[FFmpeg-user] Ffmpeg - h filter

[James Northrup]

On Wed, Jan 22, 2020 at 3:44 AM James Northrup <jim at vsiwest.com> wrote:

>
> On Wed, Jan 22, 2020 at 2:17 AM Paul B Mahol <onemda at gmail.com> wrote:
>
>> You should never parse textual output of -h help.
>>
>
since we seem to be here to tell each other how to do their job, why don't
I follow up with...

WTF ARE THESE UNDOCUMENTED FIELDS DOING IN MY BINARY HELP ?   AINTCHU NEVER
HEARD OF USERS BOY?

If you need to get options of filter use library provided API.
>>
>
> thanks Paul B Maholfor such a concise and detailed answer with such exact
> references!  top posted no less!  It almost looks like anyone not writing c
> code should go pound salt instead of use the executable!
>
> so it looks like the 8 target flags has become 10.
>
> at some point years ago i divined this struct (java interface, now
> kotlin).  AVTarget appears to be missing 2 now.  Any hints?
>
> interface AvOption {
>     val optionName: String?
>     val type: String?
>     val targets: List<AvTarget>?
>     val description: String?
>     val range1: String?
>     val range2: String?
>     val def: String?
>     val children: List<AvOption>?
>     val encoding: Boolean?
>     val decoding: Boolean?
>     val filtering: Boolean?
>     val video: Boolean?
>     val audio: Boolean?
>     val subtitle: Boolean?
>     val export: Boolean?
>     val readonly: Boolean?
>     fun addChild(o: AvOption)
>     enum class AvTarget {
>
> *        Encoding, Decoding, Filtering, Video, Audio, Subtitle, Export,
> Readonly*    }
>
>     enum class AvOptionField {
>         optionName, type, targets, description, range1, range2, def
>     }
>
>     companion object {
>         val AV_OPT_PAT =
> "^\\s+(?<${AvOptionField.optionName}>[\\w+-]+)(\\s+\\<(?<${AvOptionField.type}>\\w+)\\>)?\\s+(?<${AvOptionField.targets}>[\\w.]
> {8}
> )(\\s+(?<${AvOptionField.description}>[^(]+)(\\s+\\(from\\s+(?<${AvOptionField.range1}>.*)\\s+to\\s+(?<${AvOptionField.range2}>[^)]+)\\))?(\\s+\\(default\\s+(?<${AvOptionField.def}>[^)]+)\\))?)?$".toRegex().toPattern()
>     }
> }
>
>
>> On 1/21/20, James Northrup <jim at vsiwest.com> wrote:
>> > i am maintaining ffblockly which scrapes the ffmpeg executable for
>> filter
>> > parameters and defaults by cartesian product of e.g. >>>(below)
>> >
>> > is there a build step artifact that more cleanly has the  self-doc
>> > records?  this cmdline help has changed ever so slightly and i've got to
>> > reverse engineer again.  my initial look into the build process turned
>> up
>> > nothing conclusive, maybe some hints to get me started looking in the
>> right
>> > place
>> >
>> >>>>(below)
>> > ffmpeg -h filter=crop 2>/dev/null
>> > Filter crop
>> >  Crop the input video.
>> >    Inputs:
>> >       #0: default (video)
>> >    Outputs:
>> >       #0: default (video)
>> > crop AVOptions:
>> >  out_w             <string>     ..FV.....T set the width crop area
>> > expression (default "iw")
>> >  w                 <string>     ..FV.....T set the width crop area
>> > expression (default "iw")
>> >  out_h             <string>     ..FV.....T set the height crop area
>> > expression (default "ih")
>> >  h                 <string>     ..FV.....T set the height crop area
>> > expression (default "ih")
>> >  x                 <string>     ..FV.....T set the x crop area
>> expression
>> > (default "(in_w-out_w)/2")
>> >  y                 <string>     ..FV.....T set the y crop area
>> expression
>> > (default "(in_h-out_h)/2")
>> >  keep_aspect       <boolean>    ..FV...... keep aspect ratio (default
>> > false)
>> >  exact             <boolean>    ..FV...... do exact cropping (default
>> false)
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>> >
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>
>