true picture size from DV

[hamambocegi]

i guess i never thought about this before since i always used to convert to vcd, and the dimensions are standard.

now i discovered divx. so i've been experimenting encoding divx from my digital camera. the input is raw avi 720 x 480, and i always do a 2:1 reduction in virtualdub.

but is 720 x 480 or 360 x 240 the true represantaions of the physical world ?

what should my picture size be ? i am asking because i am confused - since VCD forces 352 x 240. so what is the true size of a picture from a DV cam ??

[kinneera]

The discrepancy between 360 and 352 has to do with comparative "pixel" sizes between TVs and computer monitors. Since a TV is analog on the horizontal resolution, it has what are analagous to rectangular pixels, whereas a computer screen has square pixels.

Anyway, to make a long story short, if you're doing Divx, I'll assume its only for computer playback. In this case, a straight 2:1 reduction to 360x240 is most appropriate.

You might even want to consider not reducing the resolution that much, since one of the focuses of Divx has been to allow high quality at high resolutions despite the heavy compression.

<font size=-1>[ This Message was edited by: kinneera on 2001-12-01 18:54:00 ]</font>

[hamambocegi]

thanks for the reply. made things crystal clear. didn't know the rectangular pixels about tvs.

i just do a 2:1 reduction and i get pretty good results at full screen at 950 kbits/sec. you cant see any pixelation and it plays very smooth (i have a 400mhz processor). so i guess i'll stick with 2:1.

[hamambocegi]

one more thing. i was checking the picture size of some of the divx movies i downloaded. and they are 640 x 272.

how come ?

i thought DVD's were wide screen and 16:9. 640 x 272 come out to be 40:17 how come there are 640 x 272 ?????

[kinneera]

The 640x272 corresponds the the 2.35:1 anamorphic widescreen format, which is the aspect ratio that many movies are filmed at.