Now after my post on how to create a video and sending it to YouTube I'd like to show basic steps when dealing with videos generated from a Smartphone.
As you may already know nowadays smartphones are able to create .3GP files, don't matter about the platform (Android, iOS, BlackBerry OS, Symbian). And even better, if you need to upload your videos directly to YouTube you don't even need to worry about them or convert from .3GP to something else, YouTube converts your videos for you, you just need to wait a while before their processing queue takes your video off and translate it to the .ogv file.
But if you don't want to wait and you'd like to have your videos publicly available instantly you'd better upload an AVI file to YouTube, because when you upload an AVI to YouTube they'll process your video immediately. You can apply the same procedure if you'd like to download a video from your smartphone to your computer and play it with a common media player program (or send it by email, etc...)
If you've read my previous post you may notice the same conversion method, in fact here it is:
ffmpeg -threads 2 -i
filefromyourphone.3gp -f avi -r 29.97 -vcodec libxvid -vtag XVID -s
1024x768 -aspect 4:3 -maxrate 1800kb -b 1500kb -qmin 3 -qmax 5
-bufsize 4096 -mbd 2 -bf 2 -flags +4mv -trellis -aic -cmp 2 -subcmp 2
-g 300 -acodec libmp3lame -ar 48000 -ab 128kb -ac 2
Just change output resolution (1024x768 in my case) to whatever you want and you'll have your new AVI (or free format) file on PC, just change filename and extension to convert it to whatever you like (OGV, MPG, …)
In the beginning I was against ffmpeg due to its surreal parameters and complexity but now I'm using it for everything
Hope it helps