[mythtv] H.264 and mythtv

Peter Schade l-case at gmx.net
Thu Sep 1 08:20:27 UTC 2005

Would an Via Board with the new CN400 chip be enough? I think Ivor wrote
about that a while ago.

But this chip has only MPEG4 Acceleration, not decoding... :(

----- Original Message ----- 
From: "Michael T. Dean" <mtdean at thirdcontact.com>
To: "Development of mythtv" <mythtv-dev at mythtv.org>
Sent: Wednesday, August 31, 2005 7:48 PM
Subject: Re: [mythtv] H.264 and mythtv

> Bernd Paysan wrote:
> >Hi,
> >
> >heise.de reports that from October, 26, two free-TV programs are going to
> >send in HDTV quality (1080i) in Germany:
> >
> >http://www.heise.de/newsticker/meldung/63402
> >
> >However, they'll use H.264, not MPEG-2. AFAIK, ffmpeg can already decode
> >H.264.
> >
> >Are there any plans to include H.264 support into mythtv?
> >
> >
> (I can't read German, but it looks to me like they're talking about
> high-def resolutions...)
> Note, however, that even top-of-the-line x86-based (including
> AMD64/EMT64) chips can not keep up with H.264 decoding at high-def
> resolutions (even 720p) with acceptable frame rates.  Microsoft lists
> minimum requirements
> ) that in truth are way too optimistic--even with Windows drivers
> providing full support for all (sound/video) card features.
> MacOS X on top-of-the-line PPC is able to decode H.264 at 1080i at 24-30fps
> iff it's QuickTime H.264.  Similarly, Windows machines have a hard time
> with QuickTime H.264, but perform much better with WMV H.264. (Perhaps
> some optimization or even reverse-optimization for the platform's
> preferred codec?)
> For H.264 in high def, we really need dedicated silicon to do the
> decoding--especially if the CPU is doing other things.  The ATI R520
> will have dedicated silicon to handle H.264 decoding (to be released
> sometime in October, probably), but whether there will be support for it
> in the Linux drivers (considering today's ATI drivers don't even have
> XVMC support) and whether there will be a standard API for using it
> (don't know of any at this point), is unknown.  NVIDIA cards will not
> have the H.264 decoding built in.
> However, another (more portable?) option is using OpenGL 2.0's GLSL with
> relatively-recent ATI and NVIDIA cards to use the programmable shaders
> for video decoding (semi-dedicated silicon).  This approach is less
> efficient than using dedicated silicon, but portability at the expense
> of efficiency is probably worthwhile.  Note that this requires
> relatively recent cards since older cards do not allow enough
> instructions for the PS to allow the GPU to do the decoding.  (Does
> ATI's Linux driver provide OpenGL 2.0 support?  NVIDIA's first to
> support 2.0 was 7664.
> http://www.nvidia.com/object/linux_display_ia32_1.0-7664.html )
> Remember when we used to have hardware DVD decoders?  They're back with
> H.264...
> If any ATI/NVIDIA guys want to provide me with a card, I'd be happy to
> add GLSL support to Myth.  :)
> Mike
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