Simon Hyde wrote: > > Ahhh...Right...now I see what you're talking about. The problem you're > seeing here has nothing to do with the MVP's support for widescreen TV. > The hardware MPEG decoder in the MVP only supports MPEGs with a standard > number of lines, 480 for NTSC and 576 for PAL (and maybe exactly half > these numbers too for VCD support, not sure about this). If you give it > an MPEG with less lines then it will simply draw it at the top of the > screen. > > As I explained in my email the only difference between a 16:9 MPEG and a > 4:3 MPEG is a flag in the headers, both MPEGs are 720x576 (or 720x480 > for NTSC). The digital video pixels when they're drawn on screen are not > necessarily square (I don't think they ever are for DVD/DVB/ATSC MPEGs) > and they're a different shape for 16:9 and 4:3 MPEGs.
Yes, it has always suprised me that so many different resolutions x to y ratios (not just with the mvpmc) can come out as 4:3 (or 16:9). > > All you should need to do to create an MVP compatible MPEG is scale to > 720x576 (or 720x480 if you're stuck with rubbishy NTSC), and make sure > that the MPEG headers reflect whether it is 16:9 or 4:3. Then if you > have "-a 4:3" the MVP will automatically letterbox any 16:9 programs, > and if you have "-a 16:9" it should send appropriate WSS to your TV to > indicate that the signal is 16:9/4:3. You shouldn't need to crop > anything (unless the MPEG your broadcasters transmit already has a > letterbox drawn on it), and definitely shouldn't need to draw a > letterbox. All you should need to do (for NTSC) is: > > mencoder -vf scale=720:480 > or > mencoder -vf scale=640:480 > or > mencoder -vf scale=704:480 > or one of the other standard resolutions which the MVP hardware > supports. I think mencoder should translate the aspect ratio into the > correct MPEG header here without any problems, but you may be able to > force it with -aspect 16:9 or -aspect 4:3 > > If you really want a bit more of a brain hurt then you'll find a quick > dig around google shows http://lipas.uwasa.fi/~f76998/video/conversion/ > which seems to do a good job of trying to explain all this malarchy. > Simon, My transcode script already takes care of properly scaling it to something that will fit with the proper size and aspect ratio intact, and then expands (centers) the resulting image on the screen to get around these issues so the TV's zoom will work nicely. The pixels look to be properly sized as I don't see any incorrect stretching of things. I will have another version of the script in the next day or two including instructions of how to put it in as a myth job. I also speed up transcoding by adjusting the scaling algorithm used by mencoder (-sws) this changed the speed from around 31fps to about 39fps on my machine, so a fairly significant speed up. Roger ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Mvpmc-users mailing list Mvpmc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mvpmc-users mvpmc wiki: http://mvpmc.wikispaces.com/
