Sound Devices 552 - Manual (Page 27)

552 User Guide and Technical Information
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Press and hold the Battery Check button to have SVEN announce the remaining card space available
in headphones. SVEN automatically announces the remaining time when 15, 10, 5, and 2 minutes are
remaining on the SD card.
File Format
WAV (Broadcast WAV)
The 552 records two-channel, polyphonic AES-31 Broadcast Wave formatted audio files. These files
place additional information in the file header, called the Broadcast Audio Extension data chunk, and
in the iXML chunk. Audio editing software that does not recognize this additional information will
ignore it and read the file as a standard WAV file. Values recorded in the BEXT and iXML are:
• time code stamp See Time Code
• time code frame rate
• time code user bits
• original date and time
• bit depth
• sampling rate
• track names
• take number
• file name
• machine serial number
• software version
MP3
MPEG-1 Layer III is a lossy compression algorithm, often used for music and transcription recording
purposes. The 552 records two-channel MP3 audio files with the following data rates.
• 64 kb/s
• 128 kb/s
• 192 kb/s
• 320 kb/s
Bit Depth
When recording WAV files, the 552 records either 16 or 24 bit files. 24-bit recording provides greater
dynamic range and addition headroom for signal peaks. Sound Devices recommends 24-bit record-
ing for all critical production.
Bit Depth and Dynamic Range
Bit depth defines the digital “word length” used to represent a given sample. Bit depth correlates
to the maximum dynamic range that is represented by the digital signal. Larger bit depths accom-
modate more dynamic range. A quick estimate of the maximum dynamic range capable of being
represented by a given word length is dynamic range ~= no. of bits x 6 dB. Bit depth is an exponen-
tial measure (exponent of 2), so as bit depth increases, the amount of data it represents increases
exponentially. The majority of field recording is done with 16-bit audio, therefore each sample is
represented by a digital word of 2^16 (65,536) possible values. 24-bit audio has a word length of 2^24
(16.7 million) possible values per sample.
Sampling Rate
The 552 records WAV files at the sampling rates selected below. The sampling frequency is set in the
Setup Menu.
• 44.1 kHz
• 48 kHz
• 88.2 kHz
• 96 kHz
Sound Devices recommends 48 kHz sampling for all 552 production applications. Sampling rate op-
tions are limited to 48 kHz and under when an MP3 or a Time Code to Track option is selected. If the
sampling rate is set to a higher rate when an MP3 option or a Time Code to Track option is selected,
the sampling rate defaults to 48 kHz.
Sampling Frequency and Audio Bandwidth
The sampling frequency is expressed in samples per second (hertz) and defines the number of times
in a second that an analog audio signal is measured. Sampling frequency determines the audio band-