[FFmpeg-devel] [PATCH 2/3] Add section describing the filtergraph.

Michael Niedermayer michaelni
Fri Dec 3 00:35:46 CET 2010


On Thu, Dec 02, 2010 at 11:43:28PM +0100, Stefano Sabatini wrote:
> On date Thursday 2010-12-02 23:07:37 +0100, Michael Niedermayer encoded:
> > On Wed, Dec 01, 2010 at 12:42:58AM +0100, Stefano Sabatini wrote:
> > > On date Sunday 2010-11-14 05:07:22 +0100, Michael Niedermayer encoded:
> > > > On Sat, Nov 13, 2010 at 10:27:29AM +0100, Stefano Sabatini wrote:
> > > > > On date Saturday 2010-11-13 02:25:47 +0100, Michael Niedermayer encoded:
> > > > > > On Sat, Nov 13, 2010 at 01:51:09AM +0100, Stefano Sabatini wrote:
> > > > > > > On date Friday 2010-11-12 19:22:55 +0100, Michael Niedermayer encoded:
> > > > > > > > On Fri, Nov 12, 2010 at 01:32:55AM +0100, Stefano Sabatini wrote:
> > > > > > > > > ---
> > > > > > > > >  doc/filters.texi |   86 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> > > > > > > > >  1 files changed, 86 insertions(+), 0 deletions(-)
> > > > > > > > 
> > > > > > > > This needs the attention of a english speaker
> > > > > > > > 
> > > > > > > > > 
> > > > > > > > > diff --git a/doc/filters.texi b/doc/filters.texi
> > > > > > > > > index 4750d32..d1ae815 100644
> > > > > > > > > --- a/doc/filters.texi
> > > > > > > > > +++ b/doc/filters.texi
> > > > > > > > > @@ -1,3 +1,89 @@
> > > > > > > > > + at chapter Filtergraph description
> > > > > > > > > + at c man begin FILTERGRAPH DESCRIPTION
> > > > > > > > > +
> > > > > > > > > +A filtergraph is a graph of connected filters.
> > > > > > > > > +
> > > > > > > > > +Each filter instance has a variable number of inputs and output pads,
> > > > > > > > > +which are used to connect it with other filters. A filter with no
> > > > > > > > > +input pads is called "source", a filter with no output pads is called
> > > > > > > > > +a "sink". A connection between an output pad and an input pad of a
> > > > > > > > > +filter is called a "link".
> > > > > > > > > +
> > > > > > > > > + at section Filtergraph syntax
> > > > > > > > > +
> > > > > > > > > +A filtergraph can be represented using a textual representation, which
> > > > > > > > > +is recognized by the @code{-vf} and @code{-af} options of the ff*
> > > > > > > > > +tools, and by the @code{av_parse_graph()} function defined in
> > > > > > > > > + at file{libavfilter/avfiltergraph}.
> > > > > > > > > +
> > > > > > > > > +A filtergraph is represented by a list of ";"-separated filterchain
> > > > > > > > > +descriptions. Each filterchain represents a sequence of connected
> > > > > > > > > +filterchain node filters (each one called "filternode").
> > > > > > > > 
> > > > > > > > you define filter instances and then use undefined terms like 
> > > > > > > > filterchain node filters and filternode instead
> > > > > > > > ive not reviewed further, this IMHO needs more work
> > > > > > > 
> > > > > > > I changed to:
> > > > > > > |A filtergraph is represented by a list of ";"-separated filterchain
> > > > > > > |descriptions. Each filterchain represents a sequence of connected
> > > > > > > |filter instances, each one called filternode.
> > > > > > 
> > > > > > whats the difference between a filter instance and a filter node ?
> > > > > 
> > > > > |A filtergraph is a graph of connected filters.
> > > > > |
> > > > > |The node of a filtergraph is a single filter instance, which has a
> > > > > |variable number of inputs and output pads, which are used to connect
> > > > > |it with other filter nodes.
> > > > 
> > > > thats not ok
> > > > you talk about filter instance and filter nodes and The node (one)
> > > > of a filtergraph.
> > > > None of this is defined or makes sense or is needed, you should pick one
> > > > word and stick to it not mix words that mean slightly different things in
> > > > contexts that _require_ identical things.
> > > > 
> > > > Iam a bit tired but if i have to try id say
> > > > 
> > > > A filtergraph is a directed graph of filters. It can contain cycles,
> > > > and there can be multiple links between a pair of filters.
> > > > Each link has one input pad on one side connecting it to one filter from which
> > > > it takes its input and one output pad on the other side connecting it to the
> > > > one filter accepting its output.
> > > 
> > > Thanks, fixed together with some other remarks.
> > > 
> > > English speakers and especially people which has no familiarity with
> > > the filtergraph syntax are welcome to comment.
> > > 
> > > Regards.
> > > -- 
> > > FFmpeg = Formidable & Friendly Merciful Peaceless Easy God
> > 
> > >  filters.texi |   88 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> > >  1 file changed, 88 insertions(+)
> > > b84511645180090cb0966a42f61751eb5202ee73  0002-Add-section-describing-the-filtergraph.patch
> > > From 721f81fea20890f170d155cf27c00b006d663357 Mon Sep 17 00:00:00 2001
> > > From: Stefano Sabatini <stefano.sabatini-lala at poste.it>
> > > Date: Sat, 6 Nov 2010 03:04:43 +0100
> > > Subject: [PATCH 2/2] Add section describing the filtergraph.
> > > 
> > > ---
> > >  doc/filters.texi |   88 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> > >  1 files changed, 88 insertions(+), 0 deletions(-)
> > > 
> > > diff --git a/doc/filters.texi b/doc/filters.texi
> > > index 9583e4e..d26a02e 100644
> > > --- a/doc/filters.texi
> > > +++ b/doc/filters.texi
> > > @@ -1,3 +1,91 @@
> > > + at chapter Filtergraph description
> > > + at c man begin FILTERGRAPH DESCRIPTION
> > > +
> > > +A filtergraph is a directed graph of filters. It can contain cycles,
> > > +and there can be multiple links between a pair of filters. Each link
> > > +has one input pad on one side connecting it to one filter from which
> > > +it takes its input and one output pad on the other side connecting it
> > > +to the one filter accepting its output.
> > > +
> > > +A filter with no input pads is called a "source", a filter with no
> > > +output pads is called a "sink".
> > > +
> > > + at section Filtergraph syntax
> > > +
> > > +A filtergraph can be represented using a textual representation, which
> > > +is recognized by the @code{-vf} and @code{-af} options of the ff*
> > > +tools, and by the @code{av_parse_graph()} function defined in
> > > + at file{libavfilter/avfiltergraph}.
> > > +
> > 
> > > +A filter in the graph is called filternode.
> > 
> > why?
> 
> That was to keep a consistent terminology:
> filternode
> filterchain
> filtergraph

not consistent at all.
consistent is either
filter, filterchain, filtergraph
or
filternode, filternodechain, filternodegraph
but later is just a hard to read mess


> 
> if you have a better suggestion you're welcome. Basically I'm
> preferring this term in favor of "filter" (which is more related to
> the "class" concept of filter) and "filter instance" (which would be
> too long and not consistent with the other terms and less expressive).
>  
> > > +
> > > +A sequence of connected filternodes, each one connected to the
> > > +previous one in the sequence, is called a filterchain. A filterchain
> > > +is represented by a list of ","-separated filternode descriptions.
> > > +
> > 
> > > +A sequence of filterchains completely describe a filtergraph. A
> > > +filtergraph is represented by a list of ";"-separated filterchain
> > > +descriptions.
> > 
> > What is a sequence of filterchains
> 
> What is a sequence of pigs?

a ordered n-tuple of pig elements
but applied to a filterchain this says nothing its just a space filler
sequence is too generic without further explanation


> 
> Rephrased:
> 
> |A filternode is a filter instance which is a node of a filter graph.

uhm, we are back to square one.
we do not have 3 different kinds of filters in this text so the use of
3 different terms to refer to a filter instance is just confusing


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

Many that live deserve death. And some that die deserve life. Can you give
it to them? Then do not be too eager to deal out death in judgement. For
even the very wise cannot see all ends. -- Gandalf
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