Using Skia to enable hardware acceleration of image codecs

[Ben Ravin]

Hi,

 

I have hardware accelerators for PNG & JPEG decoding. How can I use Skia to interface with hardware accelerators. Any example codes/doc  available ?  Since my resolutions of images  are very big how can I load the complete copmpressed image into the buffer ? Does Skia has any memory limitations on loading the compressed images into buffer ?

 

Please provide me the details.

 

-ben

[Mike Klein]

Are you saying you want to pass encoded, compressed images to Skia, have Skia call your hardware decoders, and then further use the resulting uncompressed images with Skia?  I don't believe we have any hooks exposed to allow you to replace our image decoders, but you may find an alternative just as good.

SkBitmap::setPixels() allows you to back a bitmap with externally managed pixels.  So you could call your hardware decoders yourself on some memory you control, pass a pointer to it into an SkBitmap, and run from there using the SkBitmap as you'd normally use in Skia.

If you're looking to have Skia work with compressed images that are partially decoded on the fly by hardware as needed to get pixels, I'm not aware of any support for that in Skia.

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[Ben Ravin]

[Ben Ravin]

Hi Mike,

 

Yes you are right, my requirement is to replace the soft codecs such as libjpeg, libpng and use hardware codecs.  If Skia has the hooks then with minimal changes to framework this can be done. 

 

Any plans to add these hooks ?

 

-ben.

 

On Wednesday, 19 March 2014 09:50:42 UTC+5:30, Ben Ravin wrote:

[Mike Klein]

Actually, let me step back a second and correct myself: Skia does have at least two layers of hooks for replacing software codecs with hardware codecs.

First, because Skia uses libjpeg, libpng, libwebp, etc., you can drop in an API compatible replacement library with support for your hardware and Skia should make happy use of it without any modifications.  Think libjpeg-turbo replacing libjpeg.

If that's not possible, you probably want to write new SkImageEncoders and SkImageDecoders.  Skia's image codec system uses registration, which will allow you to inject your new codecs with higher priority than the default codecs just by linking them first (or the default ones not at all).

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[Ben Ravin]

Hi Mike,

 

That's interesting. It would be great if you can share some user doc or app note on how to use the skia APIs.

 

-ben

[Ralph Thomas]

Hi Ben,

This implements a JPEG decoder for (5 years old) Skia using OpenMAX IL: https://gitorious.org/blazetablet/hardware-ti-omap3/commit/5e55eb2f149136433ae2568c2aed99ecbb3b6fe9 (I've previously found OMX super hard work, so if you have a less abstract interface to your hardware then you should probably use that instead...).

Ralph

[Ben Ravin]

Hi Ralph

On Wednesday, 19 March 2014 09:50:42 UTC+5:30, Ben Ravin wrote:

[Ben Ravin]

Hi Ralph,

 

Thanks for sharing the details. Is there any for PNG, replacing lib-png with hardware.

 

-ben

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