If you try to upload to youtube an audio file you recorded using your smartphone it will not accept because it is not a video. Then the solution is “converting” this audio in video, you can do it using a still image file as backgroung.
I used this command to do that:
$ ffmpeg -loop 1 -shortest -y -i imade.jpg -i audio.3gp -acodec copy -vcodec mjpeg result_video.avi
UPDATE: I was getting this error: Option shortest (finish encoding within shortest input) cannot be applied to input file audio.3gp — you are trying to apply an input option to an output file or vice versa. Move this option before the file it belongs to. Error parsing options for input file audio.3gpp.
I fixed it moving “-shortest” the right, just before result_video.avi.
UPDATE 2: mjpeg generate big files, use “libx264” instead and the fps was higher (more than 150 fps) using “-r 1” fixed the issue, now the complete command is:
$ ffmpeg -loop 1 -y -i meeting.jpg -i audio.3gp -acodec copy -vcodec libx264 -r 1 -shortest result_video.avi
You can find more information about similar commands here:
http://ffmpeg.org/trac/ffmpeg/wiki/Create%20a%20video%20slideshow%20from%20images
Alan C. Assis 