[FFmpeg-devel] [PATCH] Support Ctrl+Break in ffmpeg.exe on Windows as if it was Ctrl+C

Michael Niedermayer michaelni at gmx.at
Thu Jun 25 14:02:09 CEST 2015


On Wed, Jun 24, 2015 at 11:48:10PM -0600, Roger Pack wrote:
> On 6/24/15, Michael Niedermayer <michaelni at gmx.at> wrote:
> > On Wed, Jun 24, 2015 at 04:19:38AM -0600, Roger Pack wrote:
> >> On 7/5/12, Michael Niedermayer <michaelni at gmx.at> wrote:
> >> > On Mon, Jun 25, 2012 at 02:21:21PM +0200, Michael Niedermayer wrote:
> >> >> On Tue, Jun 19, 2012 at 07:10:04PM +0200, Reimar Döffinger wrote:
> >> >> > On 19 Jun 2012, at 11:31, Joe Wreschnig <joe.wreschnig at gmail.com>
> >> >> > wrote:
> >> >> > > On Windows, the Ctrl+Break key combination usually does what
> >> >> > > Ctrl+C
> >> >> > > does. It is more common for processes to send other processes
> >> >> > > Ctrl+Break rather than Ctrl+C, because sending Ctrl+C / SIGINT
> >> >> > > doesn't
> >> >> > > work if you started a child in a new process group.
> >> >> > >
> >> >> > > This patch makes ffmpeg.exe register what Windows calls a console
> >> >> > > control event handler, which allows it to intercept Ctrl+Break. It
> >> >> > > hands it off directly to the usual SIGINT/SIGTERM handler. The
> >> >> > > same
> >> >> > > function also processes closing the console window, mapping it to
> >> >> > > SIGTERM.
> >> >> > >
> >> >> > > Obviously, this is only enabled if compiling for a platform where
> >> >> > > SetConsoleCtrlHandler is available (i.e. modern Windows).
> >> >> >
> >> >> > What is "modern"? Also it is rather unusual to recompile for
> >> >> > different
> >> >> > Windows versions, couldn't you with about the same effort just use
> >> >> > GetProcAddress (more complex code, but in exchange you'd save on all
> >> >> > the
> >> >> > configure changes and #ifs).
> >> >>
> >> >> It seems versions that dont support this are no longer supported
> >> >> by microsoft. IMHO we shouldnt bother too much with such old windows
> >> >> versions unless someone wants to / volunteers to do it.
> >> >>
> >> >> thus, if there are no objections i will apply this patch once a few
> >> >> minor issues are fixed (ifdef breaking compile to be precisse)
> >> >
> >> > iam waiting for a working patch
> >> > i could try to fix it before applying myself but with patches for
> >> > non linux platforms i prefer to avoid changing as the changes would
> >> > be untested ,..
> >>
> >> Sorry I dropped the ball on this one.
> >> See attached.  The major gains we get out of this (in my head at
> >> least) is hopefully better shutdown if somebody logs out (which has
> >> bitten me before).  Or if someone closes a console window which also
> >> shuts down FFmpeg.
> >>
> >> I noticed that even with handling notifications of "logout" that
> >> ffmpeg can still easily leave behind corrupted mp4 files (it gets
> >> killed quickly after).
> >
> >> Makes me wonder if there's some way to make it shutdown more quickly,
> >> but I'm not sure if it's a problem yet or not.
> >
> > iam not sure i understand ?
> > does windows kill the process immedeatly after CtrlHandler() returns?
> > if so CtrlHandler() should wait for the main loop to exit and cleanup
> > finishing before it returns
> 
> Thanks for the pointer, you were exactly right.  Appears I can
> basically "Sleep" in that method and thus allow FFmpeg to cleanup (in
> vista+ I believe it gives a max of 5 seconds which is enough).  If
> there's some other easy way to know the main loop has exited I could
> use that I suppose, but it should have the same effect.

you could set a global volatile variable to 1 at the end of
exit_program() and wait on that to happen in the handler



[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

If a bugfix only changes things apparently unrelated to the bug with no
further explanation, that is a good sign that the bugfix is wrong.
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