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vllm-omni/vllm_omni/entrypoints/openai/serving_video_stream.py
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Python

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
"""WebSocket handler for streaming video input understanding.
Accepts video frames incrementally via WebSocket, buffers them, and
generates text + optional audio responses using the existing Qwen3-Omni
multi-stage pipeline (thinker -> talker -> code2wav).
Protocol:
Client -> Server:
{"type": "session.config", ...} # Session config (sent once)
{"type": "video.frame", "data": "..."} # base64 JPEG/PNG frame
{"type": "audio.chunk", "data": "..."} # base64 PCM16 16kHz mono
{"type": "video.query", "text": "..."} # Submit query about buffered frames
{"type": "video.done"} # End of session
Server -> Client:
{"type": "response.start"}
{"type": "response.text.delta", "delta": "..."}
{"type": "response.text.done", "text": "..."}
{"type": "response.audio.delta", "data": "...", "format": "wav"}
{"type": "response.audio.done"}
{"type": "session.done"}
{"type": "error", "message": "..."}
"""
import asyncio
import base64
import hashlib
import io
import json
import time as _time
import uuid
import wave
from typing import Any
import torch
from fastapi import WebSocket, WebSocketDisconnect
from PIL import Image
from pydantic import BaseModel, Field, ValidationError
from vllm.logger import init_logger
from vllm_omni.entrypoints.openai import video_stream_envs
from vllm_omni.entrypoints.openai.video_frame_filter import FrameSimilarityFilter
from vllm_omni.entrypoints.openai.video_stream_context import (
text_only_message,
)
from vllm_omni.outputs import OmniRequestOutput
logger = init_logger(__name__)
_DEFAULT_IDLE_TIMEOUT = 60.0
_DEFAULT_CONFIG_TIMEOUT = 10.0
_MAX_FRAME_SIZE = 10 * 1024 * 1024 # 10MB per frame
_MAX_BUFFER_FRAMES = 64
_MAX_AUDIO_BUFFER_BYTES = 4 * 1024 * 1024
_MAX_MSG_QUEUE = 200
_CODEC_FRAME_SAMPLES = 1920 # CausalConv leading-edge artifact length
_BAD_FRAME = object()
def _decode_frame_bytes(raw_bytes: bytes) -> Any:
return Image.open(io.BytesIO(raw_bytes)).convert("RGB")
class StreamingVideoSessionConfig(BaseModel):
"""Configuration sent as the first WebSocket message."""
model: str | None = None
modalities: list[str] = Field(
default_factory=lambda: ["text", "audio"],
description="Output modalities: 'text', 'audio', or both.",
)
num_frames: int = Field(
default=4,
ge=1,
le=128,
description="Max frames to sample from buffer for the model.",
)
max_frames: int = Field(
default=50,
ge=1,
le=256,
description="Max frames to keep in the buffer.",
)
system_prompt: str | None = Field(
default=None,
description="Custom system prompt.",
)
use_audio_in_video: bool = Field(
default=True,
description="Interleave audio chunks with video frames when audio input is present.",
)
sampling_params_list: list[dict[str, Any]] | None = Field(
default=None,
description="Per-stage sampling params [thinker, talker, code2wav].",
)
enable_frame_filter: bool = Field(
default=True,
description="EVS pixel-similarity pre-filter to drop near-duplicate frames.",
)
frame_filter_threshold: float = Field(
default=0.95,
ge=0.0,
le=1.0,
description="EVS similarity threshold (higher = keep more frames).",
)
class OmniStreamingVideoHandler:
"""Handles WebSocket sessions for streaming video input.
Supports:
- Concurrent frame reception during query processing (reader/processor split)
- PCM audio input (``audio.chunk``)
- Async-chunk incremental audio output via ``engine_client.generate()``
- Multi-turn conversation history
- Soft interrupt (new query cancels current generation)
"""
def __init__(
self,
chat_service: Any,
idle_timeout: float = _DEFAULT_IDLE_TIMEOUT,
config_timeout: float = _DEFAULT_CONFIG_TIMEOUT,
engine_client: Any | None = None,
) -> None:
self._chat_service = chat_service
self._idle_timeout = idle_timeout
self._config_timeout = config_timeout
self._engine_client = engine_client
async def handle_session(self, websocket: WebSocket) -> None:
"""Main session loop for a single WebSocket connection."""
await websocket.accept()
try:
config = await self._receive_config(websocket)
if config is None:
return
frame_buffer: list[str] = [] # base64-encoded JPEG frames
# Per-frame PIL cache + uuid for mm_hash reuse. Aligned with frame_buffer by index.
frame_pil_cache: dict[str, tuple[Any, str] | object] = {} # b64 -> (PIL.Image, uuid) or _BAD_FRAME
frame_filter = (
FrameSimilarityFilter(threshold=config.frame_filter_threshold) if config.enable_frame_filter else None
)
audio_buffer = bytearray() # raw PCM16 16kHz mono
message_history: list[dict[str, Any]] = []
active_request_id: str | None = None
prev_request_id: str | None = None # abort target iff prev was interrupted
prev_was_interrupted: bool = False
interrupt_event = asyncio.Event()
prewarm_tasks: set[asyncio.Task[Any]] = set()
query_task: asyncio.Task[Any] | None = None
msg_queue: asyncio.Queue[dict[str, Any] | None] = asyncio.Queue(maxsize=_MAX_MSG_QUEUE)
async def _reader() -> None:
"""Receive WebSocket messages and enqueue them."""
try:
while True:
try:
raw = await asyncio.wait_for(
websocket.receive_text(),
timeout=self._idle_timeout,
)
except asyncio.TimeoutError:
await self._send_error(websocket, "Idle timeout")
await msg_queue.put(None)
return
try:
msg = json.loads(raw)
except json.JSONDecodeError:
await self._send_error(websocket, "Invalid JSON")
continue
if not isinstance(msg, dict):
await self._send_error(websocket, "Messages must be JSON objects")
continue
msg_type = str(msg.get("type", ""))
if msg_type.startswith("_internal."):
await self._send_error(websocket, f"Unknown type: {msg_type}")
continue
await msg_queue.put(msg)
if msg.get("type") == "video.done":
return
except WebSocketDisconnect:
await msg_queue.put(None)
except Exception:
await msg_queue.put(None)
raise
async def _cancel_active_query(*, abort_now: bool = False) -> None:
"""Signal soft interrupt for the active query."""
nonlocal active_request_id, prev_was_interrupted, query_task
if active_request_id is not None:
interrupt_event.set()
prev_was_interrupted = True
logger.info("Interrupt signaled for %s", active_request_id)
if abort_now and self._engine_client:
try:
await self._engine_client.abort(active_request_id)
except Exception:
logger.debug("Abort failed for %s", active_request_id, exc_info=True)
if query_task is not None and not query_task.done():
query_task.cancel()
await asyncio.gather(query_task, return_exceptions=True)
query_task = None
async def _processor() -> None:
"""Process enqueued messages."""
nonlocal active_request_id, prev_request_id, prev_was_interrupted, query_task
while True:
msg = await msg_queue.get()
if msg is None:
await _cancel_active_query(abort_now=True)
return
msg_type = msg.get("type")
if msg_type == "_internal.frame_decode_failed":
frame_data = msg.get("b64", "")
removed = frame_data in frame_buffer
if removed:
frame_buffer[:] = [f for f in frame_buffer if f != frame_data]
if frame_pil_cache.get(frame_data) is _BAD_FRAME:
frame_pil_cache.pop(frame_data, None)
if removed:
await self._send_error(websocket, "Frame decode failed")
elif msg_type == "video.frame":
frame_data = msg.get("data", "")
if not frame_data:
continue
if len(frame_data) > _MAX_FRAME_SIZE:
await self._send_error(websocket, "Frame too large")
continue
try:
raw_bytes = base64.b64decode(frame_data, validate=True)
except Exception:
await self._send_error(websocket, "Invalid image data")
continue
if frame_filter is not None:
try:
if not frame_filter.should_retain(raw_bytes):
continue
except Exception:
await self._send_error(websocket, "Invalid image data")
continue
max_buf = config.max_frames
if len(frame_buffer) >= max_buf:
dropped = frame_buffer.pop(0)
frame_pil_cache.pop(dropped, None)
frame_buffer.append(frame_data)
# Prewarm: decode PIL off the event loop so query-time chat_template
# can skip base64+Image.open. uuid=md5 lets mm_cache dedupe identical frames.
if frame_data not in frame_pil_cache:
mm_uuid = hashlib.md5(raw_bytes, usedforsecurity=False).hexdigest()
async def _prewarm(b64: str, b: bytes, u: str) -> None:
try:
pil = await asyncio.to_thread(_decode_frame_bytes, b)
frame_pil_cache[b64] = (pil, u)
except Exception:
frame_pil_cache[b64] = _BAD_FRAME
logger.warning("prewarm decode failed for frame (len=%d)", len(b))
try:
msg_queue.put_nowait({"type": "_internal.frame_decode_failed", "b64": b64})
except asyncio.QueueFull:
logger.warning(
"frame decode failure event dropped because message queue is full"
)
task = asyncio.create_task(_prewarm(frame_data, raw_bytes, mm_uuid))
prewarm_tasks.add(task)
task.add_done_callback(prewarm_tasks.discard)
elif msg_type == "audio.chunk":
data_b64 = msg.get("data", "")
try:
pcm_bytes = base64.b64decode(data_b64)
except Exception:
continue
if len(audio_buffer) + len(pcm_bytes) > _MAX_AUDIO_BUFFER_BYTES:
await self._send_error(websocket, "Audio buffer overflow")
audio_buffer.clear()
continue
audio_buffer.extend(pcm_bytes)
elif msg_type == "video.query":
await _cancel_active_query()
query_text = msg.get("text", "")
audio_data_b64 = msg.get("audio_data")
if audio_data_b64:
try:
decoded = base64.b64decode(audio_data_b64)
if len(audio_buffer) + len(decoded) <= _MAX_AUDIO_BUFFER_BYTES:
audio_buffer.extend(decoded)
else:
await self._send_error(websocket, "Audio buffer overflow")
audio_buffer.clear()
except Exception:
pass
if not frame_buffer:
await self._send_error(websocket, "No frames buffered")
continue
# Abort only if the previous turn was interrupted mid-flight.
# A naturally-finished request is already released by the scheduler;
# aborting it again can race with stage-1/2 tear-down and has been
# observed to crash flash_attn with a mixed prefill+decode batch
# (scheduler_metadata shape mismatch) under longer sessions.
if prev_was_interrupted and prev_request_id and self._engine_client:
try:
await self._engine_client.abort(prev_request_id)
except Exception:
pass
await asyncio.sleep(0.1)
prev_was_interrupted = False
request_id = f"video-{uuid.uuid4().hex[:12]}"
active_request_id = request_id
interrupt_event.clear()
query_frames = list(frame_buffer)
query_audio_buffer = bytearray(audio_buffer)
audio_buffer.clear()
query_prewarmed_frames = dict(frame_pil_cache)
async def _run_query() -> None:
nonlocal active_request_id, prev_request_id
try:
await self._process_query(
websocket,
config,
query_frames,
query_audio_buffer,
message_history,
query_text,
request_id,
interrupt_event,
query_prewarmed_frames,
)
finally:
if active_request_id == request_id:
prev_request_id = request_id
active_request_id = None
query_task = asyncio.create_task(_run_query())
elif msg_type == "video.done":
if query_task is not None and not query_task.done():
await asyncio.gather(query_task, return_exceptions=True)
query_task = None
await websocket.send_json({"type": "session.done"})
return
elif msg_type == "ping":
try:
await websocket.send_json({"type": "pong"})
except Exception:
pass
else:
await self._send_error(websocket, f"Unknown type: {msg_type}")
reader_task = asyncio.create_task(_reader())
try:
await _processor()
finally:
reader_task.cancel()
try:
await reader_task
except (asyncio.CancelledError, Exception):
pass
for t in list(prewarm_tasks):
t.cancel()
if prewarm_tasks:
await asyncio.gather(*prewarm_tasks, return_exceptions=True)
if query_task is not None and not query_task.done():
await _cancel_active_query(abort_now=True)
except WebSocketDisconnect:
logger.info("Streaming video: client disconnected")
except Exception as e:
logger.exception("Streaming video session error: %s", e)
try:
await self._send_error(websocket, f"Internal error: {e}")
except Exception:
pass
async def _receive_config(self, websocket: WebSocket) -> StreamingVideoSessionConfig | None:
"""Wait for and validate the session.config message."""
try:
raw = await asyncio.wait_for(
websocket.receive_text(),
timeout=self._config_timeout,
)
except asyncio.TimeoutError:
await self._send_error(websocket, "Timeout waiting for session.config")
return None
try:
msg = json.loads(raw)
except json.JSONDecodeError:
await self._send_error(websocket, "Invalid JSON in session.config")
return None
if not isinstance(msg, dict) or msg.get("type") != "session.config":
await self._send_error(
websocket,
f"Expected session.config, got: {msg.get('type') if isinstance(msg, dict) else type(msg).__name__}",
)
return None
config_data = {k: v for k, v in msg.items() if k != "type"}
alias_map = {
"num_sample_frames": "num_frames",
"evs_enabled": "enable_frame_filter",
"evs_threshold": "frame_filter_threshold",
}
for old_key, new_key in alias_map.items():
if old_key in config_data and new_key not in config_data:
config_data[new_key] = config_data[old_key]
try:
config = StreamingVideoSessionConfig(**config_data)
except ValidationError as e:
await self._send_error(websocket, f"Invalid session config: {e}")
return None
return config
async def _process_query(
self,
websocket: WebSocket,
config: StreamingVideoSessionConfig,
frame_buffer: list[str],
audio_buffer: bytearray,
message_history: list[dict[str, Any]],
query_text: str,
request_id: str,
interrupt_event: asyncio.Event,
prewarmed_frames: dict[str, tuple[Any, str]],
) -> None:
"""Build prompt, run inference, stream text + audio response."""
if self._engine_client is None:
await self._send_error(websocket, "Streaming video requires an engine client")
return
await self._process_query_engine(
websocket,
config,
frame_buffer,
audio_buffer,
message_history,
query_text,
request_id,
interrupt_event,
prewarmed_frames,
)
# ------------------------------------------------------------------
# Engine-client path (async_chunk audio streaming)
# ------------------------------------------------------------------
async def _process_query_engine(
self,
websocket: WebSocket,
config: StreamingVideoSessionConfig,
frame_buffer: list[str],
audio_buffer: bytearray,
message_history: list[dict[str, Any]],
query_text: str,
request_id: str,
interrupt_event: asyncio.Event,
prewarmed_frames: dict[str, tuple[Any, str]],
) -> None:
"""Direct engine_client.generate() path for async_chunk audio."""
from vllm.entrypoints.openai.chat_completion.protocol import (
ChatCompletionRequest,
)
messages, user_message = self._build_messages(
config,
frame_buffer,
audio_buffer,
message_history,
query_text,
prewarmed_frames,
)
request_kwargs: dict[str, Any] = {
"model": config.model or "default",
"messages": messages,
"stream": True,
"modalities": config.modalities,
"add_generation_prompt": True,
"continue_final_message": False,
"add_special_tokens": False,
}
if config.use_audio_in_video and len(audio_buffer) > 0:
request_kwargs["mm_processor_kwargs"] = {
"use_audio_in_video": True,
}
if config.sampling_params_list:
request_kwargs["sampling_params_list"] = config.sampling_params_list
try:
chat_request = ChatCompletionRequest(**request_kwargs)
except Exception as e:
await self._send_error(websocket, f"Failed to build request: {e}")
return
try:
engine_prompt = await self._preprocess_to_engine_prompt(chat_request)
except Exception as e:
await self._send_error(websocket, f"Preprocess failed: {e}")
return
await websocket.send_json({"type": "response.start"})
text_parts: list[str] = []
text_done_sent = False
audio_chunk_count = 0
# Number of per-step tensors in OmniRequestOutput.audio_data already
# drained. Used by the fast path to skip already-emitted history.
audio_chunks_drained = 0
previous_text = ""
interrupted = False
t_start = _time.monotonic()
t_first_text = None
t_first_audio = None
# Wire-level async-chunk switch. "off" means
# buffer all deltas server-side and flush once at the end; the engine
# pipeline still overlaps internally.
async_chunk_mode = video_stream_envs.VLLM_VIDEO_ASYNC_CHUNK
streaming = async_chunk_mode == "on"
audio_tail_tensors: list[Any] = []
try:
result_gen = self._engine_client.generate(
prompt=engine_prompt,
request_id=request_id,
output_modalities=config.modalities,
)
async for output in result_gen:
# Soft interrupt: drain without sending
if interrupt_event.is_set():
if not interrupted:
logger.info("Generation interrupted — draining")
interrupted = True
continue
if not isinstance(output, OmniRequestOutput):
continue
out_type = getattr(output, "final_output_type", "text")
if out_type == "audio":
if streaming and not text_done_sent:
full_text = "".join(text_parts)
await websocket.send_json({"type": "response.text.done", "text": full_text})
text_done_sent = True
if t_first_audio is None:
t_first_audio = _time.monotonic()
audio_chunk_count += 1
if streaming:
b64, audio_chunks_drained = self._extract_audio_delta_b64(
output,
audio_chunks_drained,
)
if b64:
await websocket.send_json(
{
"type": "response.audio.delta",
"data": b64,
"format": "wav",
}
)
else:
audio_data = self._get_audio_data(output)
if audio_data is not None:
if isinstance(audio_data, list):
audio_tail_tensors = list(audio_data)
else:
audio_tail_tensors = [audio_data]
else:
delta_text, previous_text = self._extract_text_delta(
output,
previous_text,
)
if delta_text:
if t_first_text is None:
t_first_text = _time.monotonic()
text_parts.append(delta_text)
if streaming:
await websocket.send_json({"type": "response.text.delta", "delta": delta_text})
if not text_done_sent:
full_text = "".join(text_parts)
await websocket.send_json({"type": "response.text.done", "text": full_text})
text_done_sent = True
if not streaming and audio_tail_tensors:
try:
coalesced = (
audio_tail_tensors[0] if len(audio_tail_tensors) == 1 else torch.cat(audio_tail_tensors, dim=-1)
)
tail_np = self._tensor_to_1d_np(coalesced)
b64, _ = self._encode_tail(
tail_np,
0,
new_drained=len(audio_tail_tensors),
is_first=True,
)
if b64:
await websocket.send_json(
{
"type": "response.audio.delta",
"data": b64,
"format": "wav",
}
)
except Exception:
logger.exception("Failed to coalesce off-path audio")
if audio_chunk_count > 0:
await websocket.send_json({"type": "response.audio.done"})
response_text = "".join(text_parts)
message_history.append(user_message)
message_history.append({"role": "assistant", "content": response_text})
t_end = _time.monotonic()
logger.info(
"[TIMING] mode=%s total=%.2fs first_text=%.2fs first_audio=%.2fs audio_chunks=%d",
async_chunk_mode,
t_end - t_start,
(t_first_text - t_start) if t_first_text else -1,
(t_first_audio - t_start) if t_first_audio else -1,
audio_chunk_count,
)
except Exception:
logger.exception("Engine query failed")
await self._send_error(websocket, "Query processing failed")
if not text_done_sent:
full_text = "".join(text_parts)
await websocket.send_json({"type": "response.text.done", "text": full_text})
# ------------------------------------------------------------------
# Message building
# ------------------------------------------------------------------
def _build_messages(
self,
config: StreamingVideoSessionConfig,
frame_buffer: list[str],
audio_buffer: bytearray,
message_history: list[dict[str, Any]],
query_text: str,
prewarmed_frames: dict[str, tuple[Any, str]],
) -> tuple[list[dict[str, Any]], dict[str, Any]]:
"""Build OpenAI-style messages list and the current user message.
Returns (messages, user_message).
"""
# Stride sampling (index 0 anchor, last slot = newest). Covers full buffer + stable mm_hash.
n_buf = len(frame_buffer)
if n_buf <= config.num_frames:
frames = list(frame_buffer)
else:
stride = max(1, n_buf // config.num_frames)
idx = [i * stride for i in range(config.num_frames - 1)] + [n_buf - 1]
frames = [frame_buffer[i] for i in idx]
# Prefer prewarmed PIL + uuid so mm_cache can dedupe by hash.
prewarmed = prewarmed_frames or {}
user_content: list[dict] = []
for frame_b64 in frames:
cached = prewarmed.get(frame_b64)
if cached is _BAD_FRAME:
continue
if cached is not None:
pil, pil_uuid = cached
user_content.append(
{
"type": "image_pil",
"image_pil": pil,
"uuid": pil_uuid,
}
)
else:
user_content.append(
{
"type": "image_url",
"image_url": {"url": f"data:image/jpeg;base64,{frame_b64}"},
}
)
if len(audio_buffer) > 0:
wav_b64 = self._pcm_to_wav_b64(bytes(audio_buffer))
user_content.append(
{
"type": "input_audio",
"input_audio": {
"data": wav_b64,
"format": "wav",
},
}
)
if query_text:
user_content.append({"type": "text", "text": query_text})
user_message: dict[str, Any] = {"role": "user", "content": user_content}
messages: list[dict[str, Any]] = []
if config.system_prompt:
messages.append({"role": "system", "content": config.system_prompt})
# Add text-only history (strip images/audio from old turns).
# Keep only the last turn (2 messages) to keep prompt short
# enough for single-step mm_encoder scheduling. When prompt
# exceeds ~50 tokens, the V1 scheduler splits mm_encoder and
# text prefill, causing incomplete thinker embeddings and
# garbled audio.
recent_history = message_history[-2:] if len(message_history) > 2 else message_history
for hist_msg in recent_history:
messages.append(self._text_only_message(hist_msg))
messages.append(user_message)
return messages, user_message
# ------------------------------------------------------------------
# Audio helpers
# ------------------------------------------------------------------
@staticmethod
def _pcm_to_wav_b64(pcm_data: bytes, sample_rate: int = 16000) -> str:
"""Wrap raw PCM16 mono in a WAV container and return base64."""
buf = io.BytesIO()
with wave.open(buf, "wb") as wf:
wf.setnchannels(1)
wf.setsampwidth(2)
wf.setframerate(sample_rate)
wf.writeframes(pcm_data)
return base64.b64encode(buf.getvalue()).decode()
@classmethod
def _extract_audio_delta_b64(
cls,
result: OmniRequestOutput,
chunks_drained: int,
) -> tuple[str | None, int]:
"""Return (base64 WAV of new samples, updated chunks_drained).
`chunks_drained` is the number of per-step tensors in
``audio_data`` that have already been emitted. Each engine step appends
one tensor, so new samples are ``audio_data[chunks_drained:]`` — no
matter how many steps accumulated between reads (handles backpressure
cleanly, unlike a simple ``audio_data[-1]``).
Two paths, selected at runtime by ``VLLM_VIDEO_AUDIO_DELTA_MODE``:
* fast — only D2H the new tail. Per-call cost ∝ new chunks.
* slow — full cat + D2H each call. Per-call cost ∝ total history.
Retained for A/B; remove once downstream callers confirm.
"""
audio_data = cls._get_audio_data(result)
if audio_data is None:
return None, chunks_drained
if video_stream_envs.VLLM_VIDEO_AUDIO_DELTA_MODE == "slow":
return cls._delta_slow(audio_data, chunks_drained)
return cls._delta_fast(audio_data, chunks_drained)
@staticmethod
def _get_audio_data(result: OmniRequestOutput):
"""Navigate OmniRequestOutput → multimodal_output['audio']. None on miss."""
request_output = getattr(result, "request_output", None)
if request_output is None:
return None
outputs = getattr(request_output, "outputs", None)
if not isinstance(outputs, list) or not outputs:
return None
mm_output = getattr(outputs[0], "multimodal_output", None)
if not isinstance(mm_output, dict):
return None
return mm_output.get("audio")
@classmethod
def _delta_fast(
cls,
audio_data,
chunks_drained: int,
) -> tuple[str | None, int]:
"""Emit only tensors appended since the last call."""
# Single tensor: output_processor hands us one tensor before it becomes a
# list (see output_processor.py:89). Treat it as chunk #0.
if not isinstance(audio_data, list):
if chunks_drained >= 1:
return None, chunks_drained
tail_np = cls._tensor_to_1d_np(audio_data)
return cls._encode_tail(tail_np, chunks_drained, new_drained=1, is_first=True)
n = len(audio_data)
if n <= chunks_drained:
return None, chunks_drained
new_chunks = audio_data[chunks_drained:]
tail = new_chunks[0] if len(new_chunks) == 1 else torch.cat(new_chunks, dim=-1)
tail_np = cls._tensor_to_1d_np(tail)
return cls._encode_tail(tail_np, chunks_drained, new_drained=n, is_first=(chunks_drained == 0))
@classmethod
def _delta_slow(
cls,
audio_data,
chunks_drained: int,
) -> tuple[str | None, int]:
"""Pre-fix behaviour: concat everything each call and slice on CPU."""
if isinstance(audio_data, list):
if not audio_data:
return None, chunks_drained
audio_tensor = torch.cat(audio_data, dim=-1)
new_drained = len(audio_data)
else:
audio_tensor = audio_data
new_drained = 1
full_np = cls._tensor_to_1d_np(audio_tensor)
if full_np is None:
return None, chunks_drained
# chunks_drained doesn't map directly to sample offset without tracking
# per-chunk lengths, so we re-derive: replay the tail that corresponds
# to chunks appended since last call by slicing off the part produced
# by the already-drained prefix. For slow path this is intentionally
# wasteful — the point is to reproduce the pre-fix hot loop.
if chunks_drained == 0:
tail_np = full_np
else:
# Recover prefix length by re-concatenating the already-drained
# prefix tensors (cost intentionally identical to the baseline
# implementation this was lifted from).
if isinstance(audio_data, list) and chunks_drained < len(audio_data):
prefix_len = sum(int(t.shape[-1]) for t in audio_data[:chunks_drained])
tail_np = full_np[prefix_len:]
else:
tail_np = full_np[0:0]
return cls._encode_tail(tail_np, chunks_drained, new_drained=new_drained, is_first=(chunks_drained == 0))
@classmethod
def _encode_tail(
cls,
tail_np,
old_drained: int,
*,
new_drained: int,
is_first: bool,
) -> tuple[str | None, int]:
"""Strip the CausalConv leading artifact on first emit, then b64-encode."""
if tail_np is None or len(tail_np) == 0:
return None, new_drained
if is_first and len(tail_np) > _CODEC_FRAME_SAMPLES * 2:
tail_np = tail_np[_CODEC_FRAME_SAMPLES:]
if len(tail_np) == 0:
return None, new_drained
try:
return cls._encode_audio_wav_b64(tail_np), new_drained
except Exception:
logger.exception("Failed to encode audio delta WAV")
return None, old_drained
@staticmethod
def _tensor_to_1d_np(t):
"""Tensor → flat float32 numpy on CPU. None on failure."""
if t is None or not hasattr(t, "float"):
return None
arr = t.float().detach().cpu().numpy()
if arr.ndim > 1:
arr = arr.flatten()
return arr
@staticmethod
def _encode_audio_wav_b64(audio_np) -> str:
"""Encode numpy float32 audio to base64 WAV (24kHz)."""
from vllm_omni.entrypoints.openai.audio_utils_mixin import AudioMixin
from vllm_omni.entrypoints.openai.protocol.audio import CreateAudio
audio_obj = CreateAudio(
audio_tensor=audio_np,
sample_rate=24000,
response_format="wav",
speed=1.0,
stream_format="audio",
base64_encode=True,
)
mixin = AudioMixin()
resp = mixin.create_audio(audio_obj)
return resp.audio_data
@staticmethod
def _extract_text_delta(
result: OmniRequestOutput,
previous_text: str,
) -> tuple[str, str]:
"""Extract incremental text delta from OmniRequestOutput."""
if result.final_output_type != "text":
return "", previous_text
request_output = getattr(result, "request_output", None)
if request_output is None:
return "", previous_text
outputs = getattr(request_output, "outputs", None)
if not isinstance(outputs, list) or not outputs:
return "", previous_text
text = getattr(outputs[0], "text", None)
if not isinstance(text, str) or not text:
return "", previous_text
if text.startswith(previous_text):
return text[len(previous_text) :], text
return text, text
# ------------------------------------------------------------------
# Preprocessing
# ------------------------------------------------------------------
async def _preprocess_to_engine_prompt(self, request) -> Any:
"""Use the chat handler's preprocessing to build an engine prompt."""
handler = self._chat_service
renderer = handler.renderer
_conversation, engine_prompts = await handler._preprocess_chat(
request,
request.messages,
default_template=getattr(request, "chat_template", None) or handler.chat_template,
default_template_content_format=handler.chat_template_content_format,
renderer=renderer,
add_generation_prompt=request.add_generation_prompt,
continue_final_message=request.continue_final_message,
add_special_tokens=request.add_special_tokens,
)
return engine_prompts[0]
# ------------------------------------------------------------------
# Utilities
# ------------------------------------------------------------------
_text_only_message = staticmethod(text_only_message)
async def _send_error(self, websocket: WebSocket, message: str) -> None:
"""Send an error message to the client."""
try:
await websocket.send_json({"type": "error", "message": message})
except Exception:
pass