- Add the PyAV-backed file-video and audio fallback to the compatibility layer.
- Declare PyAV alongside OpenCV until the final dependency-removal integration.
- _VideoWriter now rejects is_color=False (NotImplementedError) instead of
silently dropping it, since the PyAV fallback only encodes 3-channel frames.
- _mux_audio cleanup (container closes, temp-file removal) is now best-effort
so a failing close/remove in finally can no longer mask the primary result
or the original exception.
- The subprocess used to validate the cv2-free fallback had no timeout;
a hang (import deadlock, codec probe stall) could block the whole CI
run. Added a 60s timeout so a hang fails fast with a clear traceback
instead of an opaque suite-wide stall.
- process_video(preserve_audio=True) docstring still described the old
ffmpeg-based muxing; audio remuxing was reimplemented with PyAV and no
longer requires an external ffmpeg executable.
- get_video_frames_generator's documented webcam fallback
(`_cv2.VideoCapture(0)`) silently fails under the PyAV backend: the
BackendUnavailableError raised for integer sources was swallowed with no
logging, so isOpened() just returns False with zero diagnostic signal.
Doc note now states the limitation explicitly and the capture logs a
warning instead of failing silently.
---------
Co-authored-by: Codex <codex@openai.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: claude[bot] <209825114+claude[bot]@users.noreply.github.com>
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