This is probably a task that every Flashcom developer will have to tackle at some stage: how to extract thumbnails images from an flv file, ideally automating this process with a free commandline tool such as ffmpeg.
I've had a shot at this once before, probably a year or two ago and I was somewhat successful. One key thing that I could not crack was the -ss flag in ffmpeg which allows you to seek to a position. Whenever I used that flag the jpg extraction/conversion wouldn't work, instead it returned something like 'unknown option -ss'.
But recently a user in my forum suggested to give this another try. I grabbed the ffmpeg executable from Riva Encoder and tried again - this time it worked, probably due to a newer version of ffmpeg.
For reference the syntax I used is below. This will produce an output file with the name of 1.jpg. It's also possible to add other text to the filename but ffmpeg insists to have a numbering system in there.
ffmpeg -i video.flv -an -ss 00:00:03 -an -r 1 -vframes 1 -y %d.jpg
the options are as follow: -i input file -an Disable audio recording -ss seek to (in this case second 3 to avoid black frame at start) -vframes no idea what this does, could be framerate? Anyone know? -y overwrite output file
Note: I am not sure if this will work reliably or at all with VP6 encoded files. Please post a comment if you know if it does or not.
My version of ffmpeg can be downloaded here.