Various tweaks, including introductions from the README.

[nageru-docs] / hardware.rst

diff --git a/hardware.rst b/hardware.rst
index d116734d58b8e48b4c77855df2212e83f08104ec..9d157807c03a6ec7d7cdd56600b1085cbd5e894a 100644 (file)
--- a/hardware.rst
+++ b/hardware.rst
@@ -39,7 +39,7 @@ output as a sort of “digital intermediate” that can much easier be stored to
 (for future editing or re-streaming) or sent to an encoder on another machine
 for final streaming.
 
-Currently, only VA-API is supported for H.264 encoding, although Nageru might
+Currently, only VA-API is supported for encoding the digital intermediate, although Nageru might
 support NVIDIA's NVENC at some point in the future. In particular, this means that Intel Quick
 Sync Video (QSV), the hardware H.264 encoder present on all modern Intel
 GPUs, is supported. QSV is more than fast enough to keep up with 720p60 in
@@ -52,13 +52,14 @@ constant bitrate, which means the bitrate will vary strongly with content.
 further editing or transcoding without strong generational loss.) Thus, the
 QSV stream is not intended for streaming to end users of the Internet; it will
 need to be reencoded by some external means, or you can use Nageru's x264
-support (see `:doc:Streaming`).
+support to produce a user-facing stream in addition to the digital intermediate
+(see :doc:`streaming`).
 
 By default, Nageru uses zerocopy from the GPU to the VA-API buffers in order to
 reduce memory transfer bandwidth, but this depends on EGL support (as opposed to
 the older GLX standard), and also that the GPU you are rendering to also
 supports VA-API. NVIDIA's proprietary drivers do not support either. Unfortunately,
-this is somewhat cumbersoe  to automatically detect before it's too late to do anything
+this is somewhat cumbersome to automatically detect before it's too late to do anything
 about it (Qt has already initialized using EGL), so on NVIDIA
 systems, Nageru will exit with an error message asking you to set *--va-display*
 to your Intel GPU manually. Simply follow the instructions printed to the terminal
@@ -115,9 +116,26 @@ interlaced input, Nageru will automatically deinterlace for you.
 Frame rates are automatically converted; one input is designated as the
 **master clock** (right-click on an input to select it as such), and gets
 to dictate the frame rate of the output. Inputs with differing frame rates
-will get frames duplicated or dropped as needed (with adaptive queueing to
+will get frames duplicated or dropped as needed (with adaptive queuing to
 account for clock and jitter).
 
 Nageru works in 16-bit floating-point RGBA internally. High-quality conversion to and
 from subsampled Y'CbCr (typically 4:2:2 for inputs and 4:2:0 for outputs)
 is done transparently on the GPU.
+
+
+Performance tips
+----------------
+
+It is strongly recommended to have the rights to run at real-time priority;
+it will make the USB3 threads do so, which will make them a lot more stable.
+(A reasonable hack for testing is probably just to run it as root using sudo,
+although you might not want to do that in production, but instead grant
+your regular user permissions in /etc/security/limits.conf.) Note also that if you
+are running a desktop compositor, it will steal significant amounts of GPU
+performance. The same goes for PulseAudio.
+
+Nageru tries to lock itself into RAM if it has the permissions to do
+so, for better realtime behavior. (Writing the stream to disk tends to
+fill the buffer cache, eventually paging less-used parts of Nageru out.)
+Again, this is something you can set in limits.conf.