Initial commit: Twitch Stream Vision Analyzer

Async pipeline: streamlink + ffmpeg frame capture → Gemini Vision API analysis → rich console output + log file.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

capture.py

@@ -0,0 +1,76 @@
+import asyncio
+import struct
+from collections.abc import AsyncIterator
+
+
+async def capture_frames(
+    channel: str, quality: str, interval: int
+) -> AsyncIterator[bytes]:
+    """Capture frames from a Twitch stream using streamlink + ffmpeg.
+
+    Yields JPEG frames as bytes at the specified interval.
+    """
+    streamlink_cmd = [
+        "streamlink",
+        "--stdout",
+        f"https://twitch.tv/{channel}",
+        quality,
+    ]
+
+    ffmpeg_cmd = [
+        "ffmpeg",
+        "-i", "pipe:0",
+        "-vf", f"fps=1/{interval}",
+        "-f", "image2pipe",
+        "-vcodec", "mjpeg",
+        "-q:v", "5",
+        "pipe:1",
+    ]
+
+    streamlink_proc = await asyncio.create_subprocess_exec(
+        *streamlink_cmd,
+        stdout=asyncio.subprocess.PIPE,
+        stderr=asyncio.subprocess.DEVNULL,
+    )
+
+    ffmpeg_proc = await asyncio.create_subprocess_exec(
+        *ffmpeg_cmd,
+        stdin=streamlink_proc.stdout,
+        stdout=asyncio.subprocess.PIPE,
+        stderr=asyncio.subprocess.DEVNULL,
+    )
+
+    # Release streamlink's stdout so ffmpeg owns the pipe
+    streamlink_proc.stdout = None
+
+    try:
+        buf = b""
+        while True:
+            chunk = await ffmpeg_proc.stdout.read(65536)
+            if not chunk:
+                break
+            buf += chunk
+
+            # Extract complete JPEG frames (SOI: FF D8, EOI: FF D9)
+            while True:
+                soi = buf.find(b"\xff\xd8")
+                if soi == -1:
+                    buf = b""
+                    break
+                eoi = buf.find(b"\xff\xd9", soi + 2)
+                if eoi == -1:
+                    # Keep from SOI onward, discard junk before
+                    buf = buf[soi:]
+                    break
+                frame = buf[soi : eoi + 2]
+                buf = buf[eoi + 2 :]
+                yield frame
+    finally:
+        for proc in (ffmpeg_proc, streamlink_proc):
+            try:
+                proc.terminate()
+            except ProcessLookupError:
+                pass
+        await asyncio.gather(
+            ffmpeg_proc.wait(), streamlink_proc.wait(), return_exceptions=True
+        )