Prevent ffmpeg pipe probe deadlock

docs/module-internals.md

@@ -149,6 +149,11 @@ regeneration. It centralizes container codecs, optional audio stream copying,
 metadata/chapter policy, encode-failure reporting, and atomic same-directory
 publication. Each mapped stream is allowed to reach its own end, so a copied
 audio tail is not shortened to the frame-input duration.
+Both the raw-BGR and timestamped-NUT stdin inputs disable ffmpeg probing before
+`pipe:0`: their format is already explicit, and ffmpeg 6 on Linux can otherwise
+wait for its normal analysis window while the producer blocks on a full pipe
+before the source-audio input opens. Command-order regressions cover both stdin
+modes; the real Linux full-clip CI job guards process completion.
 `probe_video_encode_profile` reads the first source video stream with ffprobe
 and preserves the supported properties that survive the 8-bit BGR boundary:
 `yuv420p`/`yuv422p`/`yuv444p` chroma sampling, recognized color tags, encoder

src/remove_ai_watermarks/video_encoding.py

@@ -286,8 +286,12 @@ def raw_video_command(
     ffmpeg = shutil.which("ffmpeg")
     if ffmpeg is None:
         raise RuntimeError("Video processing requires ffmpeg on PATH")
+    # The pipe format and stream geometry are already explicit. FFmpeg 6 can
+    # otherwise wait for its normal analysis window while the producer blocks
+    # on a full pipe, before the second (audio) input has been opened.
+    pipe_input = ["-analyzeduration", "0", "-probesize", "32", "-i", "pipe:0"]
     frame_input = (
-        ["-f", "nut", "-i", "pipe:0"]
+        ["-f", "nut", *pipe_input]
         if timestamped_input
         else [
             "-f",
@@ -298,8 +302,7 @@ def raw_video_command(
             f"{width}x{height}",
             "-r",
             f"{fps:.12g}",
-            "-i",
-            "pipe:0",
+            *pipe_input,
         ]
     )
     command = [

tests/test_video.py

@@ -1950,6 +1950,34 @@ class TestVideoVisibleScan:
 
 
 class TestVideoVisibleEncoding:
+    def test_raw_pipe_input_disables_redundant_ffmpeg_probing(
+        self,
+        tmp_path: Path,
+        monkeypatch: pytest.MonkeyPatch,
+    ):
+        from remove_ai_watermarks import video_encoding
+
+        monkeypatch.setattr(video_encoding.shutil, "which", lambda _name: "/usr/bin/ffmpeg")
+        command = video_encoding.raw_video_command(
+            tmp_path / "source.mp4",
+            tmp_path / "clean.mp4",
+            width=12,
+            height=8,
+            fps=24.0,
+            strip_metadata=True,
+            crf=14,
+            profile=video_encoding.VideoEncodeProfile(),
+        )
+
+        pipe_position = command.index("pipe:0")
+        assert command[pipe_position - 5 : pipe_position] == [
+            "-analyzeduration",
+            "0",
+            "-probesize",
+            "32",
+            "-i",
+        ]
+
     @staticmethod
     def _patch_single_frame_encode(
         monkeypatch: pytest.MonkeyPatch,

tests/test_video_invisible.py

@@ -102,7 +102,16 @@ def test_timestamped_encoder_reads_nut_and_passes_pts_through(
     )
 
     assert "-copyts" in command
-    assert command[command.index("-f") : command.index("-f") + 4] == ["-f", "nut", "-i", "pipe:0"]
+    assert command[command.index("-f") : command.index("-f") + 8] == [
+        "-f",
+        "nut",
+        "-analyzeduration",
+        "0",
+        "-probesize",
+        "32",
+        "-i",
+        "pipe:0",
+    ]
     assert command[command.index("-fps_mode") + 1] == "passthrough"
     assert command[command.index("-avoid_negative_ts") + 1] == "disabled"
     assert command[command.index("-enc_time_base:v") + 1] == "1/90000"