Files
voicebox/backend/backends/mlx_backend.py
T
Makinde d00e28ffda Fix: Prevent crashes when HuggingFace is unreachable
Implements offline mode patch for API stability issues:

- Add hf_offline_patch.py to monkey-patch huggingface_hub
- Force cache-only lookups before mlx_audio imports
- Create symlink from original Qwen repo to MLX community version
  when only MLX version is cached

This fixes:
- Issue #150: Internet required even with cached models
- Issue #151: API crashes when HF network fails

The patch ensures that if models are locally cached, no network
requests are made to HuggingFace during speech generation.
2026-02-22 01:57:02 -08:00

601 lines
23 KiB
Python

"""
MLX backend implementation for TTS and STT using mlx-audio.
"""
from typing import Optional, List, Tuple
import asyncio
import numpy as np
import os
from pathlib import Path
# PATCH: Import and apply offline patch BEFORE any huggingface_hub usage
# This prevents mlx_audio from making network requests when models are cached
from ..utils.hf_offline_patch import patch_huggingface_hub_offline, ensure_original_qwen_config_cached
patch_huggingface_hub_offline()
ensure_original_qwen_config_cached()
from . import TTSBackend, STTBackend
from ..utils.cache import get_cache_key, get_cached_voice_prompt, cache_voice_prompt
from ..utils.audio import normalize_audio, load_audio
from ..utils.progress import get_progress_manager
from ..utils.hf_progress import HFProgressTracker, create_hf_progress_callback
from ..utils.tasks import get_task_manager
class MLXTTSBackend:
"""MLX-based TTS backend using mlx-audio."""
def __init__(self, model_size: str = "1.7B"):
self.model = None
self.model_size = model_size
self._current_model_size = None
def is_loaded(self) -> bool:
"""Check if model is loaded."""
return self.model is not None
def _get_model_path(self, model_size: str) -> str:
"""
Get the MLX model path.
Args:
model_size: Model size (1.7B or 0.6B)
Returns:
HuggingFace Hub model ID for MLX
"""
# MLX model mapping
mlx_model_map = {
"1.7B": "mlx-community/Qwen3-TTS-12Hz-1.7B-Base-bf16",
# 0.6B not yet converted to MLX format
"0.6B": "mlx-community/Qwen3-TTS-12Hz-1.7B-Base-bf16", # Fallback to 1.7B
}
if model_size not in mlx_model_map:
raise ValueError(f"Unknown model size: {model_size}")
hf_model_id = mlx_model_map[model_size]
print(f"Will download MLX model from HuggingFace Hub: {hf_model_id}")
return hf_model_id
def _is_model_cached(self, model_size: str) -> bool:
"""
Check if the model is already cached locally AND fully downloaded.
Args:
model_size: Model size to check
Returns:
True if model is fully cached, False if missing or incomplete
"""
try:
from huggingface_hub import constants as hf_constants
model_path = self._get_model_path(model_size)
repo_cache = Path(hf_constants.HF_HUB_CACHE) / ("models--" + model_path.replace("/", "--"))
if not repo_cache.exists():
return False
# Check for .incomplete files - if any exist, download is still in progress
blobs_dir = repo_cache / "blobs"
if blobs_dir.exists() and any(blobs_dir.glob("*.incomplete")):
print(f"[_is_model_cached] Found .incomplete files for {model_size}, treating as not cached")
return False
# Check that actual model weight files exist in snapshots
snapshots_dir = repo_cache / "snapshots"
if snapshots_dir.exists():
has_weights = (
any(snapshots_dir.rglob("*.safetensors")) or
any(snapshots_dir.rglob("*.bin")) or
any(snapshots_dir.rglob("*.npz"))
)
if not has_weights:
print(f"[_is_model_cached] No model weights found for {model_size}, treating as not cached")
return False
return True
except Exception as e:
print(f"[_is_model_cached] Error checking cache for {model_size}: {e}")
return False
async def load_model_async(self, model_size: Optional[str] = None):
"""
Lazy load the MLX TTS model.
Args:
model_size: Model size to load (1.7B or 0.6B)
"""
if model_size is None:
model_size = self.model_size
# If already loaded with correct size, return
if self.model is not None and self._current_model_size == model_size:
return
# Unload existing model if different size requested
if self.model is not None and self._current_model_size != model_size:
self.unload_model()
# Run blocking load in thread pool
await asyncio.to_thread(self._load_model_sync, model_size)
# Alias for compatibility
load_model = load_model_async
def _load_model_sync(self, model_size: str):
"""Synchronous model loading."""
try:
# Get model path BEFORE importing mlx_audio
model_path = self._get_model_path(model_size)
# Set up progress tracking
progress_manager = get_progress_manager()
task_manager = get_task_manager()
model_name = f"qwen-tts-{model_size}"
# Check if model is already cached
is_cached = self._is_model_cached(model_size)
# Set up progress callback
# If cached: filter out non-download progress
# If not cached: report all progress (we're actually downloading)
progress_callback = create_hf_progress_callback(model_name, progress_manager)
tracker = HFProgressTracker(progress_callback, filter_non_downloads=is_cached)
print(f"Loading MLX TTS model {model_size}...")
# Only track download progress if model is NOT cached
if not is_cached:
# Start tracking download task
task_manager.start_download(model_name)
# Initialize progress state so SSE endpoint has initial data to send
# This provides immediate feedback while HuggingFace fetches metadata
progress_manager.update_progress(
model_name=model_name,
current=0,
total=0, # Will be updated once actual total is known
filename="Connecting to HuggingFace...",
status="downloading",
)
# IMPORTANT: Patch tqdm BEFORE importing mlx_audio
# Otherwise mlx_audio caches reference to original tqdm
tracker_context = tracker.patch_download()
tracker_context.__enter__()
# PATCH: Force offline mode when model is already cached
# This prevents crashes when HuggingFace is unreachable
original_hf_hub_offline = os.environ.get("HF_HUB_OFFLINE")
if is_cached:
os.environ["HF_HUB_OFFLINE"] = "1"
print(f"[PATCH] Model {model_size} is cached, forcing HF_HUB_OFFLINE=1 to avoid network requests")
# Import mlx_audio AFTER patching tqdm
from mlx_audio.tts import load
# Load MLX model (downloads automatically)
try:
self.model = load(model_path)
except Exception as load_error:
# If offline mode failed, try with network enabled as fallback
if is_cached and "offline" in str(load_error).lower():
print(f"[PATCH] Offline load failed, trying with network: {load_error}")
os.environ.pop("HF_HUB_OFFLINE", None)
self.model = load(model_path)
else:
raise
finally:
# Exit the patch context
tracker_context.__exit__(None, None, None)
# Restore original HF_HUB_OFFLINE setting
if original_hf_hub_offline is not None:
os.environ["HF_HUB_OFFLINE"] = original_hf_hub_offline
else:
os.environ.pop("HF_HUB_OFFLINE", None)
# Only mark download as complete if we were tracking it
if not is_cached:
progress_manager.mark_complete(model_name)
task_manager.complete_download(model_name)
self._current_model_size = model_size
self.model_size = model_size
print(f"MLX TTS model {model_size} loaded successfully")
except ImportError as e:
print(f"Error: mlx_audio package not found. Install with: pip install mlx-audio")
progress_manager = get_progress_manager()
task_manager = get_task_manager()
model_name = f"qwen-tts-{model_size}"
progress_manager.mark_error(model_name, str(e))
task_manager.error_download(model_name, str(e))
raise
except Exception as e:
print(f"Error loading MLX TTS model: {e}")
progress_manager = get_progress_manager()
task_manager = get_task_manager()
model_name = f"qwen-tts-{model_size}"
progress_manager.mark_error(model_name, str(e))
task_manager.error_download(model_name, str(e))
raise
def unload_model(self):
"""Unload the model to free memory."""
if self.model is not None:
del self.model
self.model = None
self._current_model_size = None
print("MLX TTS model unloaded")
async def create_voice_prompt(
self,
audio_path: str,
reference_text: str,
use_cache: bool = True,
) -> Tuple[dict, bool]:
"""
Create voice prompt from reference audio.
MLX backend stores voice prompt as a dict with audio path and text.
The actual voice prompt processing happens during generation.
Args:
audio_path: Path to reference audio file
reference_text: Transcript of reference audio
use_cache: Whether to use cached prompt if available
Returns:
Tuple of (voice_prompt_dict, was_cached)
"""
await self.load_model_async(None)
# Check cache if enabled
if use_cache:
cache_key = get_cache_key(audio_path, reference_text)
cached_prompt = get_cached_voice_prompt(cache_key)
if cached_prompt is not None:
# Return cached prompt (should be dict format)
if isinstance(cached_prompt, dict):
# Validate that the cached audio file still exists
cached_audio_path = cached_prompt.get("ref_audio") or cached_prompt.get("ref_audio_path")
if cached_audio_path and Path(cached_audio_path).exists():
return cached_prompt, True
else:
# Cached file no longer exists, invalidate cache
print(f"Cached audio file not found: {cached_audio_path}, regenerating prompt")
# MLX voice prompt format - store audio path and text
# The model will process this during generation
voice_prompt_items = {
"ref_audio": str(audio_path),
"ref_text": reference_text,
}
# Cache if enabled
if use_cache:
cache_key = get_cache_key(audio_path, reference_text)
cache_voice_prompt(cache_key, voice_prompt_items)
return voice_prompt_items, False
async def combine_voice_prompts(
self,
audio_paths: List[str],
reference_texts: List[str],
) -> Tuple[np.ndarray, str]:
"""
Combine multiple reference samples for better quality.
Args:
audio_paths: List of audio file paths
reference_texts: List of reference texts
Returns:
Tuple of (combined_audio, combined_text)
"""
combined_audio = []
for audio_path in audio_paths:
audio, sr = load_audio(audio_path)
audio = normalize_audio(audio)
combined_audio.append(audio)
# Concatenate audio
mixed = np.concatenate(combined_audio)
mixed = normalize_audio(mixed)
# Combine texts
combined_text = " ".join(reference_texts)
return mixed, combined_text
async def generate(
self,
text: str,
voice_prompt: dict,
language: str = "en",
seed: Optional[int] = None,
instruct: Optional[str] = None,
) -> Tuple[np.ndarray, int]:
"""
Generate audio from text using voice prompt.
Args:
text: Text to synthesize
voice_prompt: Voice prompt dictionary with ref_audio and ref_text
language: Language code (en or zh) - may not be fully supported by MLX
seed: Random seed for reproducibility
instruct: Natural language instruction (may not be supported by MLX)
Returns:
Tuple of (audio_array, sample_rate)
"""
await self.load_model_async(None)
print(f"Generating audio for text: {text}")
def _generate_sync():
"""Run synchronous generation in thread pool."""
# MLX generate() returns a generator yielding GenerationResult objects
audio_chunks = []
sample_rate = 24000
# Set seed if provided (MLX uses numpy random)
if seed is not None:
import mlx.core as mx
np.random.seed(seed)
mx.random.seed(seed)
# Extract voice prompt info
ref_audio = voice_prompt.get("ref_audio") or voice_prompt.get("ref_audio_path")
ref_text = voice_prompt.get("ref_text", "")
# Validate that the audio file exists
if ref_audio and not Path(ref_audio).exists():
print(f"Warning: Audio file not found: {ref_audio}")
print("This may be due to a cached voice prompt referencing a deleted temp file.")
print("Regenerating without voice prompt.")
ref_audio = None
# Check if model supports voice cloning via generate method
# MLX API may support ref_audio parameter directly
try:
# Try with voice cloning parameters if supported
if ref_audio:
# Check if generate accepts ref_audio parameter
import inspect
sig = inspect.signature(self.model.generate)
if "ref_audio" in sig.parameters:
# Generate with voice cloning
for result in self.model.generate(text, ref_audio=ref_audio, ref_text=ref_text):
audio_chunks.append(np.array(result.audio))
sample_rate = result.sample_rate
else:
# Fallback: generate without voice cloning
for result in self.model.generate(text):
audio_chunks.append(np.array(result.audio))
sample_rate = result.sample_rate
else:
# No voice prompt, generate normally
for result in self.model.generate(text):
audio_chunks.append(np.array(result.audio))
sample_rate = result.sample_rate
except Exception as e:
# If voice cloning fails, try without it
print(f"Warning: Voice cloning failed, generating without voice prompt: {e}")
for result in self.model.generate(text):
audio_chunks.append(np.array(result.audio))
sample_rate = result.sample_rate
# Concatenate all chunks
if audio_chunks:
audio = np.concatenate([np.asarray(chunk, dtype=np.float32) for chunk in audio_chunks])
else:
# Fallback: empty audio
audio = np.array([], dtype=np.float32)
return audio, sample_rate
# Run blocking inference in thread pool
audio, sample_rate = await asyncio.to_thread(_generate_sync)
return audio, sample_rate
class MLXSTTBackend:
"""MLX-based STT backend using mlx-audio Whisper."""
def __init__(self, model_size: str = "base"):
self.model = None
self.model_size = model_size
def is_loaded(self) -> bool:
"""Check if model is loaded."""
return self.model is not None
def _is_model_cached(self, model_size: str) -> bool:
"""
Check if the Whisper model is already cached locally AND fully downloaded.
Args:
model_size: Model size to check
Returns:
True if model is fully cached, False if missing or incomplete
"""
try:
from huggingface_hub import constants as hf_constants
model_name = f"openai/whisper-{model_size}"
repo_cache = Path(hf_constants.HF_HUB_CACHE) / ("models--" + model_name.replace("/", "--"))
if not repo_cache.exists():
return False
# Check for .incomplete files - if any exist, download is still in progress
blobs_dir = repo_cache / "blobs"
if blobs_dir.exists() and any(blobs_dir.glob("*.incomplete")):
print(f"[_is_model_cached] Found .incomplete files for whisper-{model_size}, treating as not cached")
return False
# Check that actual model weight files exist in snapshots
snapshots_dir = repo_cache / "snapshots"
if snapshots_dir.exists():
has_weights = (
any(snapshots_dir.rglob("*.safetensors")) or
any(snapshots_dir.rglob("*.bin")) or
any(snapshots_dir.rglob("*.npz"))
)
if not has_weights:
print(f"[_is_model_cached] No model weights found for whisper-{model_size}, treating as not cached")
return False
return True
except Exception as e:
print(f"[_is_model_cached] Error checking cache for whisper-{model_size}: {e}")
return False
async def load_model_async(self, model_size: Optional[str] = None):
"""
Lazy load the MLX Whisper model.
Args:
model_size: Model size (tiny, base, small, medium, large)
"""
if model_size is None:
model_size = self.model_size
if self.model is not None and self.model_size == model_size:
return
# Run blocking load in thread pool
await asyncio.to_thread(self._load_model_sync, model_size)
# Alias for compatibility
load_model = load_model_async
def _load_model_sync(self, model_size: str):
"""Synchronous model loading."""
try:
progress_manager = get_progress_manager()
task_manager = get_task_manager()
progress_model_name = f"whisper-{model_size}"
# Check if model is already cached
is_cached = self._is_model_cached(model_size)
# Set up progress callback and tracker
# If cached: filter out non-download progress
# If not cached: report all progress (we're actually downloading)
progress_callback = create_hf_progress_callback(progress_model_name, progress_manager)
tracker = HFProgressTracker(progress_callback, filter_non_downloads=is_cached)
# Patch tqdm BEFORE importing mlx_audio
tracker_context = tracker.patch_download()
tracker_context.__enter__()
# Import mlx_audio
from mlx_audio.stt import load
# MLX Whisper uses the standard OpenAI models
model_name = f"openai/whisper-{model_size}"
print(f"Loading MLX Whisper model {model_size}...")
# Only track download progress if model is NOT cached
if not is_cached:
# Start tracking download task
task_manager.start_download(progress_model_name)
# Initialize progress state so SSE endpoint has initial data to send
progress_manager.update_progress(
model_name=progress_model_name,
current=0,
total=0,
filename="Connecting to HuggingFace...",
status="downloading",
)
# Load the model (tqdm is patched, but filters out non-download progress)
try:
self.model = load(model_name)
finally:
# Exit the patch context
tracker_context.__exit__(None, None, None)
# Only mark download as complete if we were tracking it
if not is_cached:
progress_manager.mark_complete(progress_model_name)
task_manager.complete_download(progress_model_name)
self.model_size = model_size
print(f"MLX Whisper model {model_size} loaded successfully")
except ImportError as e:
print(f"Error: mlx_audio package not found. Install with: pip install mlx-audio")
progress_manager = get_progress_manager()
task_manager = get_task_manager()
progress_model_name = f"whisper-{model_size}"
progress_manager.mark_error(progress_model_name, str(e))
task_manager.error_download(progress_model_name, str(e))
raise
except Exception as e:
print(f"Error loading MLX Whisper model: {e}")
progress_manager = get_progress_manager()
task_manager = get_task_manager()
progress_model_name = f"whisper-{model_size}"
progress_manager.mark_error(progress_model_name, str(e))
task_manager.error_download(progress_model_name, str(e))
raise
def unload_model(self):
"""Unload the model to free memory."""
if self.model is not None:
del self.model
self.model = None
print("MLX Whisper model unloaded")
async def transcribe(
self,
audio_path: str,
language: Optional[str] = None,
) -> str:
"""
Transcribe audio to text.
Args:
audio_path: Path to audio file
language: Optional language hint (en or zh)
Returns:
Transcribed text
"""
await self.load_model_async(None)
def _transcribe_sync():
"""Run synchronous transcription in thread pool."""
# MLX Whisper transcription using generate method
# The generate method accepts audio path directly
decode_options = {}
if language:
decode_options["language"] = language
result = self.model.generate(str(audio_path), **decode_options)
# Extract text from result
if isinstance(result, str):
return result.strip()
elif isinstance(result, dict):
return result.get("text", "").strip()
elif hasattr(result, "text"):
return result.text.strip()
else:
return str(result).strip()
# Run blocking transcription in thread pool
return await asyncio.to_thread(_transcribe_sync)