Manual
Table Of Contents
- Introduction
- Supported Codecs and Formats
- The Sonnox Fraunhofer Pro-Codec
- Additional Information on Workflows
- Lossless Codecs (mp3-HD and HD-AAC)
- Description of Controls
- Presets and Project/Session Data Handling
- Preset Manager Toolbar
- Pro-Codec Signal and Control Flow Diagram
- Specifications
- Copyright and Acknowledgements
- Manual Revision History
- Platform Specific Supplement
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12
The NMR display is a useful indication when auditioning the mp3 or AAC codec families. If
there are areas where the NMR line is above 0dB, then those are the frequency areas of
interest. The display will highlight these frequency areas in red. It is possible, for example, to
make very quick comparisons of a selection of different bitrates while auditioning music.
The NMR calculation is less accurate for parametric codecs (those that use enhancements
such as Parametric Stereo or Spectral Band Replication). HE-AAC and HE-AACv2 use
parametric enhancements to achieve very high compression ratios. The NMR indicator is
enabled for these codecs by default, because it can still give an indication to the engineer of
frequency areas that might require examination.
Note that the NMR indicator is not present if the selected codec is lossless (ie. mp3-HD or
HD-AAC). Also, the NMR display is less accurate when SUM is selected; it is more accurate
with single audio streams.
The difference signal used in the NMR calculation is absolute. For some low level signals the
NMR might be relatively high, but any difference will be inaudible due to the low signal
level.
The NMR indicator is only valid for session sample rates 44.1, 48, 88.2, 96, 176.4 and
192kHz. In particular, it is not supported at 32kHz. The NMR display is not valid and is not
displayed above 16kHz.
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