File Formats

Audio File Formats

The 744T records audio to industry-standard file formats—Windows Wave (WAV), Broadcast Wave (BWF, monaural and polyphonic) and MPEG Layer 3 (MP3).

WAV / BWF

The 744T adheres to the AES-31 BWF file specification. The filename extension is user-selectable between .WAV or .BWF. There is no difference between the two file types except for the extension. Users wishing to record “standard” wave files should select the .WAV extension. Time code will be stamped at the head of the file, but software that does not recognize the broadcast wave data chunk will simply ignore this added information.

The BWF files created by the 744T contain production information in the Broadcast Audio Extension data chunk. Among the values recorded are:

•time code stamp

•time code frame rate

•date and time of the original recording

•bit depth

•sample rate

•originating machine serial number

All of the information contained in this chunk is available for post-production.

There are several PC and Mac utilities that will show the data from the BWF header.

MP3 – MPEG Layer 3

For music and voice recording applications where compressed audio is acceptable, the 744T can record to industry standard MPEG Layer 3 (MP3) audio files. These data-compressed files are generated using a high-quality MP3 codec. Numerous data rates are available. When recording MP3 files, the time code generator will remain running internally, but will not record time code to the file. The only time reference available is the Absolute Time (A-Time) of the file.

The 744T can play back MP3 files, as well as record them. This is very useful on-set to play a personal MP3 audio library during downtime.

By definition of the file format, MP3 recordings are limited to two tracks, therefore only tracks A and B are available for assignment. Time code is not a part of the MP3 format. Even with time code enabled and running during MP3 recording, time code will not be recorded with the file.

Recording and Playback

Recording and playback of audio are unquestionably the most important functions of the 744T. The user interface of the product has been designed to leverage the existing paradigm of a “tape record- er” so that the unit is easily understood. Recording and playback functions are quite similar to that of tape-based machines, however the nature of a non-linear recording medium provides additional control not possible with tape-based recorders.

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