Linux drivers for HDTV tuner cards

[Ted Gould]

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> On Thu, Dec 05, 2002 at 12:12:49PM -0800, Christopher Bardin wrote:
> > Seems to me that the output to the computer from any
> > TV tuner card, whether NTSC or HDTV, has to be
> > digital.  To the computer the main difference between
> > the two would be data rate and formatting.
>=20
> Erm, and the register set of the ATSC/decoder chip that
> is completely different from the BTxxx parts on older
> Hauppage, STB, ATI, etc etc etc cards.

Note, this drastically depends on what your "ATSC Card" is doing.  If it
is just a VSB demodulator that outputs an MPEG transport stream, then
that is all you have.  If it has an MPEG decoder, then it could be
roughly the same as your NTSC cards (just sending the video data into
the video card memory).  I would imagine that most of the NTSC cards
turn the video into ITU-656, and may require the CPU to put that into
video data.  Atleast the cheaper ones probably do that.

> > Just out of curiosity, how big a chunk will a two-hour
> > HDTV program take out of a hard drive?
>=20
> 8.7GB/hour of 1080i ATSC broadcast.

That's not a complete answer, basically it depends on the encoding.  The
ATSC broadcast stream is limited to 19.38 Mbps, but that usually carries
several programs.  With good compression you can put 3 HD streams or
just over 10 SD streams down that pipe.  Probably a good estimate for HD
content is about 10 Mbps, but that is assuming that your demultiplexor
is stripping out the NULL packets and the other PIDs.  (which is ~ 9 GB
for 2 hours).

Remember, that it is not in your best interest to do a recoding of the
MPEG stream, the MPEG encoders that they have at the broadcast end are
better than what ever you can do.

		Have fun,
			Ted

BTW: If you have any ATSC questions, I can probably find that answers to
those pretty easily.  I can't answer questions about specific cards, but
I could answer general ATSC/MPEG questions.

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