server: implement audio waveform download as json

Closes #136

server/reflector/views/transcripts.py

@@ -1,3 +1,5 @@
+import json
+import shutil
 from datetime import datetime
 from pathlib import Path
 from tempfile import NamedTemporaryFile
@@ -19,6 +21,7 @@ from pydantic import BaseModel, Field
 from reflector.db import database, transcripts
 from reflector.logger import logger
 from reflector.settings import settings
+from reflector.utils.audio_waveform import get_audio_waveform
 from starlette.concurrency import run_in_threadpool
 
 from ._range_requests_response import range_requests_response
@@ -40,6 +43,10 @@ def generate_transcript_name():
     return f"Transcript {now.strftime('%Y-%m-%d %H:%M:%S')}"
 
 
+class AudioWaveform(BaseModel):
+    data: list[int]
+
+
 class TranscriptText(BaseModel):
     text: str
 
@@ -112,10 +119,24 @@ class Transcript(BaseModel):
             out.close()
 
             # move temporary file to final location
-            import shutil
-
             shutil.move(tmp.name, fn.as_posix())
 
+    def convert_audio_to_waveform(self, segments_count=1000):
+        fn = self.audio_waveform_filename
+        if fn.exists():
+            return
+        waveform = get_audio_waveform(
+            path=self.audio_filename, segments_count=segments_count
+        )
+        try:
+            with open(fn, "w") as fd:
+                json.dump(waveform, fd)
+        except Exception:
+            # remove file if anything happen during the write
+            fn.unlink(missing_ok=True)
+            raise
+        return waveform
+
     def unlink(self):
         self.data_path.unlink(missing_ok=True)
 
@@ -131,6 +152,22 @@ class Transcript(BaseModel):
     def audio_mp3_filename(self):
         return self.data_path / "audio.mp3"
 
+    @property
+    def audio_waveform_filename(self):
+        return self.data_path / "audio.json"
+
+    @property
+    def audio_waveform(self):
+        try:
+            with open(self.audio_waveform_filename) as fd:
+                data = json.load(fd)
+        except json.JSONDecodeError:
+            # unlink file if it's corrupted
+            self.audio_waveform_filename.unlink(missing_ok=True)
+            return None
+
+        return AudioWaveform(data=data)
+
 
 class TranscriptController:
     async def get_all(self, user_id: str | None = None) -> list[Transcript]:
@@ -334,6 +371,24 @@ async def transcript_get_audio_mp3(
     )
 
 
+@router.get("/transcripts/{transcript_id}/audio/waveform")
+async def transcript_get_audio_waveform(
+    transcript_id: str,
+    user: Annotated[Optional[auth.UserInfo], Depends(auth.current_user_optional)],
+) -> AudioWaveform:
+    user_id = user["sub"] if user else None
+    transcript = await transcripts_controller.get_by_id(transcript_id, user_id=user_id)
+    if not transcript:
+        raise HTTPException(status_code=404, detail="Transcript not found")
+
+    if not transcript.audio_filename.exists():
+        raise HTTPException(status_code=404, detail="Audio not found")
+
+    await run_in_threadpool(transcript.convert_audio_to_waveform)
+
+    return transcript.audio_waveform
+
+
 @router.get("/transcripts/{transcript_id}/topics", response_model=list[TranscriptTopic])
 async def transcript_get_topics(
     transcript_id: str,