Introduction to multitrack audio formats

audio-speaker

Multitrack formats are a recent innovation. They are to be encapsulated in a different soundtracks file, which may then be combined by the user in the appropriate proportions.

The idea is to offer a piece of music, the track corresponding to each instrument (and voice) separately. The user can create his own version.

U-MYX was used to include bonus parts in albums.

Such formats have the disadvantage of requiring computer use. However, the emergence of smartphones capable of performing independent applications allows these formats to become portable, including reading with mixage.

iKlax

The iKlax format is an active listening digital format developed by iKlax Media and LaBRI. This file format container type allows you to organize music into different groups and to apply constraints.

The format has received scientific publication at the ICMC 2008 ( Internation Computer Music Conference) in Belfast.

U-MYX

U-MYX is a readable format with a dedicated multi-application, published by the same company that developed the format. This format was used to provide multi-version songs as bonus in the albums, the application is provided along with the songs, all on a CD session visible only if the disc is read on a computer.

Despite these examples of using the U-MYX, its future is uncertain because the company that produces it is rather vague about its future projects.

Mxp4

The Mxp4 is a multi format in which tracks are encapsulated in Ogg format. Produced by a French company, the format has received extensive media coverage in the French press, described as a ” successor to MP3 .” An expression that may seem exaggerated, multitrack formats simply play a différent role.

Proprietary formats

Some of these formats are becoming obsolete , as SDII Digidesign

Audiovisual formats

These formats contain both image files and audio files, as well as timecode or pseudo-timecode (flag).

For example: Quicktime is multi-platform and uses many of the standard free formats. Versatile and polymorphic data structure, some of them are also used for streaming.

Audio CD from 1993 ( QuickTime 1.6) ;
MPEG -1 and MIDI from 1994 ( QuickTime 2.0) ;
DV and H.261 from 1998 ( QuickTime 3.0 ) ;
H.263, Macromedia Flash and SMIL from 1999 (QuickTime 4.0) ;
MPEG-2 , MPEG-4 , AAC, 3GPP and 3GPP2 from 2002 ( QuickTime 6.0) ;
H.264 and OpenGL integration from 2005 (QuickTime 7.0).

Flow calculation and the weight of an audio file

Flow calculation:

rate ( kbit / s) = sampling frequency (kHz) x quantization (bit) x number of channels

example with an audio CD: Speed ​​= 44.1 kHz x 16 bits x 2 (=> stereo ) = 1,411,200 bit / s ( or 1378 kbit / s approx. )

Weight calculation :

For a constant flow format :

size ( K) = time (s) x rate ( kbit / s ) / 8

Example: for an MP3 file encoded at 192 kbit / s for a period of 3 minutes

size = 3 x 60 x 192 /8 = 4320 KB

Format for variable rate :

average size ( kb) = time (s) x average rate ( kbit / s ) / 8

maximum size ( kb) = time (s) x maximum rate ( kbit / s ) / 8

Metadata increases the size of audio files, their size is negligible, though they may have the effect of slowing down the playback of the file in real time.

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