Bizarre frame dropping problems converting 8mm via TRV480

[TNTJr]

I have been having some weird capture behavior related to frames being dropped.

I have searched this site and beyond trying to find an explanation. I am also confident this is not related to hardware performance (I cerified this by doing many other activities on my computer - starting up apps, surfing the web, copying files - while capturing and I was unable to make it drop frames).

I have tried this with Vegas4 video capture and scenalyzer. I am capturing analog 8mm tapes played back in a Sony TRV480. When I use Vegas, while it is capturing, it shows that it is dropping some frames, but when it is all done, the dialog that comes up reports no dropped frames (BTW, this is not the usual behavior I have seen with my DV cam – if it reports dropped frames during the capture it reports them in the dialog as well). Then, if I bring the video into VirtualDub to find the dropped frames (using <Shift>-}), it finds no dropped frames. When I compare it (frame-by-frame) to another capture of the same tape, I can usually find a spot where both the audio and video of a frame is missing. What I usually see when a frame has been dropped is the last video frame received is repeated for all the dropped frames and all the audio is there though. Next I tried the same with Scenalyzer and got basically the same results. While capturing, I got 1 dropped frame reported (this I know to be a bad spot on the tape), but on the left side of the status bar where it reports how many frames were dropped it said there were 14. Again I could not find them using CTRL-N in scenalyzer or in VirtualDub.

The spots where I do see complete (audio and video) frames missing have not been the same spots from test to test.

Is it possible that the camera is dropping them and never sending them via the Firewire port and the software is told that a frame was dropped which would explain this discrepancy? I don’t know enough about the analog->DV processing that goes on in the camera, but this is the only thing that makes any sense here.

Has anyone else experienced this phenomenon, or am I the only one ?

I am going to try a couple of other tests tonight (taking the A/V output into my DV cam as a pass through and trying a friend’s Hi8 camcoreder and using the DV cam as a passthrough) to see if I can see exactly what is being lost.

[turk690]

I have a Sony DCRTRV350K. While playing back analogue 8/Hi8 tapes on it then having the DV stream available right there and then for capture is a nifty feature I have found out over the long course that analogue capture quality is variable, determined for one by how good the tape is. Using solely the capture facility in Premiere Pro 1.0 on really bad spots on the tape capture is simply aborted/terminated, sometimes closing by itself, sometimes mercifully asking for the captured portion to be so named, and on other occasions carrying on as if drop-outs were not there (although reporting them later), all different results on the same tape(!). It's been suggested one crucial capture requirement of analogue tapes is a really good and stable sync signal; the TRV350K appears confused when this is missing, as on tapes riddled with drop-outs. I find out that, for some reason, that it is better able to capture external analogue video, for which I have retained an older TRV330K. With the latter I play back the analogue tape, connecting its analogue outputs to the TRV350K, which records the digital copy. While a bit laborious and time-consuming, for suspect tapes this arrangement yields at least two benefits: the analogue tape can drop out all it wants, but the 330 keeps on playing, and the 350 keeps on recording (all the while making a legitimate DV tape); and the digitized stable version can now be batch-captured with Premiere Pro (something not possible with using the 350 in an A-to-D fashion) without it in least balking. Note that in connecting the two camcorders together it is analogue that is used, NOT the FireWire ports (connecting so seems to replicate the problems at the beginning: capture stopping, etc.) On another note this has similarly what has kept me from getting capture cards (like the Matrox RT100X); it was supposed to be that direct analogue inputs meant one could plug in the analogue VCR outright and capture the tape, but my experience with an old RT2500 has shown it goes bonkers if there are even a few sync drop-outs on the tape (maybe newer cards are better, no?). I then had to connect the VCR (usually VHS) to a DV camcorder, digitize the troublesome tape, then connect that camcorder later to the card's FireWire input (rendering the capture card's analogue inputs mostly irrelevant).

[TNTJr]

Thanks for your reply - it may yet be one more piece to the puzzle.

To summarize:

TRV350K => Firewire => Computer
resulted in dropped frames/aborted transfer

TRV330K => TRV350K => digital8 recording of original
followed by
digital8 recording of original in TRV350K => Computer
resulted in a good transfer

Am I correct so far?

If so, then have you tried:

TRV350K => A/V out => DV camcorder w/pass-through => Computer?

If you have, what was the result?

Also, have you tried:

Analog8MM => A/V => TRV350K => Computer (using the TRV350 as an A/D converter)?

If you have, what was the result?

[turk690]

You got it right on the 1st two. I have also tried the last two scenarios where an analogue signal is input into the TRV350K (in the AVin-to-DVout passthrough mode) then connected via FireWire to the PC; when there is a glitch in the analogue signal Premiere also stops capture and wants the file to be named. This depends on the severity of the glitch or glitches. It seems one can't escape recording the analogue tape to digital first before in turn capturing with Premiere. Some have realized that all the glitches and drop-outs in the original tape have been carried over to the digitized version. The point here is, the digital tape has a valid sync over its entirety; never mind the wretched audio & video; as such it can be batch captured like any digital tape can (drop-outs edited out), and the audio and video are all still in perfect sync anywhere on the tape. On really old/bad tapes I have resigned to capturing like this; a lot of tedium and time is forgone just digitizing the analogue tape in question, then capturing that digital version (the alternative is stop-and-go capturing everytime glitches forces capture to stop). I had a feeling merely patching an AVin-to-DVout converter (be it a DV/D8 camcorder, a standalone appliance, or a capture card (like Matrox RT2500) between an analogue source and a PC's FireWire input was too good a scheme to be reliable half the time in the world of imperfect, old, drop-out laden VHS and 8/Hi8mm tapes.

[TNTJr]

An update...

I have successfully captured an 8MM tape by playing the tape in the TRV480 and using my TRV27 (DV) as a pass-through to do the A/D conversion. I don’t particularly like this solution because it means I’ve wasted about $75 (I could’ve bought the 280 which doesn’t do the DV conversion on-board) and I now have to tie up my DV cam every time I need to capture a tape.

I still think the camera is actually dropping the frame and never sending it which is why the capture programs report it while capturing and not after it is done. I think the number reported when it is done capturing is the number of frames it (the software) couldn’t write due to performance limitations.

I e-mailed Sony regarding this issue and am hopeful that being persistent will at least get me an answer – even if it is one I don’t particularly want.

I had a thought regarding Premiere aborting the capture. There is usually an option in most capture software to abort the capture if there are dropped frames. If Premiere has this option, that could be why it is stopping when it hits one of these spots. Of course you will still have dropped frames. Just something to check.

You may also want to check out Scenalyzer – there is a free trial that puts a watermark every few seconds or so, but other than that it is fully functional and will let you test out that software with your hardware, and it is pretty reasonably priced at US $39.