Mp4 Size test

[Barry Beckham]

I was thinking today that in the future, if  Mp4 videos take over as the norm for AV and presentations, which they may well do. What is the implications between images of different sizes. So, I did a quick and dirty test.

6 * 3:2AR images 6000*4000pxs saved as Jpg Level 12 and made into a 60p Mp4 =  18.177MB 

6 * 3:2AR images 6000*4000pxs saved as Jpg Level 6    and made into a 60p Mp4 =  18.177MB 

6 * 3:2AR images 2560*1706pxs saved as Jpg Level 6 and made into a 60p Mp4     =  19.552MB 

i Came back to this test on a bright new morning and got the same results. I can see how a HD video of various Jpg compressions (image sizes the same) will be evened out during the video creation process, but why are those 6 images, which are  physically smaller than the others end up 1.4MB larger when made into a video, that makes no sense to me.

I took those 6 images at 2560*1706 and reduced them still further to 1920*1280 and the 60p HD video then came out at 17.748MB 

Is anyone able to help me out with the thinking on this?

[Lin Evans]

Barry, did you control the bit-rate on all these or leave that to some default? 

Best regards,

Lin

[Barry Beckham]

I used the default settings in the Publish HD video just changing to 60p

[Picsel]

Barry,

I am not certain to understand your point perfectly well , ..

Are you aware about the mp4 coding process ?

The resulting mp4 file size will depend on video format (1920x1080 as an example), frame rate but mainly on the coding process and the coding data rate choose. Did you choose LQ, SQ, HQ ? If I remenber well the default settings are SQ with a coding scheme using variable data rate, so it is quite difficult to conclude anything, only Igor will be able to give you more details depending on the different parameters he specified for the coding process.

If you want to make easier comparisons I suggest you use a fixed coding data rate. But In any case there is no relationship between the jpeg quality of your pictures and the resulting mp4 file size.

Bets regards

Daniel

[Igor]

Barry,

H.264 encoder used by PTE 9 has at least 20-30 internal parameters which affect to final picture quality and file size. We use standard recommended parameters.

Quote

6 * 3:2AR images 6000*4000pxs saved as Jpg Level 12 and made into a 60p Mp4 =  18.177MB 

6 * 3:2AR images 6000*4000pxs saved as Jpg Level 6    and made into a 60p Mp4 =  18.177MB 

When you encode H.264 (MP4) video, PTE always re-encodes source images. Try to re-encode two same JPEG images (Jpg Level 12 and Level 6 which have different file size) into new JPEG Level 12. The final file size will be almost same.

It's difficult to predict a final file size, because it will depend on a visual content in images, animations, video clips in a project.

[Barry Beckham]

Piscal - I used the same settings for all 3 tests

Igor - I sort of expected the same file size between images of the same pixel value 6000*4000 saved at different compression, because of the reasons you said above. That the encoders use the source images. What I have trouble with is smaller images coming out larger. 

I did another test just now with 16 high resolution images into PTE, where the images are all up in the 6000px on the long side. Together the 16 images add up to about 190MB. I left a standard 2s fade 7s duration and output them as HD videos, This time I selected 1920*1080 as per screen grab.

File size as Mp4 46.655MB

 I then dragged 16 lower resolution images into PTE, where the images were 2560*1706. Together they add up to about 8MB. I left a standard 2s fade 7s duration and output them as HD videos the same as the other. 

The file size as Mp4 45.898MB

I think I can see the problem with my logic after reading your reply and looking at my second test. I think that I have been conditioned over the years with regard to  file sizes with executable files and I expected to see the same with a video, but of course if the video is being converted to 1920*1080. It doesn't matter what size the images started off at. In all my examples the starting images were always greater than 1920*1080 and that was the deciding factor. They will always come out pretty close .

This all came about after I started thinking about the future and Mp4 videos. If the publish option from PTE is to be solely an MP4, there really is no need to resize images for the creation process as long as your own PC can cope what your creating 

[Igor]

Barry,

Try to encode a simple project into MP4 video. Just 1 JPEG image, 3-5 seconds for a slide, and Quick transition (No Dissolve transitions!). The resulting video file should be very small.

Dissolving is a challenge for video compression. Whereas Pan/Zoom/Rotate are more easy task for effective video compression.

Check updated WnSoft website, I added 2 video clips as illustrations (encoded in PTE 10):

https://www.wnsoft.com/en/picturestoexe/

First video is only 1.1 MB (900 x 550, 30p, 11s, Quality: 70 for encoding)

Second video is 1.2 MB (1712 x 1038, 30p,  12s, Quality: 70)

[Barry Beckham]

It comes out much the same and confirms what I said above.

There is no real advantage to reduce image size when making a slide show.....IF........ your publish option is an Mp4 only