On Sun, 2 Aug 2009, Jean-Francois Moine wrote:
On Sat, 1 Aug 2009 16:56:06 -0500 (CDT)
Theodore Kilgore <kilgota@xxxxxxxxxxxxxxxxxxxxxx> wrote:
Several cameras are supported here, which all share the same USB
Vendor:Product number when started up in streaming mode. All of these
cameras use bulk transport for streaming, and all of them produce
frames in JPEG format.
Hi Theodore,
Your patch seems ok, but:
- there is no kfree(sd->jpeg_hdr). Should be in stop0().
OK. Will do, and resend, as asked. But before I do that, there is the
second item. It seems to raise questions of policy. I think it is
appropriate to raise that question for general discussion.
- as there is only one vend:prod, one line is enough in gspca.txt.
This is a question about which I have been curious for quite some time,
and I think that now is a good time to ask it.
Just what policy do we have about this? The information which links brand
and model to driver ought to be presented somewhere. If it does not go
into gspca.txt then where exactly is the appropriate place to put said
information?
As to these three particular cameras, perhaps one should take into account
here the fact that what we actually have here is three "different"
cameras, put on the market by three different vendors, and in at least two
different parts of the world. The Sakar camera and the Cobra camera are
for sale in the US. The FlyOne camera is for sale in Germany and perhaps
in some other parts of Europe. Furthermore, in stillcam mode they are all
three of them standard mass storage devices, but they have different IDs
from what is listed here (good for them about that!) and the stillcam IDs
are distinct, too. So in other words they are not the same camera, at all,
in spite of the fact that they all use the same ID when set up in webcam
mode.
A more general consideration is that the buyer of a camera is not helped
at all by knowing that a particular chipset combination is supported. No.
The buyer can only go by the make and model which are printed on the
outside of the plastic bubble pack. So what exactly are we, the
developers, to do in order to make the relevant information available to
the public? There is some wiki, of course. But it seems to me the wiki
itself ought to refer to the gspca.txt file, among other things.
I do think that one of the easy ways to address the above issue of helping
the camera purchaser would be to agree that gspca.txt ought to contain the
information for each individual camera which is supported. This would make
the file longer, but it is in my opinion a small price to pay, when the
goal is to have complete information, put in a central place.
In going over the gspca.txt file, I also see that the jeilinj entries are
the only place where there is a "duplicate" entry, so that I am at this
time in non-conformity. But, on checking, I also see that the SQ905
cameras (2770:9120) and the SQ905C cameras (2770:905c) are not listed at
all in gspca.txt. This could be claimed as an example of my ignorance that
I am supposed to put something there. But it is also related to the fact
that
-- there are twenty-five (25) cameras listed in
libgphoto2/camlibs/sq905/library.c, which were reported to me as working
with that particular stillcam driver. This list does not include several
other cameras that I only heard about vaguely, or that I do not even know
about at all because nobody ever reported them to me. So if I am supposed
to pick just one of these, then which one do I list in gspca.txt, when as
far as I know they all ought to work with the gspca sq905 driver?
and, as for the SQ905C cameras
-- there are seventeen (17) cameras listed in
libgphoto2/camlibs/digigr8/library.c, which were reported to me as working
with that particular stillcam driver. This list does not include several
other cameras that I only heard about vaguely, or that I do not even know
about at all because nobody ever reported them to me. If I am supposed to
pick just one of these, then which one do I list in gspca.txt, when as far
as I know they all ought to work with the gspca sq905c driver?
For the above reasons, I have up to this point not listed any of these
cameras in gspca.txt at all, as supported. Probably that is not the right
thing to do, either?
Now, in addition to the above, there is another problem which will hit
very soon, probably soon after the time that Thomas Kaiser gets back from
his vacation and starts to work again. This is the matter of the mr97310a
driver, which is almost finished now. What we have there is a list of
cameras which are all functionally identical as still cameras, but as
webcams the functionality differs in minor details. Here is what happens:
08ca:0111 Aiptek Pencam VGA+ (supported, listed in gspca.txt)
093a:010f several cameras, some functionally identical to the Aiptek
camera, and some which as webcams require a different init procedure and
use different control procedures! There are two different basic cameras
with the same USB number, and it has been necessary to create undocumented
commands to be able to tell which kind of camera we have! This has been
done, at this point. But as to documentation the question arises, that if
we choose just one of these to list in gspca.txt, should we pick one of
"Type 1" or one of "Type 2" to list?
093a:010e several cameras with this ID number, which also fall into
two disjoint sets when run in webcam mode, again requiring the development
of previously undocumented commands to be able to detect and classify
which camera it is, before initializing it. Again, which one of these
cameras is one supposed to list in gspca.txt?
Also the above account of the unexpected complications of the mr97310a
driver raises the natural problem that the same thing might happen yet
again. The differences in behavior of the different cameras seem to be
connected to such external characteristics as the type of LCD display used
on the outside of the camera, or other minor details in the construction.
Who is to say that there can not be a "Type 3" in either of the two cases
where two types have already been discovered? What is the safe thing to
do? Well, it seems to me, the only thing appropriate is to list explicitly
all the mr97310a cameras currently supported, and in the future to list
explicitly any other one which is reported as working.
As I said, this question of what to do with the mr97310a documentation
will come up very soon, unless one merely avoids the question by refusing
to make a choice. So the question of documentation becomes rather serious.
I hope that the occasion is now appropriate one deciding this issue of
documentation. My opinion is that gspca.txt ought to list individually
each camera which is known to work, as well as the driver used and the USB
ID.
Theodore Kilgore
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