I saw different bmVideoStandards with lsusb. It is the only parameter
with a different value on both sides. Meanwhile, I found a way to make
the camera work. I need to use the load option nodrop=1 in the host, but
not in the guest.
I have no idea why UVC sees incomplete frames only on host side. It is
definitely a firmware problem. Could you imagine what was not respected
there, so that almost every packet is dropped?
Stefan May
Am 26.10.2012 17:38, schrieb Alan Stern:
On Fri, 26 Oct 2012, Stefan May wrote:
it seems that data are interpreted differently. While the host is
getting tons of -71 errors, data is passed to vmware correctly.
That's a strange way of describing it. When the -71 errors occur
there _is_ no data -- the device didn't send anything. So it doesn't
make sense to say the data gets passed to VMWare correctly.
In fact, VMWare is changing the -71 error codes to 0.
I've attached two traces that I ran simultaneously on the host and the
guest. One thing that I noticed is that the same camera is setting
different video standards on both systems. While the host sees a
PAL-standard, the guest interprets it as NTSC.
How did you notice this? It doesn't show up in your usbmon traces.
#### Host ####
bmVideoStandards 0x6c
PAL - 625/50
SECAM - 625/50
PAL - 525/60
#### Guest ####
bmVideoStandards 0x32
NTSC - 525/60
NTSC - 625/50
PAL - 525/60
Maybe you are using different software or different settings in the
host and the guest.
Might this be the reason?
This is definitely not the reason for the missing -71 codes. They are
stripped out by VMWare.
Can I force the host to use NTSC?
I don't know. Whatever technique you employ to tell the guest to use
NTSC should also work with the host.
Alan Stern
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