[MPlayer-users] Why create video in 1st pass?

[Guillaume POIRIER]

Hi,

On 11/26/05, Kichigai Mentat <kichigai at comcast.net> wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> On Nov 24, 2005, at 03.34, Stefan Sassenberg wrote:
>
> > Mustafa Abbasi wrote:
> >> oh crap.
> >> is this why everytime i enabled 2 pass it created a video file.
> >> i asummed i was doing something wrong so i did not use 2 pass
> >> damn. why is this not mentioned in the man pages clearly.
> > The documentation says "you can delete the AVI" which implies that
> > there is an AVI created in the first pass. And you can delete it.
> Why even do that much work? Why not output directly to /dev/null?
> Saves time and space, since (I'm assuming by now we've tweaked
> everything) we don't need the 1st pass output file?

I'm gonna repeat myself once more: before asking weather or not the
video file should be written to save time (let alone save disk space
since the video can be written to /dev/null and use zero bytes on the
disk), you should profile your application and measure how many % of
total cpu time writing the video takes. You can use oprofile to do
this, or append "-pg" to your cflags to use groff.

Once you get the amount of time spent on that, read
http://en.wikipedia.org/wiki/Amdahl's_law and see what gain you'd get
from removing video writing.

You'll see for yourself that I am not telling your bullshit.

Guillaume
--
Remember, if you ever need a helping hand, it's
at the end of your arm, as you get older, remember
you have another hand:
The first is to help yourself,
the second is to help others.
-- Audrey Hepburn