init commit

cht/stream/ffmpeg.py

@@ -0,0 +1,148 @@
+"""
+Thin wrapper around ffmpeg-python for building and running ffmpeg pipelines.
+
+All ffmpeg command construction goes through this module so manager.py
+and other consumers never build raw CLI arg lists.
+"""
+
+import logging
+import os
+import signal
+import subprocess
+from pathlib import Path
+
+import ffmpeg
+
+log = logging.getLogger(__name__)
+
+
+def receive_and_segment(stream_url, segment_dir, segment_duration=60):
+    """Receive mpegts stream and save as segmented .ts files.
+
+    Returns an ffmpeg-python output node (not yet running).
+    """
+    stream = ffmpeg.input(stream_url, fflags="nobuffer", flags="low_delay")
+    return ffmpeg.output(
+        stream,
+        str(segment_dir / "segment_%04d.ts"),
+        c="copy",
+        f="segment",
+        segment_time=segment_duration,
+        reset_timestamps=1,
+    )
+
+
+def receive_and_segment_with_monitor(stream_url, segment_dir, fifo_path, segment_duration=60):
+    """Receive stream, save segments AND tee to a named pipe for monitoring.
+
+    Returns an ffmpeg-python merged output node.
+    """
+    if not fifo_path.exists():
+        os.mkfifo(str(fifo_path))
+
+    stream = ffmpeg.input(stream_url, fflags="nobuffer", flags="low_delay")
+
+    out_segments = ffmpeg.output(
+        stream,
+        str(segment_dir / "segment_%04d.ts"),
+        c="copy",
+        f="segment",
+        segment_time=segment_duration,
+        reset_timestamps=1,
+    )
+
+    out_monitor = ffmpeg.output(
+        stream,
+        str(fifo_path),
+        c="copy",
+        f="mpegts",
+    )
+
+    return ffmpeg.merge_outputs(out_segments, out_monitor)
+
+
+def extract_scene_frames(input_path, output_dir, scene_threshold=0.3,
+                         max_interval=30, start_number=1):
+    """Extract frames from a file on scene change.
+
+    Uses ffmpeg select filter with scene detection and a max-interval fallback.
+    Returns (process_result, stderr) for timestamp parsing.
+    """
+    select_expr = (
+        f"gt(scene\\,{scene_threshold})"
+        f"+gte(t-prev_selected_t\\,{max_interval})"
+    )
+    stream = ffmpeg.input(str(input_path))
+    stream = stream.filter("select", select_expr).filter("showinfo")
+
+    output = ffmpeg.output(
+        stream,
+        str(output_dir / "F%04d.jpg"),
+        vsync="vfr",
+        **{"q:v": "2"},
+        start_number=start_number,
+    )
+
+    return run_sync(output, timeout=120)
+
+
+def extract_audio_pcm(input_path):
+    """Extract audio as 16kHz mono PCM wav, returning an output node for piping.
+
+    Use run_async with pipe_stdout=True to stream PCM data.
+    """
+    stream = ffmpeg.input(str(input_path))
+    return ffmpeg.output(
+        stream.audio,
+        "pipe:",
+        vn=None,
+        acodec="pcm_s16le",
+        ar=16000,
+        ac=1,
+        f="wav",
+    )
+
+
+def run_async(output_node, pipe_stdout=False, pipe_stderr=False):
+    """Start an ffmpeg pipeline asynchronously. Returns subprocess.Popen."""
+    cmd = compile_cmd(output_node)
+    log.info("run_async: %s", " ".join(str(c) for c in cmd))
+    return subprocess.Popen(
+        cmd,
+        stdout=subprocess.PIPE if pipe_stdout else subprocess.DEVNULL,
+        stderr=subprocess.PIPE if pipe_stderr else subprocess.DEVNULL,
+    )
+
+
+def run_sync(output_node, timeout=None):
+    """Run an ffmpeg pipeline synchronously. Returns (stdout, stderr) as strings."""
+    cmd = compile_cmd(output_node)
+    log.info("run_sync: %s", " ".join(str(c) for c in cmd))
+    result = subprocess.run(
+        cmd,
+        capture_output=True,
+        text=True,
+        timeout=timeout,
+    )
+    return result.stdout, result.stderr
+
+
+def compile_cmd(output_node):
+    """Compile an ffmpeg-python node to a command list, adding global flags."""
+    cmd = output_node.compile()
+    # Insert global flags after 'ffmpeg'
+    idx = 1
+    for flag in ["-hide_banner", "-loglevel", "warning"]:
+        cmd.insert(idx, flag)
+        idx += 1
+    return cmd
+
+
+def stop_proc(proc, timeout=5):
+    """Gracefully stop an ffmpeg subprocess."""
+    if proc and proc.poll() is None:
+        proc.send_signal(signal.SIGINT)
+        try:
+            proc.wait(timeout=timeout)
+        except subprocess.TimeoutExpired:
+            proc.kill()