Hans de Goede wrote: > Hi, > > On 02/01/2010 11:13 PM, Németh Márton wrote: >> From: Márton Németh<nm127@xxxxxxxxxxx> >> >> The byte sequence 0xff, 0xff, 0xff 0xff is not a real marker to skip, instead >> it is one byte from the image and the following three 0xff bytes might belong >> to a real marker. Modify pixart_fill_nbits() macro to pass the first 0xff byte >> as an image data. >> > > Oh, good catch. I'm still seeing the occasional bad frame though :( The same at my side, this patch alone does not solve the whole problem complete. I have the feeling that at least same of the corrupted frames will not come with this patch, through I haven't verified this with measurement. On the other hand, in my previous email used a little bit different code: I jumped over the 1024 and 512 bytes without parsing it. That would be maybe necessary to add. By the way, is there any reason why pixart_fill_nbits() is a macro? > While on the subject of the pac7302. I've been playing around a bit, and I have the > feeling that if we were to go for a lower auto gain target (set autogain off and > lower exposure, you can do this ie with v4l2ucp), combined with a gamma correction of > 1500 (again use ie v4l2ucp), the images is much better (less over exposed, more > contrast). > > Do you agree ? Well, my Labtec Webcam 2200 works only with acceptable indoors, when I try to capture something outdoors under direct sunshine conditions I get overexposed frames. I found, however, an interesting pointer in two cameras' user's manual, see the Note column: http://linuxtv.org/wiki/index.php/PixArt_PAC7301/PAC7302#Identification There is a setting indoor/outdoor which is currently not available in gspca_pac7302 driver. Maybe this would be an interesting point to figure out which register is related to this setting. Regards, Márton Németh >> Signed-off-by: Márton Németh<nm127@xxxxxxxxxxx> >> --- >> diff -r f23c5a878fb1 v4l2-apps/libv4l/libv4lconvert/tinyjpeg.c >> --- a/v4l2-apps/libv4l/libv4lconvert/tinyjpeg.c Mon Feb 01 13:32:46 2010 +0100 >> +++ b/v4l2-apps/libv4l/libv4lconvert/tinyjpeg.c Mon Feb 01 23:05:39 2010 +0100 >> @@ -339,10 +339,15 @@ >> } \ >> break; \ >> case 0xff: \ >> - if (stream[1] == 0xff&& (stream[2]< 7 || stream[2] == 0xff)) { \ >> - stream += 3; \ >> - c = *stream++; \ >> - break; \ >> + if (stream[1] == 0xff) { \ >> + if (stream[2]< 7) { \ >> + stream += 3; \ >> + c = *stream++; \ >> + break; \ >> + } else if (stream[2] == 0xff) { \ >> + /* four 0xff in a row: the first belongs to the image data */ \ >> + break; \ >> + }\ >> } \ >> /* Error fall through */ \ >> default: \ > > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
