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H.264 encoding
Since v0.10.2, xrdp has supported H.264 encoding in graphics remoting, a feature already available in Windows-to-Windows remote desktop connections. H.264, also known as AVC (Advanced Video Coding), is a widely used video compression standard for high-definition video.
xrdp with H.264 encoding reduces the amount of data transmitted over the network and provides a much smoother, more responsive experience compared to previous versions when using graphics-intensive applications.
Currently, only software encoders are supported. xrdp supports x264 and OpenH264 as H.264 encoders.
According to developers' quick testing results, x264 provides a smoother experience than OpenH264 in the context of usage within xrdp. Therefore, we recommend using x264 if both encoders are available.
- mstsc.exe, bundled with Windows 10/11
Please check if xrdp has been compiled with H.264 enabled.
H.264 is available if you can see the string either --enable-x264 or --enable-openh264 in the result of xrdp --version.
$ xrdp --version
xrdp 0.10.2
A Remote Desktop Protocol Server.
Copyright (C) 2004-2024 Jay Sorg, Neutrino Labs, and all contributors.
See https://github.com/neutrinolabs/xrdp for more information.
Configure options:
--enable-imlib2
--enable-jpeg
--enable-painter
--enable-pam-config=freebsd
--enable-pixman
--enable-rfxcodec
--enable-strict-locations
--enable-x264
--enable-openh264
We recommend adding both --enable-x264 and --enable-openh264 to configure options if both encoders are available in the package repository. Then users can choose which encoder they prefer to use, either x264 or OpenH264.
H.264 encoding is a part of GFX extensions, so advanced settings can be configured in gfx.toml. As the filename indicates, this configuration file is in TOML format, version v1.0.0.
gfx.toml consists of the following sections:
- codec
- x264
- OpenH264
codec section defines priority of codecs and preferred H.264 encoder.
[codec]
order = [ "H.264", "RFX" ]
h264_encoder = "x264"order defines the priority of codecs. It is an array that contains H.264, RFX, or both. xrdp negotiates available codecs with clients, the first codec that the client supports will be used.
h264_encoder specifies a preferred H.264 encoder, either x264 or OpenH264. This parameter takes effect only when more than one encoder is enabled at compile time. If only one encoder is enabled at compile time, that encoder will be used, regardless of the value of this parameter. If the parameter is blank or invalid, it will default to x264.
x264 section defines encoding parameters that will be passed to x264. Only the parameters listed in the following example can be configured. See x264 --fullhelp for a detailed explanation of the parameters.
[x264.default]
# NOTE: x264 specifies bitrate in unit of kbps.
preset = "ultrafast"
tune = "zerolatency"
profile = "main" # profile is forced to baseline if preset == ultrafast
vbv_max_bitrate = 0
vbv_buffer_size = 0
fps_num = 60
fps_den = 1
[x264.lan]
# inherits default
[x264.wan]You can define six separate parameter sets for each network connection type selected on the client side. First, define the default parameter set in [x264.default]. Each connection type will inherit the parameter set defined by default, unless explicitly overridden.
List of available connection types:
- lan
- wan
- broadband_high
- satellite
- broadband_low
- modem
Currently, xrdp does not support connection type autodetection. If autodetection is selected on the client side, it will be treated as if LAN is selected.
OpenH264 section defines encoding parameters that will be passed to OpenH264. Only the parameters listed in the following example can be configured.
[OpenH264.default]
# NOTE: OpenH264 specifies bitrate in unit of bps, not kbps.
EnableFrameSkip = false
TargetBitrate = 20_000_000
MaxBitrate = 0 # unspecified
MaxFrameRate = 60.0
[OpenH264.lan]
# inherits default
[OpenH264.wan]The explanation for each parameter is as follows.
- EnableFrameSkip - allows the encoder to skip frames in order to keep the bitrate within the limits if it is about to exceed the maximum bitrate set by MaxBitrate.
- MaxBitrate - sets an upper limit on the bitrate in unit of bps.
- TargetBitrate - sets the desired average bitrate (in unit of bps) the encoder will attempt to achieve during the entire encoding process.
- MaxFrameRate - sets the maximum frame rate that the encoder will process per second.
You can define six separate parameter sets for each network connection type selected on the client side as well as x264. See x264 section above for details.