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3 File formats

Amadeus Pro supports a variety of popular sound formats, as well as its own Amadeus format. Most formats have some limitations that prevent them from being able to represent an Amadeus Pro document faithfully. It is therefore recommended to always work in the Amadeus format and to export the document to a standard format only in the very last step. The shortcomings of the various formats will be explained below.

As a general fact, sound documents can take up a large amount of disk space, and so many formats include some compression algorithm aimed at minimising the size of the resulting file. There are two families of such compression algorithms: lossy algorithms and lossless algorithms. Lossy algorithms allow for high compression rates, but this comes at the cost of a loss of information. In other words, every time you decode a document compressed with a lossy algorithm (for example to edit it) and then save it back, the sound will lose a bit of its quality. Lossless algorithms on the other hand preserve the data in its entirety, so that there is no loss of quality coming from successive edits. The downside of course is that lossless algorithms do not usually achieve very high compression rates.

If you wish to edit a file encoded with a lossy algorithm, it is therefore recommended to save intermediate steps of the editing process to an uncompressed format or a format using a lossless algorithm. Typical lossy algorithms are Mp3, AAC and Ogg Vorbis. The AIFF andWAVE formats store uncompressed data by default but also allow you to use lossy compression algorithms like µ-Law, a-Law, MACE-3, MACE- 6, QDesign Music 2, and AMR Narrowband. It is beyond the scope of this manual to discuss the suitability of these algorithms for various applications. (Please don’t send me emails asking for advice. Try to experiment by yourself or look for advice on the internet, there is plenty of information available online.) Typical lossless algorithms are FLAC and Apple Lossless.

Some algorithms compress data by a fixed factor (µ-Law and a-Law compress by a factor 2, MACE-3 and MACE-6 compress by factors 3 and 6 respectively), but most other algorithms support several compression factors. A standard measure of compression is the bitrate which measures the amount of diskspace (in bits per second) which the resulting file takes. A bitrate of 128kbps corresponds to about 16kB per second, which is roughly 10 times less than the amount of disk space taken by uncompressed sound in CD quality (44:1kHz, 16Bits, stereo). Smaller bitrates of course come at the expense of lower sound quality.

Some formats are not suitable to retain all the attributes of an Amadeus Pro document. If this is the case, a warning will be shown, together with a short explanation of the features that may be lost. The only way to be 100% certain that all features are retained is to save a document in the Amadeus Pro format.

The different file formats have specific settings that can be accessed by clicking on the Settings button in the file saving dialog. Below is a short description of each of them.

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Last updated on June 22, 2015

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