Jframe

A j-frame (also known as a j-type frame) is a type of frame similar to an i-frame used in microsofts mpeg4 variation codec wmv2. mplayer on x86 can play files containing these frames using a binary codec. ffmpeg can also play files containing j-frames, but, those frames will be skipped. j-frames have not been reverse engineered, so there is no documentation available. If a stream contains j-type frames the j-type bit will be set in the streams extradata.