Shrinking the MP4

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  • Updated 1 week ago
I have a video that was created in efforts to "repair" a zoom interview where the interviewee was unhappy with the recording.

I've got the video ready to go, but the recipient is complaining about the file size. It's nearly one gig in size and apparently they are accustomed to zoom productions that are much smaller. Somewhere in the range of 233MB for what they have done so far.

So I'm hoping to gather some ideas for what I can do to try and get that file size down. I'm presently in the process of uploading to YouTube hoping that YouTube will encode it a bit better and allow me to download it back at a reduced file size.

I believe that reducing the produced file size to 720p will help. But aside from altering the frame rate and quality, I'm not sure what else to do or consider. I've also tried running the MP4 through HandBrake. It did reduce a bit, but I'm nowhere near the range they are hoping to see.

advTHANKSance for any ideas! Rick :)
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Rick Stone

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Posted 2 weeks ago

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Robert R., Online Community Admin

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Hiya Rick!

Check the audio settings; Zoom recordings can be as low as 8 kHz with an average around 16 kHz which helps the size stay small. If you produce to 720p with audio set at say, 64 Kbps or 96 Kbps, what's the size like?

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When you exported the project from TSC as MP4, what was the quality setting at? 60-75%? It may be worth googling to see if Handbrake can export to H.265. 

From this Videomaker article: 
H.265 (MPEG-H, HEVC)
A lossy codec and the follow up to H.264, H.265 offers better compression than its predecessor. Support for H.265 is growing, and it’s quickly becoming widely used. 

H.264 (MPEG-4)

Commonly referred to as MPEG-4, H.264 uses lossy compression and is one of the most common video codecs in use today. The codec is widely supported and used in production, post and distribution of video. Many camcorders and DSLRs record in H.264. It’s the standard for Blu-ray disks as well as many web video hosts. H.264 is more efficient for compression than MPEG-2 and it typically delivers better video quality at the same bitrate.

One of the very nice things about H.264 is that you can use it at very low and very high bitrates. H.264 will send highly compressed low-resolution video across the web and then happily encode your high definition movie at super high bitrates for delivery to an HD television.

This codec is often used with .mp4 and .mov containers.

Also, not in the scope of your original question, but worth asking - is this a client? Cause storage has never been cheaper. 
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Use Handbrake from
It's free and does an awesome job of reducing video size.
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Brooks, Camtasia Technical Product Manager

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Resolution, frame rate and quality are the only thinks you can stomp on to reduce file size. Quality is the most hazy as several factors can contribute. With h.264 the profile--baseline, main, high--impact quality. The type of compression (we hide that from you) contributes. Bit rate, mostly reflected by the quality slider on Windows is how you increase / decrease the bitrate (little more complicated than that). The one other thing that is going to be a major factor is the number of keyframes in the video. I can't remember if or where we expose this on Windows off the top of my head (may be controlled in part by the quality slider).

So those are your options. Compression is a bit of a dark art. Lots of trial and error. Generally speaking Zoom meetings are super low quality. You will see more blockiness, lower bitrates, fewer keyframes and lower profiles used (usually baseline profile for streaming apps).

Camtasia Technical Product Manager
Mobile Technical Product Manager
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Ed Covney

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How did you make the changes? Or what did you do to the audio?
I suspect they do mono at 11 KHz and that alone would account for the 4X size change. If you don't have the audio s/w to convert the audio portion, Lame is great for such tasks. If you need help with the switches, just come back.

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David Bookbinder

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Run it through Handbrake and select the "Fast 1080p30" setting. This should do it, but if it's still too large, you can tinker with the other settings, but I've gotten very significant file reduction with this setting and very little visual degradation.
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Import it into Vimeo, then  download it using one of their different formats

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Rick Stone

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Thanks for the replies all! My internet dropped while I was out and I'm finally just now able to reply to this.

So what I did was to do a custom production from Camtasia. As I had a copy of the original Zoom session, I right-clicked it from Windows File Explorer and examined the specs I saw listed there. The file that resulted was very near the range they were hoping for. Crossing fingers now as I await their results.
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Jayne Davids

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Hi Rick,  what settings did you change in the custom production? I have a similar issue with another video conferencing platform. Importing into Camtasia to top and tail it, is tripling the file size and exceeds the max the client can upload. I've changed to 720p, lowered the frame rate and changed bitrate. I haven't changed the audio and wondered whether I should. 
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Joe Morgan

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Lowering the frame rate? Has a minimal impact on file size if your at 30fps to begin with.Can lead to judder, noticeable without much scrutiny.

If the audio is clean. Mixing to mono at 96kbps will should give you some pretty good audio and a smaller file, even if theres some music in there.

Dropping the bit rate is all thats left. Handbrake seems to have a secret sauce.
You might be better off using it for a full conversion?

What you probably need is a WebX format. Or web based format.
I don't deal in web uploads so I'm not up on the most popular formats.
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Rick Stone

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Hi Jayne

Sorry for the delayed response. I was AFK all day playing "Bob the Builder" installing a sturdy stair railing to help my ailing wifey.

So essentially I looked over the comments here, then had an epiphany about examining the settings I could see on the Zoom video. That told me that the zoom video was:

1366 x 768
Data Rate = 1483kbs
Total bit rate = 1536kbps
25 fps
Audio bit rate 53 kbps
Sample 32,000khz

So in Camtasia I produced and went through the dialogs and made the following changes:

Custom Production Settings
Configured the size to 1366 x 768
Configured the frame rate the 25
And in that screen where you can click the drop-down and choose between Quality and Bitrate, I changed to Bitrate. I'm not sure how this setting was selected, but it now reads 1248.
Then in the Audio  tab I configured to 48 kbps. The next one up for me was 56 and since that was higher than what the settings were on that file, I selected that.

Then I let it produce. 

The file size reduction was amazing. It dropped from about a 4GB file to 259,455KB.

On a whim, I pushed that thrugh HandBrake and all I did was end up INCREASING the file size at that point!

Then after seeing what Brooks posted, I thought perhaps I might try tweaking the Keyframe setting. Since the zoom recording was 25FPS, in my twisted little brain I thought perhaps I might nudge that keyframe setting. So instead of every 5 seconds, I tried ever 7 seconds. And when I produced, I saw another reduction in size, The resulting file was then 252,615KB.

Obviously we are sacrificing quality. But hopefully the recipient is now happy with the result.

Cheers... Rick :)
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Jayne Davids

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Thank you for your detailed response Rick. I'll check this out on the example I have. 
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Ed Covney

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I believe Camtasia records audio at 40 or 44.1 KHz. So each audio track requires a little over 11 MB/min, or 666 MB/hr. and that's for each audio track. Sitting in a studio with camera on and mouth motion produces about 2 MB/min at 720p and maybe 2.6-2.8 MB/min in HD. 

I know it sounds illogical but there's a very easy test. Save as a new project then re-render without a sound track.