Yes, we solved the issue for Sinan but the issue was server specific. His FFMPEG installation was not full and was not properly configured (it was lacking encoding libraries and the path to the ffmpeg was different from that of a regular path).
Please take a look at the installation guide I wrote here:
Especially, make sure to check the manual to see what codecs are installed and supported by your ffmpeg installation.
The version that is installed on our servers is usually FFmpeg version 0.6.5 with the following configuration:
configuration: --prefix=/usr --enable-gpl --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libx264 --enable-version3 --enable-libfaac --enable-nonfree
To check the codecs supported, type the following in command line:
ffmpeg -codecs | less
Make sure libfaac and libx264 are among the codecs available for you.
You could also try to encode a test video from the command line to make sure that ffmpeg is working correctly:
ffmpeg -y -i /path/to/source/file -acodec libfaac -vcodec libx264 -f mp4 -vtag avc1 -vpre normal -refs 1 -coder 1 -level 31 -threads 8 -partitions parti4x4+parti8x8+partp4x4+partp8x8+partb8x8 -flags +mv4 -trellis 1 -cmp 256 -me_range 16 -sc_threshold 40 -i_qfactor 0.71 -bf 0 -g 250 /path/to/new/file/to/save
If all the flags don't work for you it means something is not configured write in the ffmpeg installation. In this case you could also try to remove some of them and be left with:
-acodec libfaac -vcodec libx264 -f mp4 -threads 8 -partitions parti4x4+parti8x8+partp4x4+partp8x8+partb8x8
If you still have issues, feel free to email me at firstname.lastname@example.org and I'll do my best to help you.