One of the most popular video format in recent years is Flash Video or so called FLV because it supports streaming over the web architecture using normal http protocol. In another point of view, 3GP is widely used in mobile phone because it is very small and efficient for small screen like mobile phone. The technology is going to emerge someday. 3GP would be available on the web for massive distribution. The best approach for publishing video on the web is to use FLV. I will give an example of unattended command for converting any video files including 3GP to FLV using Mencoder.

If you want to read/write 3GP in Mencoder, you have to compile it yourself to include AMR codecs. Below is what I used.

mencoder input.3gp \
         -of lavf \
         -lavfopts i_certify_that_my_video_stream_does_not_use_b_frames \
         -ovc lavc \
         -lavcopts vcodec=flv:vbitrate=150 \
         -ofps 15 \
         -oac mp3lame \
         -lameopts abr:br=32 \
         -srate 22050 \
         -vf scale=320:-3 \
         -o output.flv

According to the command, the FLV will have 150 kbits video bitrate at 15 frame per second using codec flv. For audio, it is mp3 sampling at 22050 Hz and bitrate at 32 kbps. The output FLV will also be resized to smaller than 320 in width.

Tags: mencoder, 3gp, flv