Matrix Elements VB-800 Manual do Utilizador descarregar pdf (Página 23)

Chapter 3. Advanced streaming using the command

line

Structure of stream output

Stream output is the name of the feature of VLC that allows to output any stream read by VLC to a ﬁle or as a network

stream instead of displaying it. Different kind of processing can be applied to the stream during this process (transcoding,

re-scaling, ﬁlters, re-muxing...) Stream output includes different modules, each of them having different capabilities. You

can chain modules to enhance the possibilities.

Here is the list of the modules currently available:

• standard allows to send the stream via an access output module: for example, UDP, ﬁle, HTTP, ... You will probably

want to use this module at the end of your chains.

• transcode is used to transcode (decode and re-encode the stream using a different codec and/or bitrate) the audio and the

video of the input stream. If the input or output access method doesn’t allow pace control (network, capture devices),

this done "on the ﬂy", in real time. This can require quite a lot of CPU power, depending on the parameters set. Other

streams, such as ﬁles and disks are transcoded as fast as the system allows it.

• duplicate allows you to create a second chain, where the stream will be handled in an independent way.

• display allows you to display the input stream, as VLC would normally do. Used with the duplicate module, this allows

you to monitor the stream while processing it.

• rtp streams over RTP (one UDP port for each elementary stream). This module also allows RTSP support.

• es allows you to make separate Elementary Streams (ES) out of an input stream. This can be used to save audio and

video streams to separate ﬁles, for instance.

Each of these modules may take options. Here is the syntax that you must use:

% vlc input_stream --sout "#module1{option1=parameter1{parameter-option1},option2=parameter2}:module2{option1=...,option2=...}:..."

Note: Some of the module options (option1 in the example) have to be set, others are optional. Option parameters

(parameter-option1 in the example) are always optional. These option parameters are also often very advanced

settings. If you don’t understand their description, this certainly means that you don’t need them.

You may also use the following syntax :

% vlc input_stream --sout-module1-option1=... --sout-module1-option2=... --sout-module2-option1=... --sout-module2-option2=... ...

For example, to transcode a stream and send it, use:

% vlc input_stream --sout ’#transcode{options}:standard{options}’

Description of the modules

standard (alias std)

This module saves the stream to a ﬁle or sends it over a network, after having muxed it.

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Matrix Elements VB-800 Manual do Utilizador Página 23