Antex electronic SX-34, SX-6, SX-5e, SX-36 user manual COMPRESSION, Data RATES, and Networks

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externally, there must be 2 cards installed in the computer, so that there is one physical output for each device.

COMPRESSION, DATA RATES, AND NETWORKS

The amount of data (the size) of a sound file is affected by several factors. The most obvious is the sample rate. A file recorded at

22.05KHz will take up half as much disk space as a file recorded at 44.1 KHz. Compression formats also greatly affect the file size. (This is not to be confused with dynamic range compression. This discussion pertains to data compression.) The formula for data rate, in bytes per second, is:

Rate=Fs x N x 2 /C

Where Fs is the sample rate in samples per second (or Hz), N is the number of channels, (2 for stereo, 1 for mono), and C is the compression factor. The “2” is in the formula because the sample taken is 16 bits, or 2 bytes. A stereo file, in PCM16, which is un- compressed, at 48 KHz, would use: 48,000 x 2 x 2 /1 = 192,000 bytes/second, or 11.5 megabytes/minute.

MPEG and ADPCM are examples of file formats which utilize data compression. MPEG is the highest quality compressed format available for this family of Antex cards. A file can be created which takes up one sixth or one eighth the space that an uncom- pressed (PCM16) file would take up, with sound quality that few people would be able to tell was any different from uncom- pressed. ADPCM was originally developed for voice applications, and does not sound as good as MPEG. There are several issues to consider when trying to decide whether to compress or not, and which format and sample rate to use.

MPEG has the best sound quality for the compression. Many different bitrates are available, to find the best compromise be- tween sound quality and disk space used. The disadvantages of MPEG are that it is not easy to edit a file after it has been re- corded. Antex offers a program called FastEdit, however, it is a very simple program which allows cutting the “heads and tails” of

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Contents Antex Electronics Corporation September 17 Rev. ETh Street GARDENA, CaliforniaDeclaration of Conformity Table of Contents SX-34 Mixer and Block Diagram SX-6 Mixer and Block Diagram Figures Introduction Card InstallationSX-5e,6,34,35 & SX-36 Jumper Settings Jumper Settings & ConnectionsMaking Connections to the Card Addresses and InterruptsPage SX-35/36 Connections SX-35/36 Connector DescriptionLine I/0 JP8 MIC JP7 AUX in JP9Output Header JP5 SX-34 Connector DescriptionMicrophone Header JP7 AUX Header JP6Mono Header JP4 SX-6 Connections SX-6 Connector DescriptionMicrophone Input JP3 Line OUT JP2Balanced and Unbalanced Signals SX-5e Connector DescriptionImpedance and Signal Levels Playback and Record Devices COMPRESSION, Data RATES, and Networks ISO/MPEG-1 Bitrates 32 KHz 44.1 KHz 48 KHz Setup Tips Upgrade Driver, WIN Driver Installation WindowsSetup Tips Upgrade Driver, WIN Windows NT Antex Application Software Installation Sample Rate Using Windows Demonstration SoftwareMpeg Bitrates CompressionChannels VU MetersWave Device Record/Stop FileVolume Installing and Using Multiple Cards in a SystemDual Device Operation Mixer and Block Diagrams SX-36 Mixer and Block Diagram Page Page SX-36 Mixer SX-36 Block Diagram SX-34 Mixer SX-34 Mixer and Block DiagramSX-34 Block Diagram SX-6 Mixer and Block Diagram SX-6 Mixer SX-6 Block Diagram SX-5e Mixer SX-5e Mixer and Block DiagramPage SX-5e Block Diagram Antex Meter Antex MeterAntex Meter pull-down menu Antex Meter options Page Troubleshooting Files I record sound dull There are dropouts or pops and clicks Files recorded are of poor qualityToll Free 800 Phone 310 FAX 310 TECHNICAL/ORDERING InformationConnectors for Male Headers AppendixTerms Page Specifications All Cards as applicableSX-36 SX-6 SX-34About Digital Audio SX-5ePage Analog-to-Digital Digital-to-Analog