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

Guillaume POIRIER poirierg at gmail.com
Wed Nov 23 17:48:55 CET 2005


Hi,

On 11/23/05, Tshepang Lekhonkhobe <tshepang at gmail.com> wrote:
> Hello,
> Why is it default behaviour that MPlayer creates a video during 1st
> pass when we are interested in the 2nd pass output?
> I see some people directing it to /dev/null but isn't this unnecessary overhead?
> >From the docs, I get that the 1st pass is used to study the input
> video to make a superior 2nd pass video, so why need the 1st pass
> video output?

Strange ppl (like me) like to be able to see how the first pass looks
in order not to have to wait till the full encode is finished to bump
up the bitrate or stuff like that.
In any case, the codec still does have to encode the video to collect
stats about it, so there's no way (that I know of) to short-cut this
step of the encoding process.

In any case, please consider benchmarking/profiling when you wonder
where the hot spot of an application is, and don't ever forget
hamdahl's law: http://en.wikipedia.org/wiki/Amdahl's_law

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




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