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Unofficial VirtualDub Support Forums > General Discussion > Total Frames

Posted by: earth004 Jun 8 2014, 03:21 PM

I am finding a discrepancy between the total frame numbers between two computers. I am looking at the same videos and using the default settings. On one computer, virtual dub shows a certain frame count for a given frame. On the other computer, the frame count is off by several frames. Depending on the video, the frame count difference between the two computers is not the same. Does anyone know what might be causing this? If I scroll to the end of both videos, the total number of frames is the same on both computers.

Posted by: dloneranger Jun 8 2014, 04:09 PM

Check the file information dialog to see what codec's being used
They'll probably be different, and interpreting b-frames differently (one will probably inserting a small # of delay frames at the start)

Posted by: raffriff42 Jun 8 2014, 04:14 PM

(simul-posts again - hi dloneranger)
...Put another way, if you are opening a non-AVI file, you are probably using the built in DirectShow input driver. DirectShow is not always frame accurate, and since it loads its codecs through Windows, which codecs get loaded depend on your system configuration.

The http://forums.virtualdub.org/index.php?act=ST&f=2&t=22269&st=0#entry95795 does not have this problem, and has much better frame accuracy overall.

Certain videos are created in a way (missing index or having very long GOPs) that makes finding the exact frame (in a reasonable time, without stepping through all frames from the start) very difficult, in which case the frame number you see is approximate. In this case, if you *must* have frame accurate seeking (for editing purposes etc) you will have to make an "intermediate" video, using a lossless, I-frame only codec such as Huffyuv or Lagarith.

Posted by: earth004 Jun 8 2014, 09:33 PM

When I go to videos--> filters, there is nothing listed. What is the default codec it is using?

Posted by: earth004 Jun 8 2014, 09:42 PM

And, in video-->compression, they are both set to Uncompressed RGB/YCbCr

Posted by: dloneranger Jun 8 2014, 09:45 PM

Ah, the pick a random menu entry method ;-)

QUOTE

Check the file information dialog to see what codec's being used

On the file menu->file information

Posted by: earth004 Jun 8 2014, 10:00 PM

I tried to install the FFMpeg inputdriver plugin for VirtualDub without success. As described on that link, I put the entire FFMpegPlugin folder inside the VirtualDub folder. Then, I created a folder within the plugins32 folder (/Users/J/Desktop/VIrtualDub/plugins32/ffdlls) and added th dll files. I restart VirtualDub, open the video but see no option to select "FFMPeg supported files." When I go to information, it says I am using the ffdshow video codec.

Posted by: earth004 Jun 8 2014, 10:05 PM

In file information, it says the decompressor is FFDShow Video Codec (H264). How do I change this to one where the frames are more accurate? And, why would the same codec work differently on two different computers?

Posted by: raffriff42 Jun 9 2014, 03:32 AM

1. For FFinput, you need VirtualDub 1.10.3 or higher.

2. So the files are located like http://dl.dropboxusercontent.com/u/108089426/Screenshots/virtualdub-ffinput-location.png?

3. Same Windows version on both computers?

4. On either computer, are you accessing the file over a network?

5. In ffdshow, http://dl.dropboxusercontent.com/u/108089426/Screenshots/ffdshow-version.png, "About", are the versions the same?

6. In ffdshow http://dl.dropboxusercontent.com/u/108089426/Screenshots/ffdshow-vfw-h264.png, "Decoder" tab, "Codecs", is the format "H.264/AVC" set to "libavcodec"?

7. Also in VFW config, click "Decoder options" on the left-hand list and then "reset."

8. Do the same for "Intel® QuickSync."

9. In VirtualDub, verify "Options," "Sync to audio" and "Drop frames when behind" are set the same in both.

That's all I can think of. If the difference is small, try not to worry about it

Posted by: earth004 Jun 9 2014, 08:46 PM

Thanks for all these suggestions. After trying the same set-up (software, codec, video file), it turned out that the problem was with the operating system AND particular computer. Certain computers and OS matched while others did not.