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diff --git a/DOCS/man/options.rst b/DOCS/man/options.rst index 4e60e64c22..883c13c9d8 100644 --- a/DOCS/man/options.rst +++ b/DOCS/man/options.rst @@ -3363,6 +3363,72 @@ Miscellaneous out. This delay in reaction time to sudden A/V offsets should be the only side-effect of turning this option on, for all sound drivers. +``--video-sync=<audio|...>`` + How the player synchronizes audio and video. + + The modes starting with ``display-`` try to output video frames completely + synchronously to the display, using the detected display vertical refresh + rate as a hint how fast frames will be displayed on average. These modes + change video speed slightly to match the display. See ``--video-sync-...`` + options for fine tuning. The robustness of this mode is further reduced by + making a some idealized assumptions, which may not always apply in reality. + Behavior can depend on the VO and the system's video and audio drivers. + Media files must use constant framerate. Section-wise VFR might work as well + with some container formats (but not e.g. mkv). If the sync code detects + severe A/V desync, or the framerate cannot be detected, the player + automatically reverts to ``audio`` mode for some time or permanently. + + The modes with ``desync`` in their names do not attempt to keep audio/video + in sync. They will slowly (or quickly) desync, until e.g. the next seek + happens. These modes are meant for testing, not serious use. + + :audio: Time video frames to audio. This is the most robust + mode, because the player doesn't have to assume anything + about how the display behaves. The disadvantage is that + it can lead to occasional frame drops or repeats. If + audio is disabled, this uses the system clock. This is + the default mode. + :display-resample: Resample audio to match the video. This mode will also + try to adjust audio speed to compensate for other drift. + (This means it will play the audio at a different speed + every once in a while to reduce the A/V difference.) + :display-resample-vdrop: Resample audio to match the video. Drop video + frames to compensate for drift. + :display-resample-desync: Like the previous mode, but no A/V compensation. + :display-vdrop: Drop or repeat video frames to compensate desyncing + video. (Although it should have the same effects as + ``audio``, the implementation is very different.) + :display-desync: Sync video to display, and let audio play on its own. + :desync: Sync video according to system clock, and let audio play + on its own. + +``--video-sync-max-video-change=<value>`` + Maximum speed difference in percent that is applied to video with + ``--video-sync=display-...`` (default: 1). Display sync mode will be + disabled if the monitor and video refresh way do not match within the + given range. It tries multiples as well: playing 30 fps video on a 60 Hz + screen will duplicate every second frame. Playing 24 fps video on a 60 Hz + screen will play video in a 2-3-2-3-... pattern. + + The default settings are not loose enough to speed up 23.976 fps video to + 25 fps. We consider the pitch change too extreme to allow this behavior + by default. Set this option to a value of ``5`` to enable it. + + Note that in the ``--video-sync=display-resample`` mode, audio speed will + additionally be changed by a small amount if necessary for A/V sync. See + ``--video-sync-max-audio-change``. + +``--video-sync-max-video-change=<value>`` + Maximum *additional* speed difference in percent that is applied to audio + with ``--video-sync=display-...`` (default: 0.125). Normally, the player + play the audio at the speed of the video. But if the difference between + audio and video position is too high, e.g. due to drift or other timing + errors, it will attempt to speed up or slow down audio by this additional + factor. Too low values could lead to video frame dropping or repeating if + the A/V desync cannot be compensated, too high values could lead to chaotic + frame dropping due to the audio "overshooting" and skipping multiple video + frames before the sync logic can react. + ``--mf-fps=<value>`` Framerate used when decoding from multiple PNG or JPEG files with ``mf://`` (default: 1). |