@Chibi
And i alway thought googeling belonged to the base lessons for a researcher...
Just try a search for "mp4 aspect ratio" at google.com.
As stated in the m4if mail list archive there is a flag (atom) aspect_ratio_info in mp4, but it is the player programmers choice to use it or not. Default ratios are 12:11 and 40:33.
http://lists.m4if.org/pipermail/tech...ch/000573.html
Common Intermediate Format - CIF
A video format used in videoconferencing systems that easily supports both NTSC and PAL signals. CIF is part of the ITU H.261 videoconferencing standard. It specifies a data rate of 30 frames per second (fps), with each frame containing 288 lines and 352 pixels per line.
4CIF 704*576, comp. H.263
http://www.tele.ntnu.no/signal/cours...ge-formats.pdf
Best supported DSP Hardware Platform i found for MP4 is TMS320C62x:
http://focus.ti.com/docs/tool/list.j...DAV=Generation
Most encoders for those DSPs use CIF family sizes, so i would assume they are good for future player compatibility.