Creating an empty mp3 or jpg of a specific size

Discussion in 'Mac Programming' started by Ste5442, Feb 5, 2011.

  1. Ste5442 macrumors newbie

    Feb 5, 2011
    Hi All,

    I need to generate files of 250/500/1000MB for test purposes and they need gombe either jpg or mp3. I know how to create an empty file of specific size but a media app needs to be able to recognise the file as a jpg or mp3 so i guess it needs at least some header info in there?

    If anyone can help it really would be appreciated!

    Many thanks,


    PS: Had a look on google and some other forums but no answers :-(
  2. kainjow Moderator emeritus


    Jun 15, 2000
    What do you mean by "empty"? For example you could create a huge jpeg (say converted from a raw image) but then manually set the width and height via a hex editor to 0. But whatever program you're using might check for this and classify it as an invalid image.

    Can you be more specific on what you're trying to test?
  3. Sydde macrumors 68020


    Aug 17, 2009
    Velvet Green
    You could just create a NSImage, set its rectangle, and write its bitmap imagerep to a file as a jpeg (if you know how to use Cocoa).
  4. wlh99 macrumors 6502

    Feb 7, 2008
    250MB/500MB/or 1000MB is not empty. Do you need to create the file pragmatically, or just create them somehow to use as test data to test a program?

    For the JPG, I would create a huge file new image in photoshop or a similar image editor, apply some noise filter so it won't compress easily, then set the dimensions of the image until I got the desired file size.

    For the mp3, maybe just start recording in garage band and let is sit overnight? Or create a file with one of the included loops that is 24 or 48 hours long? Not sure as I don't use garage band.

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