TV-Tuner cards ( NTSC / PAL / SECAM ) - which works best?

[Tom Evans]

On Tue, 2008-05-27 at 08:48 +0100, Dieter wrote:
> > Hi-def in the UK is available over DVB-S and DVB-S2 (and presumably over
> > DVB-C as well, unsure), and is usually very high bitrate MPEG 4 AVC
> > MBAFF, which is EXTREMELY hard to decode in real time for a general
> > purpose computer. This either means you need a very fast (expensive)
> > computer, or you don't have hi-def support. This makes it very
> > unappealing - cheap and crap or expensive and not-quite-so-crap.
> 
> Do you have a number for this "very high bitrate MPEG 4" ?

16-20 Mbps MPEG 4 AVC MBAFF [1]

I can't find an explicit reference to the bitrate - iirc it is in the
ballpark of 20 Mbps. Here is a reference to the difficulties of decoding
it [2] under linux and windows.

> 
> > For the US market, it is much easier (I believe), as most of their HD
> > content is delivered as MPEG-2, which is much easier to decode.
> 
> US OTA is MPEG 2.  Max bitrate is approx 19.3 Mbps.
> I've read that some cable and sat is converting to MPEG 4.
> I don't have bitrate numbers for those.
> 
> Some content is only available in HD.  If you can't decode HD in
> real time you have to record it, transcode it down to SD, then watch
> the SD.  Not a great solution.  Word is that scaling is expensive,
> so a display that is at least 1920x1080 would be helpful in reducing
> CPU requirements.
> 
> You can get decoder chips, for example:
> 
>   Broadcom BCM70010 and BCM70012 claim to decode HD.
>   Mpeg2 up to 125 Mbps, H.264 up to 40 Mbps.
> 
>   Available as chips, or on PCIe, PCIe mini, and ExpressCard 34 cards.
> 
>   Under $40.
> 
>   Product brief:
>   http://www.broadcom.com/collateral/pb/70010_70012-PB00.pdf
> 
>   A BSD device driver would need to be written.  And you need
>   a free slot.  (Free slot?  What's that?)

That sounds freakin awesome. Wonder if they can handle MBAFF encoding.

> 
> 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?
> 
> 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.

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 only
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 exactly
making stellar progress :)

Cheers

Tom

[1] http://www.digitalradiotech.co.uk/uk_satellite_bit_rates.php
[2]
http://www.mythtv.org/pipermail/mythtv-users/2006-November/156604.html
[3] http://www.freedesktop.org/wiki/Software/vaapi

-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 195 bytes
Desc: This is a digitally signed message part
Url : http://lists.freebsd.org/pipermail/freebsd-multimedia/attachments/20080528/47efc230/attachment.pgp