Re: [Gnash-dev] Flash HD (H.264) video decoding acceleration

[Gwenole Beauchesne]

Hi,

Thanks for your comments.

On Wed, 23 Sep 2009, Benjamin Wolsey wrote:

> Would it be feasible to use the GnashImage with a GPU 'location' to
> replace the BitmapInfo class? The location of the image would be much
> more transparent then. The AGG renderer merely stores the bitmap in the
> same format so it could stay as a CPU-located GnashImage; no idea what
> cairo does; OGL can use GPU storage possibly for all GnashImages, as
> long as there is access to the bitmap data when required.

Actually, I originally had a GnashGLImage class, derived from GnashImage. 
It had a few accessors and new ones to automatically submit raw pixels to 
the texture and use such an object as a drop-in replacement. In other 
words, a GnashGLImage::update(pixels) would update the underlying 
GnashTexture object. Is this what you mean?

I even had the idea to store YV12 pixels and let the colorspace conversion 
be handled "late" in the renderer, e.g. with a shader program in the OGL 
renderer case.

My goal was to keep things transparent under a GnashImage (and derived 
classes) and do the necessary conversions on-demand. e.g. when data() is 
called, a GnashImage with pixels residing in 'GPU' would read the pixels 
back at this time. I finally opted for no change at all to GnashImage but 
the location info (to avoid RTTI). My initial GnashGLImage required to 
make a few other functions virtual in GnashImage and I didn't want to be 
that invasive.

BTW, Cairo could be complex because this could be anywhere depending on 
the backend needs. OpenGL and OpenVG backends are hardly used though.

> > +/* SIMD versions of DSPContext.float_to_int16_interleave() needs
> > input
> > +   and output buffers aligned to 16-byte boundaries */
> > +#define NEEDS_ALIGNED_MEMORY 1
> > +
>
> Is there a problem always using av_malloc always for this?

No, but sometimes a copy was needed IIRC. The intent was to run-time check 
alignment too to avoid such copies. But it became overly complex and I 
wanted to work on video actually and skip audio crashes with this quick 
fix.

Regards,
Gwenole.