extraction synchronized with video

[amandioc1]

Hello. It may seem a bit strange, but this is what I need to do (under Windows Xp): extract the frames from a video to a single jpg.
Very important, the extraction would need to be synchronized with the video. And if possible, at the end of the video, the extraction would restart from the beginning. Is this possible?
Besides this, I haven't been able yet to extract frames from any video using the command line, always getting the error about I/O and truncated/damaged files. Using Super though the extraction works well.
Thank you for your help.

[Baldrick]

Extract frames to A single jpg? One jpg? Or do you mean one jpg for each frame?
What do you use that gives you the error? ffmpeg,mplayer?
Syncronised with the video?

[amandioc1]

Hello Baldrick, thanks for answering. I know it seems strange. The idea is to have another program (a music visualizer), that can read jpgs but not video, read this single jpg 10-20 times per second. Very important is that the extraction should be as synched as possible with the video, since normal extraction is much faster. I'm using ffmpeg under Windows Xp.
Besides this, when I use
ffmpeg -y -i 1.wmv -f image2 out%.jpg
I get the message of I/O error and only frame 1 is extracted.