Hi,
From your message I can see that you are using a JPEG decoder, that uses hardware acceleration to do certain operations. On Wed, 2011-12-07 at 12:40 -0800, Ezequiel García wrote: > When rendering a simple jpg, sometimes I was getting this message: > > (!!!) *** WARNING [slow JPEG decode path] *** > [/home/microtrol/SetTopBox/stapi/A30-MT/apilib/src/st2fx_Andreza/src/DirectFB-1.4.3/source/interfaces/IDirectFBImageProvider/idirectfbimageprovider_jpeg.c:953 > in IDirectFBImageProvider_JPEG_RenderTo()] This is probably a grayscale JPEG image you are trying to decode. For grayscale images, a slow software path has to be taken in that version. > As I was also having some problems with fb device (stgfb) I increased > it on module insertion (from 10 Mb to 20 Mb) and now the message > is gone. or indeed alternatively you didn't have enough video memory. > I guess the WARNING means: 'I can't decoded jpeg by hardware so I will > try by software'. Right? Yes. > My question are: > > 1. Does the slow decode path means libjpeg usage? Or does it > always decode through libjpeg? In your case it will always go through libjpeg, but will use it in different ways. The 'slow' path being very slow, and the default one quite a bit faster by using different APIs and using DirectFB's own blitting functions to do the rest of the decoding. Converting YCbCr (as stored in a JPEG) to RGB is one of the most time consuming steps, this can be accelerated using DirectFB itself, which is what the jpeg decoder does. I had posted the patches a long time ago to the list, and Nils even found that DirectFB's software YCbCr -> RGB conversion is faster that libjpeg's, it's faster even if there is no gfxdriver in the system that supports the involved formats. > 2. Why does the WARNING dissapear with a larger fb video memory? The acceleration partly happens by using your gfxcard to do some of the decodes. That can only work with large enough video memory. > 3. I noticed ilixi is using DSCAPS_SYSTEMONLY for surface allocation when > rendering a jpeg. That seems a bit sub-optimal :-( as DSCAPS_SYSTEMONLY usually can't be hardware accelerated. Cheers, Andre' _______________________________________________ directfb-users mailing list directfb-users@directfb.org http://mail.directfb.org/cgi-bin/mailman/listinfo/directfb-users
