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

Michael Niedermayer michaelni
Tue Mar 6 15:29:34 CET 2007


On Tue, Mar 06, 2007 at 03:05:57PM +0100, Benoit Fouet wrote:
> Michel Bardiaux wrote:
> > Benoit Fouet wrote:
> >> Michel Bardiaux wrote:
> >>> Michael Niedermayer wrote:
> [snip]
> >>>> 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
> >>> And -r 25 would set the video fps *and* the audio sampling rate to 25?
> >>> That cant be good. What foo is a reasonable bar for both A and V?
> >>>
> >> no, rate works in a different way...
> >
> > Sorry, I dont see what you mean here. If you mean rate is a exception
> > to the generic behavior described above by Michael, then its main
> > (IMHO only) merit, that of consistency, is already lost.
> >
> that is what i meant
> if you open ffmpeg.c and libavcodec/utils.c, you'll find out how this is
> handled i think...
> to sum up:
>  - options defined in const OptionDef options[] are handled in ffmpeg.c
>  - if the current option doesn't match any, it triggers the last one,
> which is "default" option
> default options are the ones defined in libavcodec/utils.c
> this calls opt_default with this option, and in this function, we set
> the option for all avctx_opts.
> if this gives nothing, this is done with avformat_opts.
> finally, again if the previous fails, and depending on the first letter
> of the option ("a", "v" or "s" for the moment), it tries to see if the
> option without its leading letter can be applied to the corresponding
> context ("a":audio, ...)
> the only options i see for the moment that works like that are "ab" and
> "vb" (and potentially "sb")

-adebug -vdebug -debug should work too

and potentially things like -qscale, -bt, -flags bitexact, -strict
-er -ec -coder -context -minrate -maxrate, -pred, -psnr, ...

would work if a audio codec used them ...

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Observe your enemies, for they first find out your faults. -- Antisthenes
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