Some vhs-tapes drops frames, some dont??

[Valky]

How can this be possible? It doesn't matter what capture program I use, but as soosn as I start to record, the frames start immediately drop in this vhs-tape (Stone Cold, self-recorded from original). These frames start to drop even if I keep my vcr still in pause-mode.

And as soon as I ghange the tape to any other vhs-movie I have everything works great and no drops? Can you explain this to me so that I understand it?

I live in Finland and capture from pal-television scart-out to my hauppage winTV and 25 frames. Audio dosnt seem to have effect I think..And this only happens with this one vhs-movie I have. All are movies from our local video-rent shop that I have recorded several years ago..

[catback]

vhs tapes contain much more noise than dvds or even straight tv signals. everytime a capture program encounters noise, you'll get dropped frames. some may be able to minimize the drops by altering internal buffering but you will never remove them completely.

i do a lot of video captures from vhs tapes and always end up with a lot more dropped frames compared to captures from other sources. best bet is to use a good capture program like avi_io with the huffyuv or mjpeg codec to get the best capture quality as possible.

[Valky]

Actually this tapes has much more cleaner picture and is newer (less noise..) than the others I have captured, so that is not the reason?

And like I said, it doesn't matter what codec(mjpeg or huffy) or what software I use cause I have tried them all.. and this happens even on pause-mode..

could there be reason if this movie has been recorded in LP mode? I think it's not recorded in long-play mode, but if it is, should i then capture with more or less frames? or does it even matter?

[avih]

i had similar problems in the past with vhs capture. (i don't capture much from vhs though).

i think it has something to do with sync signals not working perfectly with vhs and capture cards.

these are possible solutions:

0. i didn't try that, but u can mess with the 'trecking' control of your vcr, it might improve the signal.

1. there are some hardware devices that can 'clean' the signal such that it's more proper, and it might eliminate these issues. however, i also heard these devices can be quite expensive. why won't u try my solution #2 ? :)

2. getting very annoyed about these frame drops, i played with many capture settings, and to my surprise, i found out that changing the resolution to 'wierd' ones solved it for me. i.e. capturing at 476x572 (if i remember corectly) gave me practically zero frame drops (about 1drop/few mins). i know it seems unrelated, but it just worked :)

note that if u do capture using such a resolution and then resize, make sure the 'interlaced' checkbox is checked in the resize dialog.

pls let me know if u have any success with the method #2 :)

cheers
avi.

[cypher_soundz]

if you are trying to capture too high for the capture device say it can only do 288xnnn and you are trying 12000000xnnnnnnnn (extreme example) you may get dropped frames ,try setting the format lower and use virtual dub 1.4.7. Also you could try capturing uncompressed ( 1min = ~1gb i think)

[Valky]

Hmm..like I said..no problems and dropped frames with ANY OTHER tapes with same settings (352x480) so I am not trying to capture too hard.

Picvideo (18), audio 16-bit 44khz, XP 700 Mhz 480 ram.

And software: iuVCR <-- not a single dropped frames with this one, and I have tried them all..VD,VD_sync,AVI_IO, power vcr, vid cap... all these others have troubles and drops at least a few frames..

[avih]

>"How can this be possible? It doesn't matter what capture program I use, but as soosn as I start to record, the frames start immediately drop in this vhs-tape (Stone Cold, self-recorded from original). These frames start to drop even if I keep my vcr still in pause-mode."

hmmm can u be more specific? how MANY dropped frames/min ?

[Valky]

Very many..if I get zero or few in normal 2 hour vhs-capture, now with this tape I get 4-10 in first 10 seconds..and even when I capture when vcr is still paused..

The picture and tape seems to be much more better condition (and less noise) than my previous tapes I have captured.

[ftack]

Just wanted to add my experience to this. I have quite frequent drops when capturing VHS tapes. I was at the end tweaking my system until I found that indeed the VHS source, and probably a poorly performing VHS recorder, were at the basis of all dropped frames.
I am using a DC10 card and at one time, capturing a very bad tape, I came across an option "check incoming video signal" (or something like that), which I turned off. After that, I captured 70 minutes at 2500 megabyte per second without a single dropped frame. Obviously, the captured video had flaws: fields got swapped, the image rolled, etc. so normally I would leave "check incoming video on" and accept periodical drops (about 1 drop per 1000 frames, usually).
This proved that indeed the VHS source may be the source of drops. And I was happy to discover that my system was not to blame and that my sound card is pretty much in sync :)

[Valky]

Yest, it is obvious that the reason is in that vhs-tape, cause no probs with other tapes with the same settings..

I just dont know what could be the reaosn for that.. I was actually asking if the reason could be that the tape is recorded at LP-speed(I think it is not, but cant be sure..) when others are recorded in normal SP-speed?
Could this show somehow differently in capture-software?

And where did you actually found this option 'check incoming source'-option? and what software? Did it gave you any negative issues in other tapes? I mean is it possible to leave unchecked in every capture or just in those bad tapes? Cause are you sure that you wouldn't get those negative flaws anyway in that tape?

[ftack]

Perhaps indeed, problems get worse when a source has been recorded in LP. You could do the test whether there is a difference between normal and LP recordings (keep us posted :-)I didn't captured an LP recording yet.

The card I use is a Pinnacle DC10plus. This is a hardware motion JPEG capture card. The setting is found in the accompagnying software. Probably it'll work quite well in captures of good sources. I suspect that frames that would otherwise be dropped, would show up as little tremblings in the image. For high res capture, it may occur that after a bad point, the fields are being swapped. That is why I prefer to accept some more dropped frames to be sure that the good frames are probperly captured. But perhaps, for low res capture, I may be better off turning the option off.

[avih]

Valky:
did u try methods #0 and #2 that i suggested on the 4th post on this thread?

[Valky]

Not yet, cause I have been so busy with my work but I'll let you know.

Hmm..one thing I have discoverd that I think everyone should know..:

This iuVCR-software that I have been lately very satisfied, cause it has never dropped any frames like all other softwares ( a few at least), seems to be some kind of fake-ware. It has never showed any frame drops in it's capture info and I have checked those recordings and it seems to be ok. But now I tried that bad vhs-tape with this software and captured about 15 seconds from start and no drops according to this softwares info-panel..
Then I watched this capture file (352x480 Mjpeg 18) and it seems to be just a slide-show like in all other softwares I have tried with this particular vhs-tape.. This isn't very nice..now I am pissed since I already send some kind words about this software to the author..this is something I call cheating..to offer and tell me something that isn't true.. :angry:

Now that I searched a few vhs-captures I did with this (Blind Fury and Overboard) I noticed that on second movie the audio is out of sync after the half of the movie..I didn't notice this before and the reason for this is obviously some dropped frames during the capture althought the info-panel showed 0 dropped frames after the capture..

Now it's is really hard to get that sound to synch with movie, cause I already compressed the sound to mp3 and video to divx :(

NOT GOOD!

[anarco]

are they similar ?

and .. is the framedropping actually visible in the resulting file ?

[Valky]

framerates are same, cause they are both normal pla vhs-tapes that can be rent from our local video-store (Finland, PAL 25fps)
and frame-drops can be seen cause like I said..it was like a slidemovie with this bad tape, and with those recorded in iuVCR I dont know..but I presume cause the sound was out of synch and the software showed 0 drops even with that slide show.

[unit01]

Dear Valky,

I think some sort of macrovision signal recorded on the commerical video shop tape literaly on top of vhs video signal maybe your problem.

You could check this if you connected 1 video rec video out to anothers video in and tried to watch on a tv / monitor plugged into the other vcr the picture will probably go dark / normal cycling every couple of seconds or so maybe even even rolling vertically once in that time.

I understand that the only 2 ways to combat this.

1.Is to make / build a box that filters out the teletext region of the analog pal signal if you set your tvs vertical hold to roll slowly you may see a few lines fading in and out on the top of the screen.

What happen is that the added signal confusing the other video recorder's / capture card automatic gain control circuit making it decrease the video signal so it fades and loses sync

Electronic Australia Magazine published a video enhancer about 18 months - 2 years ago that filters out 'teletext' as well as letting you boost cut the signal as well. Maybe you could go to a tech library nearby the ones here have back issues of a few electronic magazines archived.

I have never used it but if seen people post on newsgroups that it works.

2. The other solution would be to use a capture card with software that sets the brightness gain manually. I have a old Dazzle Snazzi Mpeg1 card and with the supplied 'crappy' software control you set the brightness contrast manually and because of this I think, I've been able to cap some video tapes that could'nt be recordered without a filter at least.

Note though when I use this card in avi I-frame mode in say avi_io the dark / bright macrovision problem re-appears. Also note that if you manage to get manual gain working you may have gain problems with some sources where between scenes say at night in one it will be ok but in a bright beach scene it will be too bright. Although pro commerical stuff seems to be more free of these extremes.

Hope that can help you

Regards

unit01