Specifications
Chapter 92: TL MasterMeter 513
In a recent paper [Nielsen 2003], seven con-
sumer CD players were subjected to tests de-
signed to analyze their ability to reproduce and
reconstruct signal levels above full scale
(0 dBFS). All of the players experienced diffi-
cultly dealing with signal levels this high, fur-
ther showing that, while all of the samples can
be legal, the level can still be hotter than is legal.
The result is that a CD player can be unable to
reproduce the audio accurately. In some cases,
the reconstruction sounds “perfect” to the mas-
tering engineer, because the engineer’s equip-
ment can actually reproduce the waveforms
properly.
The Red Book format for CDs and the DVD specs
both allow for this illegal content and the mas-
tering engineer is still allowed to put out re-
leases that meet the spec while allowing con-
sumers’ players to distort. With an oversampled
peak meter, the engineer will be able to know
that the music is clipping, by how much and
where. With this knowledge the engineer can
then decide with complete information whether
or not to accommodate the legal range of digital
audio on a PCM sampled system.
The goal of TL MasterMeter is to allow an engi-
neer to use a DSP model of the reconstruction
process to monitor the reconstructed waveform
for potential clipping at the final mix and mas-
tering stages. Using TL MasterMeter, engineers
can compare regular and intersample peaks over
time and make appropriate adjustments without
sacrificing overall level or dynamic range. Uti-
lizing an oversampled peak meter in the digital
audio studio that represents the reconstruction
filters in digital to analog converters is the first
step toward an improvement in audio quality in
music releases.
TL MasterMeter References and
Further Reading
Aldrich, Nika. Digital Audio Explained For the
Audio Engineer. San Francisco: Backbeat Books,
2004.
Banquer, Dan, Dick Pierce, Herbie Robinson, et
al. “Intersample Peaking.” Pro Audio Mailing
List. 21 December, 2002 - 31 December, 2002.
Nielsen, Soren and Thomas Lund. “Level Con-
trol in Digital Mastering.” Preprint 5019, 107th
AES Convention. Denmark, 1999.
Nielsen, Soren and Thomas Lund. “0 dBFS+
Levels in Digital Mastering.” TC Electronic: Ris-
skov, Denmark. 17 July, 2003. http://www.tc-
electronic.com/media/
Level_paper_AES109.pdf
Nyquist, Henry. “Certain Topics in Telegraph
Transmission Theory.” Transactions of the
AIEE. Vol. 47 (April 1928): 617-644.
Shannon, Claude E. “Communication in the
Presence of Noise.” Proceedings of the IRE. Vol.
37 (January 1949): 10-21.
Using TL MasterMeter
TL MasterMeter uses the DSP power of
Pro Tools to model the conversion process
found in typical consumer devices. In technical
terms, the TL MasterMeter algorithm uses a 31-
tap Blackman-Harris windowed sync conversion
with oversampling ratios from 2x to 8x depend-
ing on the session sample rate. The output of
this DSP algorithm is then displayed visually.
This assists engineers in highlighting potential
distortion which may be introduced on playback
of mixes, especially mixes which have been pro-
cessed to be particularly loud or “hot.”