AV::Streamer

Module to make transcoding, saving and broadcasting AV streams simple.

Documentation, usage and examples are in perldoc. To view: perldoc lib/AV/Streamer.pm

See lib/AV/Streamer/App/Stream.pm for a sample command-line application similar to ffmpeg.

INSTALLATION

This module requires libav development libraries, >= 0.7 (available from http://libav.org/download.html)

Debian: aptitude install libavformat-dev libavcodec-dev pkg-config

To install this module type the following:

perl Makefile.PL make make test make install

OVERVIEW

This module is an attempt to encapsulate high-level media streaming operations in a perl module. It does this by wrapping libav in an XS interface which is utilized by various sub-modules. (libav was formally the FFmpeg project, but forked off due to developer drama).

To understand how this module is put together, you must be familiar with how media files are structured and how libav reflects this.

A media file or media stream is generally encapsulated in a transport format which can contain any number of video, audio or subtitle streams. For a concrete example think of a DVD (containing a MPEG TS), which lets you select different audio or subtitles for the same video stream. Common transport or container formats are MOV, AVI, WebM/Matroska, FLV, MPEG TS (transport stream), OGG. These transports are handled by libavformat which understands how to mux and demux streams inside a given container. A container open for reading or writing with associated parameters is represented by an AVFormatContext.

Each stream inside a container contains video or audio data which is encoded and decoded by a codec. Common codecs are MPEG1 video, MPEG2 (DVD video), MPEG3 audio (aka MP3), MPEG4 and h264, WMV, AAC, FLV, Vorbis, Theora. libavcodec contains a vast and impressive number of codecs, and a coder or decoder instance is represented by an AVCodecContext which is an AVCodec reference plus encoding/decoding parameters.

If you were to read in an AVI file and decode it for playback with libavformat and libavcodec, you would first create an AVFormatContext for reading AVI files. Once the file is opened and loaded, you would be able to access the audio and video streams contained therein. You would locate the appropriate AVCodecs for decoding the stream data and get AVCodecContexts for each stream.

This module attempts to simplify this process. See AV::Streamer POD docs for details on usage.

ACKNOWLEDGEMENTS

This library makes use of code copied from Max Vohra's Video::FFmpeg module and Martin Boehm's avcodec sample application. Absolutely no help at all was given by anyone from the FFmpeg and libav teams who like to pretend I don't exist.

COPYRIGHT AND LICENCE

Copyright (C) 2011 by Mischa Spiegelmock

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.10.0 or, at your option, any later version of Perl 5 you may have available.