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diff --git a/2021/prepare.md b/2021/prepare.md index 9b16f933..3d78a407 100644 --- a/2021/prepare.md +++ b/2021/prepare.md @@ -100,13 +100,22 @@ WebM format if possible.* > format. The closer to this format submitted video files arrive in, > the easier it will be to process and upload them. +# Compression + If you would like to compress your video before uploading, the following shell script may be useful: Q=56 ffmpeg -y -i "$1" -c:v libvpx-vp9 -b:v 0 -crf $Q -aq-mode 2 -an -tile-columns 0 -tile-rows 0 -frame-parallel 0 -cpu-used 8 -auto-alt-ref 1 -lag-in-frames 25 -g 240 -pass 1 -f webm -threads 8 /dev/null && ffmpeg -y -i "$1" -c:v libvpx-vp9 -b:v 0 -crf $Q -c:a copy -tile-columns 2 -tile-rows 2 -frame-parallel 0 -cpu-used -5 -auto-alt-ref 1 -lag-in-frames 25 -pass 2 -g 240 -threads 8 "$2" -If you put it in a file called `compress-video.sh`, you can execute it from the command line with something like `sh compress-video.sh input-file.webm output-file.webm`. +If you put it in a file called `compress-video.sh`, you can execute it +from the command line with something like `sh compress-video.sh +input-file.webm output-file.webm`. It will compress the file in two +passes. During the first pass, the frame count will increase, but the +speed will be 0. After the first pass, it will display proper progress +information. + +# Tech check If you're planning to do live Q&A, you can check your system setup at https://test.bigbluebutton.org/ . We'll set up a tech-check call with |