Inserted frames not being reported? (VirtualDub)
 

I was yesterday years old when I learned that two identical tape captures of mine did not sync up perfectly...

So apparently, back at square one, the Pinnacle-710 USB is inserting frames- and moreso, not telling the user of when they occur (unlike the Dazzle, which immediately informs when there's frames being inserted/dropped). After my findings on my two tape captures, I went ahead and captured some tapes that had DVD counterparts, so I could have a "sync-point".

Two tapes were successful, they matched perfectly down to the frame. However my third experiment was with a tape that was jittery, and could only be fixed with an ES10. Since all my previous captures were in VirtualDub2, I figured it's possibly the software. I thought a jittery tape would be a good experiment to see if the TBC is doing it's job.

After going frame by frame, I found regardless of capture software, there's still a matter of inserted frames.

So........ what to do from here? My goal is a 100% authentic grab from the VHS, without any inserting of frames. Some tapes I have don't have DVDs, so I can't line them up to see if the sync is perfect. Let's hear this discussion.

My specs:
JVC SR-V10U + HR-S9600EU
Pinnacle-710USB
Datavideo TBC-1000
VirtualDub2 (formerly), VirtualDub 1.9.11

Attached: VirtualDub timing settings, capture details, and a video project with both captures matched to an earlier frame. Shows the end of the clip with the delay.

Home videos or commercial tapes?

Frames are inserted for a reason.

Are the inserted frames always at the same point in the tape? If not you could try multiple captures then stitch together pieces as necessary to eliminate/replace the inserted frames. You should be able to use the audio track wave forms to check sync.

I'm not expert but I've always had The Resync Mode on No 3.

Where's Sanlyn's VDub guide when you need it? :cool:

A frame is inserted by the capture software in order to keep synch between audio and video when the card did not send a frame inside the expected time slot.

It may be reported or not depending on the capture card and/or the capture software. Just as example, I found the pair Hauppauge USB Live-2 / AmarecTV beeing accurate in reporting, while sometime ATI USB 600 /VirtualDub pair does not report correctly.

If a frame is inserted and properly reported, it is marked in the captured avi file by any capture software. You can jump to it opening the file in VirtualDub and using the bindkeys "?" (previous) and "^" (next).

If you see the inserted frames exactely at the same position across multiple captures, the problem is in the tape.

If a frame is inserted and not properly reported, you can use a large set of AviSynth script to find them (basically you search for a difference = 0 between current frame and previous frame). Some example here http://avisynth.nl/index.php/CategoryDuplicate_Frame_Detectors, many other specific scripts in dedicated forums.

If a frame is dropped and not reported, there is no way to find it, except a boring step-by-step check (difficult to find it in any case) or a comparison with a different source. On my side, for a sanity check I often use a DVB dump of the same program when available or a DVD release. Be careful that a DVD release may use a remastered video and the frame alignement is sometime lost (i.e. I have seen recent DVD releases missing frames compared to previous releases; probably the frame was so bad in the original source that was simply removed).

Yeah same, I've always gotten audio drift if disabling the resync stuff.

Also note that although it's pretty rare, both the datavideo and ES10 CAN drop/insert frames in some extreme cases (an stupid example is if feeding NTSC video into either in PAL mode.) You can also get some weird extra frames when the JVC TBC acts up depending on what's next in the chain, don't remember quite how the datavideos react to it but with the ES10 you can get these weird blended/mixed frames (guessing you did not use the TBC on that tape if you needed to use the ES10 tho?). May be best to re-check if you get the same result on the specific part of the tape if you try again.

If the 710USB has some buffering internally it's possible it could too, but idk.

My NTSC DMR-ES15 and DMR-ES25 always drop/insert frames internally with VHS input; a few per hour. At one point I owned two DMR-ES15s and I captured the same VCR signal from both simultaneously. They inserted frames at different spots. I also confirmed that the DMR-ES25's inserted frames appear on its DVDR disc recording, in the same spots as the passthrough output (my ES-15s have broken drives).

It doesn't happen when they're fed a signal from a DVD player.

Do you also mean that capturing the same tape without the DMRs (if possible) there are no inserted frames?. I know that is not easy to distinguish between the 2 cases, just want to understand if the DMRs add frames by their intrisic nature or if they do in correspondance of some "event" that will produce the inserted frame even capturing without them.

Correct. (Using a test tape I recorded with burned-in frame counter.)

Thanks! An additional side effect of the usage of DVD-R recorders in passthrough mode, then. However, this can be considered very minor.

My biggest gripe in all of this is the fact the software isn't telling me- and both Inserted/Dropped values stay at 0. With my Dazzle, it had the courtesy to tell me if a tape was inserting anything, that way I can go back and resume capture from a certain point.

Perhaps, it's worth sticking to the Dazzle if it's gonna tell me when frames are being inserted?

Commercial tapes are my tests- I'm lining them up with their DVD counterparts.

I've always been against the resampling mode, primarily due to the fact that if the video is perfect, the audio shouldn't be taking a hit by slowing down or speeding up. In my eyes, a perfect preservation capture means an authentic representation of the source, both in audio and video.

I'm not sure about dropping frames, that's usually dependent on the setup of the user. Inserting frames, I wouldn't have an issue if the software told me it was doing so (usually, you want to only use a DMR passthrough to correct a problem that isn't fixable on your main gear (VCR+TBC) ). Less processing on the video being captured.

There is no way for any capture device to know when a device upstream (like DMR-ES15) is inserting or dropping frames. The only way to know is by manually analyzing, like you're doing by comparing multiple captures or to a digital source. As far as your capture device is concerned, it's receiving a stable signal from the DVD recorder's output.

Those cheap Dazzles easily insert/drop.

ES10/15 silently inserts as well. Again, not a TBC. This is a negative side effect. These are ideally only used for tapes where the net effect is improvement, not as a TBC replacement. These units have downsides, fail rates, artifacts, side effects. But it was lower cost, right? You get what you pay for.

The Pinnacle does not drop/insert without reporting. I would not use it, if that were the case.

sanlyn's VirtualDub guide has errors. Many times, different cards need different settings. For example, if you try to resync on this Pinnacle, it will actually cause audio problems. Resync should be disabled.

I've never seen an ATI 600 USB not correctly report.

Retail tapes may look cleaner, in general, but are actually some of the worst to deal with. Those tapes were usually not recorded, but made by contact.

Capture devices have no idea if upstream caused errors. It only know what it's doing. If the signal was made decent by insert/drop beforehand, then it considers the signal good for capture. Over and over and over, I discuss why certain TBCs are not good, why "also has TBC" isn't actually a TBC (internal needs, not yours), and why non-TBCs are often worse yet. This is prime example. I do often forget about the drop/insert issue, but it's top 5 on the list.

How can I see the framedrop details capturing with AmarecTV?

You select in the menu the option to write a report file:

Attachment 14834

then you read the gerated file. An nserted frames are reported as
while a drop frame is reported as
A summary is written for every frame and at the end
where the second number represents the dropped frames and the third the inserted frames (first I do not know)

I do when I compare my captures (AmarecTV + Haupauge USB Live-2) with friend's capture (VirtualDub + ATI 600 USB). I always talk about the pair capture sofware + capture card, because I am not able to differentiate between them.

Some discussion here: http://www.digitalfaq.com/forum/vide...g-options.html

To the OP: the script Capture Glitch Analyzer (detect dropped frames) is difficult to run, but can be a test for your case if you have doubts about the reporting https://forum.doom9.org/showthread.p...31#post1462931

I would like to challenge you. Presented here are samples of 2 captures via Direct Stream Copy; one PAL, one NTSC.

In the PAL capture, you can see an inserted frame from #96-#97. The head switching noise at the bottom remains the same, so it's not a fault of the master dubbed to this particular cassette.

In the NTSC capture, from frames 53-95, there is a very strange field distortion (???) that is present. I rewound the tape, and the issue does not appear again, so it's not the tape.

If this is a fault with either the Pinnacle 710 or the TBC-1000, what are the steps to take from here? Just to reiterate, VirtualDub is not reporting dropped frames or inserted frames. It has (once) on a super static tape, so I'm sure it knows when to insert when it sees a problem. But this- this is just something I have to comment on. It could be an issue that is being overlooked by even the pros here.

I see some weird combing on the left side of the video.

So you repacked the tape and the issue is gone.

Then you're right, it wasn't the tape.

That's (one of) the issue(s) though. If these are flaws being introduced by the gear, and we're not preserving an authentic representation of what's on the tape, then could we really call it a faithful preservation?

Even if the inserted frames don't throw a video off sync, the accuracy part irks me so much, it's been a battle for nearly 4 years- because if these tapes just... cease to exist, you'd want the file exactly as it was. That's why I feel it's important for even the professionals here to be aware of this.

Lollo, could you check this please? I did a capture with VDub and Amarec and VDub reported 75 inserted frames:

Attachment 14837

Amarec showed this in it's report:

It seems that the second number "(+)73" is inserted frames and the last is dropped frames.

Don't worry, through the ES-15 I got zero for both. :)

Edit:
The above test was done with my GV-USB2

I ran a test with my other capture box, a Startech USB3HDCAP and VDub reported 2 dropped and 32 inserted. Amarec reported Zero of both, even though there were obvious freezes and jumps in the video.

At least for my 2 capture sticks, it seems that VDub is more consistent for dropped and inserted frames.

Repacking can affect drops/inserts. But don't go running and repacking your tapes -- it goes both ways. And you take added risk or needlessly FF/REW tapes, especially these days.

Can TBC-1000 insert? Yes. It's a strong TBC, but errors can be stronger. Rarely happens, but happens.