Controlling the playback speed
''''''''''''''''''''''''''''''
+Most slow motion is at 0.5x speed (or equivalently, “2x slow motion”),
+and when you queue a clip from the clip list to the playlist, this is what
+it gets by default. However, you are free to change it to whatever you wish,
+like 0.333x, 0.25x (both are fairly common “super slow” standards) or even 1.0x.
+As long as you are reasonably close to a rational number with low integers
+(e.g. 1/2, 2/3, etc.), Futatabi will do its best to try to reuse as many
+original frames as possible, keeping quality and performance at their highest
+levels.
+
+In addition to the per-clip speed, it is often interesting to change the
+speed *during* playback of a clip. For instance, you could keep normal
+slow motion (0.5x) speed in the run-up to a shot, ramp down to 0.1x to get
+a good look at the actual shot, and then ramp back once it's done.
+When done right and not overused, this can create a dramatic effect that's
+hard to replicate using constant slowdown.
+
+To this effect, Futatabi supports a *master speed* control. It is found at
+the bottom of the window (or you can :ref:`control it using a MIDI device <midi-futatabi>`);
+note that by default, it is locked at 100% until you click the lock button
+to unlock it. (This is particularly important when using a MIDI device, where it is very easy
+to touch a slider inadvertedly, and very hard to set it back exactly at 100%.)
+The master speed control is multiplied in on top of all other speed factors,
+so if you have e.g. a clip at 0.5x and the master speed is set to 70%,
+the clip will effectively play back at 0.35x. The master speed can be set between
+10% and 200%, inclusive.
+
+Note that the master speed control governs the speed of the *output* clock,
+unlike any other speed control in Futatabi. In particular, this means that unlike
+the regular clip speeds, it affects fade times; if fade time is at 0.5 seconds
+and master speed is set to 70%, the fade will take approximately 0.714 seconds
+(0.5 divided by 0.7). It also means that the “remaining time” displays will be
+wrong if master speed is not at 100%. This is because the master speed
+is by nature unpredictable (the user can change it at any time); one cannot
+e.g. delay fades when the master speed is reduced, since turning it back up
+would mean the start of the fade were simply missed. Similarly, it is impossible
+to give a proper estimate of time remaining that takes master speed into account;
+it would be overestimating time significantly, given that the operator is likely
+to turn it back up to 100% again soon.
+
+Finally, note that when changing master speed, the speed is no longer at a
+rational, so most frames will be interpolated frames. If your GPU is not fast
+enough to interpolate every frame (ie., it is reliant on Futatabi's usual
+reuse of original frames), it will drop output frames. Normal behavior will
+resume from the next clip, when the clocks will again go in lockstep (assuming the master
+speed is at 100% at that point). If you're not ramping, or if you're done ramping,
+it's recommended to keep the speed lock on to avoid inadvertedly changing the speed.
+
.. _coop:
Working with your producer
be able to request replays of specific events, or ask you to save something
for later if they can't show it right now (e.g. a foul situation that wasn't called).
+Audio support
+'''''''''''''
+
+Since version 1.8.5, Futatabi has limited audio support. It is recorded
+(assuming Nageru is also at version 1.8.5 or newer) and saved for all inputs,
+and played back when showing a replay, but only when the replay speed is at
+100%, or very close to it. (At other speeds, you will get silence.)
+Furthermore, there is no local audio output; the Futatabi operator will not
+hear any audio, unless they use a video player into the Futatabi stream locally
+(with associated delay). All of this may change in the future.
+
+
Replay workflows
----------------
There are two files:
- * `Trøndisk 2018, finals only (MJPEG, 77 GB) <https://storage.sesse.net/trondisk2018-finals-multicam-mjpeg.mkv>`_:
- The final match, in MJPEG format (about 30 minutes). This can be downloaded
- and then fed directly to Nageru as if it were a real camera stream
+ * `Trøndisk 2018, final only (MJPEG, 126 GB) <https://storage.sesse.net/trondisk2018-final-multicam-mjpeg.mkv>`_:
+ The final match, in MJPEG format (about 73 minutes). This can be downloaded
+ and then fed directly to Futatabi as if it were a real camera stream
(remember the --slow-down-input option).
- * `Trøndisk 2018, entire tournament (H.264, 74 GB) <https://storage.sesse.net/trondisk2018-multicam-h264.mp4>`_: The entire tournament,
+ * `Trøndisk 2018, entire tournament (H.264, 74 GB) <https://storage.sesse.net/trondisk2018-multicam-h264.mp4>`_:
+ The entire first part of the tournament,
with no cuts (about 12 hours). However, due to space and bandwidth
constraints, it has been transcoded to H.264 (with some associated
quality loss), and needs to be transcoded to MJPEG before Nageru can use it.
to practice with.
-Transferring data to and from Nageru
-------------------------------------
-
.. _futatabiformat:
-Video format specification
-''''''''''''''''''''''''''
+Internal video format details
+-----------------------------
Futatabi expects to get data in MJPEG format only; though MJPEG is old,
it yields fairly good quality per bit for an intraframe format, supports
projects / nageru-docs / blobdiff