug:
-            debug_stats("After denormalize", sample)
+        sample = self.per_channel_statistics.un_normalize(sample)
+ 
 
         if timestep is None and self.timestep_conditioning:
             timestep = mx.full((batch_size,), self.decode_timestep)
@@ -398,8 +448,7 @@ class LTX2VideoDecoder(nn.Module):
             scaled_timestep = timestep * self.timestep_scale_multiplier
 
         x = self.conv_in(sample, causal=causal)
-        if debug:
-            debug_stats("After conv_in", x)
+       
 
         for i, block in self.up_blocks.items():
             if isinstance(block, ResBlockGroup):
@@ -408,13 +457,10 @@ class LTX2VideoDecoder(nn.Module):
                 x = block(x, causal=causal, chunked_conv=chunked_conv)
             else:
                 x = block(x, causal=causal)
-            if debug:
-                block_type = type(block).__name__
-                debug_stats(f"After up_blocks[{i}] ({block_type})", x)
+    
 
         x = self.pixel_norm(x)
-        if debug:
-            debug_stats("After pixel_norm", x)
+  
 
         if self.timestep_conditioning and scaled_timestep is not None:
             embedded_timestep = self.last_time_embedder(
@@ -431,21 +477,16 @@ class LTX2VideoDecoder(nn.Module):
             scale = ada_values[:, 1]
 
             x = x * (1 + scale) + shift
-            if debug:
-                debug_stats("After timestep modulation", x)
+          
 
         x = self.act(x)
-        if debug:
-            debug_stats("After activation", x)
+     
 
         x = self.conv_out(x, causal=causal)
-        if debug:
-            debug_stats("After conv_out", x)
-
+        
         # Unpatchify: (B, 48, F', H', W') -> (B, 3, F, H*4, W*4)
         x = unpatchify(x, patch_size_hw=self.patch_size, patch_size_t=1)
-        if debug:
-            debug_stats("After unpatchify", x)
+     
 
         return x
 
@@ -519,103 +560,3 @@ class LTX2VideoDecoder(nn.Module):
             chunked_conv=use_chunked_conv,
             on_frames_ready=on_frames_ready,
         )
-
-
-def load_vae_decoder(model_path: str, timestep_conditioning: Optional[bool] = None) -> LTX2VideoDecoder:
-    from pathlib import Path
-    import json
-    from safetensors import safe_open
-
-    model_path = Path(model_path)
-
-    # Try to find the weights file
-    if model_path.is_file() and model_path.suffix == ".safetensors":
-        weights_path = model_path
-    elif (model_path / "ltx-2-19b-distilled.safetensors").exists():
-        weights_path = model_path / "ltx-2-19b-distilled.safetensors"
-    elif (model_path / "vae" / "diffusion_pytorch_model.safetensors").exists():
-        weights_path = model_path / "vae" / "diffusion_pytorch_model.safetensors"
-    else:
-        raise FileNotFoundError(f"VAE weights not found at {model_path}")
-
-    print(f"Loading VAE decoder from {weights_path}...")
-
-    # Read config from safetensors metadata to auto-detect timestep_conditioning
-    if timestep_conditioning is None:
-        try:
-            with safe_open(str(weights_path), framework="numpy") as f:
-                metadata = f.metadata()
-                if metadata and "config" in metadata:
-                    configs = json.loads(metadata["config"])
-                    vae_config = configs.get("vae", {})
-                    timestep_conditioning = vae_config.get("timestep_conditioning", False)
-                    print(f"  Auto-detected timestep_conditioning={timestep_conditioning} from weights")
-                else:
-                    timestep_conditioning = False
-        except Exception as e:
-            print(f"  Could not read config from metadata: {e}, defaulting to timestep_conditioning=False")
-            timestep_conditioning = False
-
-    decoder = LTX2VideoDecoder(timestep_conditioning=timestep_conditioning)
-
-    weights = mx.load(str(weights_path))
-
-    # Determine prefix based on weight keys
-    has_vae_prefix = any(k.startswith("vae.") for k in weights.keys())
-    has_decoder_prefix = any(k.startswith("decoder.") for k in weights.keys())
-
-    if has_vae_prefix:
-        prefix = "vae.decoder."
-        stats_prefix = "vae.per_channel_statistics."
-    elif has_decoder_prefix:
-        prefix = "decoder."
-        stats_prefix = ""
-    else:
-        prefix = ""
-        stats_prefix = ""
-
-    # Load per-channel statistics for denormalization
-    # Note: use std-of-means (not mean-of-stds) for proper denormalization
-    mean_key = f"{stats_prefix}mean-of-means" if stats_prefix else "latents_mean"
-    std_key = f"{stats_prefix}std-of-means" if stats_prefix else "latents_std"
-
-    if mean_key in weights:
-        decoder.latents_mean = weights[mean_key]
-        print(f"  Loaded latent mean: shape {decoder.latents_mean.shape}")
-    if std_key in weights:
-        decoder.latents_std = weights[std_key]
-        print(f"  Loaded latent std: shape {decoder.latents_std.shape}")
-
-    # Build decoder weights dict with key remapping
-    decoder_weights = {}
-    for key, value in weights.items():
-        if not key.startswith(prefix):
-            continue
-
-        # Remove prefix
-        new_key = key[len(prefix):]
-
-        # Handle Conv3d weight transpose: (O, I, D, H, W) -> (O, D, H, W, I)
-        if ".conv.weight" in key and value.ndim == 5:
-            value = mx.transpose(value, (0, 2, 3, 4, 1))
-        if ".conv.bias" in key:
-            pass  # bias doesn't need transpose
-
-       
-        if ".conv.weight" in new_key or ".conv.bias" in new_key:
-            if ".conv.conv.weight" not in new_key and ".conv.conv.bias" not in new_key:
-                new_key = new_key.replace(".conv.weight", ".conv.conv.weight")
-                new_key = new_key.replace(".conv.bias", ".conv.conv.bias")
-
-        decoder_weights[new_key] = value
-
-    print(f"  Found {len(decoder_weights)} decoder weights")
-
-    ts_keys = [k for k in decoder_weights.keys() if "scale_shift" in k or "time_embedder" in k or "timestep_scale" in k]
-    print(f"  Found {len(ts_keys)} timestep conditioning weights")
-
-    # Load weights
-    decoder.load_weights(list(decoder_weights.items()), strict=False)
-
-    print("VAE decoder loaded successfully")
-    return decoder

mlx_video/models/ltx/video_vae/encoder.py

@@ -5,152 +5,9 @@ Used for I2V (image-to-video) conditioning by encoding the input image
 to latent space, which can then be used to condition video generation.
 """
 
-from pathlib import Path
-from typing import List, Tuple, Any, Optional
-import json
-
 import mlx.core as mx
-import mlx.nn as nn
+from mlx_video.models.ltx.video_vae.video_vae import VideoEncoder
 
-from mlx_video.models.ltx.video_vae.video_vae import VideoEncoder, LogVarianceType, NormLayerType, PaddingModeType
-
-
-def load_vae_encoder(model_path: str) -> VideoEncoder:
-    """Load VAE encoder from safetensors file.
-
-    Args:
-        model_path: Path to the model weights (safetensors file or directory)
-
-    Returns:
-        Loaded VideoEncoder instance
-    """
-    from safetensors import safe_open
-
-    model_path = Path(model_path)
-
-    # Try to find the weights file
-    if model_path.is_file() and model_path.suffix == ".safetensors":
-        weights_path = model_path
-    elif (model_path / "ltx-2-19b-distilled.safetensors").exists():
-        weights_path = model_path / "ltx-2-19b-distilled.safetensors"
-    elif (model_path / "vae" / "diffusion_pytorch_model.safetensors").exists():
-        weights_path = model_path / "vae" / "diffusion_pytorch_model.safetensors"
-    else:
-        raise FileNotFoundError(f"VAE weights not found at {model_path}")
-
-    print(f"Loading VAE encoder from {weights_path}...")
-
-    # Read config from safetensors metadata
-    encoder_blocks = []
-    norm_layer = NormLayerType.PIXEL_NORM
-    latent_log_var = LogVarianceType.UNIFORM
-    patch_size = 4
-
-    try:
-        with safe_open(str(weights_path), framework="numpy") as f:
-            metadata = f.metadata()
-            if metadata and "config" in metadata:
-                configs = json.loads(metadata["config"])
-                vae_config = configs.get("vae", {})
-
-                # Parse encoder blocks
-                raw_blocks = vae_config.get("encoder_blocks", [])
-                for block in raw_blocks:
-                    if isinstance(block, list) and len(block) == 2:
-                        name, params = block
-                        encoder_blocks.append((name, params))
-
-                # Parse other config
-                norm_str = vae_config.get("norm_layer", "pixel_norm")
-                norm_layer = NormLayerType.PIXEL_NORM if norm_str == "pixel_norm" else NormLayerType.GROUP_NORM
-
-                var_str = vae_config.get("latent_log_var", "uniform")
-                if var_str == "uniform":
-                    latent_log_var = LogVarianceType.UNIFORM
-                elif var_str == "per_channel":
-                    latent_log_var = LogVarianceType.PER_CHANNEL
-                elif var_str == "constant":
-                    latent_log_var = LogVarianceType.CONSTANT
-                else:
-                    latent_log_var = LogVarianceType.NONE
-
-                patch_size = vae_config.get("patch_size", 4)
-
-                print(f"  Loaded config: {len(encoder_blocks)} encoder blocks, norm={norm_str}, patch_size={patch_size}")
-    except Exception as e:
-        print(f"  Could not read config from metadata: {e}")
-        # Use default config
-        encoder_blocks = [
-            ("res_x", {"num_layers": 4}),
-            ("compress_space_res", {"multiplier": 2}),
-            ("res_x", {"num_layers": 6}),
-            ("compress_time_res", {"multiplier": 2}),
-            ("res_x", {"num_layers": 6}),
-            ("compress_all_res", {"multiplier": 2}),
-            ("res_x", {"num_layers": 2}),
-            ("compress_all_res", {"multiplier": 2}),
-            ("res_x", {"num_layers": 2}),
-        ]
-        print(f"  Using default encoder config with {len(encoder_blocks)} blocks")
-
-    # Create encoder
-    encoder = VideoEncoder(
-        convolution_dimensions=3,
-        in_channels=3,
-        out_channels=128,
-        encoder_blocks=encoder_blocks,
-        patch_size=patch_size,
-        norm_layer=norm_layer,
-        latent_log_var=latent_log_var,
-        encoder_spatial_padding_mode=PaddingModeType.ZEROS,
-    )
-
-    # Load weights
-    weights = mx.load(str(weights_path))
-
-    # Determine prefix based on weight keys
-    has_vae_prefix = any(k.startswith("vae.") for k in weights.keys())
-
-    if has_vae_prefix:
-        prefix = "vae.encoder."
-        stats_prefix = "vae.per_channel_statistics."
-    else:
-        prefix = "encoder."
-        stats_prefix = "per_channel_statistics."
-
-    # Load per-channel statistics for normalization
-    mean_key = f"{stats_prefix}mean-of-means"
-    std_key = f"{stats_prefix}std-of-means"
-
-    if mean_key in weights:
-        encoder.per_channel_statistics.mean = weights[mean_key]
-        print(f"  Loaded latent mean: shape {weights[mean_key].shape}")
-    if std_key in weights:
-        encoder.per_channel_statistics.std = weights[std_key]
-        print(f"  Loaded latent std: shape {weights[std_key].shape}")
-
-    # Build encoder weights dict with key remapping
-    encoder_weights = {}
-    for key, value in weights.items():
-        if not key.startswith(prefix):
-            continue
-
-        # Remove prefix
-        new_key = key[len(prefix):]
-
-        # Handle Conv3d weight transpose: (O, I, D, H, W) -> (O, D, H, W, I)
-        if ".weight" in key and value.ndim == 5:
-            value = mx.transpose(value, (0, 2, 3, 4, 1))
-
-        encoder_weights[new_key] = value
-
-    print(f"  Found {len(encoder_weights)} encoder weights")
-
-    # Load weights
-    encoder.load_weights(list(encoder_weights.items()), strict=False)
-
-    print("VAE encoder loaded successfully")
-    return encoder
 
 
 def encode_image(

mlx_video/models/ltx/video_vae/video_vae.py

@@ -273,9 +273,10 @@ class VideoEncoder(nn.Module):
             spatial_padding_mode=encoder_spatial_padding_mode,
         )
 
-        # Build encoder blocks - use dict with int keys for MLX parameter tracking
+        # Build encoder blocks
+        # Use dict with int keys for MLX to track parameters (lists are NOT tracked)
         self.down_blocks = {}
-        for i, (block_name, block_params) in enumerate(encoder_blocks):
+        for idx, (block_name, block_params) in enumerate(encoder_blocks):
             block_config = {"num_layers": block_params} if isinstance(block_params, int) else block_params
 
             block, feature_channels = _make_encoder_block(
@@ -287,7 +288,7 @@ class VideoEncoder(nn.Module):
                 norm_num_groups=self._norm_num_groups,
                 spatial_padding_mode=encoder_spatial_padding_mode,
             )
-            self.down_blocks[i] = block
+            self.down_blocks[idx] = block
 
         # Output normalization and convolution
         if norm_layer == NormLayerType.GROUP_NORM:
@@ -341,7 +342,8 @@ class VideoEncoder(nn.Module):
         sample = self.conv_in(sample, causal=True)
 
         # Process through encoder blocks
-        for down_block in self.down_blocks.values():
+        for i in range(len(self.down_blocks)):
+            down_block = self.down_blocks[i]
             if isinstance(down_block, (UNetMidBlock3D, ResnetBlock3D)):
                 sample = down_block(sample, causal=True)
             else:
@@ -440,8 +442,9 @@ class VideoDecoder(nn.Module):
         )
 
         # Build decoder blocks (reversed order)
-        self.up_blocks = []
-        for block_name, block_params in list(reversed(decoder_blocks)):
+        # Use dict with int keys for MLX to track parameters (lists are NOT tracked)
+        self.up_blocks = {}
+        for idx, (block_name, block_params) in enumerate(reversed(decoder_blocks)):
             block_config = {"num_layers": block_params} if isinstance(block_params, int) else block_params
 
             block, feature_channels = _make_decoder_block(
@@ -454,7 +457,7 @@ class VideoDecoder(nn.Module):
                 norm_num_groups=self._norm_num_groups,
                 spatial_padding_mode=decoder_spatial_padding_mode,
             )
-            self.up_blocks.append(block)
+            self.up_blocks[idx] = block
 
         # Output normalization
         if norm_layer == NormLayerType.GROUP_NORM:
@@ -509,7 +512,8 @@ class VideoDecoder(nn.Module):
         sample = self.conv_in(sample, causal=self.causal)
 
         # Process through decoder blocks
-        for up_block in self.up_blocks:
+        for i in range(len(self.up_blocks)):
+            up_block = self.up_blocks[i]
             if isinstance(up_block, UNetMidBlock3D):
                 sample = up_block(sample, causal=self.causal)
             elif isinstance(up_block, ResnetBlock3D):