| Principles Of MP3 |
| Written by Harry Fairhead | ||||||
| Thursday, 11 May 2017 | ||||||
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The licensing problemYou might well think that the only real legal problems with MP3 are the lawsuits aimed at stopping people swapping music for free but there is another side to the story. As an end user MP3 appears to be free but there were some hidden costs. The MP3 standard was ratified by the ISO and some source code, “the reference source code”, was issued to let programmers see exactly how to implement MP3. The source code is free to download – but if you compiled it you will triggered a patent and had to pay a royalty! The point is that the Fraunhofer Institute did most of the development work on MP3 and it patented some of the key technologies, even though they are part of the ISO standard. Under these patents the Fraunhofer Institute (in co-operation with Thompson) said that you could look at the ISO source code but you can’t compile it and you can’t distribute binaries that result from compiling it. The situation was that you could use it to develop your own decoders and give these away but if you charge for the decoders, hardware or software, you have to pay $0.75 per sale In the case of encoders the charge is $2.5 to $5 per encoder distributed, irrespective of whether you give it away or charge for it. Finally, if listeners have to pay for music in MP3 format then the royalty is 2% per sale. So as you can see MP3 wasn't free and this is the reason that Microsoft didn't include an MP3 decoder with every copy of the Media Player up to version 9 even though a decoder is available. Version 10 and higher included an official Fraunhofer decoder. If you want to create an MP3 player and give it away then you could do it without a licence, subject to a few conditions, but you have always needed a licence to even give away an encoder. However this doesn’t stop many programmers giving away MP3 encoders/decoders as freeware – presumably they just go unnoticed. There are lots of free MP3 encoders. Just do a web search and you will find ten or twenty. The best known is LAME, lame.sourceforge.net, which is an open source MP3 encoder. (See our project .NET MP3 for details of how to run the LAME encoder under the control of .NET.) If you want a plug-in for the, admittedly old, Windows Media player 9, however, the cost is around $9.00. The patent situation is so complicated that it was difficult to even predict when all of the significant patents will expire but in April 2017 Fraunhofer finally stated that it was stopping collecting MP3 licence fees. This was a tacit admission that its patents had run out. However the patent situation is still complex and there is always a possibility that someone will emerge to claim that a patent that they hold relates to MP3. However RedHat's legal department decided that this wasn't likely and authorised the inclusion of both an encoder and a decoder in their Fedora Linux operating system. This probably means that from April 2017 MP3 is officially free - or at least as free as the patent system can ever allow it to be. Beyond MP3There are a number of alternatives to MP3, which is now considered an old technology. Microsoft offers its alternative WMA, Windows Media Audio, as part of the Media player and you can save files in this format. In response MP3 was upgraded to MP3Pro, which gives a 2x improvement on MP3 compression ratios – with the huge advantage of backward and forward compatibility. You can play an MP3Pro file on an MP3 player and vice versa. Of course, you don’t get the benefits of MP3Pro unless you use an MP3Pro player but at least it works. There is also the strangely named Ogg Vorbis (www.vorbis.com). This is an open source audio compressor that has no royalty or licensing problems at all. It is also supposed to be better than MP3, MP3Pro or WMA for the same sort of compression ratios. Given its licence conditions, or rather lack of them, you would think that the music industry would be falling over itself to make use of it. Not so because the Ogg Vorbis has no rights control which stops people from copying music Napster style. However, WMA does and this, or something like it, is more attractive to the music industry, which seems to worry more about pirating than licensing. In this day of very large storage it might seem that lossy compression for audio isn't essential and if you want maximum quality then a lossless compression should win out every time. However so far this hasn't happened. There is some evidence that listeners are becoming so used to MP3 compression artifacts that it is preferred to higher quality encodings. Recent attempts to create "high end" digital audio haven't really taken off and perhaps the reason is that users who are really interested in high quality audio have retreated to vinyl and vacuum tubes! Data Compression The Dictionary Way Claude Shannon - Information Theory And More Google Zopfli - Nice Compression Shame About The Speed
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| Last Updated ( Thursday, 11 May 2017 ) |
