[Gstreamer-openmax] Support for hardware codecs

[Stephen M. Webb]

On 23/02/10 15:09, Felipe Contreras wrote:
> On Tue, Feb 23, 2010 at 4:45 PM, Stephen M. Webb <stephenw at xandros.com> 
wrote:
> >
> > What I would want is some way to expose more properties via gst-openmax,
> > at runtime.  I use gst-openmax to integrate various hardware codecs from
> > different vendors, each one with a different set of properties that may
> > need to be tweaked.  The more I can keep generic and as a single binary,
> > the happier I am.  And the easier it will be to push everything upstream.
>
> I'm not sure exactly what properties you might need. The only one I'm
> aware of is TI's "OMX.TI.VideoDecode.Param.WMVFileType" which is
> needed because the spec is missing something similar. And this one
> cannot be properly set with a configuration file, it has to be set
> programatically based on the fourcc/fomat caps.

I have one hardware vendor who does the same thing with WVC1 vs. WMV3 formats, 
only uses a different parameter name.  They also have a parameter to enable 
the use of hardware buffering -- effectively tunnelling, only tunnelled from 
their video decoder to the gstreamer-based video renderer.  Evidently there 
are other parameters but their documentation is, ah, terse.

I think what I would really like to be able to do is to be able to set OpenMAX 
parameters via GStreamer properties, not through a config file.  As long as 
the gst-openmax layer is configured to load the right component 
(introspection or configuration), if I can query and set OpenMAX parameters 
via GStreamer properties I could move most of the hardware-specific settings 
into my player software.

Hmm, I will think about this.  It doesn't sound too hard....

> Yeah, that's definitely not ideal but it would be nice to know exactly
> what are the differences each platform needs so that we know how to
> build a binary that works on all those platforms with a proper
> configuration file.

Among the things I have to configure are the OMX_ALLOCATE_ON settings and the 
fourcc caps supported by the video decoders.

-- 
Stephen M. Webb
Xandros
stephenw at xandros.com
www.xandros.com