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--- appwiki:ffmpeg [2021/06/18 19:15] – [Common Convertion] ying
+++ appwiki:ffmpeg [2022/12/07 07:21] (current) – [Common Convertion] ying
@@ Line 56: / Line 56: @@
 ffmpeg.exe -i video.mp4 -c copy -ss 00:00:09 -to 00:00:21 video_cut.mp4
-# for some video start time need to be infront
+# -ss in front means: start time (from 9s), duration time (21s)
 ffmpeg.exe -ss 00:00:09 -i video.mp4 -c copy -to 00:00:21 video_cut.mp4
 </code>
+  * combine list of videos into 1 video
+    * ref: https://stackoverflow.com/questions/7333232/how-to-concatenate-two-mp4-files-using-ffmpeg
   * gif maker <code>
@@ Line 68: / Line 71: @@
 ffmpeg -i input0.mp4 -i input1.mp4 -i input2.mp4 -i input3.mp4 -filter_complex "[0:v][1:v]hstack=inputs=2[top]; [2:v][3:v]hstack=inputs=2[bottom]; [top][bottom]vstack=inputs=2[v]" -map "[v]" finalOutput.mp4
 </code>
+  * image to square size (like convert image to texture size format) <code>
+ffmpeg -i image.jpg -vf "scale=1024:1024:force_original_aspect_ratio=decrease,pad=1024:1024:-1:-1:color=white" -q:v 1 tex_image.jpg
+# longest side, so basically original size with padding to square
+ffmpeg -i image.jpg -vf "scale=max(iw\,ih):max(iw\,ih):force_original_aspect_ratio=decrease,pad=max(iw\,ih):max(iw\,ih):-1:-1:color=white" -q:v 1 tex_image.jpg
+</code>
+====== GIF related ======
+  * use every 1 from out of 10 frame from a huge frame-by-frame gif recording, and save as a 600px width gif <code dos>
+ffmpeg.exe -i big_recording.gif -vf "select=not(mod(n-1\,10)),scale=600:-1" -vsync vfr light_10th_600w.gif
+</code>