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doc/filters: some more details and modified example to zmq/azmq

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Info about default value of bind_address option and its abbreviated
version (b). Example modified to have named instanced filter and to show
its use.

Signed-off-by: Bela Bodecs <bodecsb@vivanet.hu>
Signed-off-by: Lou Logan <lou@lrcd.com>
This commit is contained in:
Bela Bodecs 2018-04-03 16:18:02 +02:00 committed by Lou Logan
parent 233f52fd25
commit e54679b6c1
1 changed files with 22 additions and 6 deletions
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doc/filters.texi
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@ -221,6 +221,7 @@ Here is a BNF description of the filtergraph syntax:
@var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
@end example
@anchor{filtergraph escaping}
@section Notes on filtergraph escaping
Filtergraph description composition entails several levels of
@ -20270,7 +20271,7 @@ filters in the filtergraph.
@code{zmq} and @code{azmq} work as a pass-through filters. @code{zmq}
must be inserted between two video filters, @code{azmq} between two
audio filters.
audio filters. Both are capable to send messages to any filter type.
To enable these filters you need to install the libzmq library and
headers and configure FFmpeg with @code{--enable-libzmq}.
@ -20280,7 +20281,10 @@ For more information about libzmq see:
The @code{zmq} and @code{azmq} filters work as a libzmq server, which
receives messages sent through a network interface defined by the
@option{bind_address} option.
@option{bind_address} (or the abbreviation "@option{b}") option.
Default value of this option is @file{tcp://localhost:5555}. You may
want to alter this value to your needs, but do not forget to escape any
':' signs (see @ref{filtergraph escaping}).
The received message must be in the form:
@example
@ -20288,7 +20292,10 @@ The received message must be in the form:
@end example
@var{TARGET} specifies the target of the command, usually the name of
the filter class or a specific filter instance name.
the filter class or a specific filter instance name. The default
filter instance name uses the pattern @samp{Parsed_<filter_name>_<index>},
but you can override this by using the @samp{filter_name@@id} syntax
(see @ref{Filtergraph syntax}).
@var{COMMAND} specifies the name of the command for the target filter.
@ -20310,14 +20317,17 @@ will send a reply to the client, adopting the format:
Look at @file{tools/zmqsend} for an example of a zmq client which can
be used to send commands processed by these filters.
Consider the following filtergraph generated by @command{ffplay}
Consider the following filtergraph generated by @command{ffplay}.
In this example the last overlay filter has an instance name. All other
filters will have default instance names.
@example
ffplay -dumpgraph 1 -f lavfi "
color=s=100x100:c=red [l];
color=s=100x100:c=blue [r];
nullsrc=s=200x100, zmq [bg];
[bg][l] overlay [bg+l];
[bg+l][r] overlay=x=100 "
[bg][l] overlay [bg+l];
[bg+l][r] overlay@@my=x=100 "
@end example
To change the color of the left side of the video, the following
@ -20331,6 +20341,12 @@ To change the right side:
echo Parsed_color_1 c pink | tools/zmqsend
@end example
To change the position of the right side:
@example
echo overlay@@my x 150 | tools/zmqsend
@end example
@c man end MULTIMEDIA FILTERS
@chapter Multimedia Sources