Write about CasparCG integration.

[nageru-docs] / hardware.rst

diff --git a/hardware.rst b/hardware.rst
index 9d157807c03a6ec7d7cdd56600b1085cbd5e894a..5d27401bdf9eca1ac3e91cad45bb197413339ac8 100644 (file)
--- a/hardware.rst
+++ b/hardware.rst
@@ -29,8 +29,8 @@ that you have the latest drivers for your GPU.
 
 .. _digital-intermediate:
 
-VA-API H.264 encoding
----------------------
+VA-API H.264 encoding (optional)
+--------------------------------
 
 Even on modern networks and with today's large SSDs, uncompressed HD video is a
 bit unwieldy to send around (uncompressed 720p60 4:2:0 is about 79 MB/sec,
@@ -39,10 +39,15 @@ 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 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
+Although you can (since Nageru 1.5.0) use software encoding through x264 for
+the digital intermediate, it is generally preferred to use a hardware encoder
+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.
+
+QSV is more than fast enough to keep up with 720p60 in
 realtime without eating appreciably into the power budget, but it is not
 competitive with the top H.264 encoders in terms of quality per bit. Also,
 the stream is encoded using *constant quality* (fixed quantizer), not
@@ -121,7 +126,14 @@ 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.
+is done transparently on the GPU. Input and output is 8-bit Y'CbCr by default,
+but be aware that 8-bit Y'CbCr, however common, cannot capture the full color
+fidelity of 8-bit RGB (not to mention 10-bit RGB). If you have spare GPU power,
+you can enable 10-bit Y'CbCr input and output with --10-bit-input and
+--10-bit-output, respectively, although you should be aware that client
+support for 10-bit H.264 is very limited. Also, Quick Sync Video does not
+support 10-bit H.264 encoding, so in this case, the digital intermediate needs
+to be encoded in software.
 
 
 Performance tips