too high, and you might not want to involve a full extra PC just for this
anyway.
-Thus, since 1.5.0, Nageru supports using a spare output card for HDMI/SDI
+Thus, Nageru supports using a spare output card for HDMI/SDI
output, turning it into a simple, reasonably low-latency audio/video switcher.
Setting up HDMI/SDI output
--------------------------
-Turning on HDMI/SDI output is simple; just right-click on the live view and
+To turn on HDMI/SDI output, right-click on the live view and
select the output card. (Equivalently, you can access the same functionality
from the *Video* menu in the regular menu bar, or you can give the
*--output-card=* parameter on the command line.) Currently, this is supported
A video mode will automatically be picked for you, favoring 59.94 fps if possible,
but you can change the mode on-the-fly to something else if you'd like,
as long as the resolution matches with what you've set up at program start.
-Note that whenever HDMI/SDI output is active, the output card will be the
+
+
+Unsynchronized HDMI/SDI output
+------------------------------
+
+By default, whenever HDMI/SDI output is active, the output card will be the
master clock; you cannot change it to any of the input cards. This also means
that the frame rate you choose here will determine the frame rate for the
stream.
+In Nageru 2.1.0 or newer, you can use the flag --output-card-unsynchronized
+to counteract this (there is currently no way to do it from the GUI).
+This is for if you want just a monitor output without synchronizing
+your entire stream chain to the output card (ie., you want to keep
+some other camera as the master). Sound support is untested, and is
+probably going to crackle a fair bit.
+
A note on latency
-----------------
In order to optimize latency, it can be useful to measure it, but for most
people, it's hard to measure delays precisely enough to distinguish reliably
-between e.g. 70 and 80 milliseconds by eye alone. Nageru gives you some simple
+between e.g. 70 and 80 milliseconds by eye alone. Nageru gives you some
tools that will help.
The most direct is the flag *--print-video-latency*. This samples, for every
over a single *output* frame; it is *not* a measurement over the last 100
output frames, even though the statistics are only printed every 100th.
+For more precise measurements, you can use Prometheus metrics to get percentiles
+for all of these points, which will measure over all frames (over a one-minute
+window). This yields more precise information than sampling every 100 frames,
+but setting up Prometheus and a graphic tool is a bit more work, and usually not
+worth it for simple measurement. For more information, see :doc:`monitoring`.
+
Another trick that can be useful in some situations is *looping* your signal,
ie., connecting your output back into your input. This allows you to measure
delays that don't happen within Nageru itself, like any external converters,
sure your A/V chain passes the signal through without quality degradation,
if you first set up a static picture as a signal and then switch to the loop
input to verify that the signal stays stable without color e.g. shifts [#]_.
-See the section on :
ref:`the frame analyzer <analyzer>` for other ways of
+See the section on :
doc:`the frame analyzer <analyzer>` for other ways of
debugging signal integrity.)
For this, the *timecode output* is useful; you can turn it on from the Video
projects / nageru-docs / blobdiff