The ROKR E6 has a 320×240 (QVGA) screen where the QCIF is 176×144.. The aspect ratio does not match..
xCIF is mandatory with the h263 codec.. I know Rokr E6 can play h263.. But any QCIF fornat dıes not look good. The aspect ratio is 1.22 for CIF. The phone screen is 320×240 (QVGA) where the aspect ratio is 1.33. That is why it does not look good.
Checked with x264 but that is not supported by the player available with device.
Now testing an mpeg4 output ..
and voila! That works fine .. Below is how I convert an AVI file to 3gp format for Motorola ROKR E6:
$ ffmpeg -i sourcevideo.avi -s qcif -vcodec mpeg4 -acodec libfaac -ac 1 -ar 44100 -r 25 -ab 64 -y targetvideo.3gp
this way still we use the qcif resolution (where qvga is not acceptable by the device), the output looks just fine. Possibly some minor stuff is taken care of already.
