processing with High Dynamic Range (3)

This article explores how some different HDR imaging alike techniques can be adopted right into the audio domain.

The early adopters – game developers

In the lately cross-linked article “Finding Your Way With High Dynamic Range Audio In Wwise” some good overview was given on how the HDR concept was already adopted by some game developers over the recent years. Mixing in-game audio has its very own challenge which is about mixing different arbitrary occurring audio events in real-time when the game is actually played. Opposed to that and when we do mix off-line (as in a typical song production) we do have a static output format and don’t have such issues of course.

So it comes as no surprise, that the game developer approach turned out to be a rather automatic/adaptive in-game mixing system which is capable of gating quieter sources depending on the overall volume of the entire audio plus performing some overall compression and limiting. The “off-line mixing audio engineer” can always do better and if a mix is really too difficult, even the arrangement can be fixed by hand during the mixing stage.

There is some further shortcoming and from my point of view that is the too simplistic and reduced translation from “image brightness” into “audio loudness” which might work to some extend but since the audio loudness race has been emerged we already have a clear proof how utterly bad that can sound at the end. At least, there are way more details and effects to be taken into account to perform better concerning dynamic range perception. [Read more...]

processing with High Dynamic Range (2)

This comprehensive and in-depth article about HDR imaging was written by Sven Bontinck, a professional photographer and a hobby-musician.

A matter of perception.

To be able to use HDR in imaging, we must first understand what dynamic range actually means. Sometimes I notice people mistake contrast in pictures with the dynamic range. Those two concepts have some sort of relationship, but are not the same. Let me start by explaining in short how humans receive information with our eyes and ears. This is important because it influences the way we perceive what we see and hear and how we interpret that information.

We all know about the retina in our eyes where we find the light-sensitive sensors, the rods and cones. The cones provide us daytime vision and the perception of colours. The rods allow us to see low-light levels and provide us black-and-white vision. However there is a third kind of photoreceptors, the so-called photosensitive ganglion cells. These cells give our brain information about length-of-day versus length-of-night duration, but also play an important role in the pupillary control. Every sensor need a minimum amount of incitement to be able to react. At the same time all kind of sensors have a maximum amount that they may be exposed to. Above that limit, certain protection mechanisms start interacting to prevent damage occurring to the sensors. [Read more...]

processing with High Dynamic Range (1)

Back in time when I was at university, my very first DSP lectures were actually not about audio but image processing. Due to my interest in photography I followed this amazing and ever evolving domain over time. Later on, High Dynamic Range (HDR) image processing emerged and beside its high impact on digital photography, I immediately started to ask myself how such techniques could be translated into the audio domain. And to be honest, for quite some time I haven’t got a clue.

MM

This image shows a typical problem digital photography still suffers from: The highlights are completely washed out and so the lowlights are turning into black abruptly w/o containing further nuances  – the dynamic range performance is pretty much poor and this is actually not what the human eye would perceive since it features both: a higher dynamic range per se but also a better adoption to different (and maybe difficult) lighting conditions.

On top, we have to expect severe dynamic range limitations in the output entities whether that’s a cheap digital print, a crappy TFT display or the limited JPG file format, just as an example. Analog film and prints does have such problems in principle also but not to that much extend since they typically offer more dynamic resolution and the saturation behavior is rather soft unlike the digital hard clipping. And this is where HDR image processing chimes in.

It typically distinguishes between single- and multi-image processing. Within multi-image processing, a series of Low Dynamic Range (LDR) images are taken in different exposures and combined into one single new image which contains an extended dynamic range (thanks to some clever processing). Afterwards, this version is rendered back into an LDR image by utilizing special  “tone mapping” operators which are performing a sort of dynamic range compression to obtain a better dynamic range impression but now in a LDR file.

Within single-image processing, there must be one single HDR image already available and then just tone mapping is applied. As an example, the picture below takes advantage of single-image processing from a RAW file which typically does have much higher bit-depth (12 or even 14 bit as of todays sensor tech) opposed to JPG (8 bit). As a result a lot of dynamic information can be preserved even if the output file still is just a JPG. As an added sugar, such a processed image also translates way better over a wide variety of different output devices, displays and viewing light conditions.

MM-HDR

mixing kick and bass w/o EQ

Featuring FerricTDS.

Thanks to Justin for sharing!

how to mix a hit record

Featuring NastyDLA and FerricTDS.

utilizing early reflections in a production

A quite often underestimated or even forgotten production technique is to take advantage of artificial early reflections which could be added somewhere during the mixing process. Without inserting any fully fledged reverberation at all, applying such techniques allows to dramatically increase stereo width and depth perception as well as a way better instrument localization even in a busy mix. Creating density is not the goal here but the opposite is the name of the game: achieving a clear and intelligible mix.

In a simple case, one can place a short and plain delay (a slap-back echo) on a track and properly place it in the stereo field – maybe on the opposite side of the source but that’s just an example. More sophisticated tap delays could be used to create a sort of room experience and some reverberators are allowing to disable the late reverb diffusion and just to use their early reflection generation. There are no restrictions in general – allowed is what gets the job done in that specific mixing situation.

Thrillseeker XTC – behind the scenes

The basic idea to build a VoS style Enhancer/Exciter was already there way earlier but to that time it simply wasn’t doable until my ‘stateful saturation’ approach emerged. Later on and when I asked “how a modern exciter/enhancer should look like“, several concepts were laid out on the drawing board and I knew that with this exciting (sic!) new approach they all would be accomplishable w/o any compromises. Finally, one of them made it into a prototype which led to ThrillseekerXTC.

Old or modern approach?

So, is the audio Enhancer/Exciter just an ancient relict from the days of dull tape recordings or still a valid concept today? In the digital age, technology and production techniques completely changed and of course the production aesthetics did also. Opposed to the old approaches of audio excitation which mostly were focusing on high frequency loss restoration, the demand shifted towards other tasks as well. Presence and definition in the (upper) mid range is the name of the game and getting the low-end right is the key in a modern production. Instrument separation in a busy mix is a tough challenge, also.

What the heck is Mojo?

In some other cases (mostly digital productions) – definition, presence and transparency is all there but at the cost of a rather thin or sterile sounding production. Even worse, the HF department might be exaggerated too much during the processing chain and taming and sweetening is a challenge then. Some of the artifacts that we’ve found in certain analog devices might add tonal qualities described as thick, fat and round by ‘pleasingly degrading’ a sound source. This is what Mojo is all about. Whether that’s some circuit crosstalk, tape flutter or transformer distortion stuff alike. [Read more...]

working ITB at higher sampling rates

Recently, I’ve moved from 44.1kHz up to 96kHz sampling rate for my current production. I would have loved to do this step earlier but it wasn’t possible with the older DAW generation in my case. With the newer stuff I was easily able to run a 44.1kHz based production with tons of headroom (resource wise – talking about CPU plus memory and disk space) and so I switched to 96kHz SR and still there is some room left.

I know there is a lot of confusion and misinformation floating around about this topic and so this small article is about to give some theoretical insights from a developer perspective as well as some hands-on tips for all those who are considering at what SR actually to work at. The title already suggests working ITB (In The Box) and I’ll exclude SR topics related to recording, AD/DA converters or other external digital devices. [Read more...]

tasty meal preparations with Density mkIII

Since precise routing and stuff like that is not taken down into the cookbook as of now, here are some exciting tips and tricks to experiment with and maybe to obtain a different approach to cook audio with Density mkIII.

Starter

As a starter just use the default preset and dial in huge amounts of compression right with the DRIVE knob. Now mix this back to the dry signal by using the DRY:WET option to obtain a thick sounding result (New York style compression). Since the COLOR option ignores any DRY:WET settings one can dial it in afterwards to thicken the soup even further. Hmm, tasty!

Second course

Set DRY:WET back to a 100% wet signal but also pull RANGE back to the left so that there will be no gain reduction anymore. There is no compression anymore now but one can still use the MAKEUP knob to drive the gain of the non-linear circuits. Use this and experience a hot (driven) meal.

Main course

By finishing the second course, you not only have a sophisticated non-linear amplifier now where you can dial in the coloration with the COLOR knob to taste. You also can use this in M/S mode to adjust the stereo imaging in a quite unique fashion just by adjusting the amounts of saturation per channel right with the MAKEUP knobs. Omph, I’m feelin so wide now!

Dessert

Just dial in again some amounts of compression by turning RANGE clockwise, maybe full to the right but RELAX the attack times so that some transients can pass. Those will be eaten now by the non-linear amplifier as an added sugar.

Espresso, anyone?

what I’m currently working on – Vol. 7

Updates, basically. I’m still struggling with a preFIX update due to some technical issues I just can’t get, errrm, fixed (some VST hosts still do not respond to reported delay changes). Well, lets see how many month or years this will gonna take to work around or maybe then those hosts are just obsolete ;-) At least, I’m pretty much sure that we will see two other updates here during Q2: First, there will be a smaller update for the BaxterEQ where small  is indeed the proper wording because it’s mainly about an additional but just smaller GUI version. [Read more...]

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