spice图形显示优化
Gstreamer框架介绍
GStreamer是基于管道的多媒体框架。
Gstreamer是一个libraries和plugins的集合，用于帮助实现各种类型的多媒体应用程序，比如播放器，转码工具，多媒体服务器等
GStreamer插件可以分为:
- 协议处理
- 来源：音频和视频（涉及协议插件）
- 格式：解析器，格式化器，复用器，分离器，元数据，字幕
- 编解码器：编码器和解码器
- 过滤器：转换器，混音器，效果器，…
- 接收器：用于音频和视频（涉及协议插件）
GStreamer包:
- gstreamer: 核心包，包含一些基础元素和基本的应用程序gst-inspect和gst-launch
- gst-plugins-base: 基本示例性元素集
- gst-plugins-good: 此组插件中的元素具有LGPL认证
- gst-plugins-bad: 此组插件接近高品质，但是缺乏认证
- gst-plugins-ugly: 插件可能品质良好，但是会出现部署上的问题
- gst-libav: 使用libav的编解码库(libav是从ffmpeg分出的实现多种音视频编解码及转换的函数库)
- gst-plugins-vaapi: 包含可以使用vaapi的各元素
bin
多个element构成的特殊的element
pipeline
是一个特殊的bin,具有全局的时钟，有四种可能的状态，分别是NULL，READY，PAUSED，PLAYING。NULL和READY状态下，element不对数据做任何处理，PLAYING状态对数据进行处理，PAUSE状态介于两者之间，对数据进行preroll。应用程序通过函数调用控制pipeline在不同状态之间进行转换。，应用程序通过控制管道的状态进行数据流的传输。
elements
element是pipeline的最小组成部分。element提供了多个pads，或者为sink，或者为source。elements的输入叫做sink pads，输出叫做source pads。应用程序通过pad把element连接起来构成pipeline，如下图所示，其中顺着流的方向为downstream，相反方向是upstream
$ gst-inspect-1.0 x264enc
Factory Details:
Rank primary (256)
Long-name x264enc
Klass Codec/Encoder/Video
Description H264 Encoder
Author Josef Zlomek <josef.zlomek@itonis.tv>, Mark Nauwelaerts <mnauw@users.sf.net>
Plugin Details:
Name x264
Description libx264-based H264 plugins
Filename /usr/lib/x86_64-linux-gnu/gstreamer-1.0/libgstx264.so
Version 1.8.3
License GPL
Source module gst-plugins-ugly
Source release date 2016-08-19
Binary package GStreamer Ugly Plugins (Ubuntu)
Origin URL https://launchpad.net/distros/ubuntu/+source/gst-plugins-ugly1.0
GObject
+----GInitiallyUnowned
+----GstObject
+----GstElement
+----GstVideoEncoder
+----GstX264Enc
Implemented Interfaces:
GstPreset
Pad Templates:
SINK template: 'sink'
Availability: Always
Capabilities:
video/x-raw
format: { I420, YV12, Y42B, Y444, NV12, I420_10LE, I422_10LE, Y444_10LE }
framerate: [ 0/1, 2147483647/1 ]
width: [ 16, 2147483647 ]
height: [ 16, 2147483647 ]
SRC template: 'src'
Availability: Always
Capabilities:
video/x-h264
framerate: [ 0/1, 2147483647/1 ]
width: [ 1, 2147483647 ]
height: [ 1, 2147483647 ]
stream-format: { avc, byte-stream }
alignment: au
profile: { high-4:4:4, high-4:2:2, high-10, high, main, baseline, constrained-baseline, high-4:4:4-intra, high-4:2:2-intra, high-10-intra }
Element Flags:
no flags set
Element Implementation:
Has change_state() function: gst_video_encoder_change_state
Element has no clocking capabilities.
Element has no URI handling capabilities.
Pads:
SINK: 'sink'
Pad Template: 'sink'
SRC: 'src'
Pad Template: 'src'
Element Properties:
name : The name of the object
flags: readable, writable
String. Default: "x264enc0"
parent : The parent of the object
flags: readable, writable
Object of type "GstObject"
threads : Number of threads used by the codec (0 for automatic)
flags: readable, writable
Unsigned Integer. Range: 0 - 2147483647 Default: 0
sliced-threads : Low latency but lower efficiency threading
flags: readable, writable
Boolean. Default: false
sync-lookahead : Number of buffer frames for threaded lookahead (-1 for automatic)
flags: readable, writable
Integer. Range: -1 - 250 Default: -1
pass : Encoding pass/type
flags: readable, writable
Enum "GstX264EncPass" Default: 0, "cbr"
(0): cbr - Constant Bitrate Encoding
(4): quant - Constant Quantizer
(5): qual - Constant Quality
(17): pass1 - VBR Encoding - Pass 1
(18): pass2 - VBR Encoding - Pass 2
(19): pass3 - VBR Encoding - Pass 3
quantizer : Constant quantizer or quality to apply
flags: readable, writable
Unsigned Integer. Range: 0 - 50 Default: 21
multipass-cache-file: Filename for multipass cache file
flags: readable, writable
String. Default: "x264.log"
byte-stream : Generate byte stream format of NALU
flags: readable, writable
Boolean. Default: false
bitrate : Bitrate in kbit/sec
flags: readable, writable, changeable in NULL, READY, PAUSED or PLAYING state
Unsigned Integer. Range: 1 - 2048000 Default: 2048
intra-refresh : Use Periodic Intra Refresh instead of IDR frames
flags: readable, writable
Boolean. Default: false
vbv-buf-capacity : Size of the VBV buffer in milliseconds
flags: readable, writable, changeable in NULL, READY, PAUSED or PLAYING state
Unsigned Integer. Range: 0 - 10000 Default: 600
me : Integer pixel motion estimation method
flags: readable, writable
Enum "GstX264EncMe" Default: 1, "hex"
(0): dia - dia
(1): hex - hex
(2): umh - umh
(3): esa - esa
(4): tesa - tesa
subme : Subpixel motion estimation and partition decision quality: 1=fast, 10=best
flags: readable, writable
Unsigned Integer. Range: 1 - 10 Default: 1
analyse : Partitions to consider
flags: readable, writable
Flags "GstX264EncAnalyse" Default: 0x00000000, "(none)"
(0x00000001): i4x4 - i4x4
(0x00000002): i8x8 - i8x8
(0x00000010): p8x8 - p8x8
(0x00000020): p4x4 - p4x4
(0x00000100): b8x8 - b8x8
dct8x8 : Adaptive spatial transform size
flags: readable, writable
Boolean. Default: false
ref : Number of reference frames
flags: readable, writable
Unsigned Integer. Range: 1 - 12 Default: 1
bframes : Number of B-frames between I and P
flags: readable, writable
Unsigned Integer. Range: 0 - 4 Default: 0
b-adapt : Automatically decide how many B-frames to use
flags: readable, writable
Boolean. Default: true
b-pyramid : Keep some B-frames as references
flags: readable, writable
Boolean. Default: false
weightb : Weighted prediction for B-frames
flags: readable, writable
Boolean. Default: false
sps-id : SPS and PPS ID number
flags: readable, writable
Unsigned Integer. Range: 0 - 31 Default: 0
aud : Use AU (Access Unit) delimiter
flags: readable, writable
Boolean. Default: true
trellis : Enable trellis searched quantization
flags: readable, writable
Boolean. Default: true
key-int-max : Maximal distance between two key-frames (0 for automatic)
flags: readable, writable
Unsigned Integer. Range: 0 - 2147483647 Default: 0
cabac : Enable CABAC entropy coding
flags: readable, writable
Boolean. Default: true
qp-min : Minimum quantizer
flags: readable, writable
Unsigned Integer. Range: 0 - 51 Default: 10
qp-max : Maximum quantizer
flags: readable, writable
Unsigned Integer. Range: 0 - 51 Default: 51
qp-step : Maximum quantizer difference between frames
flags: readable, writable
Unsigned Integer. Range: 0 - 50 Default: 4
ip-factor : Quantizer factor between I- and P-frames
flags: readable, writable
Float. Range: 0 - 2 Default: 1.4
pb-factor : Quantizer factor between P- and B-frames
flags: readable, writable
Float. Range: 0 - 2 Default: 1.3
mb-tree : Macroblock-Tree ratecontrol
flags: readable, writable
Boolean. Default: true
rc-lookahead : Number of frames for frametype lookahead
flags: readable, writable
Integer. Range: 0 - 250 Default: 40
noise-reduction : Noise reduction strength
flags: readable, writable
Unsigned Integer. Range: 0 - 100000 Default: 0
interlaced : Interlaced material
flags: readable, writable
Boolean. Default: false
option-string : String of x264 options (overridden by element properties)
flags: readable, writable
String. Default: ""
speed-preset : Preset name for speed/quality tradeoff options (can affect decode compatibility - impose restrictions separately for your target decoder)
flags: readable, writable
Enum "GstX264EncPreset" Default: 6, "medium"
(0): None - No preset
(1): ultrafast - ultrafast
(2): superfast - superfast
(3): veryfast - veryfast
(4): faster - faster
(5): fast - fast
(6): medium - medium
(7): slow - slow
(8): slower - slower
(9): veryslow - veryslow
(10): placebo - placebo
psy-tune : Preset name for psychovisual tuning options
flags: readable, writable
Enum "GstX264EncPsyTune" Default: 0, "none"
(0): none - No tuning
(1): film - Film
(2): animation - Animation
(3): grain - Grain
(4): psnr - PSNR
(5): ssim - SSIM
tune : Preset name for non-psychovisual tuning options
flags: readable, writable
Flags "GstX264EncTune" Default: 0x00000000, "(none)"
(0x00000001): stillimage - Still image
(0x00000002): fastdecode - Fast decode
(0x00000004): zerolatency - Zero latency
frame-packing : Set frame packing mode for Stereoscopic content
flags: readable, writable
Enum "GstX264EncFramePacking" Default: -1, "auto"
(-1): auto - Automatic (use incoming video information)
(0): checkerboard - checkerboard - Left and Right pixels alternate in a checkerboard pattern
(1): column-interleaved - column interleaved - Alternating pixel columns represent Left and Right views
(2): row-interleaved - row interleaved - Alternating pixel rows represent Left and Right views
(3): side-by-side - side by side - The left half of the frame contains the Left eye view, the right half the Right eye view
(4): top-bottom - top bottom - L is on top, R on bottom
(5): frame-interleaved - frame interleaved - Each frame contains either Left or Right view alternately
Presets:
"Profile Baseline"
"Profile High"
"Profile Main"
"Quality High"
"Quality Low"
"Quality Normal"
数据流
Gstreamer支持两种类型的数据流，分别是push模式和pull模式。在push模式下，upstream的element通过调用downstream的sink pads的函数实现数据的传送。在pull模式下，downstream的element通过调用upstream的source pads的函数实现对数据的请求。
在pads之间传送的数据封装在Buffer里，Buffer中有一个指向实际数据的指针以及一些metadata。metadata的内容包括：
- 时间戳
- 偏移
- 媒体类型
- 其他
spice中gstreamer的使用
static int spice_gst_encoder_encode_frame(VideoEncoder *video_encoder,
uint32_t frame_mm_time,
const SpiceBitmap *bitmap,
const SpiceRect *src, int top_down,
gpointer bitmap_opaque,
VideoBuffer **outbuf)
{
//..........
if (rate_control_is_active(encoder) &&
(handle_server_drops(encoder, frame_mm_time) ||
frame_mm_time < encoder->next_frame_mm_time)) {
/* Drop the frame to limit the outgoing bit rate. */
return VIDEO_ENCODER_FRAME_DROP;
}
if (!configure_pipeline(encoder)) {
encoder->errors++;
return VIDEO_ENCODER_FRAME_UNSUPPORTED;
}
uint64_t start = spice_get_monotonic_time_ns();
int rc = push_raw_frame(encoder, bitmap, src, top_down, bitmap_opaque);
if (rc == VIDEO_ENCODER_FRAME_ENCODE_DONE) {
rc = pull_compressed_buffer(encoder, outbuf);
if (rc != VIDEO_ENCODER_FRAME_ENCODE_DONE) {
/* The input buffer will be stuck in the pipeline, preventing
* later ones from being processed. Furthermore something went
* wrong with this pipeline, so it may be safer to rebuild it
* from scratch.
*/
free_pipeline(encoder);
encoder->errors++;
}
}
//...........
}
static int push_raw_frame(SpiceGstEncoder *encoder,
const SpiceBitmap *bitmap,
const SpiceRect *src, int top_down,
gpointer bitmap_opaque)
{
//........对当前帧进行一些处理
GstFlowReturn ret = gst_app_src_push_buffer(encoder->appsrc, buffer);
if (ret != GST_FLOW_OK) {
spice_warning("GStreamer error: unable to push source buffer (%d)", ret);
return VIDEO_ENCODER_FRAME_UNSUPPORTED;
}
return VIDEO_ENCODER_FRAME_ENCODE_DONE;
}
gstreamer管道创建样例程序
/*
程序运行结果与命令行执行
gst-launch-1.0 filesrc location=/home/x/work/test.mp4 ! qtdemux ! avdec_h264 ! autovideosink
的结果相同
*/
#include <stdlib.h>
#include <gst/gst.h>
int main(int argc, char* argv[])
{
GstElement *pipeline;
GstElement *filesrc;
GstMessage *msg;
GstBus *bus;
GError *error = NULL;
gst_init(&argc, &argv);
if(argc != 2)
{
g_print("usage: %s <filename>\n", argv[0]);
return -1;
}
pipeline = gst_parse_launch("filesrc name=my_filesrc ! qtdemux ! avdec_h264 ! autovideosink", &error);
if(!pipeline)
{
g_print("Parse error: %s\n", error->message);
exit(1);
}
filesrc = gst_bin_get_by_name(GST_BIN(pipeline), "my_filesrc");
g_object_set(filesrc, "location", argv[1], NULL);
g_object_unref(filesrc);
gst_element_set_state(pipeline, GST_STATE_PLAYING);
bus = gst_element_get_bus(pipeline);
msg = gst_bus_poll (bus, GST_MESSAGE_EOS | GST_MESSAGE_ERROR, -1);
switch (GST_MESSAGE_TYPE (msg)) {
case GST_MESSAGE_EOS: {
g_print ("EOS\n");
break;
}
case GST_MESSAGE_ERROR: {
GError *err = NULL; /* error to show to users */
gchar *dbg = NULL; /* additional debug string for developers */
gst_message_parse_error (msg, &err, &dbg);
if (err) {
g_printerr ("ERROR: %s\n", err->message);
g_error_free (err);
}
if (dbg) {
g_printerr ("[Debug details: %s]\n", dbg);
g_free (dbg);
}
}
default:
g_printerr ("Unexpected message of type %d", GST_MESSAGE_TYPE (msg));
break;
}
gst_message_unref (msg);
gst_element_set_state (pipeline, GST_STATE_NULL);
gst_object_unref (pipeline);
gst_object_unref (bus);
return 0;
}
gstream硬件编解码
环境搭建
特别说明： 以Nvidia K1显卡为例，gstreamer版本选取1.12
需要编译安装以下软件：
Cuda 8.0 toolkit—-显卡驱动要求367.xx及以上版本，k1显卡只能安装cuda8.0
Video-codec-sdk6.0—-nvenc编码sdk
Gstreamer1.12相应的库—–gstreamer1.12版本中加入了cuda8.0的支持，要在gstreamer中使用Nvenc，需要cuda>6.5,nvenc>5.0
Cuda下载地址：https://developer.nvidia.com/cuda-toolkit-archive
Video-codec-sdk下载地址：https://developer.nvidia.com/video-codec-sdk-archive
Gstreamer源码下载地址：https://gstreamer.freedesktop.org/src/
安装nvidia驱动
- 从官网下载nvidia驱动，版本要求367.xx。
- 在内核启动项增加nouveau.modeset=0rd.driver.blacklist=nouveau，然后重启
- 运行驱动程序的.run文件
安装cuda 8.0 toolkit
- 运行.run文件，除驱动安装选项其余全部选择yes。
- 执行vim /etc/profile,在文件末尾加上
exportPATH=/usr/local/cuda/bin:$PATH exportLD_LIBRARY_PATH=/usr/local/cuda/lib64:$LD_LIBRARY_PATH - cd /usr/local/cuda/samples
- make all
- cd bin执行deviceQuery程序，有输出则安装成功
安装video-codec-sdk6.0
- 解压nvidia_video_sdk_6.0.1.zip
cp -rf nvidia_video_sdk_6.0.1/Samples/common/inc /usr/local/include/nvenc
安装gstreamer-1.12
- 先安装gstreamer-1.12.2和gst-plugins-base-1.12.2,编译参数为
./configure --prefix=/usr --libdir=/lib64 exportPKG_CONFIG_PATH=/usr/local/cuda/pkgconfig/- 安装gst-plugins-bad-1.12.2,编译参数为
NVENCODE_CFLAGS="-I/usr/local/include/nvenc"./configure--prefix=/usr --libdir=/lib64 --disable-gtk-doc
安装完成之后执行gst-inspect-1.0 nvenc，如果有输出，则安装正常
k1初步测试
K1是kepler架构，核心是gk107,有4个gpu核心
#Gstreamer编码命令
gst-launch-1.0 -v filesrc location=/root/work/1080psrc ! videoparse format=i420 width=1920 height=1080 framerate=24/1 ! autovideoconvert ! nvh264enc ! fakesink
#1080psrc是30s视频源数据
nvidia显卡编码能力图如下:
使用1080p 30秒视频源进行编码测试，七进程同时进行24fps h264编码，且运行在k1的一个gpu芯片上，编码完成时间均为30-31s，每个进程的cpu占用率为23%，基本符合图中结论。
spice优化
spice服务端设置使用h264
spice服务端源码最新版中有一个函数spice_server_set_video_codecs(SpiceServer *s, const char* video_codecs),该函数可以由QEMU调用，在spice_server初始化时，若QEMU不指定某个特定编码，spice就传入默认编码。
默认编码是spice:mjpeg,gstreammer:mjpeg,gstreammer:h264,gstreammer:vp8,gstreammer:vp9组成的数组。
在使用时，默认使用spice内置mjpeg编码。
qemu指定使用视频编码
开发使用的是qemu2.7版本的源码，该版本还不支持在启动时设置视频编码，所以需要自己在代码中加入。
具体补丁如下(qemu-kvm 2.7版本)
diff -Naur qemu-kvm-2.7.0_old/qemu-options.hx qemu-kvm-2.7.0/qemu-options.hx
--- qemu-kvm-2.7.0_old/qemu-options.hx 2017-03-31 11:32:40.831770612 +0800
+++ qemu-kvm-2.7.0/qemu-options.hx 2017-03-20 10:15:10.000000000 +0800
@@ -1062,6 +1062,7 @@
" [,jpeg-wan-compression=[auto|never|always]]\n"
" [,zlib-glz-wan-compression=[auto|never|always]]\n"
" [,streaming-video=[off|all|filter]][,disable-copy-paste]\n"
+ " [,video-codecs=<encoder1>:<codec1>[;<encoder2>:<codec2>]]\n"
" [,disable-agent-file-xfer][,agent-mouse=[on|off]]\n"
" [,playback-compression=[on|off]][,seamless-migration=[on|off]]\n"
" [,gl=[on|off]]\n"
diff -Naur qemu-kvm-2.7.0_old/ui/spice-core.c qemu-kvm-2.7.0/ui/spice-core.c
--- qemu-kvm-2.7.0_old/ui/spice-core.c 2017-03-31 11:35:48.713154167 +0800
+++ qemu-kvm-2.7.0/ui/spice-core.c 2017-03-21 14:53:48.000000000 +0800
@@ -489,6 +489,9 @@
.name = "streaming-video",
.type = QEMU_OPT_STRING,
},{
+ .name = "video-codecs",
+ .type = QEMU_OPT_STRING,
+ },{
.name = "agent-mouse",
.type = QEMU_OPT_BOOL,
},{
@@ -787,6 +790,23 @@
} else {
spice_server_set_streaming_video(spice_server, SPICE_STREAM_VIDEO_OFF);
}
+ //qemu patch for add video-codecs begin
+ str = qemu_opt_get(opts, "video-codecs");
+ if (str){
+ #if SPICE_SERVER_VERSION >= 0x000c06
+ //#if 1
+ if(spice_server_set_video_codecs(spice_server, str)){
+ error_report("Invalid video codecs.");
+ exit(1);
+ }
+ #else
+ printf("%x\n",SPICE_SERVER_VERSION);
+ error_report("this qemu build does not support the "
+ "\"video-codecs\" option");
+ exit(1);
+ #endif
+ }
+ //qemu patch for add video-codecs end
spice_server_set_agent_mouse
(spice_server, qemu_opt_get_bool(opts, "agent-mouse", 1));
spice_server_set_playback_compression
使用该补丁后，可以通过命令行在-spice之后使用video-codecs=gstreamer:h264指定spice使用264编码。
通过libvirt定义xml文件生成虚拟机时，无法指定该参数。原因是libvirt的xml域没有定义该选项，所以只能在虚拟机xml文件中用以下形式定义
<domain type='' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
.......
<qemu:commandline>
<qemu:arg value='-spice'/>
<qemu:arg value=''port=5901,addr=0.0.0.0,agent-mouse=on,disable-ticketing,image-compression=auto_glz,streaming-video=filter,seamless-migration=on,video-codecs=gstreamer:h264''/>
</qemu:commandline
</domain>
注意：
- 一旦用
qemu:commandline这个节点来定义qemu的命令行参数，若某个选项需要指定多个参数，则所有的参数都只能通过这种方法指定。例如代码中的-spice选项，后面的参数有端口，地址等等，需要将xml中的这些定义删除，和video-codecs=gstreamer:h264写在一起 - 运行qemu的服务器上必须要安装gstreamer1.0的相关库，特别是h264需要有
gstreamer1-plugins-ugly这个库。检测是否支持h264的方法是命令行运行gst-inspect-1.0 x264enc，如果命令有输出，则表示当前环境支持264编码
spice客户端使用软解
spice-gtk源码编译安装后会产生spice-client的相关动态库和spicy二进制程序。盒子使用的就是spicy二进制程序和相关的动态库。而remote-viewer只使用了spice-client相关的动态库文件。所以在与spice server交互的时候两者没有太大差别。
spice客户端要使用软解，则运行环境也必须安装gstreamer1.0相关的库。
spice客户端使用硬解
spice客户端使用硬解主要有以下两种情况
- spice客户端没有识别出视频流的编码
- 在运行环境中设置
SPICE_GSTVIDEO_AUTO的值，无论值是多少，只要该环境变量被设置即可
本机环境下使用硬解打印信息如下：
Qemu Spice视频编码性能优化方案
rdp+显卡透传
使用k1显卡在win10系统中测试可行。去掉qxl显卡，只保留透传显卡，视频和3d软件都可以使用硬件加速。win7系统有问题(nvidia 显卡透传后安装驱动失败，error code 43)，目前还没有找到解决方法。
但是使用此种方案有一个问题是，更改显卡的时机(在虚拟机配置中去掉qxl，增加透传显卡)，因为vnc和spice配置后会自动添加qxl-vga设备，虚拟机装系统的界面目前只有通过vnc和spice可以看见。
更改spice服务端编码方案
spice使用gstreamer可以进行视频流的多种编码方案。
gstreamer插件中vaapi适用intel核显，vdpau只有解码器插件，最终选择了nvidia nvenc方案。在环境中配置cuda , video_codec_sdk后gstreamer-bad库才能编译nvenc元素
Qemu Spice视频编码性能测试报告
测试环境
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CPU ： Intel i3-4150 3.5GHz
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内存 ： 8G DDR 4
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显卡 ： Nvidia K1 (Driver 367.57， CUDA 8.0， Video Codec SDK 6.0)
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系统 ： CentOS 7.2.1511 X64
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虚拟机 ： Qemu 2.7 (Spice 0.13.3, GStreamer 1.12.2)，
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虚拟机参数 ： 4 Cores(2 Cores, 2 Threads), Windowd 7/10 X64
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测试视频 ： 1080P 三原色； 720P 分歧者
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测试工具 ： PotPlayer、top、nethogs
CPU性能测试
操作系统 编码器 编码格式 QXL 硬解 宿主机 客户机 客户端
Windows 7 SPICE MJPEG 是 否 135% 16% 40%
Windows 7 GStreamer MJPEG 是 否 180% 18% 46%
Windows 7 GStreamer H.264 是 否 210% 18% 50%
Windows 7 GStreamer VP8 是 否 184% 22% 36%
Windows 7 GStreamer H.264 是 是 160% 18% 50%
网络性能测试
操作系统 编码器 编码格式 QXL 硬解 宿主机 客户机 1080P 720P
Windows 7 SPICE MJPEG 是 否 123% 25% 7MB/s 3MB/s
Windows 7 SPICE MJPEG 否 否 187% 29% 10MB/s 12MB/s
Windows 10 SPICE MJPEG 否 否 300% 90% 14MB/s
Windows 7 GStreamer MJPEG 是 否 7MB/s 4MB/s
Windows 7 GStreamer H.264 是 否 1.0MB/s 0.8MB/s
Windows 7 GStreamer H.264 是 是 1.0MB/s 0.8MB/s
测试结论
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Windows 10中目前QXL驱动无法正常工作，只能使用VGA模式，CPU占用高，连720P视频都无法正常播放；
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只有QXL驱动能正确运行时，Spice才能生成视频流，否则只是产生图片，CPU和网络性能都很差，且视频十分卡顿；
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相比于SPICE编码器，使用GStreamer编码器的CPU消耗稍微偏高，但是网络带宽占用降低明显，视频无卡顿，且效果较好；
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使用NVENC进行硬件编码加速对性能的提升并不明显，只有25%左右，且对编码格式和参数有要求，存在兼容性问题，还需更多具体测试；
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使用GStreamer编码器的H.264编码格式的压缩率最高，带宽占用最小，但是CPU消耗较多；
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使用SPICE或GStreamer编码器的MJPEG编码格式的压缩率最低，带宽占用最高，但是CPU消耗较少。
优化建议
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要想视频流畅播放，必须保证QXL驱动能正常工作（初步分析，QXL驱动会通过IO端口协调Spice创建视频流，VGA模式则无法进行）；
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想要CPU占用率低，就使用SPICE编码器的MJPEG编码格式；
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想要网络带宽低，就使用GStreamer编码器的H.264编码格式。
