Hi,
On 05. 01. 23, 10:27, Ricardo Ribalda wrote:
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.
TL/DR:
modprobe usbmon
sudo wireshark; select the usbmonX device where your device is attached
Good luck ;)
This is the last SET CUR (the "Commit" one) Windows do:
Setup Data
bmRequestType: 0x21
bRequest: SET CUR (0x01)
Control Selector: Commit (0x02)
Interface: 0x01
Entity: 0x00
wLength: 26
Probe/Commit Info
bmHint: 0x0001, dwFrameInterval
bFormatIndex: 1
bFrameIndex: 2
dwFrameInterval: 400000
wKeyFrameRate: 0
wPFrameRate: 0
wCompQuality: 0
wCompWindow: 0
wDelay: 0
dwMaxVideoFrameSize: 691200
dwMaxPayloadTransferSize: 3072
Data Fragment: 01000102801a060000000000000000000000008c0a00000c0000
I assume the Win program only pretends (recodes) as 720x576. In fact --
IMO, it grabs only 640x480. 691200 above is 2*720*480 and lsusb says
"bFrameIndex: 2" is this:
VideoStreaming Interface Descriptor:
bLength 42
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 2
bmCapabilities 0x00
Still image unsupported
wWidth 640
wHeight 480
dwMinBitRate 768000
dwMaxBitRate 196608000
dwMaxVideoFrameBufferSize 614400
dwDefaultFrameInterval 400000
bFrameIntervalType 4
dwFrameInterval( 0) 400000
dwFrameInterval( 1) 500000
dwFrameInterval( 2) 666666
dwFrameInterval( 3) 1000000
Holy crap. Can someone recommend a cheap full PAL device?
FWIW, full pcap of a piece of video grabbed in Win is at:
https://hci.fi.muni.cz/~xslaby/n/av-win.pcap
thanks,
--
js
