On Fri, Jan 22, 2010 at 2:26 AM, Tony Ross <[email protected]> wrote: > Hello Andy, it's been 7 weeks since your response, and I've used that time > to acquire and test an HVR-1600 and PVR-150 in addition to the PVR-500, with > the same "noisy" results from my old analog VHS tapes, both on Linux and > Microsoft XP. > > It's curious that a USB capture device on the XP machine doesn't display the > same "noise" in the recorded file as do the Hauppauge cards. A > low-resolution comparison of the two different captures can be seen at > http://tony.ross.mystarband.net/videos/ivtv_noise.mpeg (~38 MB). > > In the Hauppauge capture, notice the dark random bands immediately upon > exiting the aircraft, in freefall (behind the dmesg output) and especially > as my parachute opens (after the dmesg listing) -- apparently the result of > inertial tape flutter and air entering the camera housing. This kind of > noise isn't seen however on the television screen or in the USB-captured > output in the second half of the video, so apparently those two devices > share some kind of signal conditioning that the Hauppage card doesn't > perform by default.
Ah, Looking at the video, I've seen this sort of distortion before. A user reported it a couple of weeks ago on one of my em28xx cards. I helped him trace it down to a tvp5150 register related to the way hsync detection is configured. See the thread "em28xx: New device request and tvp5150 distortion issues when capturing from vcr" over on linux-media for more info. What it boiled down to was the decoder was forced into "tv mode" instead of "auto mode" or "vcr mode". And because it was in "tv mode" instead of "auto mode", the chip was not properly handling the sort of crappy hsync signal you can get with a VCR. I would look at the cx25840 docs and see if there is something comparable. Devin -- Devin J. Heitmueller - Kernel Labs http://www.kernellabs.com _______________________________________________ ivtv-users mailing list [email protected] http://ivtvdriver.org/mailman/listinfo/ivtv-users
