The Streamer itself does nothing by its own. The real work of processing the media stream is performed by a pipeline of elements linked together in a tree structure with the source element as root and sink elements as leaves. Each element is processed in turn throughout the tree structure.
The Streamer constructs the pipeline depending on the contents of the media stream. This means that a stream of MP3 music triggers the contruction of a different pipeline compared to the pipeline set up to handle a MPEG2 transport stream containing video and audio. To facilitate this mechanism the properties of each element is described by an element descriptor. When an element opens a new output pad it declares the format of the data to be sent on that pad. The Streamer searches all element descriptors for possible candidates to be inserted in the pipeline and be connected to that output pad. It picks elements in a naïve fashion, trying to pick sinks or elements that change format of the stream and inserting elements with certain traits or producing certain metadata in between.
The pipeline always begins with one source element. The source element cannot be selected from the stream format, because there's no stream to examine before it has been received from the network. Instead the source element is selected based on network protocol, which is derived from the URL used for opening the stream.
The purpose of this Streamer Element Reference is to describe the properties of the KreaTV elements.
All elements are bundled in loadable modules that may contain any number of elements. The Streamer loads all modules on startup.
In general, a source element should be distributed as an individual loadable module to facilitate easy system configuration.
RTSP
The RTSP Source Element handles
media streams stored on servers supporting the Real-Time Streaming
Protocol (RFC 2326).
More...
HTTP
The HTTP Source Element handles
media streams stored on regular web servers using the Hypertext
Transport Protocol HTTP/1.1 (RFC 2616). More...
Basic
This module contains source
elements reading streams from a file or from a multicast socket. The
Multicast Source Element receives media streams from the network by
joining multicast groups in accordance to Internet Group Management
Protocol (IGMP) version 2 or 3 (RFC 2236). More...
Bitband
The Bitband Source Element
handles media streams stored on Biband Vision 3 servers. More...
Format discovery is a very important step in the pipeline. It analyzes the raw stream produced by the source element and tries to determine the format of the data stream.
Framing
The Framing Element recognizes
ISO/IEC 13818-1 Transport Streams and Program Streams, and ISO/IEC
11172-1 System Streams and Packet Layer streams (like MP3). More...
KreaTV provides no CA modules at the moment.
Depending on the stream format, the pipeline constructed by the Streamer may differ greatly. The type of information carried in these streams also affects which elements are insterted in the pipeline.
Transport Stream
Elements handling
ISO/IEC 13818-1 Transport Streams. More...
Program Stream and System Stream
Elements handling ISO/IEC 13818-1 Program Streams and ISO/IEC
11172-1 System Streams. More...
Audio Elementary Stream
Elements
handling ISO/IEC 11172-3 audio frame streams, also referred to as
Elementary Streams in ISO/IEC 13818-1 context. Streams in
the MP3 format is a subset of the streams supported by
these elements. More...
Video PES Stream
Elements handling
ISO/IEC 13818-1 PES video streams. More...
ASF Stream
Elements handling Microsoft
Advanced Systems Format (ASF) streams. More...
Generic
This module contains a
terminator element which is used when there is branch of the
pipeline that simply needs to be terminated by releasing all stream
data of any format sent through that branch. More...
HAI Decoder
The audio and video
selected for decoding must be sent to the audio and video decoders
provided by the Hardware Abstraction Layer (HAL) through the
Hardware Abstraction Interface (HAI). More...
Teletext Subtitles
The teletext
subtitles element decodes specific pages in an
ETSI EN 300 706 teletext stream and renders them on
the video overlay. More...
DVB Subtitles
The DVB subtitles element
decodes ETSI EN 300 734 encoded subtitles bitmaps and
renders them on the video overlay. More...
Teletext VBI
The teletext VBI element
extracts teletext data and sends it to the TV. More...
MP3 Decoder
When playing a MP3 stream
this element decodes the MP3 data to an audio format accepted by the
audio decoder provided by the Hardware Abstraction Layer. More...
Some complex metadata types are described in the Complex Metadata section.