On Sun, 15 Nov 2009, Oliver Neukum wrote:
Am Sonntag, 15. November 2009 23:15:32 schrieb Theodore Kilgore:
Now, I said something about the OEM drivers. In webcam mode, all of the
OEM drivers that I know of set the default resolution setting at 320x240.
Some of them will not even let you change that. And, using the commands
which can be detected by sniffing, one can not get a 352x288-capable
camera, nor for that matter a 640x480-capable camera, to stream decently
at 352x288 or 176x144. Something comes out, but the frames jump terribly.
It was in eliminating the sources of that jumpiness that I simply got rid
of several setup commands, and thereby landed in the soup by leaving out a
command which appears to be essential for making some of the cameras
stream on a UHCI system. There are obvious lessons to be derived. I have a
long memory, and I think I will apply them.
So if I understand you correctly to make the camera work on UHCI you
have to go to a lower resolution? Thereby you are lowering the data rate,
aren't you? That does a lot less to absolve UHCI, if it works only at a lower
rate.
Regards
Oliver
Oliver,
This is a follow-up to yesterday's answer to your question. As I
understood, you asked whether the maximum framerate is degraded when the
0x093a:0x010e type 1 camera is hooked to a computer with UHCI, as opposed
to the rate which is seen with OHCI.
I was able to answer right away what is the max framerate at 352x288
resolution if the camera is hooked up through OHCI. The rate in that case,
I said, is 22 frames per second.
Today, after upgrading a discarded, secondary computer back up to current
standards so that it would accept stuff which had been compiled on another
box and then installing approximately one dozen Gnome library tarballs, I
was able to get camorama to compile on the old box, too. I mentioned that
it might take a while. It did.
But now I have the answer to your question. The max frame rate for the
same camera, at the same resolution setting, is also the same, 22 frames
per second. I do not like the output image nearly as much, but that either
relates to the old machine, or it is that yet another one of those
silly-looking commands that I left out is needed on the UHCI hardware.
I do agree that this whole question of what is happening with OHCI versus
UHCI is a very interesting one, and this particular piece of hardware has
brought the question up almost by accident. Namely, it was learned because
I on purpose left something out of my code which I had found in a sniff
log. That's as good a way as any to learn what a command does, I suppose.
Just in case it helps in this situation or in other, similar situations, I
am trying to find out if there is any USB analyser over in the College of
Engineering, and I have already asked to be authorized to buy one in case
there is not any or if whatever is there is not available for me to use. I
don't know what kind of answer I am going to get, though.
Theodore Kilgore
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