Write about Futatabi tally and talkback.

diff --git a/futatabi.rst b/futatabi.rst
index cb7c0dba5e69996e3e6b80fce764932d6eef1107..4de096e08943803e42571395020af08ae656584c 100644 (file)
--- a/futatabi.rst
+++ b/futatabi.rst
@@ -115,6 +115,11 @@ 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
@@ -289,5 +294,45 @@ Monitoring
 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
 ''''''''''''''''''

diff --git a/monitoring.rst b/monitoring.rst
index 6165e76a717bb31c2aaee11896ad2be5b2a09303..d5b490cd46ea117e7236ae0fe5c6cb48c4da5c54 100644 (file)
--- a/monitoring.rst
+++ b/monitoring.rst
@@ -32,6 +32,7 @@ some graphs could stop working. Of course, you can change the dashboard as you
 see fit; if you don't use e.g. HDMI/SDI output, you will probably want to
 remove the panels related to it.
 
+.. _tally:
 
 Tally display
 -------------