Tag: mpeg-1 audio layer 3 def

MP3, or MPEG1 layer III as a whole, has certainly become the most widely used and qualitatively least promising music carrier since CD, and on a global scale. This is just a seemingly simple trick: as much music as possible in the least possible (storage) space; and, by extension, the shortest possible transmission time (for downloading and uploading). With that MP3, he killed two birds with one stone and that combination became a source of income.

It is about data reduction, nothing more and nothing less, which required a technical approach different from the conventional method, which is based on sampling amplitudes, the precision of which is determined by the number of bits used to capture that amplitude. The bandwidth (“memory”) that the audio signal consumes is determined by three factors: 1. the number of samples taken per second (frequency); 2. the number of bits to record the amplitude (the so-called bit depth) and finally the length of the signal (time). From these three data the following calculation formula is established:

Memory = frequency x bit depth x time (per channel)

For the 16-bit audio CD, we already read about it in part I, the sample rate is 44.1 kHz. If we now put the previous formula aside, the result is:

Memory (CD) = 44,100 x 16 x 60 x 2 (channels, stereo) = 84,672,000 bits

or a little over 10 mb per minute. For a symphony with a play time of about an hour, this results in over 600MB in total. If we then look at the transmission speed of a standard modem (56 kb / s), it takes about half an hour to download music. By Eroica this would take 25 hours. Nobody wants to do that, aside from the increasing risk of signal outages during that absurdly long period. A good ADSL connection should take at least 2 hours, with an emphasis on the minimum, because the transmission speed depends on how busy the lines are and can be a fraction of what is specified. In any case, under very favorable conditions for Wagner’s Götterdämmerung, no less than one working day can be allocated. In short, another solution had to be found and it came in MP3 form.

Matter of algorithm

MP3 was developed in Germany in the late 1980s by the Fraunhofer Institute, which also owns the patents for that system. The original commission was to develop a high-quality audio system suitable for routing through the existing telephone network. So good sound through the phone. With its 2 x 64 kb / s bandwidth in duplex mode, ISDN seemed to be ideal as a starting point for such an audio concept. Fraunhofer succeeded with great success, but therefore the task was not to develop MP3, as it is now used all over the world in the field of music reproduction.

MP3 or MPEG-1 Layer III, is part of the MPEG, or Moving Picture Coding Experts Group as a whole, which was created to develop a standard for the encoded release of feature films, documentaries and audio. Audio, of course, was part of this, if only because an encoded movie without sound, of course, couldn’t. From its humble beginnings, the MPEG group grew to 350 experts representing no less than 250 companies and organizations in 20 countries. It also follows that the parties quickly agreed on a uniform approach and method of work, and thus the global standard to be used. But to prevent everyone from going their own way in MP3 development based on their own principles, an ISO standard was soon established on the basis of commonly formulated directives. Furthermore, the Internet has contributed greatly to the efficient work of the various groups within the MPEG model: technicians have the opportunity to easily exchange their findings and proposals through the MPEG ftp site. When a meeting takes place, the participants (mainly academics with technical backgrounds) are already well informed in advance. technicians have the opportunity to easily share their findings and proposals via the MPEG ftp site. When a meeting takes place, the participants (mainly academics with technical backgrounds) are already well informed in advance. technicians have the opportunity to easily share their findings and proposals via the MPEG ftp site. When a meeting takes place, the participants (mainly academics with technical backgrounds) are already well informed in advance.

World standards

MP3 is part of MPEG, or Moving Picture Coding Experts Group as a whole, which was created to develop a standard for the encoded release of feature films, documentaries, and audio.