On 8/3/19 10:09 AM, Suhail Doshi wrote:
Hi there,
My goal is to try get the frame of a desktop to do low-latency remote
desktop. I am interested in using X11 as the window manager.
When I run nvidia-smi, I noticed that X11 is a process that interacts
the GPU:
+-----------------------------------------------------------------------------+
| Processes: GPU
Memory |
| GPU PID Type Process name Usage
|
|=============================================================================|
| 0 3255 G /usr/lib/xorg/Xorg
57MiB |
| 0 3286 G /usr/bin/gnome-shell
81MiB |
+-----------------------------------------------------------------------------+
My question is: Is there a way to get an image of the desktop that
returns a pointer that's GPU memory? For example, in Windows 10, there's
an API called the Desktop Duplication API which will allows you to do
this. Then, it lets you copy the data in that GPU memory block to
another one such that you can encode the frame with H264, for example. I
am using NVIDIA GPUs and utilizing their NVENC SDK.
The video memory used for the desktop is not directly accessible by the CPU.
I am looking for an equivalent.
Right now, it appears that XShmGetImage returns the frame of the desktop
in host memory versus device memory which increases latency by 5-10ms.
For our purposes, a reduction of 5ms is meaningful.
CPU-mapped device memory is likely much slower to access than you think,
so XShmGetImage is probably much faster than the CPU-mapped approach
you're thinking of.
What it sounds like you're looking for is the NVIDIA Capture SDK, which
provides an API that applications can use to capture frames into video
memory and do on-GPU encoding to H.264 before streaming to system memory.
You can find more information at
https://developer.nvidia.com/capture-sdk
Sincerely,
Aaron
Should I use kernel-level APIs like interacting with Direct Rendering
Manager and Kernel Mode Setting to accomplish this instead?
Just looking for options. Thanks!
Suhail
--
Founder
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