Thread: The NVidia Overscan Issue and Fixing It

i have googled. have searched these forums , others.

i have ripped hair out in frustration.

as many aware, custom resolutions- "what hell" "that's messed up" or "jesus christ" "you've got kidding"- hard set under new "xorg.conf isn't used" paradigm. should not be. many ubuntu users running os on displays either nonstandard display resolutions or devices overscan display not offer 1:1 pixel display setting- such myself, on 50" samsung 1080p dlp television, connected via hdmi port.

after more year trying find hard-and-fast process fixing overscan problem (note did not "a hard-and-fast fix problem"), have decided turn collective wisdom of ubuntu user community in effort put issue bed good. end, create thread.

recent research via web has led me believe problem lies in x server not being aware of sort of valid modeline my- or your- nonstandard resolution. well-aware each solution each user different; if you're reading this, you're geek me in first place, , chops more sufficient tackle both biting off huge issue and chewing it.

question community this: how determine correct modeline add xorg.conf, how make available x server, need format modeline in valid way in xorg.conf (if necessary), , how make appear in list of valid resolutions when run nvidia-settings (or whatever command is)?

keep in mind, i'm more interested in establishing correct pipeline fixing problem , allowing arbitrary resolutions limit of given device's capacity, rather exact solution particular hardware. in other words, don't want exact answer situation; i'm looking method finding proper solution given situations similar mine.

huge issue lot of people; know endless googling on subject. if know anything how go this, please, please post know. thank you.

can start discussion brief look..& imo..

think need break issue different categories.
1. dfp dvi/hdmi
2. dfp analogue
3. crt analogue (vga or component)
4. last gen crt upscaler/digital engine

a. display of gui
b. vdpau video decode/presentation.

important info:
dfps have pre-scaler drives panel @ native resolution.
crt monitor not have pre-scaler except hd-ready models upscaler.
overscan required in crts
overscan enabled hdmi inputs not in pc mode.

modelines:
useful analogue connection. (i explain in bit).
if can find real specifications of monitor, easy calculate custom modeline. tricky/iterative part optimize over/underscan & still allow monitor sync.
there few calculators workbooks & online make easier.

analogue rgb video signal elegant serial datastream has managed remain usable decades. analogue monitor sync video signal horizontal & vertical frequency have in range.
behaviour can exploited move left-right & top -bottom margins of display.
dfp using analogue connection can manipulated same way results depend on pre-scaler.

[speculation follows because have not done experiment]
digital connected dfp may not allow same freedom because accepted video modes reduced/constrained. may not accept custom modelines.

maintain close 1:1 pixel mapping & preserve pq, better way manage dfp overscan scale display image inside display frame; mythtv does. , similar nvidia driver provides (a.)

scaling bad pq have no choice.
video encoded @ resolution; fixed video modes.
nvidia driver capable of vdpau high quality scaling (feature set c,d) video decode/playback (b.) , there many hq s/w scalers lancroz bicubic etc..
example:
mythtv allows different screen size gui & playback. able make gui smaller video mode frame size.

have not tried using nvidia overscan compensation vdpau playback.

if desktop virtual size made smaller (inside) video mode frame there existing xorg method system wide overscan adjustment.
have not tried yet.

crt tvs have service menu allows alignment/geometry adjustments.
service alignment can adjusted obtain best geometry custom modeline.
geometry alignment not problem dfps.

Forum The Ubuntu Forum Community Ubuntu Official Flavours Support Multimedia Software [ubuntu] The NVidia Overscan Issue and Fixing It

Ubuntu