Re: Mplayer equalizer doesn't work

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On Thu, 2010-10-28 at 21:06 -0500, D Wyatt wrote:
> If I wanted everything brighter, then the monitor level would
> obviously be the place to change settings.  If anything, I would
> be more likely to *lower* the monitor's brightness.  Generally,
> the whole video is acceptable but when there are, for example,
> nighttime scenes that just look black, increasing the brightness
> reveals details so you have some clue as to what is going on.

You did mention the majority of videos were too dark, which (going by
averages) suggests that your brightness is too low to start with, and
only looks okay when watching something that's already too bright.

Though, to use a computer for two wildly different things (watching
videos, and other computing tasks), really calls for adjusting something
else - "gamma" (more about that below).

> I tend to be a multi-tasker - I never do anything full-screen.
> I have been noticing a slight growth in the tendency on linux to
> configure tools with the expectation that they will be the only
> thing in use until their use is completed.

Yes...  Menus that take up a third of the desktop space, likewise with
other programs where a huge GUI means you end up with a keyhole to look
at what YOU were interested in...  And (not) sharing sound hardware...

> For example, another minor complaint w/resp to gmplayer is that
> between F12 and F13 the ability to minimize the control console of the
> gui has been eliminated.  The video window can be minimized, but not
> the control console.  In F12, both could be individually minimized.

I haven't used gmplayer for ages, I can't recall all the reasons, but
smplayer seemed better.  It works in a window, or fullscreen, and in
fullscreen with or without navigation controls (depending on if you
moved the mouse to the bottom of the screen, to make the controls
appear).

> Oh, and btw, I have not noticed any tendency for videos to be too
> bright.  I have never lowered the brightness on any video, be it
> Anime, TV show or movie.  Even youtube clips are sometimes so dark
> that i have to download the .flv or .mp4 and view it in gmplayer
> with increased brightness.

Sounds like you have settings all over the place, then.  What you've
described is the classic case seen from turning one thing up in one
place, and the same thing down, elsewhere (once destroyed, it can't be
restored, later).  e.g. Brightness down on the monitor, brightness up on
the video player.  It also sounds like a mixing up of terminology
(contrast and brightness, and playing with the wrong ones).  Not to
mention the usual computer defaults being inappropriate (jet black text
on full white background, is like staring at texta writing on a
fluorescent tube; and with a low res LCD, like staring at a fluorescent
light through flyscreen).

When you set up a computer monitor properly, so that the full range from
black to white is shown as actually black to white, with everything in
between.  You get a proper computer display, suitable for real work
(such as photo editing), or, at the very least, you get to see
everything; as well as it being suitable for play.  Though, with the
usability problem I mentioned a moment ago - thanks to the the usual
page colouring defaults.   The real solution (for that) would be to use
not-white pages, though the usual fix is turn the CONTRAST down (reduce
the range), not the brightness (make everything blacker, including
making things blacker than black).

Video, meant for watching on TV (whether that be a movie on DVD, tape,
or from your home video camera), on the other hand, has a different
gamma than a computer monitor screen.  The gamma boosts the dark end of
the range, lightening up the dark portions, without affecting (much) the
lighter portions.   Gamma correction was originally done to compensate
for the original television picture tubes - the camera was tweaked in
the opposite direction, rather than correct the TV set.  And we've been
stuck with it ever since, even when the display technology changed
(they've either done opposing gamma correction, on top of the gamma
correction, in the display; or left you to look at a malformed picture).
Now we have TV sets with a plethora of user adjustments, trying to make
something good out of something inadequate (all those cinema viewing
mode presets on your brand spanking new plasmas).

Video has more gamma than computing.  For some reason, the computing
fraternity decided to be different (still have gamma correction, but use
a different factor, even while still using the same CRT technology).
Hence, why, in most cases, watching a DVD on a computer looks awful (you
never get blacks, everything is above black - grey).  This doesn't
happen in the few cases where hardware processing of video decoding, or
software players, compensate for it.

If you haven't noticed it, it's usually because either you're using
things that compensate for it, or you've probably turned your brightness
down too far, most of the time; or you're using a CRT with a similar
gamma.

Having said all that.  I find that on a properly set up monitor, or well
set up (even if not precisely set up).  Most YouTube clips do look fine.
A bit grey instead of black, but not very bad.  Dark clips would be down
to bad clips, or your monitor being malset in the first place.

A YouTube clip I just picked at random, for an example:
http://www.youtube.com/watch?v=Dbt9pQUr71I  Shows someone demonstrating
glamour lighting for photography.  Around the girl is near dark, just
slightly brighter than the complete black border around the image.
Around 15" (seconds) to 20" in, you should only be able to determine
that's a silhouette of a photographer, not really see any details of
them.  About 45" in, the photographer's standing behind the girl yakking
about something (I had the sound off), he's moderately dark, but should
be clearly visible with good detail, other than the shadow across his
shirt.  If that one's too dark, your monitor is mal-set.

Picking on another clip by the same person, but a bit brighter:
http://www.youtube.com/watch?v=RaebMg4oSeI  It starts off nicely lit,
about 55" in is a bit less than usual video illumination of people, but
still well exposed.  If that, or any other part of the whole clip is too
dark for you to see well, you have your monitor really badly mal-set.

Of course, if you're talking about trying to see detail in deliberately
underexposed shots (such as the classic horror movie scenes where a girl
walks into a room, doesn't turn the lights on, and gets attacked), then
that's deliberately maladjusting the monitor to try and see something
they're trying to keep hard to see.

Covering the basics:

Brightness - the bias that everything rides on.  It sets the black
level, that everything is on top of.  On anything but bad hardware, the
brightness is the first thing to set, with the contrast turned all the
way down.  Set to see a black level just above no illumination.  Set too
low, and everything darker than a certain level will all become black,
too high, and you wash everything out.

Contrast - the dynamic range, how big the difference is between black
(no illumination, none blacker) and white (100%, none whiter).  On
anything but bad hardware, you're adjusting the range above black.  You
set contrast for how bright you want white to be above black.  Turned
too low, and you get low contrast, up too high, and you may be trying to
make white whiter than white, which just isn't possible.

(This is very different from photography, where things tend to centre
around the middle - contrast centred around grey.)

Gamma - deliberate non-linearity of the dynamic range.  Dark portions of
the video signal are increased, as a compensation for the CRT having the
opposite response.  Comparatively speaking, other non-CRT technologies
are linear, so video created with gamma boosting for a CRT looks washed
out.

If you want to see the effects of messing with gamma, open a photo in
the gimp, open up the "curves" control in the colour menu, and bend the
straight line so it starts to look like the top left quadrant of a
circle.  That's the direction that signal is boosted by when trying to
gamma correct the picture for a CRT (who's natural response is a curve
in the opposite direction - with the net result of one against the other
trying to get back to the straight line).  When viewing such video on
another with a different gamma curve (computer CRT, LCD, etc.), it looks
like the curve has been pushed way too far.

Tim (who works in video production, and has to deal with this all the
time, and hates how computers get it so badly wrong, all the time).

-- 
[tim@localhost ~]$ uname -r
2.6.27.25-78.2.56.fc9.i686

Don't send private replies to my address, the mailbox is ignored.  I
read messages from the public lists.



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