fix(tracks): keep the Dolby Vision record when remuxing video with ffmpeg

The MP4 muxer drops dvcC/dvvC unless -strict unofficial is set, so a repacked DV track muxed as plain HEVC and lost its DV tag

tests/core/test_repackage_dovi.py

@@ -0,0 +1,32 @@
+"""Repackaging a video keeps its Dolby Vision configuration record."""
+
+from __future__ import annotations
+
+import subprocess
+from pathlib import Path
+
+import pytest
+from langcodes import Language
+
+from unshackle.core import binaries
+from unshackle.core.tracks import Video
+
+
+def test_repackage_asks_ffmpeg_to_keep_unofficial_boxes(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+    source = tmp_path / "v.mp4"
+    source.write_bytes(b"\0")
+    calls: list[list[str]] = []
+
+    def fake_run(args: list, **kwargs: object) -> subprocess.CompletedProcess:
+        calls.append([str(a) for a in args])
+        Path(args[-1]).write_bytes(b"\0")
+        return subprocess.CompletedProcess(args, 0)
+
+    monkeypatch.setattr(binaries, "FFMPEG", "ffmpeg")
+    monkeypatch.setattr(subprocess, "run", fake_run)
+    video = Video(url="https://cdn.example/v.mp4", language=Language.get("en"))
+    video.path = source
+    video.repackage()
+
+    args = calls[0]
+    assert args[args.index("-strict") + 1] == "unofficial"

unshackle/core/tracks/track.py

@@ -1160,6 +1160,8 @@ class Track:
                     "bitexact",
                     "-codec",
                     "copy",
+                    "-strict",
+                    "unofficial",
                 ]
             )
             if bsf:

unshackle/core/tracks/video.py

@@ -392,6 +392,8 @@ class Video(Track):
                 original_path,
                 "-codec",
                 "copy",
+                "-strict",
+                "unofficial",
                 "-bsf:v",
                 f"{filter_key}=video_full_range_flag={range_}",
                 str(output_path),
@@ -503,6 +505,8 @@ class Video(Track):
                     str(original_path),
                     "-codec",
                     "copy",
+                    "-strict",
+                    "unofficial",
                     "-bsf:v",
                     bsf,
                     str(output_path),