Codex
65 lines
2.8 KiB
Python
65 lines
2.8 KiB
Python
"""On-demand H.264/AAC browser preview from a local MediaMTX substream."""
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import json
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import os
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from pathlib import Path
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import re
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import shutil
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import signal
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import subprocess
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import sys
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from urllib.parse import quote
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def main():
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name = os.environ.get('MTX_PATH', '')
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if not re.fullmatch(r'cam_[a-f0-9]{16}_compat', name):
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raise SystemExit('Invalid preview path')
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data = Path(sys.argv[1]).resolve()
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config = json.loads((data / 'mediamtx.yml').read_text(encoding='utf8'))
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original = name.removesuffix('_compat') + '_sub'
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if config['paths'].get(original, {}).get('source', 'publisher') == 'publisher':
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raise SystemExit('Camera is disabled')
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secret = next(u['pass'] for u in config['authInternalUsers'] if u['user'] == 'vision')
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base = 'rtsp://vision:' + quote(secret, safe='') + '@127.0.0.1:18554/'
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executable = shutil.which('ffmpeg')
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if not executable:
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raise SystemExit('Install FFmpeg to enable compatible preview')
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# A bounded 768x432 / 10 fps preview keeps six lenses practical on a small
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# computer. Original main/sub streams and recording retain their own codecs.
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command = [executable, '-hide_banner', '-loglevel', 'error', '-nostdin',
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'-threads', '1', '-filter_threads', '1', '-rtsp_transport', 'tcp',
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'-timeout', '15000000', '-i', base + original,
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'-map', '0:v:0', '-map', '0:a:0?', '-sn', '-dn',
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'-vf', 'fps=10,scale=768:432:force_original_aspect_ratio=decrease:force_divisible_by=2',
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'-c:v', 'libx264', '-threads', '1', '-preset', 'veryfast',
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'-tune', 'zerolatency', '-profile:v', 'baseline', '-level:v', '3.1',
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'-pix_fmt', 'yuv420p', '-crf', '26', '-maxrate', '1100k',
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'-bufsize', '2200k', '-g', '20', '-keyint_min', '20', '-sc_threshold', '0',
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'-c:a', 'aac', '-ar', '48000', '-ac', '1', '-b:a', '48k',
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'-f', 'rtsp', '-rtsp_transport', 'tcp', base + name]
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process = subprocess.Popen(command, stdin=subprocess.DEVNULL, stdout=subprocess.DEVNULL,
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stderr=subprocess.PIPE, text=True, errors='replace')
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def stop(_signum, _frame):
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if process.poll() is None:
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process.terminate()
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try:
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process.wait(timeout=5)
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except subprocess.TimeoutExpired:
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process.kill()
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signal.signal(signal.SIGTERM, stop)
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signal.signal(signal.SIGINT, stop)
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try:
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for line in process.stderr:
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# Never write connection credentials from FFmpeg diagnostics to logs.
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clean = re.sub(r'rtsp://[^\s]+', '[local stream]', line.replace(secret, '[redacted]'))
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print(name + ': ' + clean.rstrip(), file=sys.stderr, flush=True)
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return process.wait()
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finally:
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stop(None, None)
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if __name__ == '__main__':
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sys.exit(main())
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