Hi Alexey, On Monday 05 September 2011 17:48:42 Alexey Fisher wrote: > Am 31.08.2011 00:32, schrieb Laurent Pinchart: > > On Thursday 25 August 2011 09:44:10 Alexey Fisher wrote: > >> Hi Laurent, > >> > >> are there any reason why uvc_video_decode_start do not do precise header > >> size checks? Are there many cameras with broken header size too? > > > > How precise do you mean ? The driver currently doesn't use much of the > > header, so it just makes sure that the header size is smaller than or > > equal to the packet size, and that it's at least 2 bytes long. > > > >> I send you patch on what i work now to catch streams with fragmented > >> packets.. what do you think about it? Will you apply some thing like > >> this? > > > > I'm not sure about that. Webcams that would require something like that > > are so broken that I'm tempted to consider them as not UVC-compliant. > > They should be returned to vendors with a loud complaint. > > > > Your patch might help, but the sad story is that it can't completely fix > > the streams. There's always a chance that fragmented packets that > > contains no header will start with data that looks like a header. You > > won't be able to find a buller-proof solution. > > You are right, > the idea is not to show definitely broken frames. If there is some thing > what we can't filter, is ok. we did our best.
I understand. I'm not sure if this should be included in the mainline uvcvideo driver though. It makes the code more complex to support a couple of completely broken devices, and doesn't guarantee that those devices will work correctly. > I just thinking about build in uvc compliance tester insight of the module. > Some thing what users can use right in shop or at home before 14 day return > guarantee. > You enables compliance test and it print results in in dmesg. One of > test should be header check, error/drop rate, and so on. That's an interesting idea. It should probably come with a userspace stress test software as well. -- Regards, Laurent Pinchart _______________________________________________ Linux-uvc-devel mailing list Linux-uvc-devel@lists.berlios.de https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
