Re: "USB video"

On Monday 26 April 2004 02:28 pm, Stefan Richter wrote:
> On 24 Apr, Terry Hancock wrote:
> > Please, pardon my ignorance...
> >
> > I have a Panasonic "Palmcorder" (PV-DC252D) camera. It
> > is apparently able to store video in DV format on a
> > *tape*, and play it back via digital ports. One of these
> > is (I think) firewire and the other is a USB.
> >
> > Is it possible to play the video back via USB onto a
> > Linux computer,

>
> Video data transmission over the 1394 port works probably as
> isochronous transmission (data rate guaranteed, data integrity
> not guaranteed). Several different video formats can be streamed
> by means of isochronous transmissions. Furtheremore, different
> high-level protocols for the control of video devices over 1394
> exist (start, stop commands etc. by means of asynchronous
> transmissions).
>
> I never heard of ischronous transmissions over USB. I guess they
> use a proprietary protocol. Some still image devices simply work
> as standard USB storage device class though.

Hmm. Well, it could be that I misunderstood the manual. Maybe the
USB will only work to get still images. I guess the logical course
of action would be to actually get a 1394 card for this computer.
It doesn't look like they're that expensive nowadays.

Assuming that I do that, I suppose it's reasonable to use that
to download the DV files. I'm a little concerned about this "isochronous"
concept -- sounds like I might lose data in the process. I mean, I
was under the impression that the DV data was uncompressed, so it
ought to be possible to get it intact. I guess this means I need
to be concerned about the throughput of the 1394 port. Do they
vary, or is it just a case of "Firewire is firewire"?

Cheers,
Terry

--
Terry Hancock ( hancock at anansispaceworks.com )
Anansi Spaceworks  http://www.anansispaceworks.com
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