On Sat, 18 Mar 2006, Steven M. Schultz wrote: > On Sat, 18 Mar 2006, Trent Piepho wrote: > > > mplayer is right about the DAR. If you do the math, (720*10)/(480*11) = > > Actually mplayer either off or the input stream is incorrect. > > Take a 720x480 MPEG-2 file and play it and note that 1.33 is printed:
In THIS case, mplayer is wrong! Here, the mpeg2 format doesn't specify the SAR, instead there are a few choices for the DAR, like 4:3 or 16:9. The 720x480 MPEG2 file says the DAR is 4:3, but really if you displayed the whole 720 pixels, it would be wider than 4:3. You could say that due to the limitations of the mpeg2 format, the file's header is wrong. Still, this case is so common, mplayer should know better. The math is simple, sample aspect ratio times width in pixels over height in pixels equals display aspect ratio. Do you not agree with this formula? > VIDEO: MPEG2 720x480 (aspect 2) 29.970 fps 7500.0 kbps (937.5 kbyte/s) > Movie-Aspect is 1.33:1 - prescaling to correct movie aspect. > > Plain as day "Movie-Aspect is 1.33:1". The (aspect 2) means this file specifies DAR ratio number 2, which is 1.33:1. mplayer is just printing that bit from the header again when says movie-aspect is 1.33:1. > VIDEO: MPEG2 704x480 (aspect 2) 29.970 fps 7500.0 kbps (937.5 kbyte/s) > Movie-Aspect is 1.33:1 - prescaling to correct movie aspect. Ok, SAR is the same for both of these samples. The resolution is different, 704 vs 720. How can the DAR be the same? ------------------------------------------------------- This SF.Net email is sponsored by xPML, a groundbreaking scripting language that extends applications into web and mobile media. Attend the live webcast and join the prime developer group breaking into this new coding territory! http://sel.as-us.falkag.net/sel?cmd=lnk&kid=110944&bid=241720&dat=121642 _______________________________________________ Mjpeg-users mailing list Mjpeg-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mjpeg-users
