>> You you have to take a look at the center, oft the first field or >> something like that.=20 > >Yeah, funny enough, the black frame search I did in mplayer looked at >the centre of the frame and worked it's way towards the top and bottom >of the frame for just that reason, however, that defeats the >efficiencies of looking at the top of the frame -- that being the need >to only jpeg-decode a minimum number of scanlines to determine that a >frame is not black. > >If I use the centre lines, I need to decode whole frames. Even with >16:9 material, I have to decode more lines, but certainly not as many as >decoding a half a frame or more.
The first coefficient of each macroblock in JPEG is the DC value for the macroblock, right? Maybe you don't have to completely decode any scanlines at all. You'd have to decompress/unpack enough to recover the coefficients for blocks toward the center of the screen, but you shouldn't have to do any of the DCT stuff just to recover the average level of a macroblock. Maybe this works, maybe not... just throwing out ideas. -matt m. ------------------------------------------------------- This SF.Net email is sponsored by: Oracle 10g Get certified on the hottest thing ever to hit the market... Oracle 10g. Take an Oracle 10g class now, and we'll give you the exam FREE. http://ads.osdn.com/?ad_id=3149&alloc_id=8166&op=click _______________________________________________ Mjpeg-users mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/mjpeg-users
