[Perf][TTS] Add deadline-aware audio scheduling

Signed-off-by: Sy03 <1370724210@qq.com>

docs/user_guide/examples/online_serving/text_to_speech.md

@@ -457,6 +457,7 @@ python qwen3_tts/gradio_fastrtc_demo.py --api-base http://localhost:8000
 - With async chunking, Qwen3-TTS Base voice cloning sends the full reference context in the first Code2Wav packet, then caches that prefix on the Code2Wav stage for follow-up chunks in the same request.
 - `vllm_omni/deploy/qwen3_tts.yaml` is the default deploy config (loaded by HF `model_type`); per-stage runtime overrides are available via `--stage-N-<field> <value>`.
 - Under vocoder-bound overload (single-stream `rtf_p99 ≥ 1` at the target concurrency), set `active_stream_window: 2` at the top of the deploy yaml to cap simultaneously active Stage 1 streams. Off by default; trades TTFP for streaming continuity. See [#3592](https://github.com/vllm-project/vllm-omni/pull/3592) for the mechanism and tradeoff numbers.
+- For a bounded active-stream deployment, `active_stream_policy: edf` can prioritize streams whose server-estimated playback buffer is closest to exhaustion. Configure it under the connector's `extra` block and use a `codec_chunk_ramp`; this is opt-in, estimates playback from server-side PCM emission (no client playback acknowledgements), and targets first-audio latency and continuity rather than single-request completion latency.
 
 ---
 

tests/core/sched/test_omni_generation_scheduler_playback_deadline.py

@@ -0,0 +1,39 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+from types import SimpleNamespace
+
+import pytest
+import torch
+
+from vllm_omni.core.sched.omni_generation_scheduler import OmniGenerationScheduler
+
+pytestmark = [pytest.mark.core_model, pytest.mark.cpu]
+
+
+def test_generation_scheduler_records_audio_output_for_edf(mocker):
+    scheduler = OmniGenerationScheduler.__new__(OmniGenerationScheduler)
+    scheduler.chunk_transfer_adapter = SimpleNamespace(
+        playback_deadline_enabled=True,
+        record_audio_output=mocker.Mock(),
+    )
+    multimodal_output = {
+        "model_outputs": torch.zeros(24000),
+        "sr": torch.tensor(24000),
+    }
+
+    scheduler._record_playback_deadline_output("req", multimodal_output)
+
+    scheduler.chunk_transfer_adapter.record_audio_output.assert_called_once_with("req", 24000, 24000)
+
+
+def test_generation_scheduler_skips_audio_accounting_when_edf_is_disabled(mocker):
+    scheduler = OmniGenerationScheduler.__new__(OmniGenerationScheduler)
+    scheduler.chunk_transfer_adapter = SimpleNamespace(
+        playback_deadline_enabled=False,
+        record_audio_output=mocker.Mock(),
+    )
+
+    scheduler._record_playback_deadline_output("req", {"model_outputs": torch.zeros(24000)})
+
+    scheduler.chunk_transfer_adapter.record_audio_output.assert_not_called()

tests/distributed/omni_connectors/test_chunk_transfer_adapter.py

@@ -113,6 +113,7 @@ def build_adapter(monkeypatch, mocker: MockerFixture):
         *,
         stage_id: int = 1,
         model_mode: str = "ar",
+        engine_output_type: str | None = None,
         max_num_seqs: int = 2,
         active_stream_window: int = 0,
         connector_extra: dict | None = None,
@@ -143,6 +144,7 @@ def build_adapter(monkeypatch, mocker: MockerFixture):
 
         model_config = SimpleNamespace(
             worker_type=model_mode,
+            engine_output_type=engine_output_type or ("audio" if model_mode == "generation" else None),
             max_num_seqs=max_num_seqs,
             active_stream_window=active_stream_window,
             stage_connector_config={
@@ -843,6 +845,218 @@ def test_fifo_promotion(build_adapter):
     assert reqs[2].status == RequestStatus.WAITING_FOR_CHUNK
 
 
+def test_edf_requires_active_window(build_adapter):
+    with pytest.raises(ValueError, match="requires active_stream_window"):
+        build_adapter(
+            stage_id=1,
+            model_mode="generation",
+            active_stream_window=0,
+            connector_extra={"active_stream_policy": "edf"},
+        )
+
+
+def test_edf_rejects_unknown_policy(build_adapter):
+    with pytest.raises(ValueError, match="active_stream_policy"):
+        build_adapter(
+            stage_id=1,
+            model_mode="generation",
+            active_stream_window=1,
+            connector_extra={"active_stream_policy": "unknown"},
+        )
+
+
+@pytest.mark.parametrize(
+    ("key", "value", "message"),
+    [
+        ("playback_deadline_first_chunk_ms", float("nan"), "first_chunk"),
+        ("playback_deadline_safety_margin_ms", float("inf"), "safety_margin"),
+    ],
+)
+def test_edf_rejects_non_finite_timing_config(build_adapter, key, value, message):
+    with pytest.raises(ValueError, match=message):
+        build_adapter(
+            stage_id=1,
+            model_mode="generation",
+            active_stream_window=1,
+            connector_extra={"active_stream_policy": "edf", key: value},
+        )
+
+
+def test_edf_selects_earliest_playback_deadline(build_adapter, monkeypatch):
+    monkeypatch.setattr(
+        "vllm_omni.distributed.omni_connectors.transfer_adapter.chunk_transfer_adapter.time.monotonic",
+        lambda: 100.0,
+    )
+    adapter, _ = build_adapter(
+        stage_id=1,
+        model_mode="generation",
+        max_num_seqs=2,
+        active_stream_window=1,
+        connector_extra={"active_stream_policy": "edf"},
+    )
+    later = _req("later", RequestStatus.WAITING)
+    urgent = _req("urgent", RequestStatus.WAITING)
+    adapter.record_audio_output(later.request_id, 5, 1, emitted_at=100.0)
+    adapter.record_audio_output(urgent.request_id, 2, 1, emitted_at=100.0)
+    adapter.requests_with_ready_chunks.update({later.request_id, urgent.request_id})
+    waiting_queue = DummyWaitingQueue([later, urgent])
+
+    adapter.process_pending_chunks(waiting_queue, [])
+
+    assert list(adapter._active_streams) == [urgent.request_id]
+    assert waiting_queue == [urgent]
+    assert list(adapter.waiting_for_chunk_waiting_requests) == [later]
+
+
+def test_edf_balances_first_audio_against_playback_deadline(build_adapter, monkeypatch):
+    monkeypatch.setattr(
+        "vllm_omni.distributed.omni_connectors.transfer_adapter.chunk_transfer_adapter.time.monotonic",
+        lambda: 100.0,
+    )
+    adapter, _ = build_adapter(
+        stage_id=1,
+        model_mode="generation",
+        max_num_seqs=2,
+        active_stream_window=1,
+        connector_extra={
+            "active_stream_policy": "edf",
+            "playback_deadline_first_chunk_ms": 100,
+            "playback_deadline_safety_margin_ms": 0,
+        },
+    )
+    new_request = _req("new", RequestStatus.WAITING)
+    buffered = _req("buffered", RequestStatus.WAITING)
+    adapter.record_audio_output(buffered.request_id, 5, 1, emitted_at=100.0)
+    adapter.requests_with_ready_chunks.update({new_request.request_id, buffered.request_id})
+    waiting_queue = DummyWaitingQueue([buffered, new_request])
+
+    adapter.process_pending_chunks(waiting_queue, [])
+
+    assert list(adapter._active_streams) == [new_request.request_id]
+
+    adapter.cleanup_receiver(new_request.request_id)
+    adapter.restore_queues(waiting_queue, [])
+    starving = _req("starving", RequestStatus.WAITING)
+    adapter.record_audio_output(starving.request_id, 1, 1, emitted_at=98.0)
+    adapter.requests_with_ready_chunks.update({new_request.request_id, starving.request_id})
+    waiting_queue = DummyWaitingQueue([new_request, starving])
+
+    adapter.process_pending_chunks(waiting_queue, [])
+
+    assert list(adapter._active_streams) == [starving.request_id]
+
+
+def test_edf_protects_near_underrun_stream_from_overdue_first_audio(build_adapter, monkeypatch):
+    monkeypatch.setattr(
+        "vllm_omni.distributed.omni_connectors.transfer_adapter.chunk_transfer_adapter.time.monotonic",
+        lambda: 100.0,
+    )
+    adapter, _ = build_adapter(
+        stage_id=1,
+        model_mode="generation",
+        max_num_seqs=2,
+        active_stream_window=1,
+        connector_extra={
+            "active_stream_policy": "edf",
+            "playback_deadline_first_chunk_ms": 100,
+            "playback_deadline_safety_margin_ms": 250,
+        },
+    )
+    overdue_startup = _req("startup", RequestStatus.WAITING)
+    near_underrun = _req("playing", RequestStatus.WAITING)
+    adapter._playback_deadline_key(overdue_startup, order=0, now=90.0)
+    adapter.record_audio_output(near_underrun.request_id, 100, 1000, emitted_at=100.0)
+    adapter.requests_with_ready_chunks.update({overdue_startup.request_id, near_underrun.request_id})
+    waiting_queue = DummyWaitingQueue([overdue_startup, near_underrun])
+
+    adapter.process_pending_chunks(waiting_queue, [])
+
+    assert list(adapter._active_streams) == [near_underrun.request_id]
+
+
+def test_edf_reselects_at_chunk_boundaries(build_adapter, monkeypatch):
+    monkeypatch.setattr(
+        "vllm_omni.distributed.omni_connectors.transfer_adapter.chunk_transfer_adapter.time.monotonic",
+        lambda: 100.0,
+    )
+    adapter, _ = build_adapter(
+        stage_id=1,
+        model_mode="generation",
+        max_num_seqs=2,
+        active_stream_window=1,
+        connector_extra={"active_stream_policy": "edf", "playback_deadline_safety_margin_ms": 0},
+    )
+    first = _req("first", RequestStatus.WAITING)
+    second = _req("second", RequestStatus.WAITING)
+    adapter.record_audio_output(first.request_id, 1, 1, emitted_at=100.0)
+    adapter.record_audio_output(second.request_id, 2, 1, emitted_at=100.0)
+    adapter.requests_with_ready_chunks.update({first.request_id, second.request_id})
+    waiting_queue = DummyWaitingQueue([first, second])
+
+    adapter.process_pending_chunks(waiting_queue, [])
+    assert list(adapter._active_streams) == [first.request_id]
+
+    scheduler_output = SimpleNamespace(
+        scheduled_new_reqs=[SimpleNamespace(req_id=first.request_id)],
+        scheduled_cached_reqs=None,
+    )
+    adapter.postprocess_scheduler_output(scheduler_output)
+    adapter.restore_queues(waiting_queue, [])
+    adapter.record_audio_output(first.request_id, 5, 1, emitted_at=100.0)
+    adapter.requests_with_ready_chunks.add(first.request_id)
+
+    adapter.process_pending_chunks(waiting_queue, [])
+
+    assert list(adapter._active_streams) == [second.request_id]
+
+
+def test_edf_k2_orders_ready_running_and_waiting_requests(build_adapter, monkeypatch):
+    monkeypatch.setattr(
+        "vllm_omni.distributed.omni_connectors.transfer_adapter.chunk_transfer_adapter.time.monotonic",
+        lambda: 100.0,
+    )
+    adapter, _ = build_adapter(
+        stage_id=1,
+        model_mode="generation",
+        max_num_seqs=4,
+        active_stream_window=2,
+        connector_extra={"active_stream_policy": "edf", "playback_deadline_safety_margin_ms": 0},
+    )
+    later_running = _req("later-running", RequestStatus.RUNNING)
+    urgent_waiting = _req("urgent-waiting", RequestStatus.WAITING)
+    middle_running = _req("middle-running", RequestStatus.RUNNING)
+    adapter.record_audio_output(later_running.request_id, 5, 1, emitted_at=100.0)
+    adapter.record_audio_output(urgent_waiting.request_id, 1, 1, emitted_at=100.0)
+    adapter.record_audio_output(middle_running.request_id, 2, 1, emitted_at=100.0)
+    adapter.requests_with_ready_chunks.update(
+        {later_running.request_id, urgent_waiting.request_id, middle_running.request_id}
+    )
+    waiting_queue = DummyWaitingQueue([urgent_waiting])
+    running_queue = [later_running, middle_running]
+
+    adapter.process_pending_chunks(waiting_queue, running_queue)
+
+    assert list(adapter._active_streams) == [urgent_waiting.request_id, middle_running.request_id]
+    assert waiting_queue == [urgent_waiting]
+    assert running_queue == [middle_running]
+    assert list(adapter._held_non_active) == [later_running]
+
+
+def test_edf_cleanup_drops_playback_state(build_adapter):
+    adapter, _ = build_adapter(
+        stage_id=1,
+        model_mode="generation",
+        active_stream_window=1,
+        connector_extra={"active_stream_policy": "edf"},
+    )
+    adapter.record_audio_output("req", 24000, 24000, emitted_at=100.0)
+    assert "req" in adapter._playback_deadlines
+
+    adapter.cleanup_receiver("req")
+
+    assert "req" not in adapter._playback_deadlines
+
+
 def test_non_active_waiting_request_is_held_off_scheduler(build_adapter):
     adapter, _ = build_adapter(stage_id=2, max_num_seqs=2, active_stream_window=1)
     active = _req("req-active", RequestStatus.WAITING)

tests/model_executor/stage_input_processors/test_qwen3_tts_async_chunk.py

@@ -105,6 +105,122 @@ def test_flush_on_finish():
     assert len(p.codes.audio) == _Q * 24
 
 
+def _record_successful_chunk(tm, rid):
+    tm.put_req_chunk[rid] += 1
+    tm.ramp_chunk_count[rid] += 1
+
+
+def test_fixed_chunk_terminal_after_exact_initial_boundary_emits_no_audio():
+    tm = _tm(initial_chunk_frames=10)
+    rid = "fixed-exact-initial"
+
+    first = _call(tm, rid, n_frames=10, req_ic=10)
+    assert first is not None
+    _record_successful_chunk(tm, rid)
+
+    terminal = _call(tm, rid, n_frames=10, finished=True, req_ic=10)
+
+    assert terminal is not None
+    assert terminal.meta.finished.item() is True
+    assert terminal.codes.audio.numel() == 0
+
+
+def test_fixed_chunk_terminal_after_exact_steady_boundary_emits_no_audio():
+    tm = _tm(initial_chunk_frames=10)
+    rid = "fixed-exact-steady"
+
+    first = _call(tm, rid, n_frames=10, req_ic=10)
+    assert first is not None
+    _record_successful_chunk(tm, rid)
+    steady = _call(tm, rid, n_frames=35, req_ic=10)
+    assert steady is not None
+    _record_successful_chunk(tm, rid)
+
+    terminal = _call(tm, rid, n_frames=35, finished=True, req_ic=10)
+
+    assert terminal is not None
+    assert terminal.meta.finished.item() is True
+    assert terminal.codes.audio.numel() == 0
+
+
+def test_fixed_chunk_terminal_flushes_exact_boundary_not_previously_sent():
+    tm = _tm(initial_chunk_frames=10)
+    rid = "fixed-unsent-boundary"
+
+    first = _call(tm, rid, n_frames=10, req_ic=10)
+    assert first is not None
+    _record_successful_chunk(tm, rid)
+
+    terminal = _call(tm, rid, n_frames=35, finished=True, req_ic=10)
+
+    assert terminal is not None
+    assert terminal.meta.finished.item() is True
+    assert terminal.codes.audio.numel() == _Q * 25
+
+
+def test_fixed_chunk_without_initial_terminal_after_exact_boundary_emits_no_audio():
+    tm = _tm(chunk_frames=4, initial_chunk_frames=4)
+    rid = "fixed-no-initial-exact"
+
+    first = _call(tm, rid, n_frames=4, req_ic=4)
+    assert first is not None
+    _record_successful_chunk(tm, rid)
+    second = _call(tm, rid, n_frames=8, req_ic=4)
+    assert second is not None
+    _record_successful_chunk(tm, rid)
+
+    terminal = _call(tm, rid, n_frames=8, finished=True, req_ic=4)
+
+    assert terminal is not None
+    assert terminal.codes.audio.numel() == 0
+
+
+def test_fixed_chunk_terminal_after_exact_boundary_flushes_only_new_tail():
+    tm = _tm(initial_chunk_frames=10)
+    rid = "fixed-tail-after-boundary"
+
+    first = _call(tm, rid, n_frames=10, req_ic=10)
+    assert first is not None
+    _record_successful_chunk(tm, rid)
+    steady = _call(tm, rid, n_frames=35, req_ic=10)
+    assert steady is not None
+    _record_successful_chunk(tm, rid)
+
+    terminal = _call(tm, rid, n_frames=40, finished=True, req_ic=10)
+
+    assert terminal is not None
+    assert terminal.codes.audio.numel() == _Q * 5
+
+
+def test_fixed_chunk_stream_sends_every_codec_frame_exactly_once():
+    tm = _tm(chunk_frames=4, initial_chunk_frames=2)
+    rid = "fixed-unique"
+    frames = [[frame * 10 + quantizer for quantizer in range(_Q)] for frame in range(10)]
+    emitted = []
+
+    for length in (2, 6, 10):
+        tm.code_prompt_token_ids[rid] = frames[:length]
+        payload = talker2code2wav_async_chunk(
+            transfer_manager=tm,
+            multimodal_output={"codes": {"audio": torch.zeros((0,))}},
+            request=_req(rid, finished=False, initial_codec_chunk_frames=2),
+        )
+        assert payload is not None
+        emitted.extend(payload.codes.audio.reshape(_Q, -1).transpose(0, 1).tolist())
+        _record_successful_chunk(tm, rid)
+
+    terminal = talker2code2wav_async_chunk(
+        transfer_manager=tm,
+        multimodal_output=None,
+        request=_req(rid, finished=True, initial_codec_chunk_frames=2),
+        is_finished=True,
+    )
+
+    assert terminal is not None
+    assert terminal.codes.audio.numel() == 0
+    assert emitted == frames
+
+
 _CASES = [
     # ── IC boundary rule ──────────────────────────────────────────────
     # initial_codec_chunk_frames only controls the first emitted chunk.

vllm_omni/core/sched/omni_generation_scheduler.py

@@ -24,6 +24,8 @@ from vllm.v1.spec_decode.metrics import SpecDecodingStats
 from vllm_omni.core.sched.omni_scheduler_mixin import OmniSchedulerMixin
 from vllm_omni.core.sched.output import OmniCachedRequestData, OmniNewRequestData
 from vllm_omni.core.sched.utils import omni_routed_experts_for_request
+from vllm_omni.metrics import definitions as metric_defs
+from vllm_omni.metrics.utils import count_audio_frames
 from vllm_omni.outputs import OmniModelRunnerOutput
 
 logger = init_logger(__name__)
@@ -70,6 +72,14 @@ class OmniGenerationScheduler(OmniSchedulerMixin, VLLMScheduler):
             return False
         return super()._handle_stopped_request(request)
 
+    def _record_playback_deadline_output(self, request_id: str, multimodal_output: Any) -> None:
+        adapter = self.chunk_transfer_adapter
+        if adapter is None or not getattr(adapter, "playback_deadline_enabled", False):
+            return
+        audio_frames = count_audio_frames(multimodal_output)
+        sample_rate = metric_defs.resolve_audio_sample_rate(multimodal_output)
+        adapter.record_audio_output(request_id, audio_frames, sample_rate)
+
     def schedule(self, throttle_prefills: bool = False) -> SchedulerOutput:
         """One-shot generation fast path:
         - Feed all input tokens of the request at once
@@ -440,6 +450,8 @@ class OmniGenerationScheduler(OmniSchedulerMixin, VLLMScheduler):
             kv_transfer_params = None
             pooler_output = pooler_outputs[req_index] if pooler_outputs else None
             mm_output = mm_outputs[req_index] if mm_outputs else None
+            if mm_output is not None:
+                self._record_playback_deadline_output(req_id, mm_output)
             status_before_stop = request.status
             finish_reason = None
             is_segment_finished = False

vllm_omni/deploy/qwen3_tts.yaml

@@ -26,6 +26,14 @@ connectors:
       codec_left_context_frames: 72
       # Emit only the first audio chunk early, then return to codec_chunk_frames.
       initial_codec_chunk_frames: 1
+      # Optional Stage-1 EDF scheduler. Requires top-level
+      # active_stream_window > 0. It estimates each stream's playback deadline
+      # from actual PCM emitted by Code2Wav and reselects the K most urgent
+      # ready chunks at every scheduling turn. Use it with codec_chunk_ramp or
+      # an initial chunk large enough to cover the first follow-up decode.
+      # active_stream_policy: edf
+      # playback_deadline_first_chunk_ms: 100
+      # playback_deadline_safety_margin_ms: 250
       # Chunk ramp (opt-in): gradual size increase for first N chunks to
       # eliminate the IC→steady cliff (1→25). Uncomment to enable.
       # Each entry is the size of that chunk index; indices past the table

vllm_omni/distributed/omni_connectors/transfer_adapter/chunk_transfer_adapter.py

@@ -2,9 +2,11 @@
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 
 import importlib
+import math
 import time
 from collections import defaultdict, deque
 from collections.abc import Callable, Mapping
+from dataclasses import dataclass
 from typing import Any
 
 import torch
@@ -22,6 +24,13 @@ from .base import OmniTransferAdapterBase
 logger = get_connector_logger(__name__)
 
 
+@dataclass
+class _PlaybackDeadlineState:
+    first_seen_at: float
+    playback_deadline: float | None = None
+    emitted_audio_s: float = 0.0
+
+
 class OmniChunkTransferAdapter(OmniTransferAdapterBase):
     """Chunk-level transfer adapter for Omni connector pipelines.
 
@@ -42,25 +51,54 @@ class OmniChunkTransferAdapter(OmniTransferAdapterBase):
 
     def __init__(self, vllm_config: Any):
         model_config = vllm_config.model_config
+        self.model_mode = getattr(model_config, "worker_type", None) or "ar"
+        self.engine_output_type = getattr(model_config, "engine_output_type", None)
         self.scheduler_max_num_seqs = vllm_config.scheduler_config.max_num_seqs
         active_stream_window = int(getattr(model_config, "active_stream_window", 0) or 0)
         model_max_num_seqs = int(getattr(model_config, "max_num_seqs", self.scheduler_max_num_seqs) or 0)
         if model_max_num_seqs <= 0:
             model_max_num_seqs = self.scheduler_max_num_seqs
         self._active_window = min(active_stream_window, model_max_num_seqs) if active_stream_window > 0 else 0
+        connector_config = getattr(model_config, "stage_connector_config", None)
+        raw_extra = (
+            connector_config.get("extra", connector_config)
+            if isinstance(connector_config, dict)
+            else getattr(connector_config, "extra", None)
+        )
+        extra = raw_extra if isinstance(raw_extra, dict) else {}
+        self._active_stream_policy = str(extra.get("active_stream_policy", "fifo")).strip().lower()
+        if self._active_stream_policy not in {"fifo", "edf"}:
+            raise ValueError(f"active_stream_policy must be 'fifo' or 'edf', got {self._active_stream_policy!r}")
+        if self._active_stream_policy == "edf" and self._active_window <= 0:
+            raise ValueError("active_stream_policy='edf' requires active_stream_window > 0")
+        self._playback_first_chunk_slo_s = float(extra.get("playback_deadline_first_chunk_ms", 100.0)) / 1000.0
+        self._playback_safety_margin_s = float(extra.get("playback_deadline_safety_margin_ms", 50.0)) / 1000.0
+        if not math.isfinite(self._playback_first_chunk_slo_s) or self._playback_first_chunk_slo_s <= 0:
+            raise ValueError("playback_deadline_first_chunk_ms must be positive")
+        if not math.isfinite(self._playback_safety_margin_s) or self._playback_safety_margin_s < 0:
+            raise ValueError("playback_deadline_safety_margin_ms must be non-negative")
+        self._playback_deadlines: dict[str, _PlaybackDeadlineState] = {}
         if self._active_window > 0:
             logger.info(
-                "Bounded active-stream window enabled: K=%d. "
+                "Bounded active-stream window enabled: K=%d policy=%s. "
                 "Multi-replica deployments require sticky per-stream routing across Stage 1 "
                 "replicas (each replica owns an independent active-set; without sticky routing, "
                 "a stream can be active on one replica and non-active on another and both will "
                 "race to evict it).",
                 self._active_window,
+                self._active_stream_policy,
             )
         self.connector = self.create_connector(model_config)
         self.receives_chunks = stage_receives_chunks(model_config)
+        if self.playback_deadline_enabled and not extra.get("codec_chunk_ramp"):
+            initial_frames = int(extra.get("initial_codec_chunk_frames") or 0)
+            if 0 < initial_frames < 4:
+                logger.warning(
+                    "Playback EDF is enabled with initial_codec_chunk_frames=%d and no codec_chunk_ramp; "
+                    "the first audio buffer may be too short to avoid a chunk-0 underrun.",
+                    initial_frames,
+                )
         super().__init__(model_config)
-        self.model_mode = getattr(model_config, "worker_type", None) or "ar"
         # State specific to Chunk management
         self.custom_process_next_stage_input_func: Callable[..., OmniPayloadStruct | None] | None = None
         custom_process_next_stage_input_func = getattr(model_config, "custom_process_next_stage_input_func", None)
@@ -103,6 +141,51 @@ class OmniChunkTransferAdapter(OmniTransferAdapterBase):
         # OmniSchedulingCoordinator._waiting_since on the full-payload path.
         self._waiting_since: dict[str, float] = {}
 
+    @property
+    def playback_deadline_enabled(self) -> bool:
+        return (
+            self._active_stream_policy == "edf"
+            and self.model_mode == "generation"
+            and self.engine_output_type == "audio"
+        )
+
+    def record_audio_output(
+        self,
+        request_id: str,
+        audio_frames: int,
+        sample_rate: int,
+        *,
+        emitted_at: float | None = None,
+    ) -> None:
+        """Advance the server-estimated playback deadline after one PCM chunk."""
+        if not self.playback_deadline_enabled or audio_frames <= 0 or sample_rate <= 0:
+            return
+        now = time.monotonic() if emitted_at is None else float(emitted_at)
+        state = self._playback_deadlines.setdefault(request_id, _PlaybackDeadlineState(first_seen_at=now))
+        duration_s = float(audio_frames) / float(sample_rate)
+        state.emitted_audio_s += duration_s
+        # A late chunk restarts a starved player at its server emission time;
+        # otherwise append its duration to the buffered playback horizon.
+        playback_base = max(state.playback_deadline or now, now)
+        state.playback_deadline = playback_base + duration_s
+
+    def _playback_deadline_key(self, request: Request, order: int, now: float) -> tuple[int, float, float, int]:
+        state = self._playback_deadlines.setdefault(
+            request.request_id,
+            _PlaybackDeadlineState(first_seen_at=now),
+        )
+        if state.playback_deadline is None:
+            deadline = state.first_seen_at + self._playback_first_chunk_slo_s
+            protected_playback = False
+        else:
+            deadline = state.playback_deadline
+            protected_playback = deadline - now <= self._playback_safety_margin_s
+        # A stream whose buffered playback is close to exhaustion must not be
+        # preempted by a large backlog of overdue first-audio deadlines. Once
+        # established streams have enough headroom, ordinary EDF ordering lets
+        # new requests consume the available slots.
+        return (0 if protected_playback else 1), deadline, state.first_seen_at, order
+
     @staticmethod
     def _is_truthy_scalar(value: Any) -> bool:
         if isinstance(value, torch.Tensor):
@@ -465,6 +548,7 @@ class OmniChunkTransferAdapter(OmniTransferAdapterBase):
         Idempotent: calling with an already-cleaned or unknown id is safe.
         """
         self._active_streams.pop(request_id, None)
+        self._playback_deadlines.pop(request_id, None)
         self.upstream_exhausted_requests.discard(request_id)
         self.segment_finished_requests.discard(request_id)
         self.get_req_chunk.pop(request_id, None)
@@ -586,6 +670,19 @@ class OmniChunkTransferAdapter(OmniTransferAdapterBase):
                 waiting_queue.prepend_requests([request])
             return
 
+        if self.playback_deadline_enabled:
+            self._process_chunk_queue_legacy(
+                waiting_queue, self.waiting_for_chunk_waiting_requests, RequestStatus.WAITING, self._finished_load_reqs
+            )
+            self._process_chunk_queue_legacy(
+                running_queue,
+                self.waiting_for_chunk_running_requests,
+                RequestStatus.RUNNING,
+                self._finished_load_reqs,
+            )
+            self._select_playback_deadline_streams(waiting_queue, running_queue)
+            return
+
         self._promote_active_streams(running_queue)
         self._promote_active_streams(waiting_queue)
         self._process_chunk_queue(
@@ -624,6 +721,45 @@ class OmniChunkTransferAdapter(OmniTransferAdapterBase):
             # Iterating the existing queue preserves FIFO admission.
             self._active_streams[request_id] = request
 
+    def _select_playback_deadline_streams(self, waiting_queue: Any, running_queue: list[Request]) -> None:
+        """Select up to K ready chunks by server-estimated playback deadline."""
+        now = time.monotonic()
+        candidates = [
+            request
+            for request in (*running_queue, *list(waiting_queue))
+            if request.request_id in self.requests_with_ready_chunks
+        ]
+        ordered = sorted(
+            enumerate(candidates),
+            key=lambda item: self._playback_deadline_key(item[1], item[0], now),
+        )
+        selected = [request for _, request in ordered[: self._active_window]]
+        selected_ids = {request.request_id for request in selected}
+        self._active_streams = {request.request_id: request for request in selected}
+
+        for request in list(running_queue):
+            if request.request_id in self.requests_with_ready_chunks and request.request_id not in selected_ids:
+                running_queue.remove(request)
+                self._held_non_active.append(request)
+
+        held_waiting = []
+        for request in list(waiting_queue):
+            if request.request_id in self.requests_with_ready_chunks and request.request_id not in selected_ids:
+                waiting_queue.remove(request)
+                self.requests_origin_status[request.request_id] = RequestStatus.WAITING
+                self.waiting_for_chunk_waiting_requests.append(request)
+            elif request.request_id in selected_ids:
+                held_waiting.append(request)
+
+        # Keep selected running requests in EDF order so a tight token budget
+        # still admits the most urgent chunk first.
+        running_order = {request.request_id: index for index, request in enumerate(selected)}
+        running_queue.sort(key=lambda request: running_order.get(request.request_id, len(running_order)))
+        if len(held_waiting) > 1:
+            held_waiting.sort(key=lambda request: running_order[request.request_id])
+            waiting_queue.remove_requests(held_waiting)
+            waiting_queue.prepend_requests(held_waiting)
+
     def _ensure_active_stream(self, request: Request) -> bool:
         if self._active_window <= 0:
             return True

vllm_omni/model_executor/stage_input_processors/qwen3_tts.py

@@ -29,6 +29,17 @@ from vllm_omni.model_executor.stage_input_processors.tts_utils import (
 logger = init_logger(__name__)
 
 
+def _empty_finished_payload(request_id: str) -> OmniPayloadStruct:
+    return OmniPayloadStruct(
+        codes=CodesStruct(audio=torch.empty(0, dtype=torch.long)),
+        meta=MetaStruct(
+            request_id=request_id,
+            left_context_size=0,
+            finished=torch.tensor(True, dtype=torch.bool),
+        ),
+    )
+
+
 def _qwen3_tts_degenerate_finished_payload():
     """Single-placeholder-frame finished payload for a degenerate talker take.
 
@@ -162,14 +173,7 @@ def talker2code2wav_async_chunk(
 
     if length <= 0:
         if finished:
-            return OmniPayloadStruct(
-                codes=CodesStruct(audio=torch.empty(0, dtype=torch.long)),
-                meta=MetaStruct(
-                    request_id=request_id,
-                    left_context_size=0,
-                    finished=torch.tensor(True, dtype=torch.bool),
-                ),
-            )
+            return _empty_finished_payload(request_id)
         return None
 
     if ramp is not None:
@@ -179,18 +183,28 @@ def talker2code2wav_async_chunk(
         if not emit:
             return None
         if context_length == 0:
-            return OmniPayloadStruct(
-                codes=CodesStruct(audio=torch.empty(0, dtype=torch.long)),
-                meta=MetaStruct(
-                    request_id=request_id,
-                    left_context_size=0,
-                    finished=torch.tensor(True, dtype=torch.bool),
-                ),
-            )
+            return _empty_finished_payload(request_id)
     else:
-        first_chunk = int(transfer_manager.put_req_chunk.get(request_id, 0)) <= 0
+        chunk_index = int(transfer_manager.ramp_chunk_count.get(request_id, 0))
+        first_chunk = chunk_index <= 0
         use_first_chunk = initial_chunk_size > 0 and initial_chunk_size < chunk_size
 
+        if use_first_chunk:
+            emitted_frames = 0 if first_chunk else initial_chunk_size + (chunk_index - 1) * chunk_size
+        else:
+            emitted_frames = chunk_index * chunk_size
+        if finished and length <= emitted_frames:
+            # EOS is emitted on a separate talker step. If the preceding codec
+            # frame completed an exact chunk boundary, that chunk has already
+            # been sent; terminal must carry only an empty finish marker.
+            logger.debug(
+                "Qwen3-TTS terminal has no unsent codec frames: request=%s length=%d emitted=%d",
+                request_id,
+                length,
+                emitted_frames,
+            )
+            return _empty_finished_payload(request_id)
+
         if use_first_chunk and length <= initial_chunk_size:
             if not finished and length < initial_chunk_size:
                 return None