restructure and test, pure python and rust transport both _work_

tests/test_ffmpeg.py

@@ -86,6 +86,105 @@ class TestRunAsync:
         assert "tcp://0.0.0.0:4444?listen" in " ".join(cmd)
 
 
+class TestReceiveRecordRelayAndDetect:
+    """P0 regression: single-process pipeline with 3 outputs + scene detection."""
+
+    def test_compiles_three_outputs(self, tmp_path):
+        node = ff.receive_record_relay_and_detect(
+            "tcp://0.0.0.0:4444?listen",
+            tmp_path / "rec.mp4",
+            "udp://127.0.0.1:4445",
+        )
+        cmd_str = " ".join(str(c) for c in node.compile())
+        # fMP4 recording
+        assert "rec.mp4" in cmd_str
+        # UDP relay
+        assert "udp://127.0.0.1:4445" in cmd_str
+        # MJPEG pipe (scene detection output)
+        assert "pipe:1" in cmd_str
+
+    def test_fmp4_flags(self, tmp_path):
+        node = ff.receive_record_relay_and_detect(
+            "tcp://0.0.0.0:4444?listen",
+            tmp_path / "rec.mp4",
+            "udp://127.0.0.1:4445",
+        )
+        cmd_str = " ".join(str(c) for c in node.compile())
+        assert "frag_keyframe" in cmd_str
+        assert "empty_moov" in cmd_str
+
+    def test_scene_filter_uses_threshold(self, tmp_path):
+        node = ff.receive_record_relay_and_detect(
+            "tcp://0.0.0.0:4444?listen",
+            tmp_path / "rec.mp4",
+            "udp://127.0.0.1:4445",
+            scene_threshold=0.25,
+        )
+        cmd_str = " ".join(str(c) for c in node.compile())
+        assert "0.25" in cmd_str
+        assert "scene" in cmd_str
+        assert "showinfo" in cmd_str
+
+    def test_flush_expression_included_when_flush_frames_gt_0(self, tmp_path):
+        """P0 regression: flush trick must be present to push real frame through buffer."""
+        node = ff.receive_record_relay_and_detect(
+            "tcp://0.0.0.0:4444?listen",
+            tmp_path / "rec.mp4",
+            "udp://127.0.0.1:4445",
+            flush_frames=2,
+        )
+        cmd_str = " ".join(str(c) for c in node.compile())
+        # Flush expression: eq(n,prev_selected_n+1)*mod(selected_n,N)
+        assert "prev_selected_n" in cmd_str
+        assert "mod" in cmd_str
+
+    def test_no_flush_expression_when_flush_frames_zero(self, tmp_path):
+        """P0 regression: flush=0 should produce a clean scene-only filter."""
+        node = ff.receive_record_relay_and_detect(
+            "tcp://0.0.0.0:4444?listen",
+            tmp_path / "rec.mp4",
+            "udp://127.0.0.1:4445",
+            flush_frames=0,
+        )
+        cmd_str = " ".join(str(c) for c in node.compile())
+        assert "prev_selected_n" not in cmd_str
+
+    def test_flush_mod_value_matches_flush_frames(self, tmp_path):
+        """P0 regression: mod value must be flush_frames+1 to prevent chaining.
+
+        ffmpeg-python escapes commas in filtergraph as \\, so we check the
+        escaped form in the compiled command.
+        """
+        for n in [1, 2, 3]:
+            node = ff.detect_scenes_from_pipe(flush_frames=n)
+            cmd_str = " ".join(str(c) for c in node.compile())
+            # Commas in filter expressions are escaped as \, in filtergraph
+            assert f"mod(selected_n\\,{n + 1})" in cmd_str
+
+
+class TestDetectScenesFromPipe:
+    def test_reads_from_stdin(self):
+        node = ff.detect_scenes_from_pipe()
+        cmd_str = " ".join(str(c) for c in node.compile())
+        assert "pipe:0" in cmd_str
+
+    def test_writes_mjpeg_to_stdout(self):
+        node = ff.detect_scenes_from_pipe()
+        cmd_str = " ".join(str(c) for c in node.compile())
+        assert "pipe:1" in cmd_str
+        assert "mjpeg" in cmd_str
+
+    def test_includes_flush_expression(self):
+        node = ff.detect_scenes_from_pipe(flush_frames=2)
+        cmd_str = " ".join(str(c) for c in node.compile())
+        assert "prev_selected_n" in cmd_str
+
+    def test_h264_input_format(self):
+        node = ff.detect_scenes_from_pipe()
+        cmd_str = " ".join(str(c) for c in node.compile())
+        assert "h264" in cmd_str
+
+
 class TestStopProc:
     def test_sends_sigint_then_waits(self):
         proc = MagicMock()