Usually loudness measurements are performed on the final mix, the mix as it would be bounced to disk. Therefore the common place to load the plugin would be the master channel. Make sure that LevelView is the last plugin in the chain and there are no faders after that may alter the volume/gain. An alternative setup is where one would re-record the output back on a track. In that case the plugin could best be on the input channel.
When using LevelView in a surround setup it is important that the channels are in the correct order. The order is conform the SMPTE/ITU standard (L-R-C-Lfe-Ls-Rs) for AU and VST plugin hosts. In RTAS plugins the channel order is taken care of by the host.
Opening the plugin
The LevelView User Interface window now opens, as seen below.
Initially the plugin will open in EBU R128 Mode (european standard). This means the 0 LU level in the meter corresponds to -23 LUFS. The integrated measurement “I” will be gated with a relative gate, 10 LU below the ungated level. You can switch to ATSC A/85 mode (for US) by clicking the text “EBU R128” in the top right corner. The text now changes to “ATSC A/85”. This will set the 0 LU indicator in the meter to correspond to -24 LKFS and disable the gate for the integrated measurement. By clicking the text again you will see the third mode: “User”. This means you can set the 0 LU reference and enable or disable the gate manually. To do so click the reference level and fill in a value. By clicking on the “gate” text, it toggles between gated and ungated.
LevelView has two different scales. By default the meter ranges from -18dB to +9dB. This is the ‘EBU +9’ scale. You can switch to a larger scale by clicking anywhere on the meter. This will double the range from -36dB to +18dB, or ‘EBU +18’ scale.
Loudness is measured from a start point to an end point. Therefore the meter needs to be started and stopped. The basic practice is to press start (‘play’) on the meter, play your sequence and stop the meter. When the meter starts, it will reset all meters like the bendy meter and the integrated value.
Please note that since the EBU R128 recommendation includes a second absolute gate, LevelView will not record levels below -70 LUFS. When your playback cursor is not running, the levels are below this gate and therefore have no influence on the measurement. This also means it is not necessary to exactly time the start and stop moments of the meter. In other words, there’s no need to start the meter and DAW at the same time. Just press start on the meter so that it is waiting for signal, and start the sequencer whenever you’re ready. The same goes for stopping the meter. In most cases, when the audio is stopped, it will drop below the gate and therefore have no more influence on the numeric measurements (the bendy meter will continue to run).
AUTO mode is started by clicking the ‘MANUAL’ button right of the start/stop button. If you activate this mode, LevelView automatically starts, stops and resets following your DAW controls. Due to limitations of some DAW’s, the measurement in AUTO mode needs to be continuous, to ensure your measurements are 100% correct. LevelView will be reset after a pause of your transport controls.
When using the standalone version of LevelView there’s no timecode to follow. The AUTO function will then work by detecting silence. This silence is detected when the signal drops below a threshold level for a minimum duration. This automatically stops and start/resets the meter. These parameters can be set in the settings menu at the top on the right.
LINK mode is the third option, and is enabled after one more click on the ‘AUTO’ button. It is only found in the plugin version of LevelView. In this mode, loudness data is recorded and stored continuously. The advantage is that if you jump back on the time line of your DAW, LevelView will instantly indicate the local history in the bendy meter graph. The numeric values however will still reflect the I, max M, max S, LRA and max TP of the fully measured length. If you decide to change some part of your mix, these numbers will be updated right away, which frees you of the task to measure the full program again. In case you skipped parts of the time line while measuring, LevelView will show the message ‘gap’ under the I number. This indication will be cleared when you skip back and play the lacking part so the time code sequence LevelView recorded is continous. Pressing the ‘stop’ button will reset the LINK memory so you can start a new measurement. Mark that the host must provide time code for the LINK function to work. Avid Media Composer for instance does not offer this information so LINK will not work.
Reading the meters
The large digits at the right of the meter show the integrated loudness (I). The integrated loudness is like the average loudness measured over a period of time, from start to stop. Its normal use is to measure the loudness of a complete program (tv-show, movie or commercial). This is called ‘Program Loudness’. For EBU R128 it should be -23 LUFS, for ATSC A/85 it should be -24 LUFS (or “LKFS”). By clicking on the ‘LUFS’ text of LevelView, the indication toggles between the absolute LUFS indication and the relative LU indication.
Depending on the settings the average loudness is calculated from all content, or only from the content above a certain threshold level of a relative gate. In the EBU mode a -10 LU relative gate is turned on that conforms to the ITU BS.1770-2 recommendations. In the ATSC A/85 mode the gate is turned off. In User mode one can turn the gate on or off manually (see ‘Modes’). The ‘I’ meter can also be used to measure specific parts of the program like dialog.
The vintage ‘light spot’ in the outer arc indicates the momentary loudness (M). This is the fastest loudness unit (400ms) and indicates the loudness “at the current time”, hence the name momentary. It is particularly useful to display shorter loudness peaks and is therefore in some countries used to control the maximum peaks in commercials. The maximum Momentary level registered after the ‘start’ moment is indicated by a white dot in the outer ring, like a peak hold. When this ‘max M’ level exceeds +8 LU it turns orange. The max M value is also displayed in the table below the Integrated level meter. This value turns orange above +8 LU too. Keep in mind that the max M value is the level at the time of metering. When some countries prescribe a max M value, they refer to a max M relative to a Program Loudness (I) of 0 LU. So please take any deviation from -23 LUFS on the I meter into account that remains at the end of the program.
Short term Loudness
The outer ring of the rainbow (the outside of the lightest blue part of the graph) shows the Short term loudness (S). With an integration time of 3 seconds, it is a slower indication then the M meter and is therefore less influenced by short peaks. It displays an easier to read loudness level and is more constant. At the same time it is still fast enough to give a reasonable impression of the loudness of for instance the running conversation.
The S meter also features a peak hold dot and this number can be read as the max S level in the table. If the Max S exceeds +6 it will turn orange to warn you. Mark that limits of max S or max M can be different from country to country, but many are in agreement that +8 max M and +6 max S is a proper maximum value for short resp. longer program material.
The inner rings get a factor three slower for every step inwards (10, 30, 90 and 270 seconds). Even though these are not part of the official recommendations, they have proven to be a very useful tool during mixing to fill the gap between the faster (M and S) units and the Integrated loudness. You can use them as a kind of memory of your average mix levels over a certain time span.
Loudness range (LRA) is a tool to display the spread of loud parts and soft parts in a program. It is based upon the Short term (3 seconds) readings, ignoring the 10% softest parts and 5% loudest parts. It is expressed as one number, indicating the difference between the two. This number can be found in the table below the Integrated level. The LRA indication can help you decide if more compression is needed or not, since specific environments have different LRA tolerances (cinema, tv, mobile views etc). In general a LRA of more than 20 is judged as too wide for broadcasting and therefore the LRA number in the table will turn orange when it exceeds 20.
To give you more insight in the dynamics of your audio, the Short term measurements are also displayed as a histogram in the lower left corner. Softer S levels will be displayed on the left of the graph, louder ones will be displayed on the right. More dynamic audio will show a wider graph while audio with a constant loudness will result in a narrow graph. The shaded light blue area in the histogram shows the LRA span. The current level of the Integrated loudness is shown as a clear white line in the graph. If the gate is enabled (see Modes), the gate is also displayed in the graph as a dark blue line. The last indicator in this graph is the current short term loudness S which is shown as a small red line beneath the graph. It copies the levels of the S meter on the outer ring of the main meter and gives you an idea of how the current loudness corresponds to the histogram.
Keep in mind that because of its statistic nature, a larger amount of measurement points is needed for an LRA value to make sense. Therefore the LRA is only showed after about 10 seconds. Please do not use LRA for short fragments such as commercials. It is designed as a very useful tool for longer programs like movies.
True Peak Meter
In the past, there’s always been great emphasis on peak measurements. Originally to prevent overloading of systems but in recent years peak levels became target levels. With the new EBU and ATSC recommendations the emphasis is shifting to average loudness measurements and things like loudness range. The headroom is now so large that overloads will hardly occur in general use. But of course it is still important to avoid overloads and have a proper indication of this.
The most reliable way of measuring peaks is using a true peak meter. True peak means it will not just measure the highest sample values, but also take into account the influence of filtering that will take place in a DA converter or when the signal is processed in a codec or sample rate converter. Some signals will show higher peaks than the sample values because the reconstructed waveform peaks in between samples.
In LevelView the maximum true peak level is shown as a ‘max TP’ reading in the table below the Integrated loudness number. If the level exceeds -1dBTP the value will turn orange to warn you for clipping. By clicking on the ‘max TP’ text, it changes to ‘max SP’ which means ‘maximum Sample Peak’. This will reset the meter. Sample peak metering saves a little bit of CPU load, but in general we advice to use a max TP setting.
With the standalone version of LevelView you can measure loudness directly from any audio hardware input. The interface is the same as the plugin version of LevelView. The settings button in the upper left corner of the interface offers access to the standard audio driver settings and also gives you the opportunity to save the current settings to a file. LevelView will always attempt to open the interface with the settings that were active when closing the previous session. LevelView Standalone finds special application in combination with the ‘broadcast’ function that is described in the next chapter.
It is possible to connect two or more instances of LevelView to each other. This allows you to view and control LevelView over the network and the internet. The ‘broadcast’ icon, left of the ‘LevelView’ name, gives access to the remote settings.
By clicking on the broadcast icon you open access to the IP:port input field. Click in the field and enter a socket number, ie. 12345. If you are hosting for clients that will connect via the internet and you have a router and/or firewall, please make sure that the port you selected is open and redirects to your computer. Otherwise clients will not be able to connect. On Mac OS-X it is recommended to select a socket number above 1000, a lower number might prevent clients to connect to this host. By clicking on the broadcast icon again, the socket number is set.
A client instance of LevelView will act as a slave for an existing and running host instance of LevelView. Once LevelView is set to client mode, it will ignore any audio input to which it may be connected. Click on the broadcast icon and select the IP:port input field. Now enter the IP address and the chosen socket number of the host instance of LevelView. Use the format “IP:port”, for example: “127.0.0.1:12345”.
The IP can be 127.0.0.1 to use or test the functionality on one computer. When connecting to another computer on a LAN, check the IP address of the host in the ‘network’ part of the system preferences. If you like to connect via the internet, get the IP of the host’ WAN by searching (from the host connection) “my ip” on any search engine. Please keep in mind the ports should be forwarded by your modem. Any incoming signal at the modem on the port selected in LevelView should be redirected to the local ip of the server. For more information see http://en.wikipedia.org/wiki/Port_forwarding. Also, make sure the server is not blocking the port entered in LevelView so please check your firewall settings.
The broadcast icon changes colour depending on the network state. By default the colour is grey, when there is no connection. It will turn blue when the plugin is in hosting mode. This allows clients to connect. In Client mode, the icon turns green and LevelView is connected to a broadcasting host. When the icon is red there is a problem with the connection. You should check the network status message below the IP and port input field (in the remote settings). While there is an error and the view is set to display the remote settings, LevelView will try to reconnect every 10 seconds. When switching the remote settings view ‘off’ (by clicking the broadcast icon) it will stop trying to reconnect. You can disable the ‘host’ or ‘client’ state by deleting the IP:port number and clicking the broadcast icon.
LevelView can be viewed via a browser too using a dedicated webapp. Open a browser on your computer or mobile device and visit http://webview.grimmaudio.com/. This will start the WebView setup page. Here you can enter the server address and port. Then click ‘connect’ to connect to your LevelView server. WebView is designed for remote monitoring. It therefore requires a working network connection on both sides.
Master Pinguin LDNServer
LevelView can also send the loudness measurements to Master Pinguin’s LDNServer. To setup such a connection use the format: “NAME:IP:port”. The name is used by the server to identify the specific instance. For example “Studio1:127.0.0.1:12345”.
For more information about LDNServer and/or Master Pinguin please visit: http://www.masterpinguin.de.