Avoid inserted frames at recording start?

[BarryTheCrab]

Very often I get inserted frames at the start of my transfer. I try first starting the VCR, then first starting VDub, then both at the same time to no avail. There may be no inserted frames for the remainder of the capture, usually, just the start.
How do you members avoid the initial startup inserted frames, as I suspect it may be behind some of the occasional A/V sync problems I run into.

[keaton]

Without knowing more details, a natural question would be, have you read the Virtualdub Settings Guide?

This post specifically talks a lot about inserted frames, Virtualdub configuration, and TBC. http://www.digitalfaq.com/forum/vide...html#post45242

Specifically, copying directly from that post and pasting here.

Quote:

- - Insert null frames when captured frames are too far apart.
In the capture information panel, null frames (usually dupes of previous or following frames) display as the number of "inserted frames". When captured frames are timed too far apart for the intended frame rate, VirtualDub inserts dummy frames -- e.g., two captured frames timed too far apart would have a dummy (dupe) frame inserted between them. I've seen sample videos with 2 or up to 6 inserted frames.

Avoid this in the first place with a proper TBC. Again, if the audio resampling is also turned off at the same time, the result would be loss of a/v sync.

This option is enabled by default.

*** Note in the attached image for my AIW 9600XT and AIW 7500 settings that I've disabled both options. I've auditioned high quality TBC's, and even with these in circuit I would get one or two dropped or inserted frames, sometimes up to 3 or 4 over an hour. The problem seems to be that no one knows what VirtualDub considers to be the limit for "good" timing. Even a quality TBC can output minor errors that don't fit VDub's timing formula, whatever it is. Now and then I turn them back on, then off. I work with VHS restoration in very small segments and in great detail. For
years I've looked for dropped/inserted frame and haven't found any with these options disabled and a good player and TBC in use.

Without a TBC, turning on these options can result in a flood of dropped and inserted frames plus bad audio sync. Without a TBC, turning them off might result in fewer dropped frames (maybe) or maybe none reported, but you'll lose audio sycn even with the audio sync options turned on.

Moral: Options or no options, use an external frame TBC or external pass-thru DVD with decent frame timing sync. I often use a Panasonic ES10 or ES15 for pass-thru (but they don't remove Macrovision the way my AVT-8710 does and are less than perfect with really crummy tapes).

AND also pasting this from same post

Quote:

- - Sync video to audio by adjusting video timing
Tells VirtualDub to speed up or slow down the video clock to match the audio clock. This can often result in dropped/inserted frames, which is why I don't use it. The effect depends on whether your video or audio clock is the worst offender. If the audio clock is cleaner than the video clock, you could get dropped/inserted frames. If the opposite is true, you could get fewer drops and inserts. Since neither clock is always precisely accurate anyway, the choice is up to you.

With cards having integrated audio clock correction, see below. If there are any ongoing audio clock adjustment, it's reported in the info panel.

Just guessing here, but sounds like irregardless of whether the tape is already running or the capture is already running, there is an initial burst that either the tape has which takes a moment to stabilize or Virtualdub is taking a moment to stabilize, if what you are saying is that it only happens at the start.

Just my experience thus far, with a frame TBC, I've been very fortunate to have no dropped or inserted frames. Reason being, I assume, is that even when the timing of the video frame is not good enough to keep sync, the frame TBC has output properly spec'd timing for the frame(s) involved, and therefore the audio and video remain in sync.

If there's a TBC, then maybe Virtualdub settings can still be a culprit? I'd review the Virtualdub Settings Guide and try some more detective work. There's a lot of settings in Virtualdub, some of which may not play nice together. The guide seems to provide some tips in that department as well.

[BarryTheCrab]

I actually am blessed to have bought a Datavideo 1000 from his Excellency Lord Smurf.
Tonight I will review the audio setting and perhaps add and remove the ES15 to see if I still get that surge at the start.
I appreciate your input. Thanks.

[lordsmurf]

As I was just explaining at http://www.digitalfaq.com/forum/comp...html#post66496, a conversation that meandered from UPS to TBC and dropped frames, it's actually rare to not get 1 insert/drop at the start or end of a capture.

So my question is this: How many frames are being inserted?

[BarryTheCrab]

Usually when it happens it’s 15-30 to start then an inserted frame is very rare unless the recording existing on the tape stops and restarts where there is a lot of static in the interim.

[BarryTheCrab]

My poking about reveals my laptop, an old i7, performs better than my tower, with NO inserted frames at the onset. It got by me because I rarely use the lappy for capture, or anything anymore. Now it's my primary capture platform.