Virtual VCR



Virtual VCR
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Virtual VCR : General Info

Setting up a timed capture
To set up a timed capture to capture video when you are not at the computer, you can use the "Scheduled Task" system in Windows or any other scheduling software for that matter. You need to launch Virtual VCR with the "-capture" parameter to start the capture automatically. For more info on Timed Captures CLICK HERE

AV Sync
Due to the nature of separate Video and Audio capture cards not having access to a synchronized reference clock, AV sync issues can occur in video capture. Virtual VCR uses a audio resample filter to try to deal with this, more information is available CLICK HERE.

Command Line Options
There are a few command line options that you can use with Virtual VCR.

-capture (This will start Virtual VCR in capture mode)
-channel "X" (This will set the initial channel to X when Virtual VCR starts)
-profile "<file location and name>" (load a profile file when run)
-runfor "time in sec" (Capture for seconds and then stop capture)
-output "<file name>" (Over ride the filename)

virtualvcr.exe -capture -channel "9" -profile "c:\video\test.vcr" -output "d:\video.avi"

This will start Virtual VCR capturing on channel 9 with the c:\video\test.vcr profile settings and saving the AVI to d:\video.avi

Keyboard Shortcuts
There are a number of keyboard shortcut keys that can be used to do thinks with Virtual VCR, following is a list of all the keyboard shortcuts in Virtual VCR:

  • "F5" Start capture
  • "ESC" Stop capture
  • "P" Toggle preview
  • "S" Toggle stats dialog
  • "F" Toggle full screen mode
  • "H" Hide/Show Tool bar and Status bar
  • "T" Toggle "Always On Top" On/Off
  • "C" Brings up the settings dialog
  • "PageUP" Change up channel
  • "PageDOWN" Change down channel

Changing Channels using the keyboard
Apart from the above shortcuts there is a channel changing mode that allows you to change TV tuner channels using the keyboard, to use this all you have to do is hit the channel number you want followed by the enter key. If your required channel is two digits long just enter them and then hit the enter key. Entering 1 followed by 2 and then the <enter> key will change to channel 12.

Dropped Frames
The default dropped frames interface that comes with DirectShow is broken, I have created a new Dropped frame detection method that should be a lot more accurate then the default one. The new dropped frame system shows up under Dropped2 in the capture stats, it also makes available the frame numbers that were dropped be selecting "Show Dropped Frames" from the capture menu after a capture.

Dropped frames can occur for a number of reasons, CPU, Hard Drive or some other system resource overloaded with data etc can cause frames to be dropped, in this situation frames are dropped because the PC can not process all the frames fast enough and has to drop frames to keep up.

The other reason frames can be dropped is if the input signal is to degraded for the capture card to detect the frame correctly, in this situation the capture card can not digitize the frame and thus it is lost. You will see this happen when capturing from Video Tape that is old or worn.

In all situations a blank frame is inserted into the AVI index thus when you go back over the video you just captured you will see dropped frames as one or more frames of the same image etc. This also stops the video from playing faster or slower you just get duplicated frames in your AVI file.

To check a captured AVI file for dropped frames use VirtualDub to open the AVI file and then under one of the menus select jump to next dropped frame, you will then be shown the next dropped frame in the AVI file if there is one. This is the best way to check for dropped frames after you have captured a file. Logo