[FFmpeg-devel] [PATCH] Clarifying the use of the scale filter interlace option

[Michael Niedermayer]

On Thu, Mar 29, 2012 at 08:49:38AM +0100, Tim Nicholson wrote:
> On 27/03/12 18:50, Michael Niedermayer wrote:
> > On Tue, Mar 27, 2012 at 12:09:54PM +0100, Tim Nicholson wrote:
> >> On 27/03/12 07:47, Tim Nicholson wrote:
> >>> On 26/03/12 23:55, Michael Niedermayer wrote:
> >>>> On Mon, Mar 26, 2012 at 05:37:47PM +0100, Tim Nicholson wrote:
> >>>>> Based upon some recent queries on ffmpeg-user, and my own experience, a little
> >>>>> clarification of the documentation should help users in this area.
> [..]
> > 
> > applied
> > 
> 
> Whilst investigating this it occurred to me that this filter behaves
> differently by default to other filters and options.
> 
> Commonly values of 1|0|-1 are used, with -1 meaning "auto" in whatever
> way that applies to the relevant filter/option, with the other values
> forcing a particular behaviour between a choice of 2. -1 is also
> commonly the default value.
> 
> For example the following all use -1 as the default if not specified:-
> rawvideo top
> -mixing_level number
> -channel_coupling boolean
> -cpl_start_band number
> amovie|movie stream_index
> yadif
> cellauto|life random_seed
> 
> scale however only has 1|-1 with 0 having no defined meaning, although
> the logic dictates that since it is neither of the others it is an
> invalid choice and therefore ignored.

0 should mean progressive


> 
> Also unlike other cases -1 (auto) is not the default.

this could be changed if it works better overall

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Awnsering whenever a program halts or runs forever is
On a turing machine, in general impossible (turings halting problem).
On any real computer, always possible as a real computer has a finite number
of states N, and will either halt in less than N cycles or never halt.
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