adding the scripts for preprocessing zoom recordings

Author: eglerean

zoom_preprocessing/README.md

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+# Preprocess zoom recordings
+
+In this folder there are three scripts (3 steps) to preprocess zoom recordings where a single speaker is sharing their screen and webcam so that the recorded video file shows the screenshare+webcam on the same frame.
+
+- Step1 trims the video (e.g. to remove introduction and post-talk discussions)
+- Step2 extracts pngs from the video to identify the coordinates for the screenshare and the webcam view of the speaker.
+- Step3 splits the zoom video into two sub-videos: the screenshare view and the webcam view, and then overlaps the webcam view on top of the screenshare on the top right corner. 
+
+Note: if the speaker is sharing something important in the top right corner, the webcam view will hide it.

zoom_preprocessing/s1_split_videos.sh

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+#!/bin/bash
+# This script runs on triton where the module "ffmpeg" is available. Alternatively, just make sure ffmpeg is visible from your PATH
+module load ffmpeg
+
+# For each video to process, find manually the starting time (parameter for -ss) and the length (paramter for -to)
+# Here below an example that was splitting two long zoom recordings into 4 shorter videos.
+
+ffmpeg  -ss 00:03:06 -i source_videos/1.mp4 -to 00:04:00 -c copy trimmed/1_1_episode1.mp4
+ffmpeg  -ss 00:00:24 -i source_videos/2.mp4 -to 00:18:06 -c copy trimmed/2_1_episode2.mp4
+ffmpeg  -ss 00:26:32 -i source_videos/2.mp4 -to 00:23:46 -c copy trimmed/2_2_episode2.mp4
+ffmpeg  -ss 01:09:10 -i source_videos/2.mp4 -to 00:16:51 -c copy trimmed/2_3_episode2.mp4
+

zoom_preprocessing/s2_get_crop_coordinates.sh

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+#!/bin/bash
+
+# This step is needed to identify the coordinates of the screen-share and of the "webcam" of the speaker. It basically saves pngs for one frame for each video and then manually one has to identify the coordinates for step3
+
+for n in $(find trimmed -name "*.mp4");do
+	bn=$(basename $n)
+	echo 'ffmpeg -i '$n' -vf "select=eq(n\,5000)" -vframes 1 frames/'$bn'.png'
+	ffmpeg -i $n -vf "select=eq(n\,5000)" -vframes 1 frames/$bn.png
+done
+

zoom_preprocessing/s3_trim_crop_merge.sh

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+#!/bin/bash
+# Episode 1
+# x y w h
+# screen: 6 176 2230 1250 
+# camera: 2240 710 320 164
+# crop out the screen
+ffmpeg -i trimmed/1_1_episode1.mp4 -filter:v "crop=2230:1250:6:176" -c:v libx264 -crf 18 -preset fast -c:a copy cropped/1_1_episode1_screen.mp4
+
+# crop out the camera
+ffmpeg -i trimmed/1_1_episode1.mp4 -filter:v "crop=320:164:2240:710" -c:v libx264 -crf 18 -preset fast -c:a copy cropped/1_1_episode1_camera.mp4
+
+# merge screen and camera
+ffmpeg -i cropped/1_1_episode1_screen.mp4 -i cropped/1_1_episode1_camera.mp4 -filter_complex "[0:v][1:v] overlay=W-w:0" -c:v libx264 -crf 18 -preset fast -c:a copy final/episode1.mp4
+
+# Episode2_1
+# x y w h
+# 4 182 1912 1074
+# we don't have camera for this episode :(
+ffmpeg -i trimmed/2_1_episode2.mp4 -filter:v "crop=1912:1074:4:182" -c:v libx264 -crf 18 -preset fast -c:a copy final/2_1_episode2_screen.mp4
+
+# Episode2_2
+# x y w h
+# screen: 4 182 1912 1074 
+# camera: 1920 90 320 164
+# crop out the screen
+ffmpeg -i trimmed/2_2_episode2.mp4 -filter:v "crop=1912:1074:4:182" -c:v libx264 -crf 18 -preset fast -c:a copy cropped/2_2_episode2_screen.mp4
+
+# crop out the camera
+ffmpeg -i trimmed/2_2_episode2.mp4 -filter:v "crop=320:164:1920:90" -c:v libx264 -crf 18 -preset fast -c:a copy cropped/2_2_episode2_camera.mp4
+
+# merge screen and camera
+ffmpeg -i cropped/2_2_episode2_screen.mp4 -i cropped/2_2_episode2_camera.mp4 -filter_complex "[0:v][1:v] overlay=W-w:0" -c:v libx264 -crf 18 -preset fast -c:a copy final/episode2.mp4
+
+
+# Episode2_3
+# x y w h
+# screen: 4 182 1912 1074 
+# camera 1920 90 320 164
+
+# crop out the screen
+ffmpeg -i trimmed/2_3_episode2.mp4 -filter:v "crop=1912:1074:4:182" -c:v libx264 -crf 18 -preset fast -c:a copy cropped/2_3_episode2_screen.mp4
+
+# crop out the camera
+ffmpeg -i trimmed/2_3_episode2.mp4 -filter:v "crop=320:164:1920:90" -c:v libx264 -crf 18 -preset fast -c:a copy cropped/2_3_episode2_camera.mp4
+
+# merge screen and camera
+ffmpeg -i cropped/2_3_episode2_screen.mp4 -i cropped/2_3_episode2_camera.mp4 -filter_complex "[0:v][1:v] overlay=W-w:0" -c:v libx264 -crf 18 -preset fast -c:a copy final/episode2.mp4
+