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
-----------------
and for HDMI/SDI output.
+.. _measuring-latency:
+
Measuring 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,
delays in the input driver, etc.. (It can also act as a sanity check to make
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 shifts e.g. [#]_)
+input to verify that the signal stays stable without color e.g. shifts [#]_.
+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
menu, or through the command-line flag *--timecode-stream*. (You can also
projects / nageru-docs / blobdiff