Difference between revisions of "Documentation:Modules/dummy"

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(→‎Interface: Explain how a dummy interface might be useful)
 
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{{Module|name=dummy|type=Stream output|description=dummy stream output}}
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[[Dummy]] modules are the VLC equivalent of <code>/dev/null</code> on GNU/Linux: they represent doing nothing.
  
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== List ==
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<!-- Editors: category wikicode must be entered manually. -->
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{| class="wikitable sortable cellpadding-3px"
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|+ Overview of dummy modules
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! scope="col" | Type !! scope="col" | Description !! scope="col" | Shortcut(s)
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|-
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| Access [[Category:Accesses]] || Dummy input || dummy, vlc
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|-
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| Access output [[Category:Access output]] || Dummy stream output || dummy
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|-
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| Audio output [[Category:Audio output]] || Dummy audio output || dummy
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|-
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| Decoder [[Category:Codecs]] || Dummy decoder || dummy, dump
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|-
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| Encoder || Dummy encoder || dummy
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|-
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| Control interface [[Category:Interfaces]] [[Category:Control VLC]] || Dummy interface || (none)
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|-
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| Muxer [[Category:Muxers]] || Dummy/[[Raw]] muxer || dummy, raw, es
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|-
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| Stream output [[Category:Stream output]] || Dummy stream output || dummy, drop
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|-
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| Text renderer || Dummy font renderer || (none)
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|-
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| Video output [[Category:Video output]] || Dummy video output || dummy, stats
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|-
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| Video output (legacy video plugins) [[Category:Video output]] || Dummy window || dummy
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|}
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== Descriptions ==
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=== Interface ===
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A dummy interface works well with [[command-line]] usage. It consumes fewer computing resources, something that can be used to reduce a bottleneck effect during [[transcoding]], or simply when opening a window makes little sense.
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This will play an [[Ogg]] file with no interface:
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{{$}} vlc -I dummy audio.ogg vlc://quit
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No window is launched, and control is returned to the calling application after the file plays.
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This will play a [[Schroedinger]] file with a minimalist interface:
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{{$}} vlc -I dummy video.drc vlc://quit
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A window with no buttons or toolbars is launched (no [[skin]]), because [[video output]] requires a window. [[Hotkey]]s may be used to control playback by default, something that can be disabled if necessary with <code>--no-keyboard-events</code>.
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=== Stream output ===
 
Doesn't do anything. Can be used to test other stream output chain modules without actually streaming anything.
 
Doesn't do anything. Can be used to test other stream output chain modules without actually streaming anything.
  
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{{Stub}}
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== Options ==
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=== Dummy decoder ===
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{{Option
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|name=dummy-save-es
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|value=boolean
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|default=disabled
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|description=Save the raw [[codec]] data if you have selected/forced the dummy decoder in the main options.
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}}
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=== Video output ===
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{{Option
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|name=dummy-chroma
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|value=string
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|default=NULL
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|description=Force the dummy video output to create images using a specific [[chroma]] format instead of trying to improve performances by using the most efficient one.
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}}
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== Source code ==
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* {{VLCSourceFile|modules/access/idummy.c|Access}}
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* {{VLCSourceFile|modules/access_output/dummy.c|Access output}}
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* {{VLCSourceFile|modules/audio_output/adummy.c|Audio output}}
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* {{VLCSourceFile|modules/codec/ddummy.c|Decoder}}
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* {{VLCSourceFile|modules/codec/edummy.c|Encoder}}
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* {{VLCSourceFile|modules/control/dummy.c|Interface}}
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* {{VLCSourceFile|modules/mux/dummy.c|Output muxer}}
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* {{VLCSourceFile|modules/stream_out/dummy.c|Stream output}}
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* {{VLCSourceFile|modules/text_renderer/tdummy.c|Text rendering}}
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* {{VLCSourceFile|modules/video_output/vdummy.c|Video output}}
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* {{VLCSourceFile|modules/video_output/wdummy.c|Video output for legacy video plugins}}
  
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{{Documentation footer}}
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{{Documentation}}

Latest revision as of 20:08, 29 May 2019

Dummy modules are the VLC equivalent of /dev/null on GNU/Linux: they represent doing nothing.

List

Overview of dummy modules
Type Description Shortcut(s)
Access Dummy input dummy, vlc
Access output Dummy stream output dummy
Audio output Dummy audio output dummy
Decoder Dummy decoder dummy, dump
Encoder Dummy encoder dummy
Control interface Dummy interface (none)
Muxer Dummy/Raw muxer dummy, raw, es
Stream output Dummy stream output dummy, drop
Text renderer Dummy font renderer (none)
Video output Dummy video output dummy, stats
Video output (legacy video plugins) Dummy window dummy

Descriptions

Interface

A dummy interface works well with command-line usage. It consumes fewer computing resources, something that can be used to reduce a bottleneck effect during transcoding, or simply when opening a window makes little sense.

This will play an Ogg file with no interface: 

$ vlc -I dummy audio.ogg vlc://quit

No window is launched, and control is returned to the calling application after the file plays.

This will play a Schroedinger file with a minimalist interface: 

$ vlc -I dummy video.drc vlc://quit

A window with no buttons or toolbars is launched (no skin), because video output requires a window. Hotkeys may be used to control playback by default, something that can be disabled if necessary with --no-keyboard-events.

Stream output

Doesn't do anything. Can be used to test other stream output chain modules without actually streaming anything.

Options

Dummy decoder

  • dummy-save-es <boolean> : Save the raw codec data if you have selected/forced the dummy decoder in the main options. default value: disabled

Video output

  • dummy-chroma <string> : Force the dummy video output to create images using a specific chroma format instead of trying to improve performances by using the most efficient one. default value: NULL

Source code

This page is part of official VLC media player Documentation (User Guide • Streaming HowTo • Hacker Guide • Modules)
Please read the Documentation Editing Guidelines before you edit the documentation
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
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