Reduce a Video Size with ffmpeg

Basic command to reduce a video for upload to YouTube:

> ffmpeg -i input_video.mp4 -ab 56k -ar 22050 -b 300k -r 15 -s 640x360 output_video.flv

If the original size was greater and you have the time to keep it bigger, YouTube suggests a size of 1280x720 for better reproduction.

More info to come... in the meantime:
Read the man page for more information.

FFmpeg documentation.

Creating a Movie from Images (Linux)

The short story at this time. These instructions refer to the creation of MPEG4 video from JPGs images on Linux.
You need mencoder, part of the mplayer software.

Type:

> mencoder mf://<PATH>/*.jpg -mf w=320:h=240:fps=12:type=jpg
-ovc lavc -lavcopts vcodec=mpeg4:mbd=2:trell
-oac copy -o output.avi

Where you should customize at least:

• <PATH>/*.jpg is the path to the directory where your JPGs are.
• w=320:h=240 is the image size.
• output.avi is the resulting file name