Lot's of dropped frames when capturing very bad quality VHS

[RoopeT]

I can usually capture from VHS with very few dropped frames (Thunderbird 1200, Win XP, btwincap driver for Terratec Value, VDub synch, PicVideo @ Q 19, 720x576). However, I have recently tried to capture a very bad quality VHS tape, that has been copied many, many times (the tape I'm possessing might be something like 10th generation copy of a show that was originally aired in the early 80's). With this tape, I got 12000 dropped frames in an hour!

I have also tried to capture with iuVCR 4.0, FlyDS (and maybe some other software too ...) and under Windows 98 with the Terratech VfW drivers, but regardless what I do I still get thousands of dropped frames. I'll get the massive frame drops even when capturing @ 352x288! When playing the tape, the picture is ~OK in TV (well, of course bad quality but it is still running smoothly).

I live in Finland, but I have no idea where the show was aired / recorded (Maybe in Switzerland, since it's Blackfoot live in Switzerland). Could selecting a different PAL mode help ? If yes, what's the PAL standard used in Switzerland?

I try to make an XSVCD (352x576) out of the tape, but first I should figure out how to capture it with minimal frame losses. Any help welcome!

[Ookami]

From the new capture FAQ (this is the last quote, since it will be up very soon):

21.) What can I do against dropframes?

- First lets clear some misconceptions that many users have. Dropped frames
are not a disease that needs to be cured. It is simply a solution to maintain
the A/V sync by dropping or doubling a
frame. The catch is, when you dropped frames that are caused by other things than the A/V sync algorithm.
If you have so many dropped frames that you notice
them (the video "stutters" then the problem is NOT your capture software
(if you use a good one) but in your system (software and/or hardware). It is
normal that Huffyuv clips stutter as this codec was not meant to be used for
playback, first encode it to your desired format, if the picture then
"stutters" you have probably some problems.

You can also (example VirtualDub), disable the "adjust video clock" and try
to synchronize the audio after the capture (could be a bit complicated, but possible). So,
you surely have no dropped frames (at least not from the A/V sync
algorithm).

So, to test if you have dropped frames that are not caused by the A/V sync you can disable the audio capturing. If you then have dropped frames your problem lies somewhere else (software and/or hardware).

Anyway, we recommend you to use the excellent VirtualDub modification
VirtualDub_sync by Andreas Dittrich (
http://www-user.rhrk.uni-kl.de/~dittrich/sync/ ).
It uses a different approach to maintain the A/V sync, a real time audio
resample routine and it droppes only frames if the resample routine would
add audible errors.

Most users that got too many dropped frames have simply not optimized their
system. So we suggest you to go through these recommandations, also take a
look at Question 4 (recommended hardware).

- Be sure that the DMA (direct memory access) mode is activated on your HDs
- defrag your system and capture disk (you can also quick format your
capture disk if you have nothing to loose on it)
- Turn any active background processes off (virus scanners, indexing services, etc.)
- If you have a BT8x8 chip, the OVERLAY mode has to be switched
off during the capturing session.
- When using a Philips based card, the OVERLAY mode has to be
activated during a capture
- always restart before your capture (memory managment on Windows 98SE
sucks, and W98SE is, currently, the best system for capturing)
- lower your capture resolution or framerate (changing the framerate should
be the last resort, always keep the framerate same as the source, e.g. 25 for
PAL)
- use a separate HD for your captures (on a different controller than your
system disk), be sure your HD is fast enough (you can use, for instance,
VD's benchmark)
- Try to change your codec setting and/or try a different capture codec (e.g. MJPEG based instead of Huffyuv)
- Change the screen resolution to 800x600, 256 colors and 85Hz
refresh rate
- activate cropping (only useful for 16:9 video where you can crop the black
bars)
- if you use VirtualDub (or one of its modifications) make a test capture (F7) before the real capture
- make a fixed swap file or disable it
- try a different capture software (you could first try the freeware
programs and then switch to the shareware programs :) )

If all fails (still too many frame drops) try a capture without sound, if
you have NO framedrops for a long time, then your soundcard is giving a
sampling frequency that is way of the desired (instead of, for example,
44100). Possible solutions to this problem (wich for instance Ookami has)
are:

- use VirtualDub Sync (if not yet)
- try to change the frequency
- fiddle with the settings in MULTIMEDIA - AUDIO - Recording adv. properties
(Sample rate conv. and hardware acceleration)
- buy a better souncard :D


22.) I did everything by the book but it simply doesn't work!

Here are some advanced hints. Use them with care!
- Get the latest driver for your capture device or try an alternative
one (like BtWinCap).
- Get the latest drivers for your mainboard.
- Remove every PCI card except your capture device and GFX card.
- If it works with only these two insert your soundcard.
- Use the video input of your GFX card instead of the one of your
capture device
- Try another operating system.
- Deactivate unused HD controller(s).
- Change the screen resolution to 800x600, 256 colors and 85Hz
refresh rate.
- Use the latest DMA drivers for your mainboard.
- Switch PCI/AGP Latency to 32 in your BIOS.
- Use regular 33 pin cables for your UDMA disks.
- Turn off ACPI mode in the BIOS.
- Reinstall your operating system and use the latest drivers.
- Monitor the CPU temperature while you capture. Your CPU may
get too hot.


A thing that could help but is not recommended is that you could decrease your vertical resolution by a few pixels (e.g. to 572). Some users with BT cards reported that this helps. Altough, you can have quite some problems with deinterlacing, because you don't have the full resolution (all informations) anymore (xxx x 576).

This should really help :-) .

Cheers,

Mijo.

[Herske]

Use a Time Base Corrector. If the vhs quality is bad (as in Real Bad), you'll get drops even if you capture at 64x64.

[BaronVlad]

Originally posted by Ookami
From the new capture FAQ (this is the last quote, since it will be up very soon):


Oho Mijo, a beta release :) When will it be up ? It looks pretty good :D


A thing that could help but is not recommended is that you could decrease your vertical resolution by a few pixels (e.g. to 572). Some users with BT cards reported that this helps. Altough, you can have quite some problems with deinterlacing, because you don't have the full resolution (all informations) anymore (xxx x 576).

This should really help :-) .


Yes it does ! For capturing bad tapes I always cut off a bit, you will also get rid of the green line in the bottom of (bad) vhs tapes. Think they also could be the "source" for drops

[Ookami]

Herske, you read my mind :) .

I wanted to post almost the same thing. Just a note, you can use a VCR with build in TBC (like me) or a external TBC. But in some cases even a TBC isn't enough... For instance, with my VHS copy of Lone Wolf McQuade (wich has not, and probably will never have, a good DVD transfer) I got 1 dropped frame/ sec :scared: . I've managed to get it to a better number, but the source is too bad.

What is a TBC?

http://www.questronix.com.au/html/info_tbc.htm

(Link stolen from http://www.uwasa.fi/~f76998/video/ )

@BaronVlad

:D

@cropping a few pixels

I've read that some VHS control infos (VHS Steuerungsinformationen) are in the last few pixels and that they can cause "trouble". Don't know if that's rubbish or not, at least the cropping helps some users. Placebo effect :D ?

EDIT:

Yesterday I read Kika's explanation in one of my old saved threads...
I will try to find that thread again and post the translated explanation in a new posting.

Hmmm... Denke das wir diese paar Sachen auch noch in die FAQ einfuegen koennten...

Cheers,

Ookie.