Post by Ken Springer Post by SC Tom
On Fri, 28 Jul 2017 10:00:23 -0500, Rene Lamontagne
Post by Rene Lamontagne Post by Dan Jenkins
I don't have a "command" key but I do have a "windows" key.
Is the "command" key the same as the "windows" key?
Command key is an Apple Mac thing.
Thanks for clarifying why I don't have a command key on Windows.
On Windows 10, Windows+PrintScreen creates a screenshot as a PNG in the
User's home directory under "Pictures".
The file actually goes into Pictures>Screenshots unless you've changed the
Also the "Windows+3" brings up Irfanview (where "Control+11" snaps a
How does that differ functionally from what Apple does?
It seems to be the same thing, functionally, on both operating systems.
For what W10 does using keyboard shortcuts in the OS,
is the same as Shift+Command+3, which creates a screenshot of the desktop.
In Windows, to change the screenshot file format to something else, such
as a JPG, you have to change the registry, AFAIK. What file formats you
are allowed I do not know. On a Mac, you can change the file format via
command line in the terminal. There's 5 or 6 formats, IIRC, including
TIFF and PDF.
To change the location of the Screenshots folder in Windows 10 (and 8.1 I
suspect), open Properties of the Screenshots folder and change the
location. On a Mac, it's done via a command line in terminal.
Windows + Print Screen will now capture a menu dropdown, and you can do
the same on an Apple.
Up to this point, the systems are essentially the same. But going
OS X, using keyboard shortcuts from the desktop can 1) take a picture of
part of the screen, 2) take a picture of the menu. I know of no way to
do this using keyboard shortcuts in Windows.
Yes, there is the Snipping tool, added to Vista in 2007. But Apple added
the Grab utility in 2005 which does the same thing. I suspect the Apple
keyboard shortcuts just access the appropriate subroutines in Grab.
What I find rather sad is, IIRC, you could do all of this with Alt + Print
Screen in Windows for Workgroups.
Alt+PrtScn still works in Win10 to copy the window in focus, and can then be
pasted into a document or Paint, etc. Ctrl+PrtScn (or simply PrtScn)will
copy the entire desktop for pasting elsewhere.
I knew the commands were there in Win95 on, but couldn't remember if they
were available in Win3.x or not. Thanks for de-scaling that rusty part of my
The problem with the Print Screen method is you have to paste the
clipboard somewhere and save, before you can move on to the next
When I'm creating help files, I like to do all the screenshots at one time.
If you're doing a large number of screenshots, pasting them to imaginative
filenames while you're doing a "procedure" can be distracting.
You can decouple the "procedure" from the document writing later,
by just making a movie of the screen. In this example, the framerate
is set to one picture per second, in case the computer used for the
procedure doesn't have a massive processor on it. You'll hardly
notice the additional activity in the background. If you open
a pulldown menu while doing the procedure, keep it open for at
least a second, so you'll have a snapshot of the menu for later.
Visit here, download the release version (3.3.3) not the nightly.
The nightly at the current time, is missing some DLL files.
You can use a static build, select the appropriate bitness
for your machine, and download the package. Unpack it as
you see fit. My convention here, is to dump the package
Then, in a Command Prompt window, start capturing the screen.
Pressing control-c after the session is finished, will cleanly
terminate FFMPEG and your capture session. The images in this
case are JPG files, thousands of them, all dumped into one directory.
You might end up with thousands, if your lengthy procedure takes
an hour or so.
cd /d C:\path\to\pictures\directory
C:\FFMPEG\bin\ffmpeg -framerate 1 -f gdigrab -i desktop -f image2 -q:v 1 -c:v mjpeg a%05d.jpg
That will leave thousands of JPG files in "directory".
In that command, I don't know what the "-f image2" thing does,
or even if it's necessary. I presume it has
something to do with making the captured movie into
separate JPG files. The thing with FFMPEG, is the
command line evolves with time, and sometimes small
mods to a command are necessary when you go to use
it again with the latest downloaded version.
To post-process, you can use AVIDemux 2.5 to step through
the frames. The JPGs can be played like a movie. You note
the frame number of a frame you want, then go to the
"Directory" full of JPGs and grab "a12345.jpg" or whatever
from the directory. I usually just write down the frame
numbers of the ones I want, then exit AVIDemux, then just
go to the folder and work on collecting the specific JPGs
for my work directory. Now, load them into GIMP, and
chop them up as appropriate (mostly "crops").
The above command can be made more specific, like capturing
a specific window, or even capturing a subset of the screen
at a certain X,Y,W,H zone. Note that, if Adobe Flash is on
the screen, you'll want to "disable hardware acceleration"
in Flash, to force Flash to render into the "normal"
screen frame buffer.
The best tool for capturing all render surfaces, is FRAPS.
But it doesn't work on OSes like Win10, because Microsoft
broke it for them. FRAPS captures from three planes at
the same time, so whether it's the normal screen,
a Flash movie window, or a windowed 3D game playing,
it can capture everything. I think FRAPS (commercial)
works properly on Windows 7. It's possible Windows 8
and Windows 10 have a "rate limiter" on GDIGRAB, which
is one reason I own a copy of Windows 7, just so I can
grab the screen at 60FPS.
FFMPEG grabs the screen asynchronously. It's capturing
a buffer, and not the hardware screen. It doesn't wait
for vertical retrace or anything, to capture. If
you were to sample at 60Hz, sometimes you capture
the same frame twice (the buffer is just snapshotted
twice before it updates). And if you choose to "oversample",
FFMPEG has high sampling rate jitter. If you captured
at 180Hz, you'd expect three identical frames in a row.
Yet, if you do the analysis, you might see 1 unique frame,
followed by the next frame being repeated 5 times. There
is no "metronome" inside to make sampling uniform.
If you're a "professional", you would buy an HDMI capture
card with passthru connector. Any video capture done
on there is frame synchronous. If the OS throws up
barriers, you find one of those nice Chinese HDCP
removal boxes. (Some have made it to the continent,
disguised as 1:2 HDMI active buffer boxes.) And that
would strip HDCP, and make you a pirate :-) Or it
would make you a person who needs snapshots of their
screen, without a lot of hassle.
HDCP was modified at around HDMI Version 2.0. The
more modern your hardware, and output standards, the
more trouble you can expect from movie industry
countermeasures, to whatever you're doing. It's quite
possible the HDCP removal boxes aren't going to help
with HDMI 2.0 or higher.