[SDL] IMG_Load performance was Problem combining sw_scale with blit operations on surface

Mason Wheeler masonwheeler at yahoo.com
Thu Apr 9 08:03:25 PDT 2009


>----- Original Message ----

>From: Sami Näätänen <sn.ml at keijukammari.fi>
>Subject: Re: [SDL] IMG_Load performance was Problem combining sw_scale with blit operations on surface
>
>> On my machine, the command line ffmpeg program can process 180 frames per
>> second into an mp4, but IMG_Load takes 15-30mS to load one image to a
>> surface.  All the other SDL calls I make to create the alpha blended text
>> layer take a total of 5mS on my machine.  Any ideas why is IMG_Load so slow
>> or what I can do about it?
>
>Maybe this a related bug to the PNG loading bug, where the code opened and 
>closed the PNG library for every image loaded. For JPEG loading I would 
>imagine the speed loss being relatively higher than for PNG loading.

It's not exactly a bug, just a missing feature.  Try adding my IMG_Init patch.
It affects PNGs, JPEGs and TIFFs, and ought to speed up the loading by
a bit.  Just run
   IMG_Init(IMG_INIT_JPG);
before you load up any JPEG files, and see if that doesn't help things...




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