77 lines
2.1 KiB
Python
77 lines
2.1 KiB
Python
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import asyncio
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import struct
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from collections.abc import AsyncIterator
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async def capture_frames(
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channel: str, quality: str, interval: int
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) -> AsyncIterator[bytes]:
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"""Capture frames from a Twitch stream using streamlink + ffmpeg.
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Yields JPEG frames as bytes at the specified interval.
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"""
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streamlink_cmd = [
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"streamlink",
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"--stdout",
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f"https://twitch.tv/{channel}",
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quality,
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]
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ffmpeg_cmd = [
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"ffmpeg",
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"-i", "pipe:0",
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"-vf", f"fps=1/{interval}",
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"-f", "image2pipe",
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"-vcodec", "mjpeg",
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"-q:v", "5",
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"pipe:1",
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]
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streamlink_proc = await asyncio.create_subprocess_exec(
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*streamlink_cmd,
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stdout=asyncio.subprocess.PIPE,
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stderr=asyncio.subprocess.DEVNULL,
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)
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ffmpeg_proc = await asyncio.create_subprocess_exec(
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*ffmpeg_cmd,
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stdin=streamlink_proc.stdout,
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stdout=asyncio.subprocess.PIPE,
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stderr=asyncio.subprocess.DEVNULL,
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)
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# Release streamlink's stdout so ffmpeg owns the pipe
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streamlink_proc.stdout = None
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try:
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buf = b""
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while True:
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chunk = await ffmpeg_proc.stdout.read(65536)
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if not chunk:
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break
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buf += chunk
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# Extract complete JPEG frames (SOI: FF D8, EOI: FF D9)
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while True:
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soi = buf.find(b"\xff\xd8")
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if soi == -1:
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buf = b""
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break
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eoi = buf.find(b"\xff\xd9", soi + 2)
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if eoi == -1:
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# Keep from SOI onward, discard junk before
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buf = buf[soi:]
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break
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frame = buf[soi : eoi + 2]
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buf = buf[eoi + 2 :]
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yield frame
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finally:
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for proc in (ffmpeg_proc, streamlink_proc):
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try:
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proc.terminate()
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except ProcessLookupError:
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pass
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await asyncio.gather(
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ffmpeg_proc.wait(), streamlink_proc.wait(), return_exceptions=True
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)
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