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Add Frame.best_effort_timestamp - #2478
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For inputs that store only DTS, such as AVI, the PTS that `genpts` generates can go backwards when the video has B-frames. Expose FFmpeg's own estimate, which falls back to DTS when PTS is unreliable, and document that input containers set `genpts` and how to turn it off. Closes #2477
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Thanks for the prompt fix here! |
This was referenced Oct 25, 2026
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PyAV sets `AVFMT_FLAG_GENPTS` on every input (see PyAV-Org/PyAV#2477 / PyAV-Org/PyAV#2478). On containers that store DTS only (AVI, MPEG-TS) and contain B-frames, or streams that have no timestamps at all, the generated PTS can come out in the incorrect decode order. This was causing the PyAV backend to report non-monotonic timestamps in these cases, resulting in incorrect splits (#590). This PR now ensures we set `fflags=-genpts` to override the `+genpts` flag from PyAV. We also fallback from PTS to DTS, and count frames when there are no timestamps entirely. We also add support for when PyAV exposes `Frame.best_effort_timestamp` in a future release (tested locally with the development changes linked above). Lastly, a one-time warning is logged if timestamps are detected going backwards. Users hitting this issue should update PyAV to 19.1+ to resolve it. We cannot pin to PyAV 19.1+ because it requires Python 3.12, but `scenedetect` supports 3.10+ and 3.11 is supported until October 2027. Follow-ups kept as TODOs: - AVI tick rate and frame counts in `_get_duration` - MPEG-TS seeks that land after the target position
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For inputs that store only DTS, such as AVI, the PTS that
genptsgenerates can go backwards when the video has B-frames. Expose FFmpeg's own estimate, which falls back to DTS when PTS is unreliable, and document that input containers setgenptsand how to turn it off.Closes #2477