I just got a new portable media player, that has some great picture and video quality, however, many of the music videos and movies I have are having trouble transcoding properly. I have tried avidemux, transmaggedon, mencoder...etc, but the problem seems to be that the original movie files seem to be missing the codec information. I can view the content, but when I try and transcode it it doesn't know what to do.

Is the lack of codec info a problem, and if so, is there any way to edit the video metadata or something and tell it what kind of codec it is? I'd surely appreciate the help.

Thanks in advance.