Neither Vegas Video nor WinDV show dropped frames count after capture

[korey99]

Hi-

I'm capturing lots of VHS tapes through my Digital-8 camcorder, which is hooked to my computer via firewire.

What I want to be able to do is tell the computer to capture, say, 45 minutes of video then stop. Vegas Video (7.0) can do this if you set a time limit in the preferences. WinDV can do this if you use the command line interface. Both programs also show the number of dropped frames during capture. HOWEVER, once those programs stop capturing when the time limit is reached, both apps clear the count from the screen. Vegas shows "0 dropped frames" and WinDV shows "finished".

I'm aware that Vegas also can show a dialog saying that there were dropped frames, but I'd really like to know how many. If there are just a couple, I expect that, since some of the tapes I'm capturing have some rough spots.

Does anyone know how to make either of these programs show the dropped frames count AFTER capture? Is there a log file I haven't found yet that I could look in to see this count? Is there another reliable application that I could use instead?

Thanks,
Korey

[danno78]

DVIO show dropped frames. This verry small tools is my choice for DV capture (transfer).

[korey99]

Thanks, but I don't think DVIO can do a timed capture, right?

Korey

[danno78]

Right, but will show the droped frames.

[citanool]

Enosoft DV Processor [freeware] might do timed.

[korey99]

Thanks - Enosoft DV Processor is doing the trick. It's quite a bit more complicated (or powerful, depending on your perspective), but there is a "timed processing" option that will stop the recording. It also continues to show the dropped frames report after the recording has finished.

As an aside, I'm actually able to capture over the network to a share drive with Enosoft or WinDV. Vegas can't do that with my setup.

[JohnnyMalaria]

Thanks - Enosoft DV Processor is doing the trick

That wasn't an intentional feature - just a by-product It just makes more sense to reset the count when the next capture starts rather than when the current one ends.

BTW, strictly none of the software (including our own) truly reports the number of frames that are dropped as they come down the line from the camcorder. Nearly all of them use a standard piece of MS code provided in one of their sample applications for developers. What it reports is how many frames are lost by the renderer/AVI file writer (typically because they arrive late). MS emphasize that it is not guaranteed to be an accurate count. There is a common misconception that the dropped frame count indicates tape problems. Also, I'm not aware of any programs that use this MS feature that record *when* the frame was dropped. Of course, it is still of great value.

I'm considering adding an error monitor that will show true errors coming from the camcorder (as well as traditional dropped frames). I haven't decided which way to implement it - I'd like to make it useable with any capture app, not just ours.

[2Bdecided]

Doesn't the Q thing in WinDV have something to do with tape errors? It seems to correlate here.

Cheers,
David.

[JohnnyMalaria]

The Q value indicates how full the buffer is (0 to 99%). There's a rather useful interactive screenshot on the WinDV site that gives you pop-ups when you hover over a dialog control.
.

[2Bdecided]

That's a very cool way of explaining things - thank you for that hint.

It makes the behaviour I've seen very strange - I'm going to go back and look at it again!


btw, to the OP: if there's a risk of dropped frames on your PC, then your PC isn't set up correctly. You should get zero consistently.

However, IME, for tapes with gaps between recordings, WinDV doesn't always pick-up the recording after the gap properly - whereas if you re-start it during the gap it'll pick up the next recording just fine.

Cheers,
David.

[korey99]

John - thanks for all the good information! Enosoft DV Processor is a nice piece of software. The only problem I've had is that if I forget to change the output filename (when writing out a DV AVI file), it overwrites the file when I capture the next tape. That's user error, I know, but if it were me I'd like a setting to avoid overwriting the output file.

David- I'm capturing old VHS tapes (mostly around 15 years old) that in many cases my mom started by recording something incredibly important like "The Jacksons: An American Dream" in 6 hour mode, then taped over that in 2 hour mode using the old RCA camcorder. I've tried capturing with three different computers, using Enosoft, WinDV and Vegas, and I'm always getting a couple of dropped frames when the camcorder recording stops and the Jacksons kick back in. I also can consistently get a couple of dropped frames if I start capturing, start VHS playback, then scan backwards on the VCR back to the beginning of the tape, or something like that.

Thanks,
Korey

[JohnnyMalaria]

A way to prevent overwriting an existing file is to use the scene detection option (under Embedded Data Processing). Assuming you are capturing a number of tapes in a session, you would pause the processor at the end of one tape and then run it again when starting the next tape. You will end up with one file per tape with the date/time appended to the name. You either need to make sure your camcorder's clock is set (you'll see valid time/date in the display below in the input window) or add the computer's time/date to the DV (also under Embedded Dtaa Processing).

Re the couple of dropped frames - there isn't much you can do about that. In your scenario you may not have as many missing frames in the captured file as reported since the 'dropped' frames aren't dropped - they weren't there in the first place. Each frame on the VHS tape has a sync pulse to tell other equipment (TV, your camcorder etc) when the frame starts. The camcorder waits for that pulse and then reads the frame, compresses it and then sends it to the computer. The computer twiddles its thumbs waiting a frame to arrive. When a frame does arrive, it gets stamped with a time that tells a media player when to display the frame. When writing to an AVI file, the component that does that ("AVI Mux") already knows how often a frame should arrive and if a frame arrives late (based on its timestamp) it is rejected - i.e., dropped. The glitches on your tapes have no valid sync pulses and so when the next valid frame comes along it is regarded as late.

[2Bdecided]

I think it's a useful "feature" if such garbage frames are dropped.

Sometimes you lose the first bit of real content too, but I think you'll struggle to capture it properly even if you know it's been dropped on the first attempt.

Cheers,
David.

[korey99]

Thanks for all the explanation. To be clear, I not really concerned about the loss of those few frames. I'm just saying that I know I'll get a FEW dropped frames due to the aforementioned issues with the quality of the tapes. I'm saying that, unless I'm mistaken, my capturing computer can be set up right and I'll STILL lose a few frames.

John- I'm not sure your scene detection trick will work for what I'm doing, but it's not a big deal. I'm capturing VHS tapes using the passthrough Analog-to-digital feature of my camcorder, not straight from DV tape, so I don't think my camcorder's time has anything to do with it. Because my dedicated capture rig is a bit low-spec, I can really only capture 2-3 hours at once, before moving the captured files over to the file server.

Thanks again,
Korey