问题描述
我需要捕获第二个显示器的屏幕并在一个窗口内的主显示器中监视"它(缩放为x0.5并使用邻居内插法，因为我更喜欢性能而不是质量).通过这个链接，我得到了以下截屏命令:
I need to capture the screen of the second display and "monitor" it in the main display, inside a window (scaled at x0.5 and with neighbor interpolation because I prefer performance against quality). From this link, I've got this screencast command:
gst-launch ximagesrc ! ffmpegcolorspace ! queue \
! vp8enc quality=10 speed=2 ! mux. alsasrc ! audio/x-raw-int ! queue \
! audioconvert ! vorbisenc ! mux. webmmux name=mux \
! filesink location=screencast.webm
...但是它捕获到文件(不是窗口)，缺少比例尺和插值类型，不需要声音等.
... but it capture to a file (not a window), it's missing the scale and interpolation type, the sounds is not necessary, etc.
正如我对libav的熟悉一样，我正在寻找的东西与此相似:
As I'm familiar with libav, what I'm looking for is something similar to this:
avconv -f x11grab -r 30 -s 1280x1024 -i :0.1 -c:v mpeg4 -b:v 1000k \
-vf "hflip" -vf "scale=640:480" -sws_flags "neighbor" -f avi - | avplay -i -
...我会用它，但是它在帧速率方面存在一些问题(询问).因此，我正在 Gstreamer 中寻找替代方案.
... I would use it, but it has some problems with the framerate (asked here). So, I'm looking for an alternative in Gstreamer.
推荐答案
以下是gst-launch命令:
Here is the gst-launch command:
gst-launch-1.0 ximagesrc startx=1280 use-damage=0 ! video/x-raw,framerate=30/1 ! videoscale method=0 ! video/x-raw,width=640,height=480 ! ximagesink
说明:
参数startx =从像素列" 1280开始记录-也就是说，如果有两个1280宽度的监视器，它将从右侧的一个开始.
parameter startx = start recording from "pixel column" 1280 - that is if you have two 1280 width monitors it will start with the one on the right side.
参数use-damage设置为0 =不要使用 XDamage .损坏仅计算后续帧之间的差异，这显然对CPU要求很高.
parameter use-damage set to 0 = do not use XDamage. damage counts only differences between subsequent frames which is apparantly quite CPU demanding.
元素ximagesink = X服务器创建的窗口作为输出-与glimagesink(opengl加速窗口)相比，它对CPU的要求更低.
element ximagesink = X server created window as output - its less CPU demanding than glimagesink (opengl accelerated window).
element videoscale参数method设置为0表示最接近的邻居，如Mario Mey在评论中建议的那样.这使我的CPU节省从17％降至12％.
element videoscale parameter method to 0 meaning nearest neighbor as suggested by Mario Mey in comment. This resulted for me in CPU save from 17% to 12%.
还有可配置的fps和显示窗口的高度/宽度(我认为它足够清晰).
There is also configurable fps and height/width of display window(I think its clear enough).
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