@[TOC](FPV Camera(RPI3+V2.1) | wfb_ng Release 23.01 | Ubuntu 20.04 xfce软解测试)

1. 简介

与其他Linux桌面系统相比，Xfce消耗更少的CPU，仅使用1%的CPU。因此低CPU是Xfce的独特卖点之一。在FPV Camera(RPI3+V2.1) | wfb_ng Release 23.01 | Intel® Core™2 Duo CPU T6570 @ 2.10GHz 测试上，发现genome在720P 60FPS时，H264解码占用大量CPU资源，因此我们尝试减少桌面系统对CPU的占用率来看看有什么新的发现。

2. 安装xfce

xfce安装

$ sudo apt install tasksel
$ sudo tasksel install xubuntu-desktop
$ sudo apt install xfce4
$ sudo apt install xfce4-goodies

浏览器firefox无法上网，使用chromium替换

$ sudo apt-get remove firefox
$ sudo apt-get install chromium-browser

重启系统使用xfce桌面

$ sudo reboot

3. 测试

3.1 gst-launch-1.0 1280x720 720P 30FPS

gst-launch-1.0 v4l2src do-timestamp=true io-mode=mmap device=/dev/video0 \extra-controls="controls,image_stabilization=1,h264_profile=4,h264_i_frame_period=60,h264_level=11,power_line_frequency=1,exposure_metering_mong=1,exposure_dynamic_framerate=0,scene_mode=0,video_bitrate_mode=1,video_bitrate=2000000,repeat_sequence_header=1" \! video/x-h264,profile=high,width=1280,height=720,framerate=30/1,stream-format=byte-stream \! h264parse disable-passthrough=true ! rtph264pay config-interval=1 pt=96 mtu=1400 aggregate-mode=zero-latency ! udpsink host=127.0.0.1 port=5602 sync=false

gst1280x720@fps30

3.2 gst-launch-1.0 1280x720 720P 45FPS

gst-launch-1.0 v4l2src do-timestamp=true io-mode=mmap device=/dev/video0 \extra-controls="controls,image_stabilization=1,h264_profile=4,h264_i_frame_period=60,h264_level=11,power_line_frequency=1,exposure_metering_mong=1,exposure_dynamic_framerate=0,scene_mode=0,video_bitrate_mode=1,video_bitrate=2000000,repeat_sequence_header=1" \! video/x-h264,profile=high,width=1280,height=720,framerate=45/1,stream-format=byte-stream \! h264parse disable-passthrough=true ! rtph264pay config-interval=1 pt=96 mtu=1400 aggregate-mode=zero-latency ! udpsink host=127.0.0.1 port=5602 sync=false

gst1280x720fxce@fps45

3.3 gst-launch-1.0 1280x720 720P 60FPS

gst-launch-1.0 v4l2src do-timestamp=true io-mode=mmap device=/dev/video0 \extra-controls="controls,image_stabilization=1,h264_profile=4,h264_i_frame_period=60,h264_level=11,power_line_frequency=1,exposure_metering_mong=1,exposure_dynamic_framerate=0,scene_mode=0,video_bitrate_mode=1,video_bitrate=2000000,repeat_sequence_header=1" \! video/x-h264,profile=high,width=1280,height=720,framerate=60/1,stream-format=byte-stream \! h264parse disable-passthrough=true ! rtph264pay config-interval=1 pt=96 mtu=1400 aggregate-mode=zero-latency ! udpsink host=127.0.0.1 port=5602 sync=false

gst1280x720fxce@fps60

3.4 gst-launch-1.0 800x600 SVGA 60FPS

gst-launch-1.0 v4l2src do-timestamp=true io-mode=mmap device=/dev/video0 \extra-controls="controls,image_stabilization=1,h264_profile=4,h264_i_frame_period=60,h264_level=11,power_line_frequency=1,exposure_metering_mong=1,exposure_dynamic_framerate=0,scene_mode=0,video_bitrate_mode=1,video_bitrate=2000000,repeat_sequence_header=1" \! video/x-h264,profile=high,width=800,height=600,framerate=60/1,stream-format=byte-stream \! h264parse disable-passthrough=true ! rtph264pay config-interval=1 pt=96 mtu=1400 aggregate-mode=zero-latency ! udpsink host=127.0.0.1 port=5602 sync=false

gst800x600fxce@fps60

3.5 gst-launch-1.0 640x480 VGA 60FPS

gst-launch-1.0 v4l2src do-timestamp=true io-mode=mmap device=/dev/video0 \extra-controls="controls,image_stabilization=1,h264_profile=4,h264_i_frame_period=60,h264_level=11,power_line_frequency=1,exposure_metering_mong=1,exposure_dynamic_framerate=0,scene_mode=0,video_bitrate_mode=1,video_bitrate=2000000,repeat_sequence_header=1" \! video/x-h264,profile=high,width=640,height=480,framerate=60/1,stream-format=byte-stream \! h264parse disable-passthrough=true ! rtph264pay config-interval=1 pt=96 mtu=1400 aggregate-mode=zero-latency ! udpsink host=127.0.0.1 port=5602 sync=false

gst640x480fxce@fps60

3.6 gst-launch-1.0 480x320 HVGA 60FPS

gst-launch-1.0 v4l2src do-timestamp=true io-mode=mmap device=/dev/video0 \extra-controls="controls,image_stabilization=1,h264_profile=4,h264_i_frame_period=60,h264_level=11,power_line_frequency=1,exposure_metering_mong=1,exposure_dynamic_framerate=0,scene_mode=0,video_bitrate_mode=1,video_bitrate=2000000,repeat_sequence_header=1" \! video/x-h264,profile=high,width=480,height=320,framerate=60/1,stream-format=byte-stream \! h264parse disable-passthrough=true ! rtph264pay config-interval=1 pt=96 mtu=1400 aggregate-mode=zero-latency ! udpsink host=127.0.0.1 port=5602 sync=false

gst480x320fxce@fps60

4. 总结

4.1 1280x720 720P 30FPS x 3张清晰延时，统计平均 128ms，最小128ms，最大128ms

• 第一张：1019 - 891= 128 ms

• 第二张：531 - 403= 128 ms

• 第三张：843 - 715= 128 ms

4.2 1280x720 720P 45FPS x 3张清晰延时，统计平均 85ms，最小80ms，最大88ms

• 第一张：179 - 91 = 88 ms
  

• 第二张：331 - 243 = 88 ms
  

• 第三张：187 - 107= 80 ms

4.3 1280x720 720P 60FPS - 视频卡顿

鉴于该模式下，整体视频出现卡顿，延时测试取消。

4.4 800x600 SVGA 60FPS x 3张清晰延时，统计平均 85ms，最小80ms，最大88ms

• 第一张：523 - 435 = 88 ms

• 第二张：603 - 515 = 88 ms
  

• 第三张：499 - 419 = 80 ms

4.5 640x480 VGA 60FPS x 3张清晰延时，统计平均 56ms，最小40ms，最大80ms

• 第一张：323 - 283 = 40 ms

• 第二张：315 - 267 = 48 ms

• 第三张：643 - 563 = 80 ms

4.6 480x320 HVGA 60FPS x 3张清晰延时，统计平均 48ms，最小48ms，最大48ms

• 第一张：219 - 171 = 48 ms

• 第二张：379 - 331 = 48 ms

• 第三张：283 - 235 = 48 ms

4.5 视频延时测试结果

• 1280x720 720P 30FPS x 3张清晰延时，统计平均 128ms，最小128ms，最大128ms
• 1280x720 720P 45FPS x 3张清晰延时，统计平均 85ms，最小80ms，最大88ms
• 1280x720 720P 60FPS - 卡顿
• 800x600 SVGA 60FPS x 3张清晰延时，统计平均 85ms，最小80ms，最大88ms
• 640x480 VGA 60FPS x 3张清晰延时，统计平均 56ms，最小40ms，最大80ms
• 480x320 HVGA 60FPS x 3张清晰延时，统计平均 48ms，最小48ms，最大48ms

5. 参考资料

【1】wfb-ng Release 23.01镜像无头烧录&配置(2)
【2】wfb-ng Release 23.01镜像无头烧录&配置(1)
【3】wfb-ng 锁定WiFi接口
【4】Raspbian镜像无头烧录
【5】FPV Camera(RPI3+V2.1) | wfb_ng Release 23.01 | Intel® Core™2 Duo CPU T6570 @ 2.10GHz 测试
【6】How to install a web browser in XFCE?
【7】How install XFCE and remove gnome on Ubuntu 20.0.4 LTS
【8】How to Install XFCE Desktop or Xubuntu in Ubuntu 22.04|20.04
【9】Gnome vs Xfce Differences