diff --git a/images/vlc.jpg b/images/vlc.jpg
new file mode 100644
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diff --git a/images/vlc.png b/images/vlc.png
deleted file mode 100644
index aec6b6f..0000000
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diff --git a/pdf/rk3588_guide.pdf b/pdf/rk3588_guide.pdf
index fb81c03..792a646 100644
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diff --git a/rk3588_guide.pdf b/rk3588_guide.pdf
index fb81c03..d319c11 100644
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diff --git a/rk3588_guide.tex b/rk3588_guide.tex
index 3f7d383..a37ee33 100644
--- a/rk3588_guide.tex
+++ b/rk3588_guide.tex
@@ -21,6 +21,15 @@
 %%%% 导言区
 %% 文档类型为article
 \special{dvipdfmx:config z 9}
+% PDF 压缩
+% gswin64c -sDEVICE=pdfwrite -dCompatibilityLevel=1.5 -dPDFSETTINGS=/default -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf  input.pdf
+% 
+% -dPDFSETTINGS 
+% -dPDFSETTINGS=/screen质量较低，体积较小。
+% -dPDFSETTINGS=/ebook更好的质量，但略大pdf。
+% -dPDFSETTINGS=/prepress输出类似于Acrobat Distiller ``Prepress Optimized``设置
+% -dPDFSETTINGS=/printer选择类似于Acrobat Distiller ``Print Optimized``设置的输出
+% -dPDFSETTINGS=/default选择用于各种用途的输出，可能会牺牲较大的输出文件
 \documentclass[a4paper,12pt,oneside]{book}
 %1m = 39.4 inch
 %大18开 （18.5cm * 23cm)
diff --git a/tex/resource.tex b/tex/resource.tex
index 3f16ab1..9136f9b 100644
--- a/tex/resource.tex
+++ b/tex/resource.tex
@@ -249,7 +249,6 @@ c=IN IP4 192.168.1.17
     \end{figure}
     如果一切正常可以在 vlc 里面看到 HDMI 输入的视频。
 \end{enumerate}
-
 \begin{comment}
 \begin{minted}[bgcolor=lightgray!30,fontsize=\tiny]{bash}
 gst-launch-1.0 v4l2src device=/dev/video0  ! video/x-raw,width=1920,height=1080,framerate=30/1 \