Re: [Linux-uvc-devel] Slow frame rate windows/linux?
Hi Andrew, On Monday 13 September 2010 01:30:35 Andrew Leech wrote: Hi Laurent, all, That's interesting about the timestamps, I though they were supposed to be essential for synchronising audio and video properly. Yes they are... :-) I'm not using audio myself so not too concerned about that side of things. Same here, that's why timestamp support hasn't been implemented yet. And also because it doesn't seem to be supported in the USB Audio Class driver either. I'd love it if someone could write timestamps support for the uvcvideo driver, but that's a difficult task. Also, there was a small footnote on one of the msdn pages about interlacing requiring timestamps so I had tried that for make interlacing work...it didn't work and interlacing still isn't working properly so I stripped out oll the interlacing descriptors and I'm going to do deinterlacing manually now anyway because I need to do frame grabbing to disk so having proper video card deinterlacing wouldn't help much anyway. I think I may have found the source of my fps problems however, my frame is 768 x576, and as a point of convenience I found that sending 4 lines in a uvc packet seemed to work just fine. 4 x 768 + 12 (header) turns out to be 1028 x 3 isoc usb packets, which is obviously more than you're allowed, but because it was showing the picture just fine I thought it was ok. Cropping the image to a smaller width though, and making the usb packets smaller, seems to fix the frame rate in windows. It seems that while the usb stack can handle the larger isoc packets, there's some buffering in the uvc driver that's not large enough to work. I still need to do more testing to confirm that's the root of the problem however. That's actually what that other message I sent here by mistake was about, I meant to send it to the lpc3000 group, I need a lot more buffering in chip to get my usb packet sizes back down to legit sizes. I'll let you all know if I get it sorted out, because it's a pretty deceptive problem, and highlights a way your linux driver handles dodgy hardware better! Given the amount of dodgy hardware out there, I'm not surprised that the Linux driver works better than the Windows driver :-) Several vendors ship (or at least used to ship) a custom UVC driver for Windows to work around device bugs. -- Regards, Laurent Pinchart ___ Linux-uvc-devel mailing list Linux-uvc-devel@lists.berlios.de https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
Re: [Linux-uvc-devel] Slow frame rate windows/linux?
Just an update, yeah I've confirmed that the USB isoc packet sizes were the culprit. Linux can handle overspec'd usb packets (1028 bytes), it appears that the microsoft usb stack can handle them, but microsoft's usbvideo.sys can't, it misses about every second frame. Fixed the usb packet size to be = 1024 and it streams just fine in both windows and linux! Cheers, Andrew -Original Message- From: Laurent Pinchart [mailto:laurent.pinch...@ideasonboard.com] Sent: Monday, 13 September 2010 8:48 AM To: linux-uvc-devel@lists.berlios.de Cc: Andrew Leech Subject: Re: [Linux-uvc-devel] Slow frame rate windows/linux? I feel there must be something wrong in my uvc descriptors / setup that is confusing the windows driver where the linux one is more forgiving. I've tried playing with the mix/max bitrates, and continuous vs static frame intervals, all to no avail. If you post the output of lsusb -v I could check the descriptors. I've also added timestamps to my frames (uncompressed yuy2) which I think are working, but also noticed no difference. Is there any way with the linux driver to check the frame timestamps, if they're wrong it should show up as late/missed frames? The uvcvideo driver ignores timestamps at the moment; Has anyone got any suggestions? I really want to ensure my hardware is going to be stable on as wide a range of computers as possible. -- Regards, Laurent Pinchart ___ Linux-uvc-devel mailing list Linux-uvc-devel@lists.berlios.de https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
Re: [Linux-uvc-devel] Slow frame rate windows/linux?
Hi Andrew, On Wednesday 08 September 2010 02:03:02 Andrew Leech wrote: Hi everyone, This may not be most appropriate place to ask, because the UVC device I'm building (custom hardware) actually seems to be working pretty well under linux, I'm getting a nice steady 25fps PAL picture. I just feel there's a lot of expertise here that someone may be able to assist. The problem is my hardware under windows only gets ~10-12fps, and I need cross platform compatibility. It doesn't report any dropped frames, and it gets this speed no matter which renderer I use. I don't think the problem is the pc, as I've tried it on a couple of different windows boxes and the working linux is in a vmware instance on the same pc anyway. I feel there must be something wrong in my uvc descriptors / setup that is confusing the windows driver where the linux one is more forgiving. I've tried playing with the mix/max bitrates, and continuous vs static frame intervals, all to no avail. If you post the output of lsusb -v I could check the descriptors. I've also added timestamps to my frames (uncompressed yuy2) which I think are working, but also noticed no difference. Is there any way with the linux driver to check the frame timestamps, if they're wrong it should show up as late/missed frames? The uvcvideo driver ignores timestamps at the moment; Has anyone got any suggestions? I really want to ensure my hardware is going to be stable on as wide a range of computers as possible. -- Regards, Laurent Pinchart ___ Linux-uvc-devel mailing list Linux-uvc-devel@lists.berlios.de https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
Re: [Linux-uvc-devel] Slow frame rate windows/linux?
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-Original Message-
From: Laurent Pinchart [mailto:laurent.pinch...@ideasonboard.com]
Sent: Monday, 13 September 2010 8:48 AM
To: linux-uvc-devel@lists.berlios.de
Cc: Andrew Leech
Subject: Re: [Linux-uvc-devel] Slow frame rate windows/linux?
I feel there must be something wrong in my uvc descriptors / setup
that is confusing the windows driver where the linux one is more
forgiving. I've tried playing with the mix/max bitrates, and
continuous vs static frame intervals, all to no avail.
If you post the output of lsusb -v I could check the descriptors.
I've also added timestamps to my frames (uncompressed yuy2) which I
think are working, but also noticed no difference.
Is there any way with the linux driver to check the frame timestamps,
if they're wrong it should show up as late/missed frames?
The uvcvideo driver ignores timestamps at the moment;
Has anyone got any suggestions? I really want to ensure my hardware is
going to be stable on as wide a range of computers as possible.
--
Regards,
Laurent Pinchart
[Linux-uvc-devel] Slow frame rate windows/linux?
Hi everyone, This may not be most appropriate place to ask, because the UVC device I'm building (custom hardware) actually seems to be working pretty well under linux, I'm getting a nice steady 25fps PAL picture. I just feel there's a lot of expertise here that someone may be able to assist. The problem is my hardware under windows only gets ~10-12fps, and I need cross platform compatibility. It doesn't report any dropped frames, and it gets this speed no matter which renderer I use. I don't think the problem is the pc, as I've tried it on a couple of different windows boxes and the working linux is in a vmware instance on the same pc anyway. I feel there must be something wrong in my uvc descriptors / setup that is confusing the windows driver where the linux one is more forgiving. I've tried playing with the mix/max bitrates, and continuous vs static frame intervals, all to no avail. I've also added timestamps to my frames (uncompressed yuy2) which I think are working, but also noticed no difference. Is there any way with the linux driver to check the frame timestamps, if they're wrong it should show up as late/missed frames? Has anyone got any suggestions? I really want to ensure my hardware is going to be stable on as wide a range of computers as possible. Thanks, Andrew ___ Linux-uvc-devel mailing list Linux-uvc-devel@lists.berlios.de https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
