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Posted by Jukka Aho on 11/13/06 21:55
curious314159@yahoo.com wrote:
> Condition of "sufficiency" in my post refers to the device
> generating the firewire signal (i.e. DV Camera or Canopus
> box) being fully compatible with the 1394 Digital Camera
> Specification specified by the 1394 Trade Association.
It appears that you're talking about TA1998019 ("1394-based Digital
Camera Specification ver. 1.20"), TA1999023 ("IIDC 1394-based Digital
Camera Specification Version 1.30"), or TA2003017 ("IIDC 1394-based
Digital Camera Specification Ver.1.31"). See the following list of the
1394 Trade Association publications:
<http://www.1394ta.org/Technology/specifications/specifications.htm>
The 1394 Trade Association also has a PDF on its website, entitled
"Overview of 1394 Specifications" or "1394 Standards and Specifications
Summary" [1] that calls the last one "Industrial & Instrumentation
Digital Camera V1.31" (in a subsection titled "Standards for Industrial
and Military"), and notes that this is a "Protocol for setup and control
as well as data format of industrial cameras delivering uncompressed
video streams". The intended audience for the specification, according
to the PDF, is "Industrial camera vendors and Software driver
developers".
> Firewire cameras I use (NOT camcorders) do comply with these specs
> as I can assign CMU's device drivers for them and then access them
> through my c/c++ program that uses CMU's library calls.
In essence, it seems the Firewire cameras you use are comparable to
USB-based web cameras. Instead of delivering a compressed DV data
stream, using the DV25 codec, like "real" video cameras do, they deliver
an uncompressed video stream that may or may not have some/any technical
resemblance (such as resolution, or frame rate, or pixel aspect ratio)
to common digital video standards.
> My Sony DV camcorder doesn't act exactly like a firewire camera:
> if you force assign CMU's firewire device drivers and try to
> access it as a firewire device the result is a failure, device
> is not recognized/not responsive to device driver's calls.
>
> Not knowing the specifics of the IEEE 1394 camera protocol, I
> reason the DV devices maybe different than generic firewire
> cameras in the way they are accessed by various firewire
> device drivers (CMU vs. Windows).
The problem here seems to be one of terminology and viewpoint. The
discussion in this group mostly deals with TV-compatible video
standards. PAL, NTSC, DV-over-1394, ITU-R BT.601 video streams over SDI,
etc. all fall in that category.
Most writers to this group would insist that a "generic Firewire camera"
and "1394 camera protocol" both refer to DV camcorders and the
DV-streaming-over-1394 protocol. That's not an unreasonable assumption
to make since DV camcorders were originally one of the first (if not
_the_ first) real-world applications for the new IEEE-1394 (Firewire)
standard. I don't have a reliable historical 1394 timeline at my
disposal, but I'm guessing the kind of cameras you're talking about, and
the standard relating to them you're talking about, were developed
later. DV was the first video standard to take advantage of 1394.
As far as I know, DV(25) is currently specified in IEC 61883-1, IEC
61883-2 (1394-related), and IEC 61834 (the tape format.)
> Is there an Analog to Firewire conversion device that will act exactly
> as if it was a firewire camera compliant with the 1394 Digital Camera
> specifications on the Windows side (when I try to access the
> image content from my program)?
When asking this question in the future, it is probably best to quote
the exact TA specification number and make an explicit mention that DV
cameras and DV25 data stream are _not_ what you're after. Giving some
links to cameras that natively produce these kind of data streams
wouldn't hurt, either, as examples. Merely talking about "Analog to
Firewire conversion device", "a firewire camera", and "1394 Digital
Camera specifications" will just make people think about DV cameras, and
suggest analog-to-DV converters, since that's what your questions pretty
much sound like to those who don't have an intimate knowledge of the
various video streaming standards that can be implemented on top of the
IEEE-1394 bus.
_____
[1] <http://www.1394ta.org/Technology/Specifications/Standards
OrientationV5.0.pdf>
--
znark
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