On Thu, 6 Jan 2005, Dave Dodge wrote:
> On Tue, Jan 04, 2005 at 10:36:01PM -0500, sean wrote:
> > I'm trying to run an atsc ( over-the-air hdtv ) signal out the ieee1394
> > port. I have the pchdtv card which gives me the mpeg.ts stream. i have a
> > avdc300 which will take dv input and give me component output for an ntsc
> > panasonic hdtv.
> Bear in mind that some of this is just guesswork and I might be wrong...
You're spot on - interesting reading, thanks!
> Are you intending to display high definition content? Skimming the
> spec of that Canopus device reveals no mention of HDV, so it's
> probably limited to regular standard definition DV.
DV is not used for HD (and yes, the ADVC line is SD only).
> For MPEG-TS, I think the protocol is called AV/C and is what things
> like D-VHS decks and set-top boxes use to communicate. If you have a
Or sometimes simply AVC ;)
> http://sourceforge.net/projects/libavc1394
>
> which claims to support the AV/C protocol in Linux, though I don't
> know anything about the state of tools using that library to actually
That is used by, as you mention, Kino and related tools (dvgrab
for example) to start/stop/etc a DV camcorder.
> move data around. Just FYI the best-known application for processing
> AV/C this way is probably VirtualDVHS, which I think is only for MacOS X.
I use VirtualDVHS constantly. For a "test" or "demo" program
(it and DVHSCap) are part of the Firewire SDK that's available as
a free download. It includes the sourcecode so an enterprising
person (or group) might be able to implement a VirtualDVHS program
for Linux.
VirtualDVHS is a program that emulates a D-VHS VCR by responding
to the settop box's "set tape speed", "start recording", "stop",
"rewind" and so on commands. In addition to being able to capture
(record) programs the program also implements the "play" command
so it's possible from my Powerbook to send the MPEG-TS files over
the IEEE1394 bus to the ATSC receiver and that box will drive the TV.
I don't do that a lot - I'm usually taking the data and demuxing/edit-
ing and making a DVD.
I use a Samsung T-165 ATSC receiver (which is one of the FEW
receivers with IEEE1394 ports).
If you do have a Mac around this unit may be of interest:
http://www.elgato.com/index.php?file=products_eyetv500
little less than 1/2 the price of the Samsung (which is fairly hard
to find and the price has gone up since I bought mine).
> Assuming you do _not_ have 1394 input on your TV, then you do have
> to somehow get the data into analog format first. If you want HD
> video, your best bet may be something like this:
>
> - a _REALLY_ fast machine.
:-)
> - a video card with drivers supporting XvMC. Some NVIDIA cards do this
> if you use NVIDIA's drivers. I don't know about ATI. If you want to
> stay with open source drivers, then I don't know if there's any
> solution; perhaps a _REALLY_REALLY_REALLY_ fast machine could do it.
Even a ~2.8GHz IA32 system can't play back HD content reliably
without XvMC. At least that's been my experience. A dual G5 can
do a fairly good job of it though ;)
> If your goal is just SD video, then your original idea might work
> if you can get all of the pieces in place. There are a couple of
> things that come to mind, though:
>
> - you need to select the proper PIDs, demux the stream, and so on,
> to get the MPEG program that you want. With over-the-air ATSC
If you're talking about demuxing, scaling, recoding HD content down
to SD size you really need that FAST system :) And it won't be a
real time process (not even close).
> there's frequently more than one program in the raw transport
> stream; even if the broadcaster isn't sending out HD they might
> have a second SD program with a weather map or some such thing.
Very true. Some stations put up 4 or 5 ~4Mb/s SD programs. Others,
such as the PBS (KCET) put 2 programs up - one ~14Mb/s HD and one 5Mb/s
SD (the 2nd program is a digital version of their analog program).
> - you will need to decompress the MPEG stream and then (I assume)
> recompress into DV. This may require a pretty fast machine. I
> don't know what tools are available to do this on Linux. Something
Hmmm, decoding/decompressing MPEG-2 can be done with 'mpeg2dec'
from the libmpeg2 project.
The 'encodedv' program from the libdv project understands the
PGM variant that mpeg2dec emits so you could use a mpeg2dec and
encodedv pipeline.
> like ffmpeg might be able to accomplish it with the right
> command-line arguments.
ffmpeg may be able to do it as well.
> - you need to get the DV out on the wire in a format that your
> Canopus device understands. I'm guessing that it uses the
> same protocol as a DV camera. Most of the software I found in a
I think Kino can send DV data out the IEEE1394 bus (usually used to
record a video to tape) but there are utilities in the libdv project
that can also export data.
Once the data is in DV format it can be sent to the digital IN on
the Canopus unit which will convert to analog and send those signals
to the TV set via either the component out (which is a new feature
in the ADVC300 that was not in the older ADVC100. As an aside if
you need component IN for capturing you're looking at the ADVC500
which is a 19" rackmount unit costing about $1400).
> Anyway, that's just some random thoughts on the subject. I've worked
A good night for random thoughts so I thought I'd toss a few more
in <grin>
> a bit with a pchdtv card, and tried some of the above techniques
> myself with mixed results, but have never done anything with DV.
I'm thinking of getting the pchdtv card but after reading (on pchdtv's
forums) about all the woes folks have had getting the drivers to work
it sounds like a rough ride. I think one of the Eye500 units would
be a lot simpler :-)
Cheers,
Steven Schultz
-------------------------------------------------------
The SF.Net email is sponsored by: Beat the post-holiday blues
Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek.
It's fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt
_______________________________________________
Mjpeg-users mailing list
Mjpeg-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/mjpeg-users
