On Sun, 2008-11-23 at 12:25 +0100, Levente Novák wrote: > On Mon, 2008-11-10 at 23:55 +0100, Levente Novák wrote: > > Hi Andy, > > > > Back in July, we were discussing about a problem with a PVR-150 MCE > > concerning captures from the OSD of a VCR: > > > > On Sun, 2008-06-29 at 16:11 -0400, Andy Walls wrote: > > > As root, for those two scenarios, if you provide the output of: > > > > > > # v4l2-dbg -R type=i2cdrv,chip=cx25840 > > > > > > This will let me see how the cx25843 is set and what it's status is > > > (i.e. does it have horizontal sync). > > > > > > I think it will be a matter of setting amplifier gain and clamping > > > settings. > > > > At that time, my kernel was compiled without kernel debug info so > > v4l2-debug was unable to dump the registers. As it was just before my > > holidays, later I completely forgot the issue since I rarely use the > > composite input. > > > > Last sunday (faced again with the problem), I compiled the new kernel > > with debug on, and finally dumped the registers of the cx25840 as you > > will find attached (static.dump for the OSD without tape played and > > dynamic.dump when playing back a tape). > > > > There are obviously lots of differences between them, but I have no > > knowledge of the register structure of the chip. Could you have a look > > at these files, maybe it will give you an idea about the nature of the > > problem. > > > > Thanks for your help and my excuses for the really huge delay in my > > reply. > > Does somebody know how to interpret the register dump of the cx25840 > (and also how to set a register to a given value)? Some of the registers > are clearly different during a static OSD capture and a dynamic one > (when the tape is being played).
Sorry. Your previous mail got lost in my inbox. I'm feeling rather under the weather right now and a US holiday is coming up this week, so I'm probably not going to look at it soon. If you want to take a look at it, the data sheet is here: http://dl.ivtvdriver.org/datasheets/video/cx25840.pdf All the information you should need is there, but it's densely written in places, light on details in other places, sometimes the information is spread across several sections, etc. but it's there. You may need to read some sections several times to "get it" and it helps to have a moderate understanding of the baseband composite TV signal. Having an electrical engineer nearby to answer questions wouldn't hurt either. The registers definitions are near the back of the document. The video processing registers are usually in the 0x400-0x4ff range. The Analog front end registers are usually in the 0x100-0x1ff range. Register 0x488 in particular has the current state of the Analog Front End's (AFE) Variable Gain Amplifier (VGA) and the Digital Front End's (DFE) Automatic Gain Control (AGC). If the VGA is near the top of it's range, then you have a weak analog signal or one that is fooling the VGA into thinking that it is weak - this can cause sync problems. Regards, Andy > Levente _______________________________________________ ivtv-users mailing list [email protected] http://ivtvdriver.org/mailman/listinfo/ivtv-users
