add is_morphable api

run.py

@@ -483,6 +483,33 @@ def multi_synthesis(
             background=BackgroundTask(delete_file, f.name),
         )
 
+    @app.get(
+        "/is_morphable",
+        response_class=bool,
+        tag=["音声合成"],
+        summary="2人の話者でモーフィングが可能かどうか返す",
+    )
+    def is_morphable(
+        base_speaker: int,
+        target_speaker: int,
+        core_version: Optional[str] = None,
+    ):
+        """
+        指定された2人の話者でモーフィング機能を利用可能か返します。
+        モーフィングの許可/禁止は`/speakers`の`speaker.supportedFeatures.synthesisMorphing`に記載されています。
+        プロパティが存在しない場合は、モーフィングが許可されているとみなします。
+        """
+        engine = get_engine(core_version)
+
+        is_permitted = is_synthesis_morphing_permitted(
+            engine, base_speaker, target_speaker
+        )
+
+        if is_permitted is None:
+            raise HTTPException(status_code=404, detail="該当する話者が見つかりません")
+
+        return is_permitted
+
     @app.post(
         "/synthesis_morphing",
         response_class=FileResponse,

voicevox_engine/morphing.py

@@ -8,7 +8,7 @@
 
 from voicevox_engine.synthesis_engine.synthesis_engine_base import SynthesisEngineBase
 
-from .model import SpeakerSupportSynthesisMorphing, AudioQuery
+from .model import AudioQuery, SpeakerSupportSynthesisMorphing
 from .synthesis_engine import SynthesisEngine
 
 
@@ -67,11 +67,9 @@ def is_synthesis_morphing_permitted(
     if base_speaker_info is None or target_speaker_info is None:
         return None
 
-    base_speaker_morphing_info: SpeakerSupportSynthesisMorphing = (
-        base_speaker_info.get("supported_features", dict()).get(
-            "synthesis_morphing", SpeakerSupportSynthesisMorphing(None)
-        )
-    )
+    base_speaker_morphing_info: SpeakerSupportSynthesisMorphing = base_speaker_info.get(
+        "supported_features", dict()
+    ).get("synthesis_morphing", SpeakerSupportSynthesisMorphing(None))
 
     target_speaker_morphing_info: SpeakerSupportSynthesisMorphing = (
         target_speaker_info.get("supported_features", dict()).get(
@@ -85,8 +83,7 @@ def is_synthesis_morphing_permitted(
     ):
         return False
     if (
-        base_speaker_morphing_info
-        == SpeakerSupportSynthesisMorphing.SELF_MORPHING_ONLY
+        base_speaker_morphing_info == SpeakerSupportSynthesisMorphing.SELF_MORPHING_ONLY
         or target_speaker_morphing_info
         == SpeakerSupportSynthesisMorphing.SELF_MORPHING_ONLY
     ):