Export Video Quality-Size


I have 3 videos. in total : 133 MB . small videos.

now I mounted them, added sound., text-transitions…

When I say export, the size is around 133 mb, or here it is around 140 mb…

How can I do this calculation?

  • I mean, I want to get output like what this example video quality is.


@Ertan - if you are worried about the size of the exported videos, than you must check the export settings and adjust them accordingly.

On a side note, I use a free open source software called Handbrake to compress my videos after exporting them from Shotcut - you can download it here: - https://handbrake.fr/

cheerios :smiley:


Ok. Handbrake does not reduce video quality ? size getting smaller…

It helps in reducing the file size without decreasing the quality :smiley:

Ok. let me find this too… Thank you.

You don’t give any details about your project, so it is difficult to advise. e.g. if you are using the Youtube export settings, DON’T, they are not very good and lead to file sizes that are larger than they need to be. Are you exporting at 60fps? If so, try 30fps and you’ll effectively halve the size, for little if no loss of quality.

There are various posts on the forum that discuss Output Quality vs Size such as this one,

These posts have useful informatiion that you might like to try, rather than exporting a video with un-tailored parameters that requires you to use another utility to compress further.

Shotcut does everything that Handbrake and tons more. No need to use it after.

1 Like

Ohk, I guess I haven’t reached that stage of expertise with Shotcut to realize that - but thank you for letting me know - do kindly point me to the link that will improve my knowledge about compression. Thank you so much :smiley:

I get a standard output. Without any settings… .mp4
However, the quality is low. I changed the setting from this part and increased it.

1 Like 70%… not bad right now…


Anything above 67% is really over-kill. For H.264 67% is really the limit of what is termed “Visually Lossless” i.e.using normal screen the human eye cannot detect any difference between a vdeo created at 67% and one at 100%. Above 67% you are just increasing the filesize for no gain in percieved quality.

1 Like

67% OK. I understand

For example, in my example the quality was 55%. result : size of 43 ~ 45 mb has occurred. And I personally realized that the quality was low.

Then I did it at a value of around 70%, which also increased to around 120 mb. and the quality was better than before.

I mean, it seems to me that there is a direct proportion between size and quality. But of course, I am not very experienced in these matters.

If you want to learn more there is an interesting article here: CRF Guide (Constant Rate Factor in x264, x265 and libvpx)

Thank you.


So how can I find the optimum crf value?

Ertan, the bad news is that there is no such thing as the optimal crf value. It is always a tradeoff between quality and file size. What is “optimal” for one use case will not be optimal for a different use case.

In general, for any given codec,* there is a direct (though not linear**) relationship between quality and file size - there is no way to reduce the file size without impacting the quality; there is no way to increase the quality without increasing the file size. The key question is always, what quality is good enough and what file size is manageable for the intended usage. If you are generating videos that will be streamed to a smart phone with a so-so 4G connection, the “optimal” mix will probably be smaller file size and lesser quality - but good enough quality that someone would have to look really, really closely to be able to tell the difference. If you are generating 4K broadcast TV or something to be shown in a movie theater, you’ll probably decide that it is worthwhile to manage a much larger file size in order to gain greater quality.

*Note that some codecs are more efficient than others, providing greater compression at a similar level of quality. Thus, one way to reduce the file size may be to change from, say, the H264 codec to the H265 codec … assuming that the target usage can handle the latter format.

**Not linear - in general, the relationship between quality and size is some sort of a curve, where at the lower end, a certain increase in size allows a relatively significant increase in quality, while at the upper end, that same increase in size makes only a marginal difference in quality. In other words, the higher you go, the more you get diminishing returns.

1 Like

I understand. Thank you so much.

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