From e82d3c20bc32c36061291c831bf4168dcb66aa98 Mon Sep 17 00:00:00 2001 From: "Steinar H. Gunderson" Date: Wed, 9 Nov 2016 21:41:53 +0100 Subject: [PATCH] Write more about multichannel audio; adapted from my blog post. --- audio.rst | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 58 insertions(+), 4 deletions(-) diff --git a/audio.rst b/audio.rst index 65fe9af..ea94983 100644 --- a/audio.rst +++ b/audio.rst @@ -117,6 +117,7 @@ are indications of common issues: A healthy stereo stream will usually have a correlation somewhere around 0.7–0.8, and this section is marked in green. +.. _audio-strip: The audio strip --------------- @@ -209,6 +210,7 @@ several buses. Each bus has a name (for instance, something like Nageru doesn't care what you write here, but the labels are useful for the operator. + Input mappings '''''''''''''' @@ -267,10 +269,62 @@ keys on the keyboard) allow you to select between two views: .. image:: images/audio-bus-controls.png -There's one set each of these controls for every bus. - -(TODO: write more) - +(TODO: fix image) + +There's one set each of these controls for every bus. The most +important parts of the mix are given the most screen estate, +so even though the way through the signal chain is left-to-right +top-to-bottom, we'll go over it in the opposite direction. + +By far the most important part is the audio level, so the **fader** naturally is +very prominent. (Note that the scale is nonlinear; you want more resolution +in the most important area.) Changing a fader with the mouse or keyboard is +possible, and probably most people will be doing that, but Nageru also +supports USB faders (see :ref:`midi-control`). There's a mute button +if you just want to silence a bus temporarily; it has exactly the same +effect as pulling the fader all the way down, ie., it will make the bus +go all silent. + +Then there's the **peak meter** to the left of that. For each bus, unlike +for the meters used for mastering (see :ref:`audio meters`), +you don't want to know loudness; you want to know recording levels, +so this is a peak meter, *not* a loudness meter. (There's some holdoff +so you can see the actual peaks over a short period.) In particular, +you don't want the bus to send clipped data to the master +(which would happen if you set it too high); Nageru can handle +this situation pretty well (unlike most digital mixers, it mixes in +full 32-bit floating-point so there's no internal clipping, +and the limiter described in :ref:`audio-strip` will usually save you) +but it's still not a good place to be in, so if you peak, +the **historical peak label** under the meter will go red if it happens. +If you want to reset it, click on it using the mouse. + +The peak meter doubles as an input peak check during +setup; if you turn off all the effects and set the fader to neutral, you can +see if the input hits peak or not, and then adjust it down. Left and right +channel are shown separately, so you can see if they are approximately +the same level or even completely mono. + +The **compressor** is well-known from the simple audio mode, but in this view, +it also has a **reduction meter**, so that you can see whether it kicks in or not. +(This is also nonlinear, and each step is marked with number of decibels +the compressor had to reduce the signal.) Most casual users +would want to just leave the gain staging and compressor settings alone, but +a skilled audio engineer will know how to adjust these to each speaker's +antics—some speak at a pretty even volume and thus can get a bit of +headroom, while some are much more variable and need tighter settings. + +Finally (or, well, first), there's the EQ section. The **lo-cut** is again +well-known from the simple audio mode (the filter is separate for each +bus, the cutoff **frequency** is the same across all buses), +but there's now also a simple **three-band EQ** per bus. Simply ask the speaker +to talk normally for a bit, and tweak the controls until it sounds good. +People have different voices and different ways of holding the microphone, +and if you have a reasonable ear, you can use the EQ to your advantage to +make them sound a little more even on the stream. Either that, or just +put it in neutral, and the entire EQ code will be bypassed. + +.. _midi-control: MIDI control ------------ -- 2.39.2