[FFmpeg-devel] [PATCH] Use ff_thread_once() to initialize sin/cos static tables.

Ronald S. Bultje rsbultje at gmail.com
Sun Oct 25 12:56:49 CET 2015


On Sun, Oct 25, 2015 at 7:48 AM, Derek Buitenhuis <
derek.buitenhuis at gmail.com> wrote:

> On 10/25/2015 11:44 AM, Michael Niedermayer wrote:
> >> One could argue this is not a representative sample. It's a single
> small file,
> >> which must always init (as opposed to a longer running process such as
> Chrome.
> >> Whereas if you have a longer sample, it wouldn't even be within the
> margin of
> >> error, I bet.
> >
> > If the usecase is to probe many files, then file duration would not
> > help hideing the init time. (to fill a GUI list or whatever)
> I reject this notion. You are completely discounting that people use
> libavcodec *as a library*, and not via CLI.
> > Also startup time for normal playback itself does matter, as its
> > part of user vissible responsiveness, the user clicks play in his
> > players playlist and if that isnt instantaneaously starting playback
> > the user notices. So IMO startup time is not irrelevant
> I agree, but neither is thread-safety. Perhaps there is a middle ground.

So this is likely because we init all tables instead of just these that we
need, right? So how about having one ff_once per table? That should be
trivial to implement.

Obviously anyone using shell scripts and calls to CLI ffmpeg versions to do
probing of production-level numbers of files on production systems deserves
the results (s)he'll be getting.


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