2020. 8. 29. 04:07ㆍ카테고리 없음
As loudness standards evolve, so we need new metering plug-ins. Izotope's suite covers all the bases.
The Insight suite is highly configurable. This arrangement shows bar-graph level meters, loudness readouts and a spectral analyser.
Dec 16, 2014 This free educational tutorial reviews the essentials of loudness compliant metering using the iZotope Insight plug-in. Download a free, 10 day trial of Insi. Insight 2 has an updated design that matches the rest of the iZotope family. The most important targets have been emphasized to make Insight 2 easier to read at a glance. Now you can easily resize individual meters in the main window by clicking and dragging between two-meter frames.
In almost all recording, mixing and mastering contexts, decent analysis and metering tools make the job a whole lot easier — if only to confirm what your ears are telling you. Most DAWs are reasonably well equipped when it comes to basic needs such as mid-side metering and audio vectorscopes (goniometers), but the recent introduction of a Loudness Metering standard has skewed the playing field somewhat. Although this standard only directly affects broadcasters at present, it is certain to have some impact on the way we all create and optimise mixes in the near future.
The new broadcast standards require that material is balanced using 'loudness normalisation', where the relative loudness is determined by a new form of meter complying with the ITU-R BS.1770 (and related) specifications. The aim of this new approach is primarily to overcome the hugely annoying problem of widely varying levels when switching between TV stations, or during ad breaks within a programme, and it is working extremely well for those broadcasters that have already adopted this new way of working. Most major broadcasters will adopt the system over the coming year, and work has already started on adapting the format for the radio industry. The really interesting side-effect of loudness normalisation, though, is what happens to hyper-compressed, peak-normalised material. As you might expect, it ends up sounding really weak, feeble, and utterly boring because it has no dynamics! Everyone's music ends up sounding as loud as everyone else's, because that's what loudness normalisation does, but the reintroduction of a headroom margin allows — and even encourages — the kind of wide, natural, dynamic range that has been practically lost through the 'loudness wars'. Music can be punchy and dynamic once again, with creative light and shade, choruses louder than versus, and a sense of vitality that an entire generation probably doesn't know to be possible!
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Insight
Lots of manufacturers now offer meter plug-ins that include the BS.1770 loudness format, but Izotope's new Insight software goes further than most. This is a complete audio analysis package, with fully customisable and scalable level meters (true peak, RMS and K-system), loudness meters (ITU-R BS.1770 and EBU R-128, plus a loudness history graph mode), 2D and 3D spectrogram, spectrum analyser, and both a stereo vectorscope and surround scope.
Insight is available as a stand-alone metering product in RTAS, AAX, Audiosuite, Audio Unit, Direct X and VST/VST3 formats, the last with both 32- and 64-bit code, and is also included as part of the Meter Bridge application in Izotope's Ozone Advanced mastering software. Authorisation is via either a serial number or an iLok dongle, and a 10-day unlimited demo is also available if you would like to try before buying.
The graphical interface has a subdued green, 'techy' air about it, and it can be customised to include or hide each of the available elements, as required, with minimised sections appearing as tabs along the bottom of the screen. A large number of pre-defined display configurations is also available from a Presets button on the bottom bar, and an adjacent Options button opens a multi-tabbed window to configure how the various analysis displays and meters work. There are separate pages for setting up the spectrum analysis, spectrogram, sound field, level meters, I/O and the more general system aspects of the Insight tools. The I/O page, for example, allows the input and meter display channel orders to be customised for working in surround, with preset options for the film, AES/SMPTE and DTS standards.
On The Level
Here, the basic metering in the first screenshot is joined by a sound-field display (top left) and loudness history (bottom).
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The level meters window shows the channel signal levels on a set of vertical bar-graphs on the left-hand side, with three loudness bar-graphs on the right, and some numerical readouts in the centre. In the default Peak+RMS mode the level meters show the RMS level as a solid bar, with the true-peak value as a bar at the top of a dimmer section. A bright floating line above that represents the peak hold value. For anyone unfamiliar with the term, 'true-peak' metering indicates the real level of the reconstructed waveform, not just the individual sample amplitudes, and thus includes any 'inter-sample peaks' that conventional 'sample-meters' miss. The dBFS meter scale can be switched between linear and non-linear displays: the former provide uniform 6dB increments, while the latter expands the top end for finer resolution. The meter integration and peak-hold times can also be adjusted.
K-System metering is an alternative to the Peak+RMS mode, and also shows peak and RMS values, but the zero reference of the scale can be adjusted to show 12, 14 or 20dB of headroom. The K-12 format is intended for dynamically controlled broadcast material, K-14 is for moderately compressed music, and K-20 for wide dynamic range 'audiophile' material. The 'clip level' can be adjusted as required, and is set relative to 0dBFS for the Peak+RMS meter, and relative to the zero level of the selected K-System meters.
The Loudness Meter section provides a surprisingly accurate indication of the perceived loudness of the audio in real time. Three bar graphs indicate the momentary (M), short-term (S) and integrated (I) loudness values, the three differing in their integration times. The momentary meter uses a 400ms window and provides an idea of the instantaneous loudness that is useful for initial level-setting. The short-term meter uses a three-second window and is useful when mixing, as it shows current trends. The integrated meter uses an indefinite window time and builds up a loudness value over the entire duration of a programme. Quiet sections are automatically gated out to prevent false readings, and this is the loudness value by which material is judged and compared. Again, several meter scale options are available, to suit different applications.
The TV broadcast standards require programmes to have a loudness value of -23LUFS or thereabouts, while radio will probably be around -15LUFS — the LUFS term meaning 'Loudness Units (relative to digital) Full Scale'. The actual loudness target can be adjusted, and is indicated by the meter bars changing colour. In addition to the meters, the centre of the meter panel also has numerical displays for the momentary, short-term and integrated figures, along with the loudness range in loudness units (LU). The loudness range is indicated on the integrated meter by a pair of yellow 'brackets', and some broadcasters require certain types of programme material to fall within a defined loudness range to ensure that the dynamic range is adequately controlled for domestic listening.
The Loudness History graph is a separate but related display option which plots any or all of the momentary, short-term and integrated values relative to the target loudness value, across a constantly condensing timeline. If the integrated value exceeds the target, that portion of the graph is coloured red to highlight the problem. The momentary plot makes the display look very erratic, though it gives a good idea of dynamic range; showing just the short-term and integrated values makes for a neater and more meaningful display. Both axes can be scaled as required, simply by placing the mouse on the appropriate axis and using the mouse wheel.
A very neat feature provided by Insight is that, in DAWs that support the facility, if the plug-in is inserted in a track and track automation is enabled, automation data will be written back into the DAW indicating any areas where the signal exceeds the loudness target level. The intention is to provide a flag to help locate problem areas so that the relevant sections can be rebalanced as necessary. Audio below the loudness target is logged with a minimum automation value, whereas overs are logged with a maximum value.
Rays & Wobbles
The 3D spectrogram is both informative and attractive!
Moving on, Insight also includes a couple of variations on the vectorscope theme to analyse stereo imaging and mono compatibility. The Polar-S mode places a dot representing the image position for each stereo pair of samples in a semicircular display that indicates the stereo spread. The dots fade over time to give a sense of the audio history and trends, and good mono compatibility is assured if the dots lie mainly within a ±45-degree angle from the centre. An alternative Polar-L mode plots 'rays' or lobes, with the lobe angle representing the image position and length its amplitude. The peak levels form an outer 'skin', which gradually contracts to indicate the audio history.
The third option is a more traditional Lissajous display or goniometer, which plots the audio image within a diamond-shaped frame. Mono signals produce a thin vertical line and wide stereo is shown as a spherical blob. Good mono-compatibility is assured when the blob is taller than it is wide! A 'balance meter' and phase-correlation meter are also included, and there are various configuration options to fine-tune the way information is displayed in all the vectorscopes.
When working in surround, a variation on the Polar-L mode can be used to plot the surround sound image as a 'blob' within a circular frame, with the blob expanding and contracting to indicate the amplitude in each channel. DK Technologies came up with the original version, which they called a 'jellyfish' display: a very descriptive term! A bright dot inside the blob indicates the averaged centre of the surround sound image.
Spectrum Analysis
Spectrum analysers are commonly included in DAW EQ plug-ins these days, so the Insight spectrum analyser will be a familiar tool. Once again, there are numerous configuration options to determine how the response is measured and displayed, including a linear FFT mode, or bar-charts showing 1/3 or full octave, or critical bands. Both the frequency and amplitude scale can also be zoomed as required.
Expanding on the spectrum analysis theme, Insight also includes both 2D and 3D Spectrogram modes. In essence, these plot the frequency spectrum against time, with frequency on the vertical axis and time on the horizontal axis. Amplitude is represented by colour and, in the case of the 3D version, by the spectrogram's varying surface height. This way of visualising the audio is very good for spotting various problems, such as excessive low-frequency content or low-level whines and whistles, for example — and there are copious options for configuring the displays in different ways, as you would expect.
A very useful option that I'd not come across before is provided by an additional plug-in included in the Insight suite, called Meter Tap. When inserted into separate channels, this plug-in provides a discrete metering signal that can be used to plot different channels with different colours within the spectrogram display, making it possible to keep an eye on multiple channels at once.
Impressions
With my background in broadcasting and broadcast training, I followed the development of the ITU-R loudness standards very closely, and have been using loudness metering for some time now, mainly with a hardware DK Technologies MSD600 meter, or the ZPlane PPMulator or TC Electronic LM2 RADAR plug-ins. The Insight loudness meters perform very well, are easy to read, and conform precisely to the readings obtained with my other meters — as they should, of course!
The inclusion of K-System metering scales is handy, and I really enjoyed using the Polar sound-field displays. The spectrogram display can be useful for troubleshooting and forensic work, and overall I have to say I am very impressed with, and have become very attached to, the Insight suite. I even like its laid-back green colour scheme which is very easy on the eye — and that makes a big difference when working on long programmes. This is a very comprehensive suite of audio analysis and measurement tools that ticks all the boxes. Highly recommended.
Pros
- Peak and average metering with numerous options (including K-system).
- Standardised Loudness Metering with comprehensive displays.
- Stereo and surround sound-field displays.
- Spectrum analyser, as well as 2D and 3D spectrograms.
- Highly configurable.
- Available in 64-bit VST format.
Cons
- The suite is relatively expensive.
- The green colour scheme won't be to everyone's taste.
Summary
The Insight software package is a very comprehensive metering suite that really does cover all bases, and allows a useful degree of user customisation too. The Loudness Metering facilities meet all current standards variations and provide clear and easy-to-use displays, and the history chart is a nice addition.
information
£375 including VAT.
Time + Space +44 (0)1837 55200.
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