Video distortion Video 8mm ->Computer

[taliyev]

Hello everybody!

I am trying to capture my home video from my old 8mm Sony camcorder. The problem is that video gets to my PC in distorted form even when I am just viewing it without capturing into mpeg. The distortion happens mostly at the top portion of the screen where video gets dynamically shifted to the right. In general all video looks like there is dynamically changing horizontal misalignment. Portions getting shifted left and other shift right .It is not constant . Sometimes video looks just fine and then everything gets shifted again. I have tried two computers and three different capture devices and capture programs…. Does not make any difference… The strange thing is that this distortion does not happen when I view video in the viewfinder of the camera or on the screen of my TV…. None… everything is just fine…

I am guessing that there is some kind of frequency variation in the output of my camcorder and computers seem to be more susceptible to this that TVs…. Although my digital projector does not seem to be affected by this either…

Does anybody have any suggestion on what I should do to fix this problem?

Thanks,

Tim

[Tommyknocker]

Well, you can start by posting what capture method you are using, what card, what program, what settings, and of course, what you have tried so far.

[taliyev]

Here it goes:

Hardware:
Pentium 4 700 – Dazzle DVC 80 USB1.1
Pentium 4 700 – Plextor PX-M402U USB2.0
Pentium 4 1.7 – Dazzle DVC 80 USB 1.1
Pentium 4 1.7 – AverTV Internal Card
Pentium 4 1.7 - Plextor PX-M402U USB 2.0

Software:

VirtualDub
Win DVD Creator
Ulead VideoStudio 6
Dscaler
CyberLink Power VCR

The problem is not with compression but with the actual video stream passed or accepted by my camcorder and computers. I cannot find any access to frequency/synchronization adjustments in my drivers or other software to compensate for video stream inconsistency….

Thanks

Tim

[Tommyknocker]

So, are you saying the only corrupted video has gone through the Dazzle?

[taliyev]

Does not matter what computer/software/capture device - always the same problem - bad horizontal synchronization of the signal when passed to PC, otherwise ( TV,VCR or projector) everything looks OK.

[Dr_Layne]

Sounds to me like you need a Time Base Corrector. Ths will correct the sync issues you are having. Look for a Datavideo TBC1000 or AVT 8710

Steve

[taliyev]

Here is an ‘artistic’ way of describing video distortion that I get… It feels like strong gusty wind is blowing from the left to the right and video lines cannot stay where they supposed to and get constantly blown/shifted to the right…

[Cornucopia]

If it's only at the very top or bottom of the screen, that's because of the time base instability of the tape playing back in the camcorder and an everpresent mismatch in the headwrap/interchange. Note: this is present in EVERY analog tape, but only to a very miniscule degree in Pro units like BetaSP, and only to a small degree in good prosumer units like SVHS & Hi8, and only to a modest degree in newer, good quality tapes & units of VHS and 8mm. UNLESS, the tape is worn and/or heatstressed. Note also: this doesn't happen to Digital tape formats.
Many times you don't see this problem on regular TV's because it is covered up by the overscan. On a PC, it'll be visible.
If your tape is supposed to be in good condition and you're using the camcorder that you recorded the tape in originally AND it's still in great condition, there's nothing you can do short of a hardware Time Base Corrector (and even that won't completely eliminate the head-wrap problem). A true TBC can work wonders on an analog signal.

Scott

>>>>>>>>>>>
edit: after the fact of digitizing, if your still not happy, you'll probably just have to crop & letterbox the offending area.

If you have this problem in some other area of the screen, then

[taliyev]

This affects much more than top portion of the video. About 25-30% badly affected the rest is so-so.

Once again, on TV it all looks great!

[luigi2000]

The problem that taliyev describes is called skew error. If parts of the playback of this tape are fine and other parts exhibit skew error, then the tape is worn or stretched. If skew errors are present throughout the playback, then your old 8mm tape transport is not playing back with the same amount of tape tension that existed during record. In this case the tension is too low.

Standard TV sets have slow horizontal lock circuitry to mask small upsets in the video signal.

If playback of all tapes show this error when viewed from a computer monitor, then your tape transport needs adjustment to the forward holdback tension.

A very good time base corrector can help in these cases. However skew error is not a time base error of the drum or capstan servo. Skew is a discontinuity of the signal due to mechanical misalignment.

Use another camcorder.

Buona fortuna

[taliyev]

Thank you luigi2000!

I was leaning toward using other camcorder myself, but first I have to get one Hopefully actual recording is OK ….

[grantdoug]

I am having precisely the same problem with my Sony TR81 hi8 transferring through Elgato to my MacBook Pro. The playback is slightly distorted in viewfinder of camera or output to TV, but very distorted when captured on my PC.

It seems more likely to happen with TDK tapes than with Sony tapes.. and it seems to be getting worse.

Any suggestions that are not expensive, such as cleaning my camcorder capstan?

Thanks,

Doug

[JVRaines]

Not much you can do unless you find a way to increase the tape tension in your Hi-8 player. Magnetic tapes shrink very slightly as they age. To get rid of the flagging, you have stretch the tape back out. Industrial and broadcast machines have a skew control for this, but even then, there's only so much you can do for a 20-year-old tape.