Using WinDV causing Dropped Frames

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Ron P.
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Using WinDV causing Dropped Frames

Post by Ron P. »

I received the following PM concerning usage of WinDV causes dropped frames..
backert1 wrote:Hello,

After my recent string of issues with VS11+ and the suggestions from several to us winDV, I downloaded and tried that this morning. Many comments have been made that it will not drop frames. Well, in recoding (I am the one doing 8mm analog sony through a ADS550 Pyro box) using wind DV today, the dropped frames counter continues to click up missed frames - about 100 for 1 hour video. Not a lot of frames but also not zero. What frames would actually be dropped? Would it be the "partiall complete" frames that are recroded during the camcorder recording startup or end of each scene or would they just be random?

When I reviewed a 1 hour video that I burned to DVD yesterday that was captured using VS11+ there are jittery (sound and video) or pixelized frames at some of the scene transitions that are not present on viewing the tape directly. What causes this? Kind of 2 different questions here.

Thanks,

Todd
WinDV transfers the video from your camcorder to your PC, much the same as transferring a file from one location to another on your PC, ie; copy and pasting. When we copy and paste or move small files it does very fast, and can hardly be noticed. However if you have moved large files, you see a small window showing you the progress of the transfer, and an estimation on the time left. WinDV is behaving in much the same way.

WinDV claims it can do so without dropped frames. Basically this means that it is not going to loose any data in the transfer process. It makes this claim based on using a large memory buffer.

While transferring data if the memory buffer used is small and fills up, then the stream (data transfer) must stop while this buffer is cleared to make room for more data. With video, your camcorder continues to play-on, and those "frames' that are playing while this clearing occurs is not transferred, thus dropped.

However as stated that WinDV claims to use a large memory buffer, so that buffer should not fill up, and stop the transfer. If it does, something is interfering, such as not having sufficient amount of memory, or running some large programs simultaneously, taking away resources.

Another possible cause could be a start/stop in the recording on the tape, where you have glitches, a poor quality recording, or "drop-off", where the tape is loosing it's magnetic properties, thus the recorded material is no longer there.

Jittery Playback on DVD

Without knowing what properties used in the Project, it is difficult to determine the causes. However this is commonly due to reversing or using the wrong Field Order setting. For all DV video the field order in your Project Properties must be set to Lower Field First. This must be maintained clear through the burn. In the burn module (Share>Create Disc) you must set the Project Properties again. This is basically a separate program/utility, and has it's own Preferences and Project settings.
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Trevor Andrew

Post by Trevor Andrew »

Hi Todd

Transferring digital video DV-Avi to the pc using VS or Win-Dv should not show dropped frames. The connection should be firewire from source to pc.
There is no re-coding of the data, what you have is what you get, no changes.
Digital to Digital. Easy on your pc.

But you are transferring/capturing analogue video.
Analogue to Digital

How are you connecting the devices?
Are you using USB? (not a good idea)

Somewhere along the line this source video has to be recoded.

Your 8mm tape runs in real time, the re-code has to keep up.

There are two things to consider:-
1 / the transfer/capture is constant, the tape runs in real time. (the transcode buffer should cope with that)( you would have to manually pause capture should the buffer kick in.)

2 / re-coding the video data has to keep pace with the tape.

I would suspect that the re-code could cause the captured dropped frames.
If the pc cannot re-code the incoming stream fast enough, you will get dropped frames.

Changing the capture settings/properties may reduce the load on the pc, allowing for a faster re-code, reducing dropped frames to zero.

What settings are you using to capture your video.?
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Post by Black Lab »

Also, do you have programs running in the background, such as automatic updates?

Try capturing in smaller time blocks. Say 10 or 15 minutes instead of 1 hour at a time.
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