Archived from groups: alt.tv.tech.hdtv (
More info?)
On Thu, 1 Sep 2005 16:56:49 -0400 Jeff Rife <wevsr@nabs.net> wrote:
| (phil-news-nospam@ipal.net) wrote in alt.tv.tech.hdtv:
|> Here are some things that could be done. Do not assume this is my intent,
|> but rather, as examples to give you the idea of what the bit stream layer
|> means:
|>
|> 1. Delay an entire OTA TV broadcast, all subchannels together, for some
|> number of minutes or hours.
|>
|> 2. Transport the ATSC bit stream(s) over network protocols to somewhere
|> else, or transport extracted channels that way (see RFC2250 and RFC2343
|> of internet standards for examples). Think: "remote receiver".
|>
|> 5. Extraction of MPEG/AC3 video/audio components for use in other formats
|> that use these same components, or the reverse of this.
|
| I do these every day, right now with off-the-shelf equipment, as do many,
| many other people.
You might want to describe this "off-the-shelf equipment" a little better.
My reference to possibilities involves things that can be done by programming
inside a computer ... once the raw ATSC bit stream is delivered to that
computer. Obviously extraction of MPEG/AC3 video/audio components has no
value if you don't do something with it. I mention the reverse of this so
I could, for example, re-assemble the components back together in different
arrangements.
BTW, I will just this "off-the-shelf equipment" not in terms of whether
or not it can meet that one particular capability, but rather, whether it
lets be do _every_ one of them all in the same box. A computer _can_ do
that, with some programming (of which I have over 33 years experience in).
But I am curious. Does this "off-the-shelf equipment" you refer to actually
do what it does to an incoming ATSC bit stream, and give an ATSC bit stream
output (and thus require the use of a modulator and demodulator), or does
it have the modulator and demodulator intengrated? Or is it really doing
something else entirely different?
What other format would you be putting the extracted MPEG/AC3 components
into? COFDM? If so, Bob Miller would be so proud
Somehow I doubt
if that is what you are doing. But maybe you are doing DVB of some sort.
Or maybe RTP?
|> 4. Juggle subchannels around within an ATSC channel, or with multiple
|> units, between channels.
|
| Why would you need to do this? All streams are available directly, so the
| assigned channel number is unimportant. But, it's easy enough to do just
| by changing the PSIP information...you don't even need to touch the data
| streams, nor would you want to, since the channel-number order doesn't have
| to relate to the order of data in the packets. In other words, sub-channel
| #4 can be the first thing in a packet, while sub-channel #1 is the second,
| and sub-channel #3 is the third, and there is no sub-channel #2.
I'm not going to answer the why question, because my list of examples was
intended to illustrate what _could_ be done in a computer that gets the raw
ATSC bit stream, and can output an ATSC bit stream to an 8VSB modulator.
I could add more examples to this list of many things, most, if not all,
being totally useless. But the point you seemed to miss, probably because
you didn't read the disclaimer I put there saying these are not necessarily
my intentions, is that I don't necessarily intend to do any or all of these.
If you are wanting to know what I actually do intend to do, then you will
have to deal with the lack of an answer for two reasons. The first is that
it is none of your damn business (if I want to discuss it openly, you can
be sure I'll post a new thread about it), and the second is that I do not
want to box myself in to a limited set of capabilities, as I will likely have
when buying some "off-the-shelf equipment". I want the wide open capability
afforded by having a raw ATSC bit stream path in to my computer from 8VSB RF
signals, as well as a raw ATSC bit stream path out from my computer going to
an 8VSB RF signal. I have 33 years computer programming experience, 23 of
which is in the C programming language, and much of that working with many
different protocols and data formats (many of which I created for specific
purposes). Thus I know, at least for myself, that having the raw ATSC bit
stream in my computer opens a vast range of possibilities, most of which I
would never need. Who knows, maybe I'll even come up with something really
cool that even you would end up using (via being sold to some manufacturer
that integrates it into some "off-the-shelf equipment" you would buy without
ever knowing it was me who wrote the software inside).
--
-----------------------------------------------------------------------------
| Phil Howard KA9WGN | http
/linuxhomepage.com/ http
/ham.org/ |
| (first name) at ipal.net | http
/phil.ipal.org/ http
/ka9wgn.ham.org/ |
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