Downsampling when using higher sample rates, 2 downsampling when using higher sample rates – Sonnox Fraunhofer Pro-Codec User Manual
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5.3 Online Auditioning and Configuring Codecs
5 THE PRO-CODEC PLUG-IN
of frequency areas that might require examination.
The
NMR indicator is not present when HD-AAC is selected. Also, the NMR display is
less accurate when SUM is selected; it is most accurate with single audio streams.
Note:
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 for a 32 kHz sample rate. The NMR indicator is
not valid and is not displayed for frequencies above 16kHz.
5.3.2 Downsampling When Using Higher Sample Rates
There are several circumstances when the plug-in internally down-samples. One example
is where the session sample rate is higher than the highest sample rate that the selected
codec supports. In this case, the audio is down-sampled for the codec, and then
up-sampled for audition. In this case, a down-sampled signal is available in the codec for
writing to a file in online encode mode.
This is not the case in the Manager application. The user cannot offline encode a WAV file
whose channel configuration and sample-rate is not a match for the codec settings. This
is because of possible indeterminate behaviour if the configurations are not compatible.
This is particularly important if you are working with higher sample rate files.
If you are working at higher sample rates, the options are exemplified by:
1. Master at high sample rate to produce a gold master, then audition and online
encode at the same high sample rate.
2. Master at high sample rate and produce a gold master. Down-sample to 44.1 kHz
(for CD). Load CD master session and audition codecs, then encode the CD master
with the Manager application.