Files
mlx-video/mlx_video/generate.py

1079 lines
42 KiB
Python

import argparse
import time
from pathlib import Path
from typing import Optional
import mlx.core as mx
import numpy as np
from PIL import Image
from rich.console import Console
from rich.progress import Progress, SpinnerColumn, TextColumn, BarColumn, TaskProgressColumn, TimeRemainingColumn
from rich.panel import Panel
from rich.status import Status
# Rich console for styled output
console = Console()
from mlx_video.models.ltx.config import LTXModelConfig, LTXModelType, LTXRopeType
from mlx_video.models.ltx.ltx import LTXModel
from mlx_video.models.ltx.transformer import Modality
from mlx_video.convert import sanitize_transformer_weights
from mlx_video.utils import to_denoised, load_image, prepare_image_for_encoding, get_model_path
from mlx_video.models.ltx.video_vae.decoder import load_vae_decoder
from mlx_video.models.ltx.video_vae.encoder import load_vae_encoder
from mlx_video.models.ltx.video_vae.tiling import TilingConfig
from mlx_video.models.ltx.upsampler import load_upsampler, upsample_latents
from mlx_video.conditioning import VideoConditionByLatentIndex, apply_conditioning
from mlx_video.conditioning.latent import LatentState, apply_denoise_mask
# Distilled sigma schedules
STAGE_1_SIGMAS = [1.0, 0.99375, 0.9875, 0.98125, 0.975, 0.909375, 0.725, 0.421875, 0.0]
STAGE_2_SIGMAS = [0.909375, 0.725, 0.421875, 0.0]
# Audio constants
AUDIO_SAMPLE_RATE = 24000 # Output audio sample rate
AUDIO_LATENT_SAMPLE_RATE = 16000 # VAE internal sample rate
AUDIO_HOP_LENGTH = 160
AUDIO_LATENT_DOWNSAMPLE_FACTOR = 4
AUDIO_LATENT_CHANNELS = 8 # Latent channels before patchifying
AUDIO_MEL_BINS = 16
AUDIO_LATENTS_PER_SECOND = AUDIO_LATENT_SAMPLE_RATE / AUDIO_HOP_LENGTH / AUDIO_LATENT_DOWNSAMPLE_FACTOR # 25
def create_position_grid(
batch_size: int,
num_frames: int,
height: int,
width: int,
temporal_scale: int = 8,
spatial_scale: int = 32,
fps: float = 24.0,
causal_fix: bool = True,
) -> mx.array:
"""Create position grid for RoPE in pixel space.
Args:
batch_size: Batch size
num_frames: Number of frames (latent)
height: Height (latent)
width: Width (latent)
temporal_scale: VAE temporal scale factor (default 8)
spatial_scale: VAE spatial scale factor (default 32)
fps: Frames per second (default 24.0)
causal_fix: Apply causal fix for first frame (default True)
Returns:
Position grid of shape (B, 3, num_patches, 2) in pixel space
where dim 2 is [start, end) bounds for each patch
"""
# Patch size is (1, 1, 1) for LTX-2 - no spatial patching
patch_size_t, patch_size_h, patch_size_w = 1, 1, 1
# Generate grid coordinates for each dimension (frame, height, width)
t_coords = np.arange(0, num_frames, patch_size_t)
h_coords = np.arange(0, height, patch_size_h)
w_coords = np.arange(0, width, patch_size_w)
# Create meshgrid with indexing='ij' for (frame, height, width) order
t_grid, h_grid, w_grid = np.meshgrid(t_coords, h_coords, w_coords, indexing='ij')
# Stack to get shape (3, grid_t, grid_h, grid_w)
patch_starts = np.stack([t_grid, h_grid, w_grid], axis=0)
# Calculate end coordinates (start + patch_size)
patch_size_delta = np.array([patch_size_t, patch_size_h, patch_size_w]).reshape(3, 1, 1, 1)
patch_ends = patch_starts + patch_size_delta
# Stack start and end: shape (3, grid_t, grid_h, grid_w, 2)
latent_coords = np.stack([patch_starts, patch_ends], axis=-1)
# Flatten spatial/temporal dims: (3, num_patches, 2)
num_patches = num_frames * height * width
latent_coords = latent_coords.reshape(3, num_patches, 2)
# Broadcast to batch: (batch, 3, num_patches, 2)
latent_coords = np.tile(latent_coords[np.newaxis, ...], (batch_size, 1, 1, 1))
# Convert latent coords to pixel coords by scaling with VAE factors
scale_factors = np.array([temporal_scale, spatial_scale, spatial_scale]).reshape(1, 3, 1, 1)
pixel_coords = (latent_coords * scale_factors).astype(np.float32)
# Apply causal fix for first frame temporal axis
if causal_fix:
# VAE temporal stride for first frame is 1 instead of temporal_scale
pixel_coords[:, 0, :, :] = np.clip(
pixel_coords[:, 0, :, :] + 1 - temporal_scale,
a_min=0,
a_max=None
)
# Convert temporal to time in seconds by dividing by fps
pixel_coords[:, 0, :, :] = pixel_coords[:, 0, :, :] / fps
# Always return float32 for RoPE precision - bfloat16 causes quality degradation
return mx.array(pixel_coords, dtype=mx.float32)
def create_audio_position_grid(
batch_size: int,
audio_frames: int,
sample_rate: int = AUDIO_LATENT_SAMPLE_RATE,
hop_length: int = AUDIO_HOP_LENGTH,
downsample_factor: int = AUDIO_LATENT_DOWNSAMPLE_FACTOR,
is_causal: bool = True,
) -> mx.array:
"""Create temporal position grid for audio RoPE.
Audio positions are timestamps in seconds, shape (B, 1, T, 2).
Matches PyTorch's AudioPatchifier.get_patch_grid_bounds exactly.
"""
def get_audio_latent_time_in_sec(start_idx: int, end_idx: int) -> np.ndarray:
"""Convert latent indices to seconds."""
latent_frame = np.arange(start_idx, end_idx, dtype=np.float32)
mel_frame = latent_frame * downsample_factor
if is_causal:
mel_frame = np.clip(mel_frame + 1 - downsample_factor, 0, None)
return mel_frame * hop_length / sample_rate
start_times = get_audio_latent_time_in_sec(0, audio_frames)
end_times = get_audio_latent_time_in_sec(1, audio_frames + 1)
positions = np.stack([start_times, end_times], axis=-1)
positions = positions[np.newaxis, np.newaxis, :, :] # (1, 1, T, 2)
positions = np.tile(positions, (batch_size, 1, 1, 1))
return mx.array(positions, dtype=mx.float32)
def compute_audio_frames(num_video_frames: int, fps: float) -> int:
"""Compute number of audio latent frames given video duration."""
duration = num_video_frames / fps
return round(duration * AUDIO_LATENTS_PER_SECOND)
def denoise(
latents: mx.array,
positions: mx.array,
text_embeddings: mx.array,
transformer: LTXModel,
sigmas: list,
verbose: bool = True,
state: Optional[LatentState] = None,
# Audio parameters (optional)
audio_latents: Optional[mx.array] = None,
audio_positions: Optional[mx.array] = None,
audio_embeddings: Optional[mx.array] = None,
) -> tuple[mx.array, Optional[mx.array]]:
"""Run denoising loop with optional conditioning and optional audio.
Args:
latents: Noisy video latent tensor (B, C, F, H, W)
positions: Video position embeddings
text_embeddings: Video text conditioning embeddings
transformer: LTX model
sigmas: List of sigma values for denoising schedule
verbose: Whether to show progress bar
state: Optional LatentState for I2V conditioning
audio_latents: Optional audio latent tensor (B, C, T, F) for audio generation
audio_positions: Optional audio position embeddings
audio_embeddings: Optional audio text embeddings
Returns:
Tuple of (video_latents, audio_latents) - audio_latents is None if audio disabled
"""
dtype = latents.dtype
enable_audio = audio_latents is not None
# If state is provided, use its latent (which may have conditioning applied)
if state is not None:
latents = state.latent
desc = "[cyan]Denoising A/V[/]" if enable_audio else "[cyan]Denoising[/]"
num_steps = len(sigmas) - 1
with Progress(
SpinnerColumn(),
TextColumn("[progress.description]{task.description}"),
BarColumn(),
TaskProgressColumn(),
TimeRemainingColumn(),
console=console,
disable=not verbose,
) as progress:
task = progress.add_task(desc, total=num_steps)
for i in range(num_steps):
sigma, sigma_next = sigmas[i], sigmas[i + 1]
b, c, f, h, w = latents.shape
num_tokens = f * h * w
latents_flat = mx.transpose(mx.reshape(latents, (b, c, -1)), (0, 2, 1))
# Compute per-token timesteps
# For I2V: conditioned tokens get timestep=0 (mask=0), unconditioned get timestep=sigma (mask=1)
if state is not None:
# Reshape denoise_mask from (B, 1, F, 1, 1) to (B, num_tokens)
denoise_mask_flat = mx.reshape(state.denoise_mask, (b, 1, f, 1, 1))
denoise_mask_flat = mx.broadcast_to(denoise_mask_flat, (b, 1, f, h, w))
denoise_mask_flat = mx.reshape(denoise_mask_flat, (b, num_tokens))
# Per-token timesteps: sigma * mask (preserve dtype)
timesteps = mx.array(sigma, dtype=dtype) * denoise_mask_flat
else:
# All tokens get the same timestep (use latent dtype)
timesteps = mx.full((b, num_tokens), sigma, dtype=dtype)
video_modality = Modality(
latent=latents_flat,
timesteps=timesteps,
positions=positions,
context=text_embeddings,
context_mask=None,
enabled=True,
)
# Prepare audio modality if enabled
audio_modality = None
if enable_audio:
ab, ac, at, af = audio_latents.shape
audio_flat = mx.transpose(audio_latents, (0, 2, 1, 3)) # (B, T, C, F)
audio_flat = mx.reshape(audio_flat, (ab, at, ac * af))
audio_modality = Modality(
latent=audio_flat,
timesteps=mx.full((ab, at), sigma, dtype=dtype),
positions=audio_positions,
context=audio_embeddings,
context_mask=None,
enabled=True,
)
velocity, audio_velocity = transformer(video=video_modality, audio=audio_modality)
mx.eval(velocity)
if audio_velocity is not None:
mx.eval(audio_velocity)
velocity = mx.reshape(mx.transpose(velocity, (0, 2, 1)), (b, c, f, h, w))
denoised = to_denoised(latents, velocity, sigma)
# Handle audio velocity if enabled
audio_denoised = None
if enable_audio and audio_velocity is not None:
ab, ac, at, af = audio_latents.shape
audio_velocity = mx.reshape(audio_velocity, (ab, at, ac, af))
audio_velocity = mx.transpose(audio_velocity, (0, 2, 1, 3)) # (B, C, T, F)
audio_denoised = to_denoised(audio_latents, audio_velocity, sigma)
# Apply conditioning mask if state is provided
if state is not None:
denoised = apply_denoise_mask(denoised, state.clean_latent, state.denoise_mask)
mx.eval(denoised)
if audio_denoised is not None:
mx.eval(audio_denoised)
# Euler step (preserve dtype by converting Python floats to arrays)
if sigma_next > 0:
sigma_next_arr = mx.array(sigma_next, dtype=dtype)
sigma_arr = mx.array(sigma, dtype=dtype)
latents = denoised + sigma_next_arr * (latents - denoised) / sigma_arr
if enable_audio and audio_denoised is not None:
audio_latents = audio_denoised + sigma_next_arr * (audio_latents - audio_denoised) / sigma_arr
else:
latents = denoised
if enable_audio and audio_denoised is not None:
audio_latents = audio_denoised
mx.eval(latents)
if enable_audio:
mx.eval(audio_latents)
progress.advance(task)
return latents, audio_latents if enable_audio else None
def load_audio_decoder(model_path: Path):
"""Load audio VAE decoder."""
from mlx_video.models.ltx.audio_vae import AudioDecoder, CausalityAxis, NormType
from mlx_video.convert import sanitize_audio_vae_weights
decoder = AudioDecoder(
ch=128,
out_ch=2, # stereo
ch_mult=(1, 2, 4),
num_res_blocks=2,
attn_resolutions=set(),
resolution=256,
z_channels=AUDIO_LATENT_CHANNELS,
norm_type=NormType.PIXEL,
causality_axis=CausalityAxis.HEIGHT,
mel_bins=64,
)
weight_file = model_path / "ltx-2-19b-distilled.safetensors"
if weight_file.exists():
raw_weights = mx.load(str(weight_file))
sanitized = sanitize_audio_vae_weights(raw_weights)
if sanitized:
decoder.load_weights(list(sanitized.items()), strict=False)
if "per_channel_statistics._mean_of_means" in sanitized:
decoder.per_channel_statistics._mean_of_means = sanitized["per_channel_statistics._mean_of_means"]
if "per_channel_statistics._std_of_means" in sanitized:
decoder.per_channel_statistics._std_of_means = sanitized["per_channel_statistics._std_of_means"]
return decoder
def load_vocoder(model_path: Path):
"""Load vocoder for mel to waveform conversion."""
from mlx_video.models.ltx.audio_vae import Vocoder
from mlx_video.convert import sanitize_vocoder_weights
vocoder = Vocoder(
resblock_kernel_sizes=[3, 7, 11],
upsample_rates=[6, 5, 2, 2, 2],
upsample_kernel_sizes=[16, 15, 8, 4, 4],
resblock_dilation_sizes=[[1, 3, 5], [1, 3, 5], [1, 3, 5]],
upsample_initial_channel=1024,
stereo=True,
output_sample_rate=AUDIO_SAMPLE_RATE,
)
weight_file = model_path / "ltx-2-19b-distilled.safetensors"
if weight_file.exists():
raw_weights = mx.load(str(weight_file))
sanitized = sanitize_vocoder_weights(raw_weights)
if sanitized:
vocoder.load_weights(list(sanitized.items()), strict=False)
return vocoder
def save_audio(audio: np.ndarray, path: Path, sample_rate: int = AUDIO_SAMPLE_RATE):
"""Save audio to WAV file."""
import wave
if audio.ndim == 2:
audio = audio.T # (channels, samples) -> (samples, channels)
audio = np.clip(audio, -1.0, 1.0)
audio_int16 = (audio * 32767).astype(np.int16)
with wave.open(str(path), 'wb') as wf:
wf.setnchannels(2 if audio_int16.ndim == 2 else 1)
wf.setsampwidth(2)
wf.setframerate(sample_rate)
wf.writeframes(audio_int16.tobytes())
def mux_video_audio(video_path: Path, audio_path: Path, output_path: Path):
"""Combine video and audio into final output using ffmpeg."""
import subprocess
cmd = [
"ffmpeg", "-y",
"-i", str(video_path),
"-i", str(audio_path),
"-c:v", "copy",
"-c:a", "aac",
"-shortest",
str(output_path)
]
try:
subprocess.run(cmd, check=True, capture_output=True)
return True
except subprocess.CalledProcessError as e:
console.print(f"[red]FFmpeg error: {e.stderr.decode()}[/]")
return False
except FileNotFoundError:
console.print("[red]FFmpeg not found. Please install ffmpeg.[/]")
return False
def generate_video(
model_repo: str,
text_encoder_repo: str,
prompt: str,
height: int = 512,
width: int = 512,
num_frames: int = 33,
seed: int = 42,
fps: int = 24,
output_path: str = "output.mp4",
save_frames: bool = False,
verbose: bool = True,
enhance_prompt: bool = False,
max_tokens: int = 512,
temperature: float = 0.7,
image: Optional[str] = None,
image_strength: float = 1.0,
image_frame_idx: int = 0,
tiling: str = "auto",
stream: bool = False,
# Audio options
audio: bool = False,
output_audio_path: Optional[str] = None,
):
"""Generate video from text prompt, optionally conditioned on an image and with audio.
Args:
model_repo: Model repository ID
text_encoder_repo: Text encoder repository ID
prompt: Text description of the video to generate
height: Output video height (must be divisible by 64)
width: Output video width (must be divisible by 64)
num_frames: Number of frames (must be 1 + 8*k, e.g., 33, 65, 97)
seed: Random seed for reproducibility
fps: Frames per second for output video
output_path: Path to save the output video
save_frames: Whether to save individual frames as images
verbose: Whether to print progress
enhance_prompt: Whether to enhance prompt using Gemma
max_tokens: Max tokens for prompt enhancement
temperature: Temperature for prompt enhancement
image: Path to conditioning image for I2V (Image-to-Video)
image_strength: Conditioning strength (1.0 = full denoise, 0.0 = keep original)
image_frame_idx: Frame index to condition (0 = first frame)
tiling: Tiling mode for VAE decoding. Options:
- "auto": Automatically determine based on video size (default)
- "none": Disable tiling
- "default": 512px spatial, 64 frame temporal
- "aggressive": 256px spatial, 32 frame temporal (lowest memory)
- "conservative": 768px spatial, 96 frame temporal (faster)
- "spatial": Spatial tiling only
- "temporal": Temporal tiling only
stream: Stream frames to output as they're decoded (requires tiling)
audio: Enable synchronized audio generation
output_audio_path: Path to save audio file (default: same as video with .wav)
"""
start_time = time.time()
# Validate dimensions
assert height % 64 == 0, f"Height must be divisible by 64, got {height}"
assert width % 64 == 0, f"Width must be divisible by 64, got {width}"
if num_frames % 8 != 1:
adjusted_num_frames = round((num_frames - 1) / 8) * 8 + 1
console.print(f"[yellow]⚠️ Number of frames must be 1 + 8*k. Using nearest valid value: {adjusted_num_frames}[/]")
num_frames = adjusted_num_frames
is_i2v = image is not None
mode_str = "I2V" if is_i2v else "T2V"
if audio:
mode_str += "+Audio"
# Display header panel
header = f"[bold cyan]🎬 [{mode_str}] Generating {width}x{height} video with {num_frames} frames[/]"
console.print(Panel(header, expand=False))
console.print(f"[dim]Prompt: {prompt[:80]}{'...' if len(prompt) > 80 else ''}[/]")
if is_i2v:
console.print(f"[dim]Image: {image} (strength={image_strength}, frame={image_frame_idx})[/]")
# Calculate audio frames if enabled
audio_frames = None
if audio:
audio_frames = compute_audio_frames(num_frames, fps)
console.print(f"[dim]Audio: {audio_frames} latent frames @ {AUDIO_SAMPLE_RATE}Hz[/]")
# Get model path
model_path = get_model_path(model_repo)
text_encoder_path = model_path if text_encoder_repo is None else get_model_path(text_encoder_repo)
# Calculate latent dimensions
stage1_h, stage1_w = height // 2 // 32, width // 2 // 32
stage2_h, stage2_w = height // 32, width // 32
latent_frames = 1 + (num_frames - 1) // 8
mx.random.seed(seed)
# Load text encoder
with console.status("[blue]📝 Loading text encoder...[/]", spinner="dots"):
from mlx_video.models.ltx.text_encoder import LTX2TextEncoder
text_encoder = LTX2TextEncoder()
text_encoder.load(model_path=model_path, text_encoder_path=text_encoder_path)
mx.eval(text_encoder.parameters())
console.print("[green]✓[/] Text encoder loaded")
# Optionally enhance the prompt
if enhance_prompt:
with console.status("[magenta]✨ Enhancing prompt...[/]", spinner="dots"):
prompt = text_encoder.enhance_t2v(prompt, max_tokens=max_tokens, temperature=temperature, seed=seed, verbose=verbose)
console.print(f"[dim]Enhanced: {prompt[:150]}{'...' if len(prompt) > 150 else ''}[/]")
# Get embeddings - with audio if enabled
if audio:
text_embeddings, audio_embeddings = text_encoder(prompt, return_audio_embeddings=True)
mx.eval(text_embeddings, audio_embeddings)
else:
text_embeddings, _ = text_encoder(prompt, return_audio_embeddings=False)
audio_embeddings = None
mx.eval(text_embeddings)
model_dtype = text_embeddings.dtype # bfloat16 from text encoder
del text_encoder
mx.clear_cache()
# Load transformer
transformer_desc = "🤖 Loading transformer (A/V mode)..." if audio else "🤖 Loading transformer..."
with console.status(f"[blue]{transformer_desc}[/]", spinner="dots"):
raw_weights = mx.load(str(model_path / 'ltx-2-19b-distilled.safetensors'))
sanitized = sanitize_transformer_weights(raw_weights)
# Convert transformer weights to bfloat16 for memory efficiency
sanitized = {k: v.astype(mx.bfloat16) if v.dtype == mx.float32 else v for k, v in sanitized.items()}
# Configure model type based on audio flag
model_type = LTXModelType.AudioVideo if audio else LTXModelType.VideoOnly
config_kwargs = dict(
model_type=model_type,
num_attention_heads=32,
attention_head_dim=128,
in_channels=128,
out_channels=128,
num_layers=48,
cross_attention_dim=4096,
caption_channels=3840,
rope_type=LTXRopeType.SPLIT,
double_precision_rope=True,
positional_embedding_theta=10000.0,
positional_embedding_max_pos=[20, 2048, 2048],
use_middle_indices_grid=True,
timestep_scale_multiplier=1000,
)
if audio:
config_kwargs.update(
audio_num_attention_heads=32,
audio_attention_head_dim=64,
audio_in_channels=AUDIO_LATENT_CHANNELS * AUDIO_MEL_BINS, # 8 * 16 = 128
audio_out_channels=AUDIO_LATENT_CHANNELS * AUDIO_MEL_BINS,
audio_cross_attention_dim=2048,
audio_positional_embedding_max_pos=[20],
)
config = LTXModelConfig(**config_kwargs)
transformer = LTXModel(config)
transformer.load_weights(list(sanitized.items()), strict=False)
mx.eval(transformer.parameters())
console.print("[green]✓[/] Transformer loaded")
# Load VAE encoder and encode image for I2V conditioning
stage1_image_latent = None
stage2_image_latent = None
if is_i2v:
with console.status("[blue]🖼️ Loading VAE encoder and encoding image...[/]", spinner="dots"):
vae_encoder = load_vae_encoder(str(model_path / 'ltx-2-19b-distilled.safetensors'))
mx.eval(vae_encoder.parameters())
# Load and prepare image for stage 1 (half resolution)
input_image = load_image(image, height=height // 2, width=width // 2, dtype=model_dtype)
stage1_image_tensor = prepare_image_for_encoding(input_image, height // 2, width // 2, dtype=model_dtype)
stage1_image_latent = vae_encoder(stage1_image_tensor)
mx.eval(stage1_image_latent)
# Load and prepare image for stage 2 (full resolution)
input_image = load_image(image, height=height, width=width, dtype=model_dtype)
stage2_image_tensor = prepare_image_for_encoding(input_image, height, width, dtype=model_dtype)
stage2_image_latent = vae_encoder(stage2_image_tensor)
mx.eval(stage2_image_latent)
del vae_encoder
mx.clear_cache()
console.print("[green]✓[/] VAE encoder loaded and image encoded")
# Stage 1: Generate at half resolution
console.print(f"\n[bold yellow]⚡ Stage 1:[/] Generating at {width//2}x{height//2} (8 steps)")
mx.random.seed(seed)
# Position grids stay float32 for RoPE precision
positions = create_position_grid(1, latent_frames, stage1_h, stage1_w)
mx.eval(positions)
# Create audio positions if enabled
audio_positions = None
audio_latents = None
if audio:
audio_positions = create_audio_position_grid(1, audio_frames)
audio_latents = mx.random.normal((1, AUDIO_LATENT_CHANNELS, audio_frames, AUDIO_MEL_BINS)).astype(model_dtype)
mx.eval(audio_positions, audio_latents)
# Apply I2V conditioning if provided
state1 = None
if is_i2v and stage1_image_latent is not None:
# PyTorch flow: create zeros -> apply conditioning -> apply noiser
# Create initial state with zeros
latent_shape = (1, 128, latent_frames, stage1_h, stage1_w)
state1 = LatentState(
latent=mx.zeros(latent_shape, dtype=model_dtype),
clean_latent=mx.zeros(latent_shape, dtype=model_dtype),
denoise_mask=mx.ones((1, 1, latent_frames, 1, 1), dtype=model_dtype),
)
conditioning = VideoConditionByLatentIndex(
latent=stage1_image_latent,
frame_idx=image_frame_idx,
strength=image_strength,
)
state1 = apply_conditioning(state1, [conditioning])
# Apply noiser: latent = noise * (mask * noise_scale) + latent * (1 - mask * noise_scale)
# For Stage 1, noise_scale = 1.0 (first sigma)
noise = mx.random.normal(latent_shape, dtype=model_dtype)
noise_scale = mx.array(STAGE_1_SIGMAS[0], dtype=model_dtype) # 1.0
scaled_mask = state1.denoise_mask * noise_scale
state1 = LatentState(
latent=noise * scaled_mask + state1.latent * (mx.array(1.0, dtype=model_dtype) - scaled_mask),
clean_latent=state1.clean_latent,
denoise_mask=state1.denoise_mask,
)
latents = state1.latent
mx.eval(latents)
else:
# T2V: just use random noise
latents = mx.random.normal((1, 128, latent_frames, stage1_h, stage1_w), dtype=model_dtype)
mx.eval(latents)
latents, audio_latents = denoise(
latents, positions, text_embeddings, transformer, STAGE_1_SIGMAS,
verbose=verbose, state=state1,
audio_latents=audio_latents, audio_positions=audio_positions, audio_embeddings=audio_embeddings,
)
# Upsample latents
with console.status("[magenta]🔍 Upsampling latents 2x...[/]", spinner="dots"):
upsampler = load_upsampler(str(model_path / 'ltx-2-spatial-upscaler-x2-1.0.safetensors'))
mx.eval(upsampler.parameters())
vae_decoder = load_vae_decoder(
str(model_path / 'ltx-2-19b-distilled.safetensors'),
timestep_conditioning=None # Auto-detect from model metadata
)
latents = upsample_latents(latents, upsampler, vae_decoder.latents_mean, vae_decoder.latents_std)
mx.eval(latents)
del upsampler
mx.clear_cache()
console.print("[green]✓[/] Latents upsampled")
# Stage 2: Refine at full resolution
console.print(f"\n[bold yellow]⚡ Stage 2:[/] Refining at {width}x{height} (3 steps)")
# Position grids stay float32 for RoPE precision
positions = create_position_grid(1, latent_frames, stage2_h, stage2_w)
mx.eval(positions)
# Apply I2V conditioning for stage 2 if provided
state2 = None
if is_i2v and stage2_image_latent is not None:
# PyTorch flow: start with upscaled latent -> apply conditioning -> apply noiser
state2 = LatentState(
latent=latents, # Start with upscaled latent
clean_latent=mx.zeros_like(latents),
denoise_mask=mx.ones((1, 1, latent_frames, 1, 1), dtype=model_dtype),
)
conditioning = VideoConditionByLatentIndex(
latent=stage2_image_latent,
frame_idx=image_frame_idx,
strength=image_strength,
)
state2 = apply_conditioning(state2, [conditioning])
# Apply noiser: latent = noise * (mask * noise_scale) + latent * (1 - mask * noise_scale)
# For Stage 2, noise_scale = stage_2_sigmas[0]
# Conditioned frames (mask=0) keep image latent, unconditioned get partial noise
noise = mx.random.normal(latents.shape).astype(model_dtype)
noise_scale = mx.array(STAGE_2_SIGMAS[0], dtype=model_dtype)
scaled_mask = state2.denoise_mask * noise_scale
state2 = LatentState(
latent=noise * scaled_mask + state2.latent * (mx.array(1.0, dtype=model_dtype) - scaled_mask),
clean_latent=state2.clean_latent,
denoise_mask=state2.denoise_mask,
)
latents = state2.latent
mx.eval(latents)
# Audio also gets noise for stage 2 if enabled
if audio and audio_latents is not None:
audio_noise = mx.random.normal(audio_latents.shape).astype(model_dtype)
one_minus_scale = mx.array(1.0, dtype=model_dtype) - noise_scale
audio_latents = audio_noise * noise_scale + audio_latents * one_minus_scale
mx.eval(audio_latents)
else:
# T2V: add noise to all frames for refinement
noise_scale = mx.array(STAGE_2_SIGMAS[0], dtype=model_dtype)
one_minus_scale = mx.array(1.0 - STAGE_2_SIGMAS[0], dtype=model_dtype)
noise = mx.random.normal(latents.shape).astype(model_dtype)
latents = noise * noise_scale + latents * one_minus_scale
mx.eval(latents)
# Audio also gets noise for stage 2 if enabled
if audio and audio_latents is not None:
audio_noise = mx.random.normal(audio_latents.shape).astype(model_dtype)
audio_latents = audio_noise * noise_scale + audio_latents * one_minus_scale
mx.eval(audio_latents)
latents, audio_latents = denoise(
latents, positions, text_embeddings, transformer, STAGE_2_SIGMAS,
verbose=verbose, state=state2,
audio_latents=audio_latents, audio_positions=audio_positions, audio_embeddings=audio_embeddings,
)
del transformer
mx.clear_cache()
# Decode to video with tiling
console.print("\n[blue]🎞️ Decoding video...[/]")
# Select tiling configuration
if tiling == "none":
tiling_config = None
elif tiling == "auto":
tiling_config = TilingConfig.auto(height, width, num_frames)
elif tiling == "default":
tiling_config = TilingConfig.default()
elif tiling == "aggressive":
tiling_config = TilingConfig.aggressive()
elif tiling == "conservative":
tiling_config = TilingConfig.conservative()
elif tiling == "spatial":
tiling_config = TilingConfig.spatial_only()
elif tiling == "temporal":
tiling_config = TilingConfig.temporal_only()
else:
console.print(f"[yellow] Unknown tiling mode '{tiling}', using auto[/]")
tiling_config = TilingConfig.auto(height, width, num_frames)
# Save outputs
output_path = Path(output_path)
output_path.parent.mkdir(parents=True, exist_ok=True)
# Stream mode: write frames as they're decoded
video_writer = None
stream_progress = None
if stream and tiling_config is not None:
import cv2
fourcc = cv2.VideoWriter_fourcc(*'avc1')
video_writer = cv2.VideoWriter(str(output_path), fourcc, fps, (width, height))
stream_progress = Progress(
SpinnerColumn(),
TextColumn("[progress.description]{task.description}"),
BarColumn(),
TaskProgressColumn(),
console=console,
)
stream_progress.start()
stream_task = stream_progress.add_task("[cyan]Streaming frames[/]", total=num_frames)
def on_frames_ready(frames: mx.array, _start_idx: int):
"""Callback to write frames as they're finalized."""
# frames: (B, 3, num_frames, H, W)
frames = mx.squeeze(frames, axis=0) # (3, num_frames, H, W)
frames = mx.transpose(frames, (1, 2, 3, 0)) # (num_frames, H, W, 3)
frames = mx.clip((frames + 1.0) / 2.0, 0.0, 1.0)
frames = (frames * 255).astype(mx.uint8)
frames_np = np.array(frames)
for frame in frames_np:
video_writer.write(cv2.cvtColor(frame, cv2.COLOR_RGB2BGR))
stream_progress.advance(stream_task)
else:
on_frames_ready = None
if tiling_config is not None:
spatial_info = f"{tiling_config.spatial_config.tile_size_in_pixels}px" if tiling_config.spatial_config else "none"
temporal_info = f"{tiling_config.temporal_config.tile_size_in_frames}f" if tiling_config.temporal_config else "none"
console.print(f"[dim] Tiling ({tiling}): spatial={spatial_info}, temporal={temporal_info}[/]")
video = vae_decoder.decode_tiled(latents, tiling_config=tiling_config, tiling_mode=tiling, debug=verbose, on_frames_ready=on_frames_ready)
else:
console.print("[dim] Tiling: disabled[/]")
video = vae_decoder(latents)
mx.eval(video)
mx.clear_cache()
# Close progressive video writer if used
if video_writer is not None:
video_writer.release()
if stream_progress is not None:
stream_progress.stop()
console.print(f"[green]✅ Streamed video to[/] {output_path}")
# Still need video_np for save_frames option
video = mx.squeeze(video, axis=0)
video = mx.transpose(video, (1, 2, 3, 0))
video = mx.clip((video + 1.0) / 2.0, 0.0, 1.0)
video = (video * 255).astype(mx.uint8)
video_np = np.array(video)
else:
# Convert to uint8 frames
video = mx.squeeze(video, axis=0) # (C, F, H, W)
video = mx.transpose(video, (1, 2, 3, 0)) # (F, H, W, C)
video = mx.clip((video + 1.0) / 2.0, 0.0, 1.0)
video = (video * 255).astype(mx.uint8)
video_np = np.array(video)
# For audio mode, save to temp file first
if audio:
temp_video_path = output_path.with_suffix('.temp.mp4')
save_path = temp_video_path
else:
save_path = output_path
# Save video
try:
import cv2
h, w = video_np.shape[1], video_np.shape[2]
fourcc = cv2.VideoWriter_fourcc(*'avc1')
out = cv2.VideoWriter(str(save_path), fourcc, fps, (w, h))
for frame in video_np:
out.write(cv2.cvtColor(frame, cv2.COLOR_RGB2BGR))
out.release()
if not audio:
console.print(f"[green]✅ Saved video to[/] {output_path}")
except Exception as e:
console.print(f"[red]❌ Could not save video: {e}[/]")
# Decode and save audio if enabled
audio_np = None
if audio and audio_latents is not None:
with console.status("[blue]🔊 Decoding audio...[/]", spinner="dots"):
audio_decoder = load_audio_decoder(model_path)
vocoder = load_vocoder(model_path)
mx.eval(audio_decoder.parameters(), vocoder.parameters())
mel_spectrogram = audio_decoder(audio_latents)
mx.eval(mel_spectrogram)
audio_waveform = vocoder(mel_spectrogram)
mx.eval(audio_waveform)
audio_np = np.array(audio_waveform)
if audio_np.ndim == 3:
audio_np = audio_np[0]
del audio_decoder, vocoder
mx.clear_cache()
console.print("[green]✓[/] Audio decoded")
# Save audio
audio_path = Path(output_audio_path) if output_audio_path else output_path.with_suffix('.wav')
save_audio(audio_np, audio_path, AUDIO_SAMPLE_RATE)
console.print(f"[green]✅ Saved audio to[/] {audio_path}")
# Mux video and audio
with console.status("[blue]🎬 Combining video and audio...[/]", spinner="dots"):
temp_video_path = output_path.with_suffix('.temp.mp4')
success = mux_video_audio(temp_video_path, audio_path, output_path)
if success:
console.print(f"[green]✅ Saved video with audio to[/] {output_path}")
temp_video_path.unlink()
else:
temp_video_path.rename(output_path)
console.print(f"[yellow]⚠️ Saved video without audio to[/] {output_path}")
del vae_decoder
mx.clear_cache()
if save_frames:
frames_dir = output_path.parent / f"{output_path.stem}_frames"
frames_dir.mkdir(exist_ok=True)
for i, frame in enumerate(video_np):
Image.fromarray(frame).save(frames_dir / f"frame_{i:04d}.png")
console.print(f"[green]✅ Saved {len(video_np)} frames to {frames_dir}[/]")
elapsed = time.time() - start_time
console.print(Panel(
f"[bold green]🎉 Done![/] Generated in {elapsed:.1f}s ({elapsed/num_frames:.2f}s/frame)\n"
f"[bold green]✨ Peak memory:[/] {mx.get_peak_memory() / (1024 ** 3):.2f}GB",
expand=False
))
if audio:
return video_np, audio_np
return video_np
def main():
parser = argparse.ArgumentParser(
description="Generate videos with MLX LTX-2 (T2V, I2V, and Audio)",
formatter_class=argparse.RawDescriptionHelpFormatter,
epilog="""
Examples:
# Text-to-Video (T2V)
python -m mlx_video.generate --prompt "A cat walking on grass"
python -m mlx_video.generate --prompt "Ocean waves at sunset" --height 768 --width 768
python -m mlx_video.generate --prompt "..." --num-frames 65 --seed 123 --output my_video.mp4
# Image-to-Video (I2V)
python -m mlx_video.generate --prompt "A person dancing" --image photo.jpg
python -m mlx_video.generate --prompt "Waves crashing" --image beach.png --image-strength 0.8
# With Audio (T2V+Audio or I2V+Audio)
python -m mlx_video.generate --prompt "Ocean waves crashing" --audio
python -m mlx_video.generate --prompt "A jazz band playing" --audio --enhance-prompt
python -m mlx_video.generate --prompt "Waves crashing" --image beach.png --audio
"""
)
parser.add_argument(
"--prompt", "-p",
type=str,
required=True,
help="Text description of the video to generate"
)
parser.add_argument(
"--height", "-H",
type=int,
default=512,
help="Output video height (default: 512, must be divisible by 32)"
)
parser.add_argument(
"--width", "-W",
type=int,
default=512,
help="Output video width (default: 512, must be divisible by 32)"
)
parser.add_argument(
"--num-frames", "-n",
type=int,
default=100,
help="Number of frames (default: 100)"
)
parser.add_argument(
"--seed", "-s",
type=int,
default=42,
help="Random seed for reproducibility (default: 42)"
)
parser.add_argument(
"--fps",
type=int,
default=24,
help="Frames per second for output video (default: 24)"
)
parser.add_argument(
"--output-path", "-o",
type=str,
default="output.mp4",
help="Output video path (default: output.mp4)"
)
parser.add_argument(
"--save-frames",
action="store_true",
help="Save individual frames as images"
)
parser.add_argument(
"--model-repo",
type=str,
default="Lightricks/LTX-2",
help="Model repository to use (default: Lightricks/LTX-2)"
)
parser.add_argument(
"--text-encoder-repo",
type=str,
default=None,
help="Text encoder repository to use (default: None)"
)
parser.add_argument(
"--verbose",
action="store_true",
help="Verbose output"
)
parser.add_argument(
"--enhance-prompt",
action="store_true",
help="Enhance the prompt using Gemma before generation"
)
parser.add_argument(
"--max-tokens",
type=int,
default=512,
help="Maximum number of tokens to generate (default: 512)"
)
parser.add_argument(
"--temperature",
type=float,
default=0.7,
help="Temperature for prompt enhancement (default: 0.7)"
)
parser.add_argument(
"--image", "-i",
type=str,
default=None,
help="Path to conditioning image for I2V (Image-to-Video) generation"
)
parser.add_argument(
"--image-strength",
type=float,
default=1.0,
help="Conditioning strength for I2V (1.0 = full denoise, 0.0 = keep original, default: 1.0)"
)
parser.add_argument(
"--image-frame-idx",
type=int,
default=0,
help="Frame index to condition for I2V (0 = first frame, default: 0)"
)
parser.add_argument(
"--tiling",
type=str,
default="auto",
choices=["auto", "none", "default", "aggressive", "conservative", "spatial", "temporal"],
help="Tiling mode for VAE decoding (default: auto). "
"auto=based on video size, none=disabled, default=512px/64f, "
"aggressive=256px/32f (lowest memory), conservative=768px/96f, spatial=spatial only, temporal=temporal only"
)
parser.add_argument(
"--stream",
action="store_true",
help="Stream frames to output file as they're decoded (requires tiling). Allows viewing partial results sooner."
)
# Audio options
parser.add_argument(
"--audio", "-a",
action="store_true",
help="Enable synchronized audio generation"
)
parser.add_argument(
"--output-audio",
type=str,
default=None,
help="Output audio path (default: same as video with .wav)"
)
args = parser.parse_args()
generate_video(
model_repo=args.model_repo,
text_encoder_repo=args.text_encoder_repo,
prompt=args.prompt,
height=args.height,
width=args.width,
num_frames=args.num_frames,
seed=args.seed,
fps=args.fps,
output_path=args.output_path,
save_frames=args.save_frames,
verbose=args.verbose,
enhance_prompt=args.enhance_prompt,
max_tokens=args.max_tokens,
temperature=args.temperature,
image=args.image,
image_strength=args.image_strength,
image_frame_idx=args.image_frame_idx,
tiling=args.tiling,
stream=args.stream,
audio=args.audio,
output_audio_path=args.output_audio,
)
if __name__ == "__main__":
main()