Document unsynchronized HDMI/SDI output.

[nageru-docs] / hardware.rst

diff --git a/hardware.rst b/hardware.rst
index 272330f3384ed973f495f9e87af6994a1ee4c9ca..1ff9b64fa2663ec83fc332bbbb3c8f86183446a7 100644 (file)
--- a/hardware.rst
+++ b/hardware.rst
@@ -14,11 +14,10 @@ high-quality (as in e.g. gamma-correct fades and high-quality scaling)
 HD video without a monster CPU, but it also comes with certain caveats.
 
 In particular, Nageru's use of multithreaded OpenGL trickles bugs in
-some drivers, as most games access the GPU from only one thread;
-Mesa didn't work properly at all before version 11.2, and there are still
-bugs left as of 13.0. However, in general, Intel GPUs from the Haswell
-generation and newer should work well with Nageru as long as you stick to
-720p60 (ie., no 1080i inputs, which require deinterlacing). NVIDIA's
+some drivers. in general, Intel GPUs from the Haswell
+generation and newer should work well with Nageru, although they may
+see performance issues if you connect interlaced sources (since the
+automatic deinterlacing applied requires a fair bit of computing power). NVIDIA's
 proprietary drivers (occasionally known as nvidia-glx) are generally excellent
 and should give few issues in this regard.
 
@@ -45,7 +44,8 @@ if it is available. Currently, VA-API is the only hardware encoding method
 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.
+Intel GPUs, is supported. If possible, Nageru uses zerocopy from the GPU to the
+VA-API buffers in order to reduce memory transfer bandwidth.
 
 QSV is more than fast enough to keep up with 720p60 in
 realtime without eating appreciably into the power budget, but it is not
@@ -58,10 +58,12 @@ 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 to produce a user-facing stream in addition to the digital intermediate
-(see :doc:`streaming`).
-
-If possible, Nageru uses zerocopy from the GPU to the VA-API buffers in order to
-reduce memory transfer bandwidth.
+(see :doc:`streaming`). You can also use x264 to produce the recording to disk
+instead of Quick Sync, using the --x264-record-video flag. If you wish to have
+separate flags for streaming and storing to disk (e.g., to keep a digital intermediate
+on disk), and have Nageru 2.1.0 or newer, you can use the --separate-x264-disk-encode flag (and associated
+--x264-separate-disk-bitrate flags etc.). Otherwise, the same stream will go
+to the network and to disk.
 
 
 Video capture cards