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Date:      Thu, 29 May 2008 14:38:44 +0100
From:      Tom Evans <tevans.uk@googlemail.com>
To:        Dieter <freebsd@sopwith.solgatos.com>
Cc:        freebsd-multimedia@freebsd.org
Subject:   Re: TV-Tuner cards ( NTSC / PAL / SECAM ) - which works best?
Message-ID:  <1212068324.10665.59.camel@localhost>
In-Reply-To: <200805281615.QAA16740@sopwith.solgatos.com>
References:  <200805281615.QAA16740@sopwith.solgatos.com>

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On Wed, 2008-05-28 at 09:15 +0100, Dieter wrote:
> > > You can get decoder chips, for example:
> > >=3D20
> > >   Broadcom BCM70010 and BCM70012 claim to decode HD.
> > >   Mpeg2 up to 125 Mbps, H.264 up to 40 Mbps.
> > >=3D20
> > >   Available as chips, or on PCIe, PCIe mini, and ExpressCard 34 cards=
.
> > >=3D20
> > >   Under $40.
> > >=3D20
> > >   Product brief:
> > >   http://www.broadcom.com/collateral/pb/70010_70012-PB00.pdf
> > >=3D20
> > >   A BSD device driver would need to be written.  And you need
> > >   a free slot.  (Free slot?  What's that?)
> >=20
> > That sounds freakin awesome. Wonder if they can handle MBAFF encoding.
>=20
> I don't know.  We need a data sheet for the chip.
>=20
> That is one problem with decoder chips, they may not work with new codecs=
.
> Some of them are said to not work well with freeze frame, slow/fast motio=
n,
> reverse, etc, anything but normal forward 1x play.
>=20
> Another method is a DSP chip.  Less expensive and less power/heat than
> a CPU.  And you can program it to handle new codecs.  The problem is
> finding one that is fast enough.
>=20
> > > ATI has documented some of their graphics chips.  The penguins
> > > have them offloading some of the video decode work.  Is anyone
> > > working on getting this working with BSD?
> > >=3D20
> > > The 780G is supposed to be able to decode HD H.264, but I don't know
> > > if they've documented that chip or not.
> >=20
> > All Nvidia chips from 6600 (ish) up can accelerate H264, and all Ati
> > with 'avivo' (1xxx series) can also do it. The problem is, they can onl=
y
> > accelerate within windows. Theres no open API that would allow apps +
> > drivers to accelerate video decoding. There is a started project at
> > freedesktop working on video acceleration apis [3], but it isn't exactl=
y
> > making stellar progress :)
>=20
> I was thinking Xv and XvMC.   IIUC the penguins have at least Xv working
> with some ATI chips.

Xv and Xvideo work well with both the beasty and the penguin, at least
for intel, nvidia (closed source). Xv/Xvideo are good for displaying
video (its a good overlay api), not so good for accelerating codecs.
XvMC works on nvidia, intel and via unichrome - I expect the new open
source ati drivers will support it as well, sooner rather than later,
but that does no good for anything other than MPEG-2, and from what I've
read, is virtually no use for H264.=20

My best results for H264 come using the 'gl2 (multiple texture)' driver
in mplayer, as opposed to rather than xv or xvmc. XvMC reduces CPU usage
when viewing MPEG-2 content, but I only have access to 480i/p MPEG-2
(standard def DVB-T transmissions and DVDs), so the net effect is
reducing CPU usage from 10% to 5%. If you are fortunate enough though to
get HD content in MPEG-2 format, XvMC is the meal-ticket. According to
the myth wiki[1], even crappy CPUs/platforms can handle 1080i MPEG-2
content with XvMC.

I'm picking up a DVB-S card for my mythtv linux box this weekend, I'll
grab some sample HD content to examine..

Cheers

Tom

[1] http://www.mythtv.org/wiki/index.php/XvMC

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