Seminar on instrument design, software, control

Online seminar March 21

Trond Engum and Sigurd Saue (Trondheim)
Bernt Isak Wærstad (Oslo)
Marije Baalman (Amsterdam)
Joshua Reiss (London)
Victor Lazzarini (Maynooth)
Øyvind Brandtsegg (San Diego)

Instrument design, software, control

We now have some tools that allow practical experimentation, and we’ve had the chance to use them in some sessions. We have some experience as to what they solve and don’t solve, how simple (or not) they are to use. We know that they are not completely stable on all platforms, there are some “snags” on initialization and/or termination that give different problems for different platforms. Still, in general, we have just enough to evaluate the design in terms of instrument building, software architechture, interfacing and control.

We have identified two distinct modes of working crossadaptively: The Analyzer-Modulator workflow, and a Direct-Cross-Synthesis workflow. The Analyzer-Modulator method is comprised of extracting features, and arbitrarily mapping these features as modulators to any effect parameter. The Direct-Cross-Synthesis method is comprised by a much closer interaction directly on the two audio signals, for example as seen with the liveconvolver and or different forms of adaptive resonators. These two methods give very different ways of approaching the crossadaptive interplay, with the direct-cross-synthesis method being perceived as closer to the signal, and as such, in many ways closer to each other for the two performers. The Analyzer-Modulator approach allows arbitrary mappings, and this is both a strngth and a weakness. It is powerful by allowing any mapping, but it is harder to find mappings that are musically and performatively engaging. At least this can be true when a mapping is used without modification over a longer time span. As a further extension, an even more distanced manner of crossadaptive interplay was recently suggested by Lukas Ligeti (UC Irvine, following Brandtsegg’s presentation of our project there in January). Ligeti would like to investigate crossadaptive modulation on MIDI signals between performers. The mapping and processing options for event-based signals like MIDI would have even more degrees of freedom than what we achieve with the Analyzer-Modulator approach, and it would have an even greater degree of “remoteness” or “disconnectedness”. For Ligeti, one of the interesting things is the diconnectedness and how it affects our playing. In perspective, we start to see some different viewing angles on how crossadaptivity can be implemented and how it can influence communication and performance.

In this meeting we also discussed problems of the current tools, mostly concerned with the tools of the Analyzer-Moduator method, as that is where we have experienced the most obvious technical hindrance for effecttive exploration. One particular problem is the use of MIDI controller data as our output. Even though it gives great freedom in modulator destinations, it is not straightforward for a system operator to keep track of which controller numbers are actively used and what destinations they correspond to. Initial investigations of using OSC in the final interfacing to the DAW have been done by Brandtsegg, and the current status of many DAWs seems to allow “auto-learning” of OSC addresses based on touching controls of the modulator destination within the DAW. a two-way communication between the DAW and ouurr mapping module should be within reach and would immensely simplify that part of our tools.
We also discussed the selection of features extracted by the Analyzer, whic ones are more actively used, if any could be removed and/or if any could be refined.

Initial comments

Each of the participants was invited to give their initial comments on these issues. Victor suggests we could rationalize the tools a bit, simplify, and get rid of the Python dependency (which has caused some stability and compatibility issues). This should be done without loosing flexibility and usability. Perhaps a turn towards the originally planned direction of reying basically on Csound for analysis instead of external libraries. Bernt has had some meetings with Trond recently and they have some common views. For them it is imperative to be able to use Ableton Live for the audio processing, as the creative work during sessions is really only possible using tools they are familiar with. Finding solutions to aesthetic problems that may arise require quick turnarounds, and for this to be viable, familiar processing tools.  There have been some issues related to stability in Live, which have sometimes significantly slowed down or straight out hindered an effective workflow. Trond appreciates the graphical display of signals, as it helps it teaching performers how the analysis responds to different playing techniques.

Modularity

Bernt also mentions the use of very simple scaled-down experiments directly in Max, done quickly with students. It would be relatively easy to make simple patches that combines analysis of one (or a few) features with a small number of modulator parameters. Josh and Marije also mentions modularity and scaling down as measures to clean up the tools. Sigurd has some other perspectives on this, as it also relates to what kind of flexibility we might want and need, how much free experimentation with features, mappings and desintations is needed, and also to consider if we are making the tools for an end user or for the research personell within the project. Oeyvind also mentions some arguments that directly opposes a modular structure, both in terms of the number of separate plugins and separate windows needed, and also in terms of analyzing one signal with relation to activity in another (f.ex. for cross-bleed reduction and/or masking features etc).

Stability

Josh asks about the stability issues reported. any special feature extractors, or other elements that have been identified that triggers instabilities. Oeyvind/Victor discuss a bit about the Python interface, as this is one issue that frequently come up in relation to compatibility and stability. There are things to try, but perhaps the most promising route is to try to get rid of the Python interface. Josh also asks about the preferred DAW used in the project, as this obviously influence stability. Oeyvind has good experience with Reaper, and this coincides with Josh’s experience at QMUL. In terms of stability and flexibility of routing (multichannel), Reaper is the best choice. Crossadaptive work directly in Ableton Live can be done, but always involve a hack. Other alternatives (Plogue Bidule, Bitwig…) are also discussed briefly. Victor suggests selecting a reference set of tools, which we document well in terms of how to use them in our project. Reaper has not been stable for Bernt and Trond, but this might be related to  setting of specific options (running plugins in separate/dedicated processes, and other performance options). In any case, the two DAWs of immediate practical interest is Reaper (in general) and Live (for some performers).  An alternative to using a DAW to host the Analyzer might also be to create a standalone application, as a “server”, sending control signals to any host. There are good reasons for keeping it within the DAW, both as session management (saving setups)  and also for preprocessing of input signals (filtering, dynamics, routing).

Simplify

Some of the stability issues can be remedied by simplifying the analyzer, getting rid of unused features, and also getting rid of the Python interface. Simplification will also enable use for less trained users, as it enable self-education and ability to just start using it and experiment. Modularity might also enhance such self-education, but a take on “modularity” might simply hiding irrelevant aspects of the GUI.
In terms of feature selection the filtering of GUI display (showing only a subset) is valuable. We see also that the number of actively used parameters is generally relatively low, our “polyphonic attention” for following independent modulations generally is limited to 3-4 dimensions.
It seems clear that we have some overshoot in terms of flexibility and number of parameters in the current version of our tools.

Performative

Marije also suggests we should investigate further what happens on repeated use. When the same musicians use the same setup several times over a period of time, working more intensively, just play, see what combinations wear out and what stays interesting. This might guide us in general selection of valuable features. Within a short time span (of one performence), we also touched briefly on the issue of using static mappings as opposed to changing the mapping on the fly. Giving the system operator a more expressive role, might also solve situations where a particular mapping wears our or becomes inhibiting over time. So far we have created very repeatable situations, to investigate in detail how each component works. Using a mapping that varies over time can enable more interesting musical forms, but will also in general make the situation more complex. Remembering how performers in general can respond positively to a certain “richness” of the interface (tolerating and even being inspired by noisy analysis), perhaps varying the mapping over time also can shift the attention more on to the sounding result and playing by ear holistically, than intellectually dissecting how each component contributes.
Concluding remarks also suggests that we still need to play more with it, to become more proficient, having more control, explore and getting used to (and getting tired of) how it works.

 

 

 

Live convolution with Kjell Nordeson

Session at UCSD March 14.

Kjell Nordeson: Drums
Øyvind Brandtsegg: Vocals, Convolver.

Contact mikes

In this session, we explore the use of convolution with contact mikes on the drums to reduce feedback and cross-bleed. There is still some bleed from drums into the vocal mike, and there is some feedback potential caused by the (miked) drumheads resonating with the sound coming from the speaker. We have earlier used professional contact mikes, but found that our particular type did have a particularly low output, so this time we tried simple and cheap piezo elements from Radio shack, directly connected to high impedance inputs on the RME soundcard. This seems to give very high sensitivity and a fair signal to noise ratio. The frequency response is quite narrow and “characteristic” to put it mildly, but for our purposes, it can work quite well. Also, the high frequency loss associated with convolution is less of an issue when the microphones have such an abundance of high frequencies (and little or no low end).

IR update triggering

We have added the option of using a (midi) pedal to trigger IR recording. This allows a more deliberate performative control of the IR update. This was  first used by Kjell, while Øyvind was playing through Kjell’s IR. Later switched roles. Kjell notes that the progression from IR to IR works well, and that we definitely have some interesting interaction potential here. The merging of the sound from the two instruments creates a “tail” of what has been played, and that we continue to respond to that for a while.
When Kjell recorded the IR, he thought it was an extra distraction to have to also need to focus on what to record, and to operate the pedal accordingly. The mental distraction probably is not so much in the actual operation of the pedal, but in the reflection over what would make a good sound to record. It is not yet easy to foresee (hear) what comes out of the convolution process, so understanding how a particular input will work as an IR is a sort of remote and second-degree guesswork. This is of course also further complicated by not knowing what the other performer will play through the recorded IR. This will obviously become better with more experience using the techniques.
When we switched roles (vocal recording the IR), the acoustic/technical situation became a bit more difficult. The contact mikes, would pick up enough sound from the speakers (also through freely resonating cymbals resting on the drums, and via non-damped drum heads) to create feedback problems. This also creates extra repetitions of the temporal pattern of the IR due to the feedback potential. It was harder to get the sound completely dry and distinct, so the available timbral dynamic was more in the range from “mushy” to “more mushy” (…). Still, Kjell felt this was “more like playing together with another musician”. The feeling of playing through the IR is indeed the more performatively responsive situation, overpowered by the reduction in clarity that was caused by the technical/acustical difficulties. Similarly, Øyvind thought it was harder because the vocals only manifest themself as the ever changing IR, and the switching if the IR does not necessarily come across as a real/quick/responsive musical interaction. Also, delivering some material for the IR makes the quality of the material and the exact excerpt much more important. It is like giving away some part of what you’ve played, and it must be capable of being transformed out of your own control, so the material might become more transparent to it’s weaknesses. One can’t hide any flaws by stringing the material together in a well-flowing manner, rather the stringing-together is activated by the other musician. Easily, I can recognize this as the situation any musician being live sampled or live processed must feel, so it is a “payback time” revelation for me, having been in the role of processing others for many years.

Automatic IR update

We also tried automatic/periodic IR updates, as that would take the distraction of selecting IR material away, and we could more easily just focus on performing. The automatic updates shows their own set of weaknesses when compared with the manually triggered ones. The automatic update procedure essentually creates a random latency for the temporal patterns created by the convolution. This is because the periodic update is not in any way synchronized to the playing, and the performers do not have a feedback (visually or auditively) on the update pulse. This means the the IR update might happen offbeat or in the middle of a phrase. Kjell suggested further randomizing it as one solution. To this, Øyvind responds that it is already essentially random since the segmentation of input and the implied pulse of the material is unrelated, so it will shift in an unpredictable and always changing manner. Then again, following up on Kjells suggestion and randomizing it further could create a whole other, more statistical approach.  Kjell also remarks that this way of playing it feels more like “an effect”, something added, that does not respond as interactively. It just creates a (echo pattern) tail out of whatever is currently played. He suggested updating the IR at a much lower rate, perhaps once every 10 seconds. We tried a take with this setting too.

Switching who has the trigger pedal

Then, since the automatic updates seems not to work too well, and the mental distracion of selecting IR material seems unwanted, we figured, maybe the musician playing through the IR should be the one triggering the IR recording. This is similar (but exactly opposite) to the previous attempts at manual IR record triggering. Here, the musician playing through the IR is the one deciding the time of IR recording, and as such has some influence over the IR content. Still he can not decide what the other musician is playing at the time of recording, but this type of role distribution could create yet another kind of dynamic in the interplay. Sadly the session was interrupted by practical matters at this point, so the work must continue on a later occation.

Audio

kjellconvol1 kjellconvol1

Take1: Percussion IR, vocal playing through the IR. Recording/update of IR done by manual trigger pedal controlled by the percussionist. Thus it is possible to emphasize precise temporal patterns. The recording is done only with contact mikes on the drums, so there is some “disconnectedness” to the acoustic sound.

 

kjellconvol2 kjellconvol2

Take2: Vocal IR, percussion playing through the IR. Recording/update of the IR done by manual trigger pedal controlled by the singer. As in take 1, the drums sound going into the convolver  is only taken from the piezo pickups. Still, there is a better connectedness to the acoustic drum sound, due to an additional room mike being used (dry).

 

kjellconvol3 kjellconvol3

Take3: Percussion IR, automatic/periodic IR update. IR length is 3 seconds, IR update rate is 0.6 Hz.

 

kjellconvol4 kjellconvol4

Take4: Percussion IR, automatic/periodic IR update. IR length is 2.5 seconds, IR update rate is 0.2 Hz.

Other reflections

IR replacement is often experienced as a sudden musical change. There is no artifacts caused by the technical operation of updating the IR, but the musical result is more often a total change of “room characteristic”. Maybe we should try finding methods of slowly crossfading when updating the IR, keeping some aspects of the old one in a transitory phase. There is also a lot to be gained performatively, by the musician updating the IR having these transitions in mind. Choosing what to play and what to record is an effective way of controlling if the transitions should be sudden or slow.