Frames: Dropped, Inserted, Duplicates and the AmarecTV log

[Alwyn]

Hello all, another topic has piqued my interest in these because I'm not sure I understand what they actually are and their relationship with each other.

I checked the log of a recent capture and found 2 "+" frames but with no "dropped" frames, which ended up being duplicates. My query is: were they a replacement for a dropped frame, an insertion because of a missed frame or what? I suppose one of my issues is I don't understand what the log is actually telling me.

Here's the appropriate part of the log (my bolding):

VT=00:56:02.433s(84055f), Cap=84315f( 0D), Enc= 1.648ms, Siz= 259KB( 32%)KEY, Drp=0, (+)0, (-)0, Buf= 1, o
VT=00:56:02.466s(84056f), Cap=84316f( 0D), Enc= 1.611ms, Siz= 260KB( 32%)KEY, Drp=0, (+)0, (-)0, Buf= 1, o
AT=00:56:02.466s(84055f), Bsy= 0ms, Dif=-5760, Smp=9600
VT=00:56:02.528s(84057f), Cap=84317f( 0D), Enc= 1.631ms, Siz= 259KB( 32%)KEY, Drp=0, (+)0, (-)0, Buf= 1, o
NT=00:56:02.528s(84058f), Total=1
VT=00:56:02.562s(84059f), Cap=84318f( 0D), Enc= 2.618ms, Siz= 260KB( 32%)KEY, Drp=0, (+)1, (-)0, Buf= 1, o
VT=00:56:02.594s(84060f), Cap=84319f( 0D), Enc= 2.790ms, Siz= 259KB( 32%)KEY, Drp=0, (+)1, (-)0, Buf= 1, o
VT=00:56:02.625s(84061f), Cap=84320f( 0D), Enc= 2.474ms, Siz= 259KB( 32%)KEY, Drp=0, (+)1, (-)0, Buf= 1, o

I've attached a video of the offending frame 84058.

Using VDub's Shift+] finds no dropped frames.

And, of course, what should I do about it (I know how to remove dupes)? The audio at the end of the tapes was in-sync as far as I could tell. If I start pulling those dupes out, the sync is going to be affected. I realise the perfectionists would not like them staying there, but I didn't notice them, even while editing the video.

Workflow: Panny EZ-48>GV-USB2>AmarecTV

[Sharc]

Not sure if I understand it correctly. Your attached video shows motion at frame 31,95,153,211,265,379,435,491, means repeated frames in between of 31,65,58,58,54,114,56,56 frames. Do you refer to the big step of 114 repetitions between frame 265 and 379 which is about 2x(54.....65)?
Is it a slowdown version of the original capture?

If the capture SW was not VDub but AmarecTV, VDub can't/won't report dropped frames.

What can you do?
- Nothing if it's just one frame in a long run
- Cut the video duplicate and possibly the audio sample. Check for audio click. Smooth the transition if it is annoying.
- Cut the video duplicate(s) and resample the audio (align the duration)
- Replace the duplicate with a synthesized temporal interpolated frame
- Recapture that section and replace it
- ......?

[lollo]

NT=00:56:02.528s(84058f), Total=1

This means that the frame 84058 is a duplicate of the previous frame, and is reported as such.
From that point AmarecTV reports that duplicated frame:

Drp=0, (+)1, (-)0, Buf= 1

for every line.

An "Inserted" frame is not a real frame (it does not exist), but an indication in the stream to repeat the previous frame. It can be easily found in the log or opening the raw capture with VirtualDub and using its menus. Note that VirtualDub call "dropped frames" what in reality is an "inserted frame".
Once you process/encode/whatever the capture that "information" about the inserted frames is deleted and cannot be found anymore.

A frame is dropped by the capture software when it does not arrive "in time" and there is nothing it can do. A frame is inserted (duplication of the previous) when a frame does not arrive in time but the software can act to keep a/v in synch.

If you have just 1/2 frames just keep them (a/v will be sinch).If you have many, recapture the tape with a different setup. Indications from Sharc are also appropriate

[Alwyn]

Sorry Sharc, my attachment was confusing. It was a screencapture of me stepping through the video with the arrow keys. I've replaced it with the actual capture video in my first post.

[Alwyn]

@Lollo, thanks, that makes it clearer. So, for that Amarec log specifically, in my case, frame 84058 is an insert and is depicted by (+)1.

What would the (-)0 be?

Have you ever seen any actual Drp=x indicated in the log?

[Sharc]

Looking at the motion it seems to me like the frame got inserted without an associated dropped frame. So it may be deleted, but check against the audio sync. Sometimes it is difficult to spot dropped frames though.

[lollo]

@Lollo, thanks, that makes it clearer. So, for that Amarec log specifically, in my case, frame 84058 is an insert and is depicted by (+)1.

What would the (-)0 be?

Have you ever seen any actual Drp=x indicated in the log?

Here an example of mine:

VT=00:32:34.471s(48862f), Cap=49261f(  0D), Enc= 2,668ms, Siz= 262KB( 32%)KEY, Drp=0, (+)0, (-)0, Buf= 1, o
AT=00:32:34.471s(48854f), Bsy=  0ms, Dif= 4896, Smp=9600
NT=00:32:34.471s(Drop), Total=1
VT=00:32:34.551s(48863f), Cap=49263f(  0D), Enc= 1,942ms, Siz= 264KB( 32%)KEY, Drp=0, (+)0, (-)1, Buf= 1, o

At time 00:32:34.471 the frame after 48862 is dropped, and reported as such(NT=...(Drop)). Starting from there the global counter changes from

Drp=0, (+)0, (-)0, Buf= 1

to

Drp=0, (+)0, (-)1, Buf= 1

Later in the capture I have an inserted frame, reported as NT=...:

VT=00:50:20.876s(75516f), Cap=75824f(  0D), Enc= 3,006ms, Siz= 369KB( 45%)KEY, Drp=0, (+)0, (-)1, Buf= 1, o
NT=00:50:20.876s(75517f), Total=1
VT=00:50:20.957s(75518f), Cap=75825f(  0D), Enc= 2,989ms, Siz= 373KB( 46%)KEY, Drp=0, (+)1, (-)1, Buf= 1, o

and the global counter changes from

Drp=0, (+)0, (-)1

to

Drp=0, (+)1, (-)1

[Alwyn]

Good oh. So it looks like the (-) is for cumulative drops and the (+) is for cumulative inserts.

Thanks.