On 05. 01. 23, 8:23, Laurent Pinchart wrote:
On Wed, Jan 04, 2023 at 02:12:44PM +0100, Ricardo Ribalda wrote:
Hi Jiri
I think that /dev/video3 belongs to your notebook webcam, not to the EasyCAP.
That looks correct.
Yes, you are right -- only 2 devices (4+5) are created. I don't know why
I thought there are 3.
720x480 I believe is the NTSC resolution.
Ah, that makes sense. Which leads me to: sometimes, the picture distorts
after I start playing the video. It's skewed and halves of the picture
switched [1]. I assume the driver expects NTSC@720x480, but the device
sends PAL@720x576, actually. Sometimes, there are also color strips.
[1] https://hci.fi.muni.cz/~xslaby/n/skew.jpg
Can you try starting the
VHS, *before* you connect the grabber to the USB? Maybe that way the
device realises that it should be working in PAL not in NTSC.
Good idea. The device advertises a maximum resolution of 720x480 in the
UVC descriptors it exposes to the host, so there's nothing the driver
can really do to obtain 720x576.
That doesn't help. Maybe it would sound foolish (I don't know the
internals), but would it make sense to re-read UVC parameters on each
device start in open? Only as a debug aid to see if they change.
If plugging an active PAL source to the device before plugging it to the
USB port doesn't help, another option for investigation is to capture
USB traffic under Windows to check what happens there.
OK, I can try it. I have win10 virt machine set up. So that should be
easy using usbmon. Except I don't know how to read the mon dumps. I
should start at Documentation/usb/usbmon.rst, I believe.
thanks,
--
js
suse labs
