On Saturday 27 February 2010, [email protected] wrote: > Is this fix likely to matter for 250's as well?
Possibly. I haven't tested it, but the patch doesn't check the card type. > I no longer use my 350 for capture for various reasons (though I do > still use it for display), but some maybe 5%? 1%? of my 250 captures > display ghosting---sometimes slight, sometimes pretty objectionable. > In some captures, it persists for the entire capture; in others, I > can see a visible one-frame flash and -then- the rest of the capture > is ghosted until the stream is closed. Typically there are faint > vertical black/gray bands as well, most-obviously if the source is > letterboxed because they show up against the uniform background; > typically three are 3-5 of them across the width of the screen. > > The ghosting typically manifests as the image contents (or perhaps > just edges, e.g., the derivative of the image) shifted sideways about > 1/4 of the width of the screen or so. Really does look for all the > world like the typical multipath ghost from RF days. The type of ghosting you describe is what this hopefully stops, but only when it persists for the entire recording. This ghosting affects all sources, not just the tuner. You can easily check for it by setting the temporal filter to 31. For current drivers this can be done by running 'v4l2-ctl --set-ctrl=temporal_filter=31' (btw the normal value is 8 - Be sure to reset it to avoid screwed up recordings) With a full res capture it should only suffer motion blur. If the glitch has been triggered it will produce a weird effect with a trail of images across the screen. (It must be a full res capture, as the temporal filter was partially disabled a few years ago due to the ghosting issues). > P.S. I -do- recall an obnoxious flickering of the upper 1/4 of the > screen that was often provoked by a loss of sync on the input---that > was in the days when I took RF directly from a cable, and one of our > local PBS stations had a tendency to transmit badly-corrupted bursts > of video (also really badly overmodulated, so much so that white areas > caused audio buzzing) a few times a day. I don't know offhand if it > -only- manifested on 350 capture, and I rather suspect not. (I could > possibly research it if it mattered, based on my records.) I haven't > seen it in quite some time, but I don't know if it's because I stopped > capturing on my 350 or because I switched to STB-only sources; the two > happened at pretty much the same time, I think. This sounds like the flicker this patch should also fix, but like the ghosting, only where it affects the entire recording. As before, this glitch isn't restricted to the tuner. My understanding is that with current drivers, this type of glitch is primarily a PVR350 problem. The patch does not remove the trigger event for either of these issues. The capture init sequence itself produces a trigger and if it happens at just the right time either glitch can occur, with ghosting the most common. With the patch installed, the firmware will recover itself from both issues before capture actually starts. -- Ian _______________________________________________ ivtv-devel mailing list [email protected] http://ivtvdriver.org/mailman/listinfo/ivtv-devel
