On Thu, 30 Mar 2006 19:03:49 +0200 Bernhard Praschinger <[EMAIL PROTECTED]> wrote:
> Hallo
>
> > I'm trying to digitize old VHS tapes with a DC30+.
> > I ran into one clearly reproducible problem:
> > Capturing at PAL/fullframe (lavrec -q50) apparently works perfectly
> > with nearly no framedrops or A/V sync problems recognized.
> If you capture VHS Full size makes little sense, because of the low
> quality on the tape. -d 2 is usually enought.
I tried and compared the results.
I can see a clear difference between -d1 and -d2 on my "good quality" tapes.
With medium sharp tapes you're right. But I want to have a unique
workflow and half of my tapes need -d1.
>
> > Looking at the resulting avi I can see that sometimes the second field
> of a
> > frame is shifted one line down. (there seems to be one line inserted at
> top).
> > In order to exclude the possibillity of having a field order problem I
> looked
> > a a movie sequence with slow horizontal, but no vertical motion. I
> converted
> > the avi into a sequence of pnm-images, one for every field (not frame).
> > scrolling through the sequence (with xv) it is obvious that the temporal
> order
> > of the fields is correct (horizontal motion is in sequence). But it is
> also
> > clearly visible that sometimes the 2nd field of a frame is shifted down
> one
> > line. The 1st field does not have this problem. This of cause completely
> ruins
> > deinterlacing. In order to check my analysis wrote a yuv-filter which
> shifts
> > the 2nd field up. After this the bad sequences look good (but the good
> ones
> > get bad, of cause).
> Is it possible to make a short sequence aviable ?
Sure, but it's big. A good example would be a few megs.
Is this OK for you?
If yes, then I'll upload a sequence to my ftp server at monday. (I have only
modem at home, but DSL at work)
>
> > The phenomenon appears and disappeares at random positions of the avi
> and stays
> > for a sequence of frames (sometimes seconds or minutes). When I
> recapture the
> > movie the changes (problem on/off) appear at different places, but they
> appear.
> Do you get lost/ins frames when you take a look at the output of lavrec
> ?
I get much more problem-on/off-transitions than frame drops/inserts.
Most of the time I get no lost/inserted frames at all. At tape positions where
the camera is stopped/restarted (no sync signals on tape) capturing
of cause completely pauses but restarts correctly when the new scene starts.
During long, continuous sequences I get at most 5 inserts per hour. Somtimes
none at all.
>
> > The problem seems not to depend on the video source (I captured from VHS
> > recorder (playback and tuner) and from DVBT). I tried two Computers
> > (AthlonXP/32, Athlon64). I bought a second DC30+ from ebay, same problem.
> > Software is SuSE-93/original kernel (2.6.11.4), mjpegtools 1.8.
> How many lost inserted frames do you have when you record from a good
> source like DVB-T or SAT ? A VCR is usually not a good video source.
Capturing from DVD-player, DVB-T or VCR is nearly perfect. I get 0-5
inserts per hour from both sources. Normally I capture with an idle machine,
but even when the machine is under heavy load (swapping, "find" running, load
average above 10) capturing does not suffer. My problem does not depend on the
load of the machine while capturing.
>
> Sometimes it is related to the mainboard when something is "blocking"
The Mainboard (ASUS K8N-E deluxe, 2GB, Athlon/64b 3400+, nForce 505-Gb) seems
to be perfect for digitizing, as even heavy load does not change capturing
behaviour.
> the data transfer, than the card/lavrec throws away a field/frame.
That's interesting! Field or frame? I don't know how the DC30+ presents its
output to the driver. Framewise or fieldwise? Does the driver really drop
half-frames without regenerating them in the output? This would result in
field-polarity-changes. I cannot believe this.
>
> Which zoran driver do you use (The one that comes with Suse kernel or a
> different one ?)
I use the original one from the SuSE-kernel.
>
> > Is there anyone who experienced the same problem?
> I know that my DC30 drops sometimes a frame. I belive that it got better
> with the late 2.6.14 kernel. I have never used a original Suse kernel so
> I really can't tell if that one would have worked well on my machine.
> Currently I use a Suse 10 and a 2.6.15 kernel.
>
> > Is there a develloper who knows if there is a switch on the DC30+ which
> could
> > be relevant in this context? Could my problem be caused by some
> > misconfiguration of the card?
> Sorry I don't know a magich switch. I think in the 2.6.11 kernel there
> is a bug in the DC30 driver that prevented from recording from the
> SVHS-In.
OK, SVHS probably isn't the thing I need because my VCR is only VHS and a
cable won't make it better ;-(
I'm nearly at the point to try to write a deinterlacer which fits the 2nd
field into the 1st one by x/y-shifting it. Needs motion search. But this would
be a workaroud, not a fix. I would really prefer to solve the problem, but I
don't know what causes it.
Regards,
Ralf Oehler
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