[Ffmpeg-devel] [PATCH] Update docs according to new "ab" parameter unit

Michael Niedermayer michaelni
Tue Mar 6 13:02:01 CET 2007


On Tue, Mar 06, 2007 at 10:06:23AM -0000, M?ns Rullg?rd wrote:
> Benoit Fouet said:
> > Hi,
> >
> > Michel Bardiaux wrote:
> >> Benoit Fouet wrote:
> >>> Hi Takis,
> >>>
> >> [snip]
> >>
> >>>>
> >>> well, if you update this, you have also to change "-b" to "-vb"
> >>> in fact, the behaviour now is that one:
> >>> - "ab" option sets audio bitrate
> >>> - "vb" option sets video bitrate
> >>> - "b" option sets both
> >>> so, if we have on the same line a "ab" option followed by a "b"
> >>> option... the latter will overwrite the former...
> >>>
> >> Is this *really* what we want? This new meaning for -b will break
> >> *every* example in the archives, every script using ffmpeg,... in a
> >> not-so-obvious way. It might be better to remove with -b entirely.
> >
> > should have been a great idea to have those remarks in the dedicated
> > thread, when i exposed it :)
> > i cannot see an easy way to get rid of "b" option, though...
> > and if you want the same bitrate for audio and video, it is quite useful
> > too to handle "b" option...
> Wanting the same audio and video bitrate seems rather unlikely to me.
> I don't think having a shorthand for such a bizarre coincidence is
> really warranted.

argh i cant even sleep a few hours without people flaming each other
without anyone even bothering to look at the code :(
not to mention the thread where i asked if anyone would mind the -b change ...

so again
-foobar sets  foobar for all contextx
-afoobar sets foobar for the audio context
-vfoobar sets foobar for the video context

that is nicely consistent but changes a few cases like -ab X -b Y in 
unexpected ways

we could of course add -b with a function which av_log()exits()

or we could revert the whole and find a different solution how to set
parameters for specific contexts with AVOption

one alternative solution would be to duplicate all AVOptions which are
usefull for more then one out of (Audio,Video,subs) in that case we could
give each any name and default we like but it would increase the number 
of AVOptions and the simple generic afoobar is the matching part of vfoobar
would be lost unless we are very carefull with selecting the names

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Let us carefully observe those good qualities wherein our enemies excel us
and endeavor to excel them, by avoiding what is faulty, and imitating what
is excellent in them. -- Plutarch
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