Difference between revisions of "Old Python bindings"

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= Python binding documentation =
+
{{Historical|Use [[Python bindings]]}}
 +
== Python binding documentation ==
 +
'''NOTE: this version of python bindings (compiled C-module) is deprecated in favor of the new [[PythonBinding]].'''
  
−
For a while, there has been a basic python binding for libvlc, that was used for streaming. A more complete (with a hopefully generic API that can be reused by other players) has been developped, based on the [[MediaControlAPI]].
+
The old version of python bindings, which can be found in <code>bindings/python</code>, is a python C-based module. Sources are browsable from [http://trac.videolan.org/vlc/browser/bindings/python python binding] and a code sample can be found in the sources (file [http://trac.videolan.org/vlc/browser/bindings/python/vlcwidget.py vlcwidget.py]).
  
−
Sources are browsable from [http://trac.videolan.org/vlc/browser/trunk/bindings/python python binding] and a code sample can be found in [http://liris.cnrs.fr/advene/download/].
+
It has been compiled, and is being used, on Linux, Windows and Mac OS X.
  
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= Basics =
+
== Compile HOWTO ==
  
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The vlc python module provides 2 main classes : MediaControl and Object.
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Only for < 0.9.0 versions: If you want to include the python bindings in your build, you must pass --enable-python-bindings (svn version) or --enable-mediacontrol-python-bindings (0.8.6* versions) to ./configure as it is disabled by default.
  
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'''vlc.Object''' provides a binding to the vlc object architecture. It allows to manipulate variables and configuration options, and explore the object hierrarchy. The vlcdebug.py script, located in the python bindings directory, wraps around the vlc.Object to provide an easier access to variables and objects (as illustrated in the code sample in [http://liris.cnrs.fr/advene/download/]).
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For >= 0.9.0 versions, python bindings cannot be compiled at the same time as the main VLC tree. They can (and event must) be compiled from a compiled VLC, provided that appropriate headers and libraries (libvlc.so/.dll) are available.
  
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'''vlc.MediaControl''' implements the [[MediaControlAPI]].
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=== Linux/Debian ===
  
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Methods taking positions as parameters expect a '''vlc.Position''' object, that provides a very flexible way to address absolute or relative positions, in a number of units (milliseconds, frames or bytes). For convenience, the python binding automatically converts integer positions into milliseconds '''vlc.Position''' objects.
+
On Debian:
 +
* install the libvlc2-dev package
 +
* Get the python bindings sources from the Git repository :
 +
* in the python directory, launch
 +
  python setup.py build
 +
The module will be built in  
 +
build/lib.linux-i686-2.5
 +
* install the module through (as root)
 +
  python setup.py install
 +
or simply copy the vlc.so file to some appropriate directory.
  
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= Tips and tricks =
+
=== Windows ===
  
−
== Snapshot support ==
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* Get and install a nighty-built package from http://nightlies.videolan.org/build/windows/
 +
* Get and extract the corresponding sources from http://nightlies.videolan.org/build/source/
 +
* Create a .libs subdirectory in vlc/src
 +
* Copy the libvlc.dll file from c:\Program Files\VideoLAN\VLC into src/.libs
 +
* Go into the vlc/bindings/python directory and run
 +
  python setup.py build --compiler=mingw32
 +
You should get a vlc.pyd (or vlc.dll) file in the build/ subdirectory.
  
−
In order to get snapshot support, you have to activate the snapshot vout module through a clone video filter.  The following code gives a way to achieve this :
+
== Basics ==
  
−
  mc=vlc.MediaControl([ "--vout-filter", "clone" ])
+
The vlc python module provides 4 main classes : MediaControl, Instance, MediaPlayer and Media.
−
  o=VLC.Object(0)
 
−
  o.config_set("clone-vout-list", "default,snapshot")
 
−
  o.config_set("snapshot-width", 320)
 
−
  o.config_set("snapshot-height", 200)
 
  
−
Note that all config options could have been given on the command line, but this illustrates the use of the vlc.Object API.
+
'''vlc.MediaControl''' implements the [[MediaControlAPI]]. Methods taking positions as parameters expect a '''vlc.Position''' object, that provides a very flexible way to address absolute or relative positions, in a number of units (milliseconds, frames or bytes). For convenience, the python binding automatically converts integer positions into milliseconds '''vlc.Position''' objects.
  
−
There is a snapshot functionality built in the vlc core, associated to a hotkey. The MediaControlAPI could (should ?) use it, but
+
'''vlc.Instance''', '''vlc.MediaPlayer''' and '''vlc.Media''' match the new [[LibVLC]] API. Refer (for now) to the docstrings provided by the python objects to get their usage.
  
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* it did not exist at the time the extension was developped
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== Tips and tricks ==
−
* the builtin snapshot functionality is oriented towards interactive use (hotkey activation, saving into a file) and should be revamped to take into accound a more programmatic use
 
−
* the snapshot vout module holds a cache of reduced-size snapshots, that allow to take into account the reaction time of the user (around 200ms) and also to select the more appropriate snapshot from the cache.
 
  
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== Win32 initialization ==
+
=== Building notes ===
  
−
If the vlc module was not compiled with the exact same prefix as the VLC installation (e.g. c:\\Program Files\\Videolan), then it cannot find itself the installation directory (stored in the registry Software\VideoLAN\VLC\Path), and the MediaControl instanciation will fail with a message like "Cannot find interface plugins".  
+
* on 0.8.6(a), the --enable-mediacontrol-python-bindings option is not compatible with --enable-libtool. If you need libtool support, please use the svn version.
  
−
The workaround consists in changing directory to the VLC installation directory before instanciating the MediaControl object.
+
=== Python specificities ===
  
 +
The python bindings provide a binding for the [[MediaControlAPI]], with some variations :
 +
 +
* the methods taking a ''vlc.Position'' parameter also accept an integer, which will then be converted to a relative position in milliseconds (vlc.MediaTime)
 +
* the start, stop, pause and resume method position parameter is optional. If omitted, it will default to a 0-relative position.
 +
* RGBPicture (returned by snapshot) and StreamInformation (returned by get_stream_information) are not objects with attributes, but instead dictionaries.
 +
 +
=== Snapshot support ===
 +
 +
In the current svn revision, we use the core snapshot functionality of vlc, which is simpler to setup (no additional module, see below) and directly returns PNG, but less precise.
 +
 +
Prior to revision 13881, in order to get snapshot support, you had to activate the snapshot vout module through a clone video filter.  The following code gives a way to achieve this :
 +
 +
  mc=vlc.MediaControl("--vout-filter clone --clone-vout-list default,snapshot --snapshot-width 320 --snapshot-height 200".split())
 +
 +
Advantages of the old (filter-based) approach:
 +
* the snapshot vout module holds a cache of reduced-size snapshots, that allow to take into account the reaction time of the user (around 200ms) and also to precisely select the more appropriate snapshot from the cache.
 +
 +
=== Win32 initialization ===
 +
 +
If the vlc module was not compiled with the exact same prefix as the VLC installation (e.g. c:\\Program Files\\Videolan), then it cannot find itself the installation directory (stored in the registry Software\VideoLAN\VLC\InstallDir), and the MediaControl instanciation will fail with a message like "Cannot find interface plugins".
 +
 +
The workaround consists in changing directory to the VLC installation directory before instanciating the MediaControl object, since VLC will look for its plugins in the current directory.  Another way is to pass the correct --plugin-path option.
 +
<syntaxhighlight lang="python">
 
     def get_registry_value (self, subkey, name):
 
     def get_registry_value (self, subkey, name):
 
         import _winreg
 
         import _winreg
Line 59: Line 93:
 
         os.chdir(vlcpath)
 
         os.chdir(vlcpath)
 
         mc=vlc.MediaControl()
 
         mc=vlc.MediaControl()
 +
</syntaxhighlight>
 +
 +
== Source code ==
 +
Formerly located at bindings/python/
 +
 +
[[Category:Bindings]]

Latest revision as of 05:48, 29 March 2019

This page is obsolete and kept only for historical interest. It may document features that are obsolete, superseded, or irrelevant. Do not rely on the information here being up-to-date.
Additional information: Use Python bindings

Python binding documentation

NOTE: this version of python bindings (compiled C-module) is deprecated in favor of the new PythonBinding.

The old version of python bindings, which can be found in bindings/python, is a python C-based module. Sources are browsable from python binding and a code sample can be found in the sources (file vlcwidget.py).

It has been compiled, and is being used, on Linux, Windows and Mac OS X.

Compile HOWTO

Only for < 0.9.0 versions: If you want to include the python bindings in your build, you must pass --enable-python-bindings (svn version) or --enable-mediacontrol-python-bindings (0.8.6* versions) to ./configure as it is disabled by default.

For >= 0.9.0 versions, python bindings cannot be compiled at the same time as the main VLC tree. They can (and event must) be compiled from a compiled VLC, provided that appropriate headers and libraries (libvlc.so/.dll) are available.

Linux/Debian

On Debian:

  • install the libvlc2-dev package
  • Get the python bindings sources from the Git repository :
  • in the python directory, launch
 python setup.py build

The module will be built in build/lib.linux-i686-2.5

  • install the module through (as root)
 python setup.py install

or simply copy the vlc.so file to some appropriate directory.

Windows

 python setup.py build --compiler=mingw32

You should get a vlc.pyd (or vlc.dll) file in the build/ subdirectory.

Basics

The vlc python module provides 4 main classes : MediaControl, Instance, MediaPlayer and Media.

vlc.MediaControl implements the MediaControlAPI. Methods taking positions as parameters expect a vlc.Position object, that provides a very flexible way to address absolute or relative positions, in a number of units (milliseconds, frames or bytes). For convenience, the python binding automatically converts integer positions into milliseconds vlc.Position objects.

vlc.Instance, vlc.MediaPlayer and vlc.Media match the new LibVLC API. Refer (for now) to the docstrings provided by the python objects to get their usage.

Tips and tricks

Building notes

  • on 0.8.6(a), the --enable-mediacontrol-python-bindings option is not compatible with --enable-libtool. If you need libtool support, please use the svn version.

Python specificities

The python bindings provide a binding for the MediaControlAPI, with some variations :

  • the methods taking a vlc.Position parameter also accept an integer, which will then be converted to a relative position in milliseconds (vlc.MediaTime)
  • the start, stop, pause and resume method position parameter is optional. If omitted, it will default to a 0-relative position.
  • RGBPicture (returned by snapshot) and StreamInformation (returned by get_stream_information) are not objects with attributes, but instead dictionaries.

Snapshot support

In the current svn revision, we use the core snapshot functionality of vlc, which is simpler to setup (no additional module, see below) and directly returns PNG, but less precise.

Prior to revision 13881, in order to get snapshot support, you had to activate the snapshot vout module through a clone video filter. The following code gives a way to achieve this : 

 mc=vlc.MediaControl("--vout-filter clone --clone-vout-list default,snapshot --snapshot-width 320 --snapshot-height 200".split())

Advantages of the old (filter-based) approach:

  • the snapshot vout module holds a cache of reduced-size snapshots, that allow to take into account the reaction time of the user (around 200ms) and also to precisely select the more appropriate snapshot from the cache.

Win32 initialization

If the vlc module was not compiled with the exact same prefix as the VLC installation (e.g. c:\\Program Files\\Videolan), then it cannot find itself the installation directory (stored in the registry Software\VideoLAN\VLC\InstallDir), and the MediaControl instanciation will fail with a message like "Cannot find interface plugins".

The workaround consists in changing directory to the VLC installation directory before instanciating the MediaControl object, since VLC will look for its plugins in the current directory. Another way is to pass the correct --plugin-path option. 

    def get_registry_value (self, subkey, name):
        import _winreg
        value = None
        for hkey in _winreg.HKEY_LOCAL_MACHINE, _winreg.HKEY_CURRENT_USER:
            try:
                reg = _winreg.OpenKey(hkey, subkey)
                value, type_id = _winreg.QueryValueEx(reg, name)
                _winreg.CloseKey(reg)
            except _winreg.error:
                pass
        return value
    
    vlcpath=get_registry_value('Software\\VideoLAN\\VLC','InstallDir')
    if vlcpath is None:
        print "Cannot locate VLC installation directory"
    else:
        os.chdir(vlcpath)
        mc=vlc.MediaControl()

Source code

Formerly located at bindings/python/

Retrieved from "https://wiki.videolan.org/index.php?title=Old_Python_bindings&oldid=60388"