mirror of
https://gitlab.freedesktop.org/gstreamer/gstreamer.git
synced 2024-11-22 09:41:07 +00:00
64 lines
1.5 KiB
Text
64 lines
1.5 KiB
Text
1) playing DVD on 4:3 screen
|
|
|
|
PAL DVD:
|
|
- video size in pixels: 720x576
|
|
- intended physical aspect ratio: 4/3
|
|
- pixel aspect ratio: 16/15
|
|
|
|
normal 4:3 computer screen:
|
|
- screen size in pixels: 1024x768
|
|
- physical aspect ratio: 4/3
|
|
- pixel aspect ratio: 1/1
|
|
|
|
-> scale to video size 720 . 16 / 576 . 15 = 11520 / 8640 = 144 / 108
|
|
= 4 / 3
|
|
|
|
2) playing PAL DVD on PAL TV
|
|
|
|
PAL DVD:
|
|
- video size in pixels: 720x576
|
|
- pixel aspect ratio: 16/15
|
|
|
|
=> intended display aspect ratio: 4/3
|
|
|
|
w/h = DAR/PAR (with w and h of pixel video size)
|
|
|
|
DirectFB PAL TV output:
|
|
- screen size in pixels: 720x576
|
|
- pixel aspect ratio: 16/15
|
|
|
|
=> display aspect ratio: 4/3
|
|
|
|
(v = video, source material - d = display)
|
|
DARv = DARd <=> wv / hv * PARv = wd / hd * PARd
|
|
<=> wd / hd = wv / hv * (PARv / PARd)
|
|
no scaling necessary
|
|
|
|
|
|
4) playing an NTSC vob on PAL TV
|
|
|
|
NTSC VOB (4/3):
|
|
- video size: 720x480
|
|
- pixel aspect ratio: 8/9
|
|
|
|
=> intended DAR: DAR = 720/480 * 8/9 = 80 / 60 = 4 /3
|
|
|
|
wd / hd = wv / hv * PARv / PARd
|
|
= 720/480 * 8/9 / (16/15)
|
|
= 720 * 8 * 15 / (480 * 9 * 16)
|
|
= 120 * 1 * 5 / (80 * 3 * 2)
|
|
= 15 / 12
|
|
= 5 / 4
|
|
|
|
--> 720 x ( 720 * 4 / 5) = 720 x 576
|
|
|
|
|
|
5) other examples
|
|
- 720 x 480, 32/27 on a square display
|
|
-> intended DAR: DAR = 720/480 * 32/27 = 80/3 * 1/15 = 16/9
|
|
|
|
keeping w constant:
|
|
720/h * 1/1 = 16/9 -> h = 720/16 * 9 = 45 * 9 = 405
|
|
|
|
keeping h constant:
|
|
w/480 * 1/1 = 16/9 -> w = 480 * 16 / 9 = 160 / 3 * 16 = 853.33
|