Speaker


         Sound
Audio, Sound and music are the most important elements of Multimedia. There are various audio formats which can be used not only offline but also online, for example Wave, Aiff, Midi and so on.

One of the most important and in the last couple of years most famous formats is MP3 ( MPEG 1 Layer 3 - developed by Fraunhofer Institut in Erlangen/Germany ). By using MP3, it is possible to transfer musik files almost in CD quality in a small size through the internet ( of course it depends on the compress rate ). This is also the main reason that has made this format so popular. However, it has a disadvantage too, at least from the view of the music industry, because MP3 format offers no copyright protection.


The future of MP3

The successor will be probably the AAC format. It is a part of the MPEG II standard and a co-development of Fraunhofer Institut, U.S. firm AT&T, Sony and the Dolby company. AAC also supports some effects like Surround Sound and could offer an even better sound quality than MP3 with the same compress rate. At the present, it is used at broadcasting companies and by digital satelite transfer.


Alternatives

Beside MP3 there are other interesting digital audio formats like VQF (developed by Nippon Telegraph & Telephon Corp.) and WMA from Microsoft. An encoded VQF file with 96 Kbit/s is about one third smaller than a MP3 file and should reach the same sound quality as a MP3 file with 128 Kbit/s compressing rate. But the WMA is supposed to be better than VQF. An audio file in this format has only the half of the size of an encoded 128 Kbit/s MP3 file. WMA files with 64Kbit/s encoding can reach approximate CD quality.


Other techniques

In case of live broadcasting other formats and techniques can be applied. In addition to MP3, which has a "Headerless File" format and is streaming capable as well, there are other streaming formats like Real Networks Streaming Audio. Streaming Audio offers the big advantage that sound can be already played during the download and must not be completely saved before.


PodcastingPodcasting
The word Podcasting is a combination of the well known MP3 Player iPod from Apple, and the word broadcasting. It is about providing and publishing of Audio & Video material to the Internet or downloading from the Internet.

First sound or audio data are recorded as audio files, then they should be converted to an appropriate format like MP3, WMA or others and after that they will be uploaded to a Podcasting server. Based on RSS-Feed these audio files can be found on the net by the users under the corresponding web adress.

The RSS-Feeds are text files which contain details about the audio data, their format and length, the date of production and so on. However, they do not contain the audio files that are on the webserver.

The interested users can find the audio publications in various Podcast-directories and download them with the suitable Podcasting client program ( which is capable of playing back the files ) to their computer.

If you choose the MP3 format for your files, so you can use the so called ID3-Tags to save more details in them, these could be infos about the music, its interpreter, the music album and further informations which can be displayed on the screen of the MP3 player.

Podcasting is actually similar to video on demand services, where you can download your favorite film and play it back whenever you want. But, no matter what format you choose for your files, the choice is really huge.