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Loch Phillipps
Known Participant
December 31, 2020
Answered

Compression problem, frame size inversely related to file size?

  • December 31, 2020
  • 2 replies
  • 706 views

I have compressed a long string of 4k video hoping to create a file close to 1GB in H.264. When I compress it at 960x480, at medium resolution, I get a 2.67GB file. Strangely, when I compress the same sequence to a 640x360 fram size at medium resolution, I get a 5.86GB file. This makes no sense to me.

It could be that my resolution is changing as I muck with the frame size setting and add a time code window, but I don't see why it would be twice a big a file. Am I doing something wrong? Should I compress to a format other than H.264? Is there a way to keep the resolution the same, because every time I change it, the frame size reverts to the original size, which is 4k?

Thanks!

This topic has been closed for replies.
Correct answer R Neil Haugen

File size is mostly determined by bitrate times the length of the video. The framesize only sets how sharp things are in the image. The bitrate sets the file size as far as bytes.

 

Neil

2 replies

R Neil Haugen
R Neil HaugenCorrect answer
Legend
December 31, 2020

File size is mostly determined by bitrate times the length of the video. The framesize only sets how sharp things are in the image. The bitrate sets the file size as far as bytes.

 

Neil

Everyone's mileage always varies ...
    M
    Community Expert
    Michael GrenadierCommunity Expert
    Community Expert
    December 31, 2020

    Neil, are you saying that a 4k file with the same compression settings will be the same size as a 720 file?

      Ann Bens
      Community Expert
      Ann BensCommunity Expert
      Community Expert
      December 31, 2020

      Yes: you can check this yourself in the export settings. Make everything the same except the height and width.

        M
        Community Expert
        Michael GrenadierCommunity Expert
        Community Expert
        December 31, 2020

        what do you mean by "medium resolution?"  Resolution usually refers to pixel dimensions (at least I think it does).  do you mean bit-rate or quality?"  Try working with one of the h264 presets (such as those for youtube) to start with and then adjust the parameters if necessary...

          L
          Loch PhillippsAuthor
          Known Participant
          December 31, 2020

          Yes, my bad. I meant quality.

           

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