[linux-dvb] Re: ATSC/DTV question

[Olivier Hault <hault@cybernet.be>]

Anyone has more information about the Conexant's D-Stream design (which
strips all of the hardware decoding in favor of software-only decoding) ?

Currently, I wonder if that software architecture could also be technically
implemented on top of Hauppauge DVB-S or is only possible with board like
Hauppauge Nova (w/o AV7110)?

Thx,
Olivier

----- Original Message -----
From: Daniel Schmelzer <dschmelzer@hotmail.com>
To: <linux-dvb@linuxtv.org>
Sent: Tuesday, January 23, 2001 6:44 PM
Subject: [linux-dvb] Re: ATSC/DTV question


> Hi All--
>
> Pardon me if some of this has already been addressed or it is old news.  I
> just picked up the mailing list and this thread.
>
> There are at least three boards on the consumer market that pick up an
ATSC
> stream:  Hauppauge's WinTV-D, Hauppauge's WinTV-HD, and Telemann's HiPix.
> So far, the Telemann board is the only one with accompanying Windows
> software to save an ATSC transport stream to disk.  It does so in
one-minute
> files with a Telemann header attached.  Hauppauge also has a beta stream
> capture program for its WinTV-D that captures the stream raw.
>
> Elecard's (www.elecard.com) MPEG decoder has a demuxer that can demux the
> raw ATSC stream that the WinTV-D capture program saves to disk.  The
demuxer
> is in the form of a DirectShow filter and breaks out all of the program
> streams in the transport stream--most often, US TV stations include at
least
> two video streams and two audio streams in one raw ATSC stream.
>
> I suspect that the differences between the DVB and ATSC streams is *quite*
> small, because Elecard was able to modify its demuxer in one evening to
> handle the raw ATSC files.  However, as has been pointed out, I'm not sure
> about all of the multiple program streams, channel mapping and other stuff
> going on that are needed to fill out the functionality...
>
> As for the hardware, both the HiPix and the WinTV-HD are based on the
Janus
> reference design, so if you support one, you can support the other (and
any
> subsequent cards) fairly easily.
>
> Other substantial designs include Conexant's D-Stream design, which strips
> all of the hardware decoding in favor of software-only decoding.  I think
> that it uses a modified 878a chip and DMAs the ATSC stream to memory.  I
> haven't seen any consumer cards based on this yet, if only because few
> machines can handle the load on a 1080i stream.
>
> IIRC, the bandwidth for ATSC is 6 MHz--channels can be found exactly where
> they were with UHF.  Subchannels are just different substreams within the
> raw ATSC stream.
>
> Not surprisingly, the ATSC info can be found at www.atsc.org.
>
> Please let me know if you need any testing done at dschmelzer@hotmail.com.
> I have the HiPix and access to digital channels that have various types of
> streams (480i, 480p, 720p, 1080i), but little coding knowledge or
experience
> (and very modest experience with Linux).  I can also provide some raw ATSC
> files and HiPix headed files if you need them.
>
> Regards--
>
> Dan
>
>
> -------
> The DVB demux software works by filtering out IP packets from DSM-CC
> sections, and DSM-CC sections from TS packets. (Checkout the standard  EN
> 101 192 (V1.2.1: 06/99) and the guidelines TR 101 202 (V1.1.1: 02/99) from
> http://www.etsi.org/ or directly http://webapp.etsi.org/pda/QueryForm.asp)
>
> First you must find out how ATSC encapsulates its IP data into the TS from
> the ATSC standards (I would be interested to know when you find out). Then
> modify demux.h for ATSC and demux.c for your hardware. (I suspect demux.h
> changes will be small)
>
> Next up is to find out what tuning parameters are needed for your ATSC
> frontend, such as how are centre frequency, modulation parameters,
bandwidth
> etc. specified and which are always the same. e.g. DVB-T signals can be on
> bandwidths of 6, 7 and 8 MHz, but maybe ATSC uses a fixed bandwidth. I
would
> also be delighted to find out what you discover for this. Then modify
> frontend.h for ATSC and frontend.c for your hardware. /dev/ost/vsb8fe
might
> be a suitable location (but make sure you don't link into /dev/ost/qpskfe
> instead)
>
> Assuming you already know the correct tuning parameters and demux
parameters
> (PID, MAC etc.) - that's all you need for IP data.
>
> However, if you need SI information (i.e. the service information tables)
> then you will need to parse those to work out the demux parameters for a
> particular stream. I think VDR has been doing this for DVB, and I'm pretty
> sure ATSC uses DSM-CC sections to put SI in so maybe this would not be a
big
> task by reusing code.
>
> Vague disclaimer: I've never done anything with ATSC (other than read a
> little) so don't blame me if all goes wrong, but I hope this helps you.
>
> Cheers,
> Rod.
>
> >-----Original Message-----
> >From: ext Keith Craigie [mailto:kcraigie@mediabolic.com]
> >Sent: 20 January, 2001 0:04
> >To: Rod.Walsh@nokia.com
> >Cc: rjkm@convergence.de; linux-dvb@linuxtv.org
> >Subject: Re: [linux-dvb] Re: ATSC/DTV question
> >
> >
> >Well probably the first course of action is to actually work
> >on supporting
> >an ATSC-compliant DTV receiver board for Linux.  As there
> >don't seem to be
> >any on the market - we're probably going to port Broadlogic's DTA-100
> >driver ourselves.
> >
> >Our goal is to be able to receive the data IP packets from the
> >transmission, muxed in with the standard DTV video, and route
> >them to a
> >LAN - and thereafter extract the contained data on the client
> >machines.
> >From what I understand, this simply involved demuxing the MPEG TS and
> >feeding it to a perhaps modified Linux TCP stack?  Is there
> >support for
> >this in the current version of the DVB software?
> >
> >Keith
> >
> >On Fri, 19 Jan 2001 Rod.Walsh@nokia.com wrote:
> >
> > > ATSC uses VSB8 modulation so you'll need a new tuning
> >driver (just the same
> > > for DVB-T which uses OFDM+QAM/QPSK) - note DVB-S which uses QPSK.
> > > (Practically this is compiling with new or improved
> >frontend.c and .h)
> > >
> > > Some of the DVB and ATSC SI tables are common (because they
> >are both based
> > > on MPEG TS) and some are different so here's another place
> >for work (VDR
> > > guys?).
> > >
> > > I am not an ATSC expert so I can't tell you exactly how
> >ATSC encapsulates
> > > IP, but I guess you'll be needing modifications to demux.h and more
> > > significant ones to demux.c (as you might expect).
> > >
> > > Naturally, it would be great if the same API handled all
> >DTV methods (anyone
> > > interested in the Japanese system?) so thanks to those who want this
> > > challenge.
> > >
> > > Good luck!!!
> > > Rod.
> > >
> > > PS For those confused: ATSC is the North American
> >'equivalent' for DVB-T.
> > > DVB-T is the terrestrial (i.e. standard antenna) version of
> >DVB - the rest
> > > you can work out for fun :)
> > >
> > >
> > > > -----Original Message-----
> > > > From: ext Ralph Metzler [mailto:rjkm@convergence.de]
> > > > Sent: 19 January, 2001 4:43
> > > > To: Keith Craigie
> > > > Cc: linux-dvb@linuxtv.org
> > > > Subject: [linux-dvb] ATSC/DTV question
> > > >
> > > >
> > > > Keith Craigie writes:
> > > >  > Hi there,
> > > >  >
> > > >  > Now I know this is the DVB mailing-list ... but now that
> > > > ATSC is more
> > > >  > available, is there plans to start a parallel project on
> > > > linuxtv for
> > > >  > supporting the American standard?  Also, if anyone knows
> > > > any links to
> > > >  > projects/mailing lists for ATSC, I'd appreciate their
> > > > passing them on.
> > > >
> > > > According to the ATSC specs, it looks similar enough to DVB
> > > > that a lot of
> > > > the DVB software can be reused for ATSC.
> > > > There are some differences in the hardware as well as the
> > > > specifications
> > > > for service information. But I see no reason why the DVB
> >API we are
> > > > using for our driver could not be used for ATSC as well.
> > > > I would welcome any discussion on this.
> > > >
> > > > Ralph
> > > >
> > > >
> > > > ---
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> > > > "unsubscribe linux-dvb" as subject.
> > > >
> > >
> > >
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> > >
> >
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