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I used to use the Zoom application on my desktop to record the explanation of my lectures to my students starting from March 2020.

The idea is to open a new meeting, share my slides and record the meeting so I get the explanation video.

Everything was fine, especially that the size of a video of 20min is about 15MB or even less.

The problem started some days ago, when Zoom started to give me very big videos even for lectures of small durations (30MB for 11 mins).

Even though I am using the same background (PPT presentations), and I checked the settings, I uninstall then install it again, but no clear improvement occurs.

Can some one give me either an alternative (screen recorder giving small size videos) or a suggestion how to deal with the Zoom application.

PS: I know that I can compress the video later after recording, but I prefer directly to have the right video.

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  • 30MB for 11 minutes of video these days is already very small, which indicates either low resolution of low quality. You can try lowering the quality even more or use some other encoder afterwards for further reduce the size (sacrificing evenmore quality), but you possibly can't go much below that.
    – Alejandro
    Oct 7 '20 at 13:46
  • you mean 300 mb? or really 30 mb?
    – BCLC
    Nov 21 '20 at 8:27
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I've struggled with this same problem and I've found a solution that works for me.

I don't know why but I haven't found any screen recording software that supports V9 video compression format which is smaller than other formats. It was open-sourced by Google and developed as a way to improve YouTube video performance.

There are a number of great options for Windows. If you are using a Mac, I recommend CloudApp because they support video annotations. Either way, you'll end up with a video in a MPEG-4 digital multimedia container format (.mp4).

You'll then want to convert the .mp4 video format into .webp video format. There are plenty of websites that can that for you.(link) If you have privacy concerns about converting formats using a unknown third-party, you can use a something like ffmpeg. I prefer the second method because I can control exactly what is happening between the scenes.

Once you download ffmpeg and add the bin folder to your PATH here's the command you are looking for:

ffmpeg -i mp4towebm.mp4 -c:v libvpx-vp9 -b:v 2M output.webm

If you use two-pass, you will get a higher-quality video and you run ffmpeg twice:

ffmpeg -i mp4towebm.mp4 -c:v libvpx-vp9 -b:v 2M -pass 1 -an -f null /dev/null && \
ffmpeg -i mp4towebm.mp4 -c:v libvpx-vp9 -b:v 2M -pass 2 -c:a libopus output2.webm

Essentially it gives the compression algorithm another chance to optimize perceived quality without sacrificing file size. Source

Here's a quick proof of concept that I used downloading a sample video

The original video is 10 M and webm compressed it ~20% smaller: https://share.getcloudapp.com/kpuwDjLO

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  • Actually I am using widows 7. Anyways thanks fo ryour answer.
    – Nizar
    Oct 18 '20 at 7:28
  • ffmpeg works with Windows and CloudApp has a windows client that's compatible with Window 7 I believe
    – bradhanks
    Oct 18 '20 at 17:11

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