Live Runner + Scope support

examples/echo/README.md

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+# Echo Live Runner Demo
+
+This example demonstrates:
+
+* Runner registration
+* Video input - taken from a local file
+* Video output - echoed to output with blur applied
+* Parameter updates - adjust the amount of blur
+
+Start go-livepeer:
+
+```sh
+./livepeer -orchestrator -useLiveRunners -serviceAddr localhost:8935 -v 99 -orchSecret abcdef
+```
+
+Start the runner:
+
+```sh
+uv run examples/echo/runner.py --orchestrator https://localhost:8935 --orchSecret abcdef
+```
+
+Run the client with a local sample input (`~/samples/bbb_720p.mp4`):
+
+```sh
+uv run examples/echo/client.py --blur ~/samples/bbb_720p.mp4
+```
+
+The resulting file is stored at echo-out.ts. To use a different file
+or redirect to stdout for live playback:
+
+```sh
+uv run client.py --blur --output - ~/samples/bbb_720p.mp4 | ffplay -
+```
+
+The client discovers the `livepeer-sample/echo` runner automatically. To use a
+different orchestrator or discovery endpoint:
+
+```sh
+uv run examples/echo/client.py --discovery http://localhost:8935/discovery --blur ~/samples/bbb_720p.mp4
+```

examples/echo/client.py

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+#!/usr/bin/env python3
+from __future__ import annotations
+
+import argparse
+import asyncio
+import sys
+import time
+from contextlib import nullcontext, suppress
+from pathlib import Path
+
+import av
+
+from livepeer_gateway.errors import LivepeerGatewayError
+from livepeer_gateway.live_runner import stop_runner_session
+from livepeer_gateway.media_output import MediaOutput
+from livepeer_gateway.media_publish import MediaPublish
+from livepeer_gateway.http import post_json
+from livepeer_gateway.selection import reserve_session
+
+DEFAULT_DISCOVERY = "http://localhost:8935/discovery"
+ECHO_APP_ID = "livepeer-sample/echo"
+DEFAULT_OUTPUT = "echo-out.ts"
+BLUR_UPDATE_INTERVAL_S = 0.01
+MAX_BLUR_RADIUS = 100
+
+
+def _log(*args: object) -> None:
+    print(*args, file=sys.stderr)
+
+
+def _parse_args() -> argparse.Namespace:
+    parser = argparse.ArgumentParser(description="Run the proxied echo Live Runner demo.")
+    parser.add_argument("input")
+    parser.add_argument("--discovery", default=DEFAULT_DISCOVERY)
+    parser.add_argument("--output", default=DEFAULT_OUTPUT)
+    parser.add_argument("--radius", type=int, default=75)
+    parser.add_argument("--max-frames", type=int, default=0, help="Stop after this many input video frames (0 = full file).")
+    parser.add_argument("--blur", action="store_true", help="Sweep blur radius while publishing the sample.")
+    return parser.parse_args()
+
+
+def _channel_url(echo_response: dict[str, object], name: str) -> str:
+    url = echo_response.get(name)
+    if not isinstance(url, str) or not url:
+        raise LivepeerGatewayError(f"echo response missing {name!r} url")
+    return url
+
+
+async def _publish_video(
+    input_path: Path,
+    publish_url: str,
+    *,
+    max_frames: int = 0,
+    app_url: str = "",
+    blur: bool = False,
+) -> None:
+    input_ = av.open(str(input_path))
+    try:
+        if not input_.streams.video:
+            raise LivepeerGatewayError(f"No video stream found in input file: {input_path}")
+        publisher = MediaPublish(publish_url)
+        prev_pts_time: float | None = None
+        prev_wall: float | None = None
+        next_update_pts_time: float | None = None
+        blur_radius = 0
+        blur_direction = 1
+
+        try:
+            for index, frame in enumerate(input_.decode(video=0), start=1):
+                if max_frames > 0 and index > max_frames:
+                    break
+                current_pts_time = None
+                if frame.pts is not None and frame.time_base is not None:
+                    current_pts_time = float(frame.pts * frame.time_base)
+                    if next_update_pts_time is None:
+                        next_update_pts_time = current_pts_time
+
+                while (
+                    blur
+                    and app_url
+                    and current_pts_time is not None
+                    and next_update_pts_time is not None
+                    and current_pts_time >= next_update_pts_time
+                ):
+                    await post_json(f"{app_url.rstrip('/')}/update", {"mode": "blur", "radius": blur_radius})
+                    if blur_radius == MAX_BLUR_RADIUS:
+                        blur_direction = -1
+                    elif blur_radius == 0:
+                        blur_direction = 1
+                    blur_radius += blur_direction
+                    next_update_pts_time += BLUR_UPDATE_INTERVAL_S
+
+                if (
+                    prev_pts_time is not None
+                    and prev_wall is not None
+                    and current_pts_time is not None
+                ):
+                    delta_s = current_pts_time - prev_pts_time
+                    elapsed_s = time.monotonic() - prev_wall
+                    sleep_s = max(0.0, delta_s - elapsed_s)
+                    if sleep_s > 0:
+                        await asyncio.sleep(sleep_s)
+
+                if current_pts_time is not None:
+                    prev_pts_time = current_pts_time
+                    prev_wall = time.monotonic()
+
+                await publisher.write_frame(frame)
+        finally:
+            await publisher.close()
+    finally:
+        input_.close()
+
+
+async def main() -> None:
+    args = _parse_args()
+    input_path = Path(args.input).expanduser()
+    output_stdout = args.output.strip().lower() in {"-", "stdout"}
+    output_path = None if output_stdout else Path(args.output).expanduser()
+    if not input_path.exists():
+        raise SystemExit(f"input file does not exist: {input_path}")
+
+    session = None
+
+    try:
+        session = await reserve_session(discovery_url=args.discovery, app=ECHO_APP_ID)
+        _log("runner_url:", session.runner.url if session.runner is not None else session.runner_url)
+        _log("session_id:", session.session_id)
+        _log("app_url:", session.app_url)
+
+        echo = await post_json(f"{session.app_url.rstrip('/')}/echo", {"radius": args.radius})
+        in_url = _channel_url(echo, "in")
+        out_url = _channel_url(echo, "out")
+        _log("in:", in_url)
+        _log("out:", out_url)
+
+        with nullcontext(sys.stdout.buffer) if output_stdout else output_path.open("wb") as fh:
+            def _write_chunk(chunk: bytes) -> None:
+                fh.write(chunk)
+                if output_stdout:
+                    fh.flush()
+
+            async with MediaOutput(out_url, on_bytes=_write_chunk):
+                await _publish_video(
+                    input_path,
+                    in_url,
+                    max_frames=max(0, args.max_frames),
+                    app_url=session.app_url,
+                    blur=args.blur,
+                )
+                _log("publish complete; waiting for output to drain...")
+            fh.flush()
+    except LivepeerGatewayError as exc:
+        raise SystemExit(f"ERROR: {exc}") from exc
+    finally:
+        if session is not None:
+            with suppress(Exception):
+                await stop_runner_session(session)
+
+
+if __name__ == "__main__":
+    asyncio.run(main())