It is strongly recommended to run Futatabi on a separate machine from Nageru,
not the least because you probably want a different person to operate the replay
-while the producer is operating Nageru.
+while the producer is operating Nageru. (See :ref:`coop`.)
Like Nageru, Futatabi uses your GPU for nearly all image processing.
However, unlike Nageru, Futatabi requires a powerful GPU for interpolation;
Getting started
---------------
+Futatabi always pulls data from Nageru over the network; it doesn't support SDI
+input or output. Assuming you have a recent version of Nageru (typically one
+that comes with Futatabi), it is capable of sending all of its cameras as one
+video stream (see :ref:`futatabiformat`), so you can start Futatabi with
+
+ ./futatabi http://nageru-server.example.org/multicam.mp4
+
+If you do not have a running Nageru installation, see :ref:`sampledata`.
+
+Once you are up and connected, Futatabi will start recording all of the frames
+to disk. This process happens continuously for as long as you have disk space,
+even if you are playing something back or editing clips, and the streams are
+displayed in real time in mini-display as they come in. You make replays in
+the form of *clips* (the top list is the clip list), which are then queued into
+the *playlist* (the bottom list). Your end result is a live HTTP stream that
+can be fed back into Nageru as a video input; by default, Futatabi listens
+on port 9096.
+
+Futatabi has the concept of a *workspace*, which defaults to your current
+directory (you can change it with the -d option). This holds all of the
+recorded frames, all metadata about clips, and preferences set from the menus
+(interpolation quality and cue point padding). If you quit Futatabi and
+restart it (or you go down as the result of a power failure or the likes),
+it will remember all the state and frames for you. As a special case,
+if you give */dev/null* in place of an input URL or file, you can keep using
+your workspace without getting any new frames added.
+
+.. _basicui:
+
+Basic UI operations
+'''''''''''''''''''
+
+Nageru can be operated using either the keyboard and mouse, or using a MIDI
+controller with some help of the mouse. In this section, we will be discussing
+the keyboard and mouse only; see :ref:`midi-futatabi` for details on using MIDI
+controllers.
+
+A clip in the clip list consists simply of an in and an out point; it represents
+an interval of physical time (although timed to the video clock). A clip in the
+playlist contains the same information plus some playback parameters, in particular
+which camera (stream) to play back.
+
+Clicking the ”Cue in” button, or pressing the A key, will start a new clip in
+the clip list that begins at the current time. Similarly, clicking the ”Cue
+out” button, or pressing the S key, will set the end point for said clip.
+(If you click a button twice, it will overwrite the previous result.)
+Now it is in a state where you can queue it to the play list (mark the camera
+you want to use and click the “Queue” button, or Q on the keyboard) for
+playing, or you can preview them using the “Preview” button (W on the
+keyboard). Previewing can be done either from the clip list the clip list or
+the playlist; they will not be interpolated or faded, but will be played back
+in the right
+
+You can edit cue points, both in the clip and the playlist, in two ways:
+Either use the scroll wheel on the mouse, or hold down the left mouse button
+and scrub left or right. (You can hold down Shift to change ten times as fast,
+or Alt to change at one-tenth the speed.) You'll see the new cue points as you
+change them in the preview window. You can also give clips names; these don't
+mean anything, but can be good references to locate a specific kind of clip
+for later use. Once you're happy with a playlist, and your producer is ready
+to cut to your channel, click on the first clip you want to play back and
+click the “Play” button (space on the keyboard); the result will both be
+visible in the top screen and go out live over the network to Nageru.
+
+.. _speed:
+
+Controlling the playback speed
+''''''''''''''''''''''''''''''
+
+.. _coop:
+
+Working with your producer
+''''''''''''''''''''''''''
+
+Generally, we recommend that the producer (Nageru operator) and slow motion
+operator (Futatabi operator) sit closely together and can communicate verbally.
+Good cooperation between the two is essential to get a good final product;
+especially the switches to and from the replays can be a critical point.
+
+The general rule for working together is fairly obvious: The producer should
+switch to a replay when there's something to show, and switch away when there's
+nothing more to show (or, less ideally, when something live takes priority).
+Generally, when you have a playlist ready, inform your producer; they will
+count you in (three, two, one, go). At one, start playing so that you have some
+margin. If the Nageru theme is set up correctly (see :ref:`talkback`), they will
+know how much is queued up so that they can switch back before the replay runs
+out, but it doesn't hurt to give a warning up-front. The producer might also
+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).
+
+Replay workflows
+----------------
+
+On top of the basics outlined in :ref:`basicui`, there are many possible
+workflows; we'll discuss only two. Try out a few and see which ones fit your
+style and type of event.
+
+Repeated cue-in
+'''''''''''''''
+
+In many sports, you don't necessarily know when a replay-worthy event has happened
+before it's already happened. However, you may reasonably know when something is
+*not* happening, and it would be a good time to start a clip if something is happening
+immediately afterwards. At these points, you can make repeated cue-ins, ie., start
+a clip without finishing it. As long as you keep making cue-ins, the previous one
+will be discarded. Once you see that something *is* happening, you can wait until
+it's done, and then do a cue-out, which gives you a good clip immediately.
+
+For instance, in a basketball game, you could be seeing a series of uninteresting
+passes, clicking cue-in on each of them. However, once it looks like there's an
+opportunity for a score, you can hold and see what happens; if the shot happens,
+you can click cue-out, and if not, you can go back.
+
+Before playing the clip, you can make adjustments to the in and out points
+as detailed above. This will help you trim away any uninteresting lead-ups,
+or add more margins for fades. If you consistently find that you have too
+little margin, you can use the *cue point padding* feature (either from the
+command line using *--cue-point-padding*, or set from the menu). If you set
+cue point padding to e.g. two seconds, the cue-in point will automatically be set
+two seconds ago when you cue-in, and the cue-out point will be set two seconds
+into the future when you cue-out.
+
+
+Instant clips
+'''''''''''''
+
+Like the previous section explained how you generally would know the *start*
+of an interesting event (at least if discarding most of the candidates),
+you would be even more sure about the *end* of one. Thus, you can simply wait
+until something interesting has happened, and then click cue-in immediately
+followed by cue-out. This will give you a clip of near zero length, ending
+at the right point. Then, edit this clip to set the starting point as needed,
+and it's ready to play.
+
+Again, you can use the cue point padding feature to your advantage; if so,
+your clips will not be of zero length, but rather of some predefined length
+given by your chosen cue point padding.
+
+
+.. _sampledata:
+
Sample multicamera data
'''''''''''''''''''''''
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 (roughly 52 minutes). This can be downloaded
+ 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
(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,
- with no cuts (roughly 12 hours). However, due to space and bandwidth
+ 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.
on the camera operators. In short, they should be realistic input material
to practice with.
-Please download these files only once, instead of streaming them directly over
-HTTP each time you want to test.
-
Transferring data to and from Nageru
------------------------------------
Video format specification
''''''''''''''''''''''''''
+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
+4:2:2 without too many issues, and has hardware support through VA-API
+for both decode (since Ivy Bridge) and encode (since Skylake). The latter
+is especially important for Futatabi, since there are so many high-resolution
+streams; software encode/decode of several 1080p60 streams at the same time
+is fairly taxing on the CPU if done in software. This means we can easily
+send 4:2:2 camera streams back and forth between Nageru and Futatabi without having
+to scale or do other lossy processing (except of course the compression itself).
+
+However, JPEG as such does not have any way of specifying things like color
+spaces and chroma placement. JFIF, the *de facto* JPEG standard container,
+specifies conventions that are widely followed, but they do not match what
+comes out of a capture card. Nageru's multicam export _does_ set the appropriate
+fields in the output Matroska mux (which is pretty much the only mux that can
+hold such information), but there are few if any programs that read them and give
+them priority over JFIF's defaults. Thus, if you want to use the multicam stream
+for something other than Futatabi, or feed Futatabi with data not from Nageru,
+there are a few subtle issues to keep in mind.
+
+In particular:
+
+ * Capture cards typically send limited-range Y'CbCr (luma between 16..235
+ and chroma between 16..240); JFIF is traditionally full-range (0..255
+ for both). (See also :ref:`synthetictests`.) Note that there is a special
+ private JPEG comment added to signal this, which FFmpeg understands.
+ * JFIF, like MPEG, assumes center chroma placement; capture cards and most
+ modern video standards assume left.
+ * JFIF assumes Rec. 601 Y'CbCr coefficients, while all modern HD processing
+ uses Rec. 709 Y'CbCr coefficients. (Futatabi does not care much about
+ the actual RGB color space; Nageru assumes it is Rec. 709, like for capture
+ cards, but the differences between 601 and 709 here are small. sRGB gamma
+ is assumed throughout, like in JFIF.)
+
+Many players may also be confused by the fact that the resolution can change
+from frame to frame; this is because for original (uninterpolated) frames,
+Futatabi will simply output the received JPEG frame directly to the output
+stream, which can be a different resolution from the interpolated frames.
+
+Also, even though Futatabi exists to make a fixed-framerate stream out of
+something that's not, the output stream can be variable-framerate (VFR) due to
+pauses and frame drops. In particular, when the stream is paused, frames are
+only output about every 100 milliseconds.
+
+Finally, the subtitle track with status information (see :ref:`talkback`) is
+not marked as metadata due to FFmpeg limitations, and as such will show up
+raw in subtitle-enabled players.
+
+
+.. _midi-futatabi:
+
+Using MIDI controllers
+----------------------
+
+This section assumes you have already read the section about
+`MIDI controllers in Nageru <audio.html#midi-controllers>`__. MIDI controllers
+in Futatabi are fairly similar, but there are also some important differences,
+since they control replay and not audio:
+
+ * There is no concept of a bus (there is only one video output channel).
+ Thus, the concept of guessing also is obsolete.
+ * Since there are no buses, there are also usually plenty of buttons
+ and controls, rendering the bank concept less useful. It *is* supported,
+ but activity highlights (to show which bank is active) are not.
+ * Finally, outputs (controller lights and button lights) frequently have
+ more than one state depending on the velocity sent, e.g. 1 for on and 2 for
+ blinking. Thus, the Futatabi MIDI mapping editor allows you to change the
+ note velocities from the default 1.
+
+Futatabi has been tested with the `Behringer CMD PL-1 <https://www.musictribe.com/Categories/Behringer/Computer-Audio/DJ-Controllers/CMD-PL-1/p/P0AJF>`_;
+it is not originally designed for slow motion (it is a DJ controller), but provides everything you
+need (a jog wheel, a slider that works as a T bar for master speed, and plenty
+of buttons) at a fraction of the price of a “real” slow motion remote.
+A sample MIDI mapping is included with Futatabi.
+
+Futatabi currently does not support classic RS-422 controllers, only MIDI
+controllers.
+
+
Monitoring
----------
+.. _talkback:
+
Tally and status talkback
'''''''''''''''''''''''''
+In addition to the verbal communication between the two operators
+(see :ref:`coop`), it is also useful to have automatic communication
+between Nageru and Futatabi. This goes both ways.
+
+First, Futatabi can consume :ref:`Nageru's tally data <tally>` like any camera
+can; give the correct channel URL to *--tally-url* on the Futatabi command line,
+and the color around the live view will show up when you are ready or playing
+(e.g. *--tally-url http://nageru-server.example.org:9096/channels/2*).
+
+Second, Futatabi can export its current status in two ways. The simplest is
+through a REST call; the HTTP server that exposes the stream also exposes
+the endpoint */queue_status* (e.g. http://futatabi-server.example.org:9096/queue_status).
+This contains the same text as is below the live window, ie., how much time
+is queued or left.
+
+The same status is also exported programmatically in the video output from
+Futatabi, as a subtitle track. This allows the Nageru theme not only to display
+it if desired, but even to act automatically to switch to a different channel
+when the playlist is nearing its end. (See :ref:`subtitle-ingest` for information
+on how to digest such information from the Nageru side.)
+
+Each subtitle entry is displayed momentarily before the frame it belongs to,
+and has the following format:
+
+ Futatabi 1.8.2;PLAYING;6.995;0:06.995 left
+
+The semicolon-separated columns are as follows:
+
+ * The first column is the identifier for the Futatabi version in use; if the format
+ should ever diverge between versions, it can serve as a way to distinguish between
+ them if needed. (The version may also change without the format changing.)
+ For now, however, you can ignore it.
+ * The second column is either PLAYING or PAUSED, depending on the current status.
+ * The third column is how many seconds is queued up (PAUSED) or remaining (PLAYING).
+ It is always in C locale, no matter what the user has set (ie., the decimal point
+ will always be a period). Note that this does not take into account the master
+ speed (see :ref:`speed`).
+ * Finally, the fourth column is a human-readable string, the same as is exposed
+ on the /queue_status endpoint above.
+
Prometheus metrics
''''''''''''''''''
+
+Like Nageru, Futatabi supports a series of Prometheus metrics for monitoring;
+see :doc:`monitoring` for general information. Futatabi provides entirely different
+metrics, though, mostly related to performance. There is no predefined Grafana
+dashboard available at the current time.
projects / nageru-docs / blobdiff