A Dialog showing installation of the Script

mencoder Filename.flv -nosound -ovc lavc -lavcopts vcodec=mpeg4 -vop expand=176:144,scale=176:-2 -o temp.avi -ofps 15

Here in the above command Filename.flv is the name of the video file you want to convert to mobile phone format and temp.avi would be the file in which the converted video would be written. 176:144 Is the size of mobile screen of the phone to which we want to resize the video clip. -ofps 15 specifies the frame rate per second.

Now we extract a audio stream from the FLV movie and store it in a external wav file soundump.wav

mplayer -vo null -ao pcm -af resample=8000,volume=+4db:sc filename.flv

This extracts the audio from the file filename.flv and resamples the sound to 8 kHz It also applies a soft clip filter. The result is a file called audiodump.wav that contains the sound. We need to extract sound as 8Khz since FFmpeg wont encode our file if it is higher.

Now a major problem (maybe some legal issue because of proprietary media format) is that because of some reasons the FFmpeg binary that comes dosent include the files to handle the AMR file that is used by 3gp files for storing audio , hence we need to recompile the FFmpeg library to include support for the AMR file.

So first download FFmpeg source-code from Source Code can be obtained from this website : - http://ffmpeg.mplayerhq.hu/ . Extract the source-code to a suitable directory and go to that directory and chdir to doc here you would find a .texi file FFmpeg-doc open that file in text editor or convert the texi file to dvi using tex program and search for AMR you would find a section like this :-

@item For AMR WB floating-point download TS26.204 V5.1.0 from
@url{http://www.3gpp.org/ftp/Specs/archive/26_series/26.204/26204-510.zip}
and extract the source to @file{libavcodec/amrwb_float/}.

@item For AMR NB floating-point download TS26.104 REL-5 V5.1.0 from
@url{http://www.3gpp.org/ftp/Specs/archive/26_series/26.104/26104-510.zip}
and extract the source to @file{libavcodec/amr_float/}.
If you try this on Alpha, you may need to change @code{Word32} to
@code{int} in @file{amr/typedef.h}.

@item For AMR NB fixed-point download TS26.073 REL-5 V5.1.0 from
@url{http://www.3gpp.org/ftp/Specs/archive/26_series/26.073/26073-510.zip}
and extract the source to @file{libavcodec/amr}.
You must also add @code{-DMMS_IO} and remove @code{-pedantic-errors}
to/from @code{CFLAGS} in @file{libavcodec/amr/makefile}, i.e.
``@code{CFLAGS = -Wall -I. $(CFLAGS_$(MODE)) -D$(VAD) -DMMS_IO}.

Here copy the address for AMR NB loating point download the file http://www.3gpp.org/ftp/Specs/archive/26_series/26.104/26104-510.zip extract it in a temporary directory . Create a directory ffmpegsourcecode-directory/libavcodec/amr_float and extract the zip file contained in it in the newly created directory ffmpegsourcecode-direcotry/libavcodec/amr_float .

Now make to compile the source code

and make install to install the compiled files.

Now if everything went fine in above steps . FFmpeg should be configured to encode 3gp files properly, now we combine the two pieces to create a one 3gp file using FFmpeg

ffmpeg -i temp.avi -i audiodump.wav -b 48 -ac 1 -ab 12 -map 0.0 -map 1.0 filename.flv

After this command the flv file should be ready to be transferred to a mobile device , and should work fine on any phone capable of playing the 3gp format.