pyr0ball
a6f60c9e07
Full FastAPI backend for the AI music continuation editor:
Services
- chain.py: chain + node CRUD, commit/discard, recursive CTE spine query
- musicgen.py: MusicGenClient with cf-orch allocation + mock mode (CF_MUSICGEN_MOCK=1)
- stems.py: Demucs 4-stem separation subprocess wrapper + mock mode
- export.py: ffmpeg concat demuxer to stitch committed spine into WAV/MP3
API endpoints
- chains: CRUD, multipart audio upload (WAV/MP3/FLAC/OGG/M4A/AIFF)
- nodes: branch creation (202 + BackgroundTasks), commit, discard, audio stream
- gpu: cf-orch capacity status; session allocation stubbed pending cf-orch#43
- stems: Paid-tier stem separation (Demucs, gated via tiers.py)
- export: POST /{chain_id}/export → FileResponse download
- events: SSE stream (node-status events) per chain via asyncio Queue pub/sub
Infrastructure
- lifespan: reads SPARROW_DB_PATH/DATA_DIR at startup (not import time)
- events_store: subscribe/unsubscribe/broadcast pattern for SSE
- CORS: open in dev, SPARROW_CORS_ORIGINS in production
- Background generation opens its own DB connection (WAL-safe)
Tests: 30/30 passing across service units and API integration
80 lines
2.4 KiB
Python
80 lines
2.4 KiB
Python
# app/services/export.py — Stitch committed spine audio files via ffmpeg
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#
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# Uses ffmpeg concat demuxer (list-form args, no shell injection).
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# WAV output: copy codec. MP3 output: libmp3lame 320k.
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from __future__ import annotations
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import asyncio
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import logging
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import os
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import shutil
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import tempfile
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from pathlib import Path
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from typing import Literal
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logger = logging.getLogger(__name__)
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ExportFormat = Literal["wav", "mp3"]
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async def stitch(
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audio_paths: list[str],
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output_path: str,
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fmt: ExportFormat = "wav",
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) -> str:
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"""
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Concatenate audio_paths in order and write to output_path.
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Returns output_path on success. Raises RuntimeError on ffmpeg failure.
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Requires ffmpeg on PATH.
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"""
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if not audio_paths:
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raise ValueError("No audio paths to stitch.")
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Path(output_path).parent.mkdir(parents=True, exist_ok=True)
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# Single file: just copy, no concatenation needed
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if len(audio_paths) == 1:
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shutil.copy2(audio_paths[0], output_path)
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return output_path
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# Write ffmpeg concat file list to a tempfile
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with tempfile.NamedTemporaryFile(
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mode="w", suffix=".txt", delete=False
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) as flist:
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for p in audio_paths:
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# ffmpeg concat list format requires one "file '/abs/path'" per line
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flist.write(f"file '{p}'\n")
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flist_path = flist.name
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try:
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codec_args: list[str] = (
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["-c:a", "copy"] if fmt == "wav"
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else ["-c:a", "libmp3lame", "-b:a", "320k"]
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)
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# create_subprocess_exec uses a list of args — no shell interpolation
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proc = await asyncio.create_subprocess_exec(
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"ffmpeg", "-y",
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"-f", "concat",
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"-safe", "0",
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"-i", flist_path,
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*codec_args,
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output_path,
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stdout=asyncio.subprocess.PIPE,
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stderr=asyncio.subprocess.PIPE,
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)
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_, stderr = await proc.communicate()
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if proc.returncode != 0:
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raise RuntimeError(
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f"ffmpeg concat failed (exit {proc.returncode}): {stderr.decode()}"
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)
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finally:
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os.unlink(flist_path)
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logger.info("Stitched %d files -> %s", len(audio_paths), output_path)
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return output_path
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def make_export_path(data_dir: str, chain_id: str, fmt: ExportFormat) -> str:
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"""Standard export output path."""
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return str(Path(data_dir) / "chains" / chain_id / f"export.{fmt}")
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