feat: CosyVoice 한국어 엔진 통합 (Apache-2.0, GPU)

- vendor/CosyVoice: 패치된 CosyVoice 코드 + Matcha-TTS 벤더링
- cosyvoice_worker: 전용 venv에서 상주하는 합성 워커(FastAPI, 모델 1회 로드)
- app/engines/cosyvoice_engine: HTTP 프록시 엔진(속도/피치)
- Dockerfile: 전용 venv(torch cu128) + 모델 베이킹 + 빌드 워밍업
- entrypoint.sh: 워커(8001) + 메인앱(8788) 동시 기동

vendor/CosyVoice/cosyvoice/utils/losses.py

@@ -0,0 +1,57 @@
+import torch
+import torch.nn.functional as F
+from typing import Tuple
+
+
+def tpr_loss(disc_real_outputs, disc_generated_outputs, tau):
+    loss = 0
+    for dr, dg in zip(disc_real_outputs, disc_generated_outputs):
+        m_DG = torch.median((dr - dg))
+        L_rel = torch.mean((((dr - dg) - m_DG) ** 2)[dr < dg + m_DG])
+        loss += tau - F.relu(tau - L_rel)
+    return loss
+
+
+def mel_loss(real_speech, generated_speech, mel_transforms):
+    loss = 0
+    for transform in mel_transforms:
+        mel_r = transform(real_speech)
+        mel_g = transform(generated_speech)
+        loss += F.l1_loss(mel_g, mel_r)
+    return loss
+
+
+class DPOLoss(torch.nn.Module):
+    """
+    DPO Loss
+    """
+
+    def __init__(self, beta: float, label_smoothing: float = 0.0, ipo: bool = False) -> None:
+        super().__init__()
+        self.beta = beta
+        self.label_smoothing = label_smoothing
+        self.ipo = ipo
+
+    def forward(
+        self,
+        policy_chosen_logps: torch.Tensor,
+        policy_rejected_logps: torch.Tensor,
+        reference_chosen_logps: torch.Tensor,
+        reference_rejected_logps: torch.Tensor,
+    ) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
+        pi_logratios = policy_chosen_logps - policy_rejected_logps
+        ref_logratios = reference_chosen_logps - reference_rejected_logps
+        logits = pi_logratios - ref_logratios
+        if self.ipo:
+            losses = (logits - 1 / (2 * self.beta)) ** 2  # Eq. 17 of https://arxiv.org/pdf/2310.12036v2.pdf
+        else:
+            # Eq. 3 https://ericmitchell.ai/cdpo.pdf; label_smoothing=0 gives original DPO (Eq. 7 of https://arxiv.org/pdf/2305.18290.pdf)
+            losses = (
+                -F.logsigmoid(self.beta * logits) * (1 - self.label_smoothing)
+                - F.logsigmoid(-self.beta * logits) * self.label_smoothing
+            )
+        loss = losses.mean()
+        chosen_rewards = self.beta * (policy_chosen_logps - reference_chosen_logps).detach()
+        rejected_rewards = self.beta * (policy_rejected_logps - reference_rejected_logps).detach()
+
+        return loss, chosen_rewards, rejected_rewards