Manual

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mp3-HD 24-bit dither/truncation
The noise floor of the input signal is displayed as around -175dB (~30dB down from -
144dB).
The diff signal is indicating -135dB with overtones at around -100dB (this is an error
condition because the 24-bit input contains information that the 16-bit output of the codec
cannot reproduce).
The bit meter shows incorrect dither activity in bits 17 to 24.
5.3 Normal Signal Treatment with Lossless Codecs
Following on from above, we can now investigate the behaviour of the lossless codecs under
normal signal conditions. A typical audio signal is shown with the display zoomed in. As the
signal level is high, we would expect activity at the top of the bit-meter.
5.3.1 HD-AAC
HD-AAC input from 24-bit wav file
The diff signal and the bit-meter are indicating no presence of audio data input at bits greater
than 24.