What common file extension refers to the fraunhoffer mpeg-1 layer 3 codec?

A key technology like Layer-3 is useful for a pretty large spectrum of applications - practically almost any system with a limited channel capacity may benefit from it. The following chapters identify some main areas and list some companies that are actively exploiting the Layer-3 technology. For product-related information, please contact these directly.

Music Links via ISDN

Digital telephone networks (ISDN = Integrated Services Digital Network) offer reliable dial-up links with two 64 kbps data channels per basic rate adapter; other regional networks (in North-America) use 56 kbps data links. Transmission fees are often rather similar or identical to the traditional analog phone lines - those allow to transmit up to 28.8 kbps (V.34 modem) or even 32 kbps ("V.34+").

Using Layer-3, a low-cost narrowband ISDN connection allows to transmit CD-quality sound. Audio professionals, like broadcasting stations and sound studios, benefit from the "music-by-phone" application in various ways. They save money, as they only pay transmission fees for the actual time of usage (not 24 h a day in case of a leased phone line) and for a rather small data channel (one ISDN phone connector for a stereo music link). Radio stations increase the attractiveness of their programs, as reporters transmit high-quality takes (e.g. an interview) or live news without annoying "telephone sound". And new applications become possible, e.g. a "virtual studio", where remote artists may play along some preproduced material, without actually travelling to the studio.

Examples:

• In 1992, Radio FFN, a private broadcasting station in Niedersachsen, Germany, replaced its leased phone lines with ISDN and Layer-3 codecs, to transmit 8 local programs 20 min per day to the central broadcasting studio. This move saved them transmission fees of more than 300.000 US$ per year.
• As one of the first real-world trials, all private radio stations of Germany very successfully used Layer-3 codecs during the Winter Olympic Games in Albertville (France) as reporter links between the various sporting events and their central studio in Meribel.
• At the International Music Festival 92 in Bergen, Arne Nordheim composed a piece of music, where an organ in the church of Trondheim played along with the symphony orchestra in Bergen; the sound of the organ was transmitted via ISDN and a Layer-3 codec.

Since 1992, various manufacturers are providing equipment ("codecs") for professional audio applications: , , , , .

Digital Satellite Broadcasting

Pioneered by , a worldwide satellite digital audio broadcasting system is under construction. Its name is "WorldStar", and it will use three geostationary orbit satellites called "AfriStar 1" (21 East), "CaribStar 1" (95 West), and "AsiaStar 1" (105 East), with AfriStar 1 being launched in mid-1998. The other satellites will follow until mid-1999. Each satellite is equipped with three downlink spot beams that are pointed so as to cover populations that provide the greatest radio listener base. Each downlink uses TDM (time division multiplexing) to carry 96 prime rate channels (16 kbps each). The prime rate channels are combined to carry broadcast channels ranging from 16 kbps to 128 kbps; the broadcast channels are coded using MPEG Layer-3. The prime rate channels may even be dynamically allocated to meet the demands of the broadcast service (e.g. 4 channels combined for 1 hour to allow FM quality stereo (64 kbps) for the transmission of a concert with classic music, followed by 1 hour with 4 separate news channels (16 kbps) in 4 different native tongues).

WorldSpace is offering channels on its three satellites for lease to international and national broadcasters. Channel reservation agreements already have been signed with a number of major broadcasters, including Voice of America, Radio Nederland, the Kenya Broadcasting Corporation, the national broadcasting authority of Ghana, the national broadcasting authority of Zimbabwe, New Sky Media of Korea, and RCN of Columbia. Nearly 1 billion $ in private financing has been raised to cover acquisition of the satellites and for most of the operational costs through full system implementation in 1999. France´s Alcatel Espace is the spacecraft prime contractor and supplies the telecommunications payload.

The radio receivers will be designed for maximum convenience of use at a minimum cost. Low cost receiver will use a small compact patch antenna, will require practically no pointing, and will tune automatically to selected channels. Higher end receivers are also envisioned. In a press release from 5. June 96 (Montreux, Switzerland), WorldSpace declared that it has awarded production contracts for two million receiver chips; the contracts were issued to SGS-Thomson and ITT Intermetall, authorizing each company for an initial production of one million receiver chip-sets.

has already gained Layer-3 knowhow by using its mask-programmed DSP technology to develop a single-chip Layer-3 decoder named "MAS 3503 C". This chip supports only MPEG-1 Layer-3.

November 1997:
There is a new chip - "Intermetall MAS3507D" - available, which decodes Layer-2 and Layer-3. For Layer-3 all features of MPEG-1 and MPEG-2 as well as Fraunhofer specific - so called "MPEG-2.5" - features for low bit rates are included. A DC/DC converter for battery-based operation is included. Power consumption is 90 mW up to a sampling frequency of 24 kHz. Two housings are available 44-pin PLCC or QFP.

Audio-on-Demand

The Internet is a world-wide packet-switched network of computers linked together by various types of data communications systems. Professional Internet providers usually access the network through rather high bit-rate links (e.g., primary rate ISDN with 2 Mbps or ATM with up to 2 Gbps). However, the average consumer uses low cost, low bit-rate connections (e.g., basic rate ISDN with 64 kbps or phone line modems with 28.8 or 14.4 kbps). The actual transmission rate depends on the current user load and the infrastructure of the part of the Internet in use. From a client´s point of view, it may unpredictably vary between zero and the maximum bit-rate of its network modem, with an average bit-rate somewhere in between.

Without audio coding, downloading uncompressed high-quality audio files from a remote Internet server would result in unfavourably long transmission times. For example, with an average transmission rate of 28.8 kbaud (optimistic guess), a single 3-min stereo track from a CD (31.7 Mbyte) would require a download time of more than 2 hours. Therefore, audio on the Internet calls for an audio coding scheme that maintains sound quality as far as possible and allows real-time decoding on a large number of computer platforms without special add-on hardware. Layer-3 fits very well into this scenario - real-time players (like ) are available. Intranets present an interesting special case, as they usually provide sufficient bitrate to allow a number of real-time audio links. Furthermore, our experiments indicate that using the http protocol, a real-time connection with 56 (112) kbps is possible with one (two) ISDN phone line(s).

If content providers are willing to add audio data onto their Internet servers, they have to consider carefully the copyright aspects of the music industry (e.g., artists, producers, record companies). They must not violate these rights by their actions! In the framework of a European project called (for "Music-on-Demand"), we developed a flexible protection scheme called (for "MultiMedia protection protocol") that effectively addresses this issue. Furthermore, MMP allows to distribute real-time players "virtually free".

Audio servers may be used plainly for promotional purposes. E.g., museums may increase the attractiveness of their WWW pages by adding some sound files, or mail-order services may add sound excerpts to their server to increase their CD sales numbers. , a spin-off from , offers system solutions for this type of application. In spring 1996 (CeBit Hannover), they successfully demonstrated an "audio-on-demand" application via T-Online together with the and a broadcasting station, the Suedwestfunk Baden-Baden.

Another music sales systems has been developed by The company uses a personalized real-time Layer-3 player and a proprietary encryption scheme to sell sound files via the Internet on a "per song" base. Music servers and mirror sites are currently located in London, New York, Tokyo and Rio; Melbourne and Berlin will follow soon.

"Audio-on-the-Internet" is currently a very popular topic. It does not only comprise audio file transfers with download times as low as possible, but also streaming audio applications, like "Internet Radio". As Layer-3 offers a sound quality "better than shortwave" at a bitrate of 16 kbps (and, with some modifications, may even be useful at 8 kbps), various companies currently work on this Internet subject - e.g., or .

In a partnership with Apple, Telos introduced in September 96 the technology to support "Internet Radio" applications with a live audio input processed by a Layer-3 NetCoder Hardware.

In December 96, Microsoft announced to support MPEG Layer-3 as part of their NetShow multimedia server technology.

As first multimedia authoring tools, "Director Multimedia Studio 2" and "SoundEdit 16" (from ) use Layer-3 to generate compressed sound files for the "shockwave" format.

Layer-3 encoders and decoders are not only available as studio equipment, but also as ISA-bus PC boards from , along with application software, or as low-cost (decoder only) PC boards from ; recording and playback tools are also available from , along with a special decoder module (called "CenLay3") that allows to playback Layer-3 files via the parallel printer port. Proton Data has also developed a "cutting tool" that allows to manipulate audio data at Layer-3 level.

In addition, a file-oriented Layer-3 encoder and decoder (called "L3ENC" and "L3DEC") is available as shareware for various platforms. Registration is processed by . Please note that even for registered users, the use of the shareware is limited to "personal edition" purposes.

Real-time Layer-3 players

WinPlay3

"WinPlay3" allows the decoding simply by software on any Pentium PC in real time. A 80486 class CPU with a built-in floating-point-unit will also allow some limited operation. For the availability of supported modes, please refer to the following performance matrix:

Pentium486DX4-133486DX2-66486DX-50486DX-33MPEG-1 stereo

ok

ok

---MPEG-1 downmix*

ok

okok--MPEG-1 mono

ok

okokok-MPEG-2 stereo

ok

okokok-MPEG-2 downmix

ok

okokokokMPEG-2 mono

ok

okokokok

*downmix: the original stereo signal will be played back as a mono signal
"MPEG-1" = "MPEG-1 Layer-3", i.e. sample rates 32, 44.1 or 48 kHz
"MPEG-2" = "MPEG-2 Layer-3", i.e. sample rates 16, 22.05 or 24 kHz

On a Pentium-90, WinPlay3 consumes less than 30 % of the CPU power to decode Layer-3 stereo @ 44.1 kHz, or around 5 % of the CPU power to decode Layer-3 mono @ 16 kHz.
At least, a 8-bit stereo sound card is required. For full quality audio, a 16-bit card is recommended. The card´s MCI driver should support sampling frequencies from 8 kHz to 48 kHz.
A standard VGA graphics card is required.
As WinPlay3 buffers up to 4 seconds of sound data due to the limitations of the Microsoft Windows multitasking architecture, around 1 MByte free physical memory must be available.
WinPlay3 runs with the following operating systems: Microsoft Windows 3.1/3.11 (in extended 386 mode), Windows 95 und Windows NT (long file names not yet supported).
WinPlay3 supports file play back of *.mp3 files and direct play from an URL via HTTP. WinPlay3 can simply be integrated as an helper application in common browsers, for example Netscape or Mosaic.
WinPlay3 is available at http://www.iis.fhg.de/departs/amm/layer3/winplay3/.

The unregistered player is limited to a reproduction time of 20 sec (now unlimited V2.3) , i.e. it will playback each plain Layer-3 file only for this time. If you want to use your player without limitation, you have to register your player with .

MMP

As many applications require a player that is "free" for the user, the latest versions of WinPlay3 (starting with version 2.0) also support the new "MMP" ("MultiMedia protection protocol") format.

MMP is a very flexible data format that may support the following functions:

• "unlocking" playback (no more 20 sec limitation)
• "copyright protection" by applying encryption methods to (part of) the data
• "title associated data" (e.g. ISRC code, user data)
• "expiry date" to allow only a limited use

More detailed information is available at http://www.iis.fhg.de/departs/amm/layer3/mmp/.

In a typical "audio-on-demand" application, the content provider may "on-the-fly" convert its plain Layer-3 data into MMP data, by using a "MMP tagger" software (available at ). The client may use its unregistered player to playback these files without limitation - the player is "virtually free". The client need not pay fees - this issue now may be covered at the server side.

MPEG Layer 3 Player

For Mac OS users, a real-time player called "MPEG Layer 3 Player" with a similar look and feel (and similar features) like "WinPlay3" will be released very soon. This new player will (finally!) replace the much simpler (and somewhat buggy) pre-version 0.99 beta that has been available from http://www.iis.fhg.de/departs/amm/layer3/macplay3/.

Layer-3 Sound on CD-ROMs

CD-ROMs (and hard disks) have become most popular to store "multimedia" data. Even with the advent of the new DVD standard, memory capacity will remain a precious resource for many applications. For uncompressed stereo signals from a CD, more than 10 MByte are necessary to store one minute of music. Using Layer-3, less than 1 MByte is enough for the same playing time. And significantly less memory is necessary, if some limitations in performance are acceptable. As CD-ROM readers (and pretty soon, writers too) have already gained a significant market share, typical applications focus today on storing compressed sound files on CD-ROMs, introducing more or better sound tracks into the product. Real application examples are video games, music catalogues or encyclopedias with sound excerpts (e.g., "MusicFinder" by ), or talking books for blind people.

Since fall 96, Bertelsmann is selling their new CD-ROM encyclopedia "Discovery 97" providing information to around 100.000 key words, with rich multimedia information (e.g. more than 2400 coloured photos and images, 41 interactive maps, more than 30 minutes of movie clips, 27 slide shows) including 150 minutes of sound tracks coded with MPEG Layer-3.

Layer-3 Sound on Silicon

Up to now, solid-state memories (RAMs, Flash-ROMs) are only used as audio storage devices in special (niche) applications, as the costs per byte are much higher than with other types of media (magneto-optical disks or magnetic tapes). Speech announcement systems for mass transit vehicles (e.g., busses, subways or trains) are an example for such special applications, as the rough environment requires to use ROM based memories. Since 1993, manufactures speech announcement systems with Layer-3, significantly reducing the precious memory capacity and, at the same time, significantly improving the sound quality (compared with their older 64 kbps PCM "phone sound").

Today, PC-Cards with Flash-ROMs are available, offering a memory capacity up to 100 MByte and more, but at prohibitive high costs for a consumer application. Here, further advances in memory and card technology may trigger a new interesting market segment of "audio-chip-card"-applications. At a press conference in August 95 in Munich, Germany announced the advent of a new cost-effective ROM technology called the "ROS chip" (ROS = Record-on-Silicon). The first generation of ROS chips will be in production in 1997, with a storage capacity of 64 Mbit; a next generation with 256 Mbit as well as a one-time user programmable version will follow. The ROS chips will be embedded in the new "MultiMedia-Card" from Siemens, a cost-effective card media that will store data, text, graphics, images and sound. Siemens has already demonstrated a battery-powered audio player using a prototype "Audio-Card" containing sound tracks coded with MPEG-Layer-3.

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