- Canopus proprietary? Exact meaning!?
- Posted by Gary Smith on June 2nd, 2004
Lot's of the historical threads touch on this but never quite seem to
address it directly.
The Canopus ADVC units use a Canopus-proprietary codec. This causes
me several points of confusion.
1) Does this mean only that the algorithms which generate the output
format (DV I/O) are proprietary --OR-- does it mean that the output
itself -- meaning the payload riding through the firewire -- is in a
proprietary encoded format???
2) To get from DV I/O to even the least-processed DV file format
(whatever that is), doesn't the PC software need to understand the
encoding of the DV I/O signal? Or, is there actually a processing
path which takes DIF sequences off the wire and simply blasts them
serially into a raw file dump? And, if so, what is the resulting file
format called? Is this what AVI actually is? But no, this can't be
what AVI is because AVI comes in at least a couple flavors, which
implies processing, right?
I'm a pretty expert Googler and an engineer to boot! But, I've tried
on several occasions, for hours at a crack, to find a lucid
explanation of what's really going on here and so far I've got bupcus!
- Posted by Markus Zingg on June 2nd, 2004
None of the above. It simply means that if you use a Canopus provided
capture software that it will add a different FourCC code in the avi
file header instead of the one that is otherwise used.
No, capture programms usually don't process the video content but
instead move frames around like black boxes.
No, to my knownleadge some Linux Systems operate on raw DV streams.
With avi the DV stream is always embedded within the avi format which
in case of DV is really just a very light wigth wrapper.
The main difference with DV avi is how audio is treated, but there are
mayn threads in this NG that cover this (search for DV type 1 and type
2)
Again, the only difference that makes Cannopus DV files proprietary is
the FourCC string in the header. You can simply patch it and voila you
have a file that can be processed elsewhere. If memory serves there
are even tools around that do this but since I never owned Cannopus
hardware (just did not happen, they are fine) I don't have a pointer.
HTH
Markus
- Posted by DeepOne@ix.netcom.com on June 2nd, 2004
Markus Zingg <m.zingg@nct.ch> wrote:
I have an ADVC-100, and it did not come with any capture software (or
any software or drivers of any kind). It works fine with non-Canopus
software.
- Posted by Gary Smith on June 3rd, 2004
Correct DeepOne! The ADVC line is not just a bidirectional A/D. It
also applies chip-based DV codecs. When digitizing, the compression
of the digitized video is completed internally, before the transition
to DV I/O. If the readers reexamine my questions in that light, my
questions (and their answers) will make more sense.
On Wed, 02 Jun 2004 21:51:03 GMT, DeepOne@ix.netcom.com wrote:
- Posted by Gary Smith on June 5th, 2004
OK, I've gone elsewhere and seem to have found an answer to my
question. So, I'm bringing the conclusion back here.
You can read the entire dialog at:
http://www.digitalfaqsupport.com/
The topic is titled "DV myths vs. Canopus (hype?)"
This is the understanding I recorded there. Any comments?
"So, the bottom line on DV is that there may be technical difference
but most "normal" people ignore them. Or, when they do pay attention
to them the result will vary depending on taste.
Thus, while it may be true that only a Canopus codec will decode a
Canopus-encoded DV in the exact way that Canopus intended --- that way
may not be the way preferred by the end user.
The end user may actually prefer the results obtained by decoding a
Canopus DV using an MS codec.
I just need to loosen my sphincter a little and accept that. The DV
realm is more an artist's quarter than a scientific community."
