Streaming Media

Streaming media refers to the simultaneous transmission and reproduction of video and audio data over a network. To perform the data transfer itself is called streaming, and transmitted ( " streamed " ) programs are known as live stream or short stream. Streaming media, which was initiated via the WWW and HTML, also web radio or web TV is called. Contrary to download the target when streaming is not to create a copy of the media with the user, but the media is to be output directly, then the data is discarded.

In Live Stream is not broadcasting. While in broadcasting, a transmitter can be received by a plurality of receivers, streaming for each user is realized separately at its request as a point-to -point connection between the media server of the sender and the user's computer, which contradicts the idea of broadcasting (see also section problems ), since, according to the Broadcasting Act must be a release to the general public.

History

Streaming media has been around since the mid-20th century. During the first decades of little progress has been made ​​since the technology expensive and the capacity of computer hardware were limited.

In the late 1980s, the PCs were powerful enough to display various media. The primary requirements to receive streams, were a strong CPU and a sufficient BUS (network) bandwidth for the required data rates.

In the late 1990s, larger data rates were available, including access to the Internet has been made easier. In addition, there were standard protocols and formats, such as the Internet Protocol Suite and HTML. The Internet was commercialized. These advances in computer networking combined with powerful computers and modern operating systems, streaming media made ​​possible for ordinary users. For the first time stood on-demand services like YouTube or " media libraries " of individual television stations available to a wide audience, it established itself Live streaming (Internet radio and television ), and a v. originated in the corporate sector with video conferencing and video telephony for other applications.

There are now more and more offers and new streaming protocols such as the Microsoft Media Server Protocol ( MMS) and the Real Time Streaming Protocol (RTSP ), as well as picture and sound quality have been improved.

Software

To use streaming media services, special software is required on the receiver side. This can be a plug- in that is integrated into a web browser, but also a stand-alone playback program. The former is called automatically when a requested page streaming media data contains. These plug-ins and playback programs (English players ) are usually offered for free, in contrast to the streaming servers that send the data.

There exists a variety of different streaming media competing techniques. The best known are:

Audio and video container formats:

• Flash Video Streaming
• MP3
• MP4
• Nullsoft Streaming Video
• Ogg ( Vorbis, Theora )
• QuickTime
• Real Media
• Windows Media
• FLAC

Streaming software and servers:

• Catra Streaming Platform
• Darwin Streaming Server / QuickTime Streaming Server
• Ffserver
• Helix Server
• Icecast ( open source, audio only)
• Icecast2 ( Free Software )
• Jinzora broadcast server software (free software )
• LSCube / Feng (free software ), RTSP - capable, master even newer free audio and video formats
• MediaTomb (Open Source), UPnP enabled, streaming server for the home network (PC and standalone devices ) Supports real-time encoding
• No23Live ( freeware, audio only)
• Peer Stream Broadcast Server
• PS3 Media Server Special software for streaming videos, music and photos from a Windows PC to a PlayStation 3 in many different formats
• Shoutcast
• VideoLAN Server (free software )
• Wirecast

Data transfer rate

Typical data transfer rates of the output data are:

Typical available data rates are:

Since the reproduction of the data to be held simultaneously with the receipt, must have sufficient data transfer rate available. It is necessary that the data transfer rate, which stands for the transmission is available is greater than the data transmission rate used for streaming. The to send audio and video data must therefore be compressed before transmission. In most cases this is lossy, because the only way a manageable amount of data per unit of time can be achieved.

To compensate for different durations of the data packets in the network and thereby prevent related stoppages, in media player, a buffer will be used. Therefore, the playback is also slightly delayed, typically around 2-6 seconds. There is not enough of this buffer, it is dynamically increased by some media players.

Since video data generally have a higher data rate than the audio data, in this case also a substantially greater compression is required. This is with respect to the algorithms used, and more sophisticated with respect to the required computational power consuming.

With the same type of compression while the quality decreases with the data transfer rate to which the data stream is to be reduced. Therefore, the visible and audible quality of a stream depends essentially on the following factors:

• The type and quality of the starting material
• The compression method used
• Exploited for transmission Data transfer rate which is usually limited by the internet connection.

Species

" On- demand streaming "

• Data are transmitted by the server over the network to the client.
• Playback is already in transit.
• Buffering for gapless playback is needed.
• Pre- Pausing and rewinding is possible.
• Protocols: HTTP, FTP

" Live Streaming "

• Provision of the offer in real time
• Protocols: RTP, RTCP, RTSP, SIP
• Special Form: phonecast (dissemination via telephone server )

Streaming Media in Education

In recent years, increasingly implemented by systems for recording lectures in Europe. In Delft, for example, all lectures are recorded to make them available to students at home available. Especially since the student protests of 2009, many universities started to develop their own systems, or set up systems that already exist (Sonic Foundry, Camtasia, Lecture2Go, and others).

These two types are distinguished from records:

• Recording hardware (Sonic Foundry ): There is a hardware streamer, be connected and recorded over the sources. This possibility is simple but costly.

• Software solutions ( Camtasia, Lecturnity, and others): A software is installed on the presentation computer and then recorded the presentation. This option is inexpensive, however, post-processing is necessary.

Problems

While traditional broadcasting services ( radio, television, etc.) seek the widest possible range at the lowest possible cost of energy and other resources, streaming media deals with a growing number of participants will be more expensive, because the data must be sent individually to each recipient. In the network technology of multicast mode, although it is known in which an outgoing from the streaming server data stream at a lower network load can be sent simultaneously to several recipients, but that it is up to now not used in practice because not support him many routers on the Internet. So-called overlay networks can be used instead of streaming services with a mass audience (about transfers of the Bundesliga football or pop concerts ), which considers the network-wise data to be transmitted in many places at the same time provide.

Since " streaming media " have particular strengths in the real-time transmission and this transmission is not designed in any case, just as for permanent storage, the quality can often be rather low to ensure a liquid transfer case with the current data transfer rates. From this perspective, the use of streaming technology with content where it does not depend on real-time transmission appears (eg in trailers ) rather questionable.

Various content providers use the streaming technology also with the aim to make it difficult even tech savvy end users to store the received data permanently. This is namely, if the stream is not transmitted via HTTP, only with special software (such as MPlayer ) is possible and can be complicated by other measures. Thus, the stream must be constantly reloaded, which in turn causes unnecessary data transfer on the server side and the user.

Legal issues

When streaming, the data is first not permanently stored on the device of the end user, this means no copy is made, such as the download. Only in this way it is possible to look at the endpoint streamed media, not supporting downloads arbitrary files, such as some smartphone or tablet. Since this can be circumvented in special cases with the help of additional software by the user, try provider partly to impede or prevent this storing data. Whether it is actually constitutes an abuse of streaming technology is debatable if the data consist of about GEMA repertoire, the provider is this even required. From the perspective of the author, the streaming can be seen as a means to present his works and still technically keep the ability to control the recovery and make money from the use of his works.

Still, it is hard to check that as the use of a spread on the internet music channel takes place only in the country in which the operator has bought the rights. The resulting legal problems have not even been discussed to some extent, and there is certainly no experience in the form of judgments or laws.

In December 2005, the GEMA had for Web TV ( streaming TV ) yet no compensation plan. Provisionally, therefore, a fee of 30 euros per month was charged.

Meanwhile, the GEMA has adopted a compensation model for " Web - TV provider ," which provides a staggering according to the music share. As described in the form, web TV is from the perspective of GEMA, the transmission of moving images in a compiled by the operator sequence to which the user has no control. This fall, almost all Web TV channels from the area covered by this Agreement, as an archive to retrieve the "Videos on Demand" maneuvered the station already from the GEMA - definition.