grayscale, Gray Code
2004-01-07 by Robert Welcyng
The grayscale attached to the DKV pedal shaft is used to encode the position of the shaft and damper. Think of a piece of film, attached to the pedal shaft, so that as the shaft moves up and down, the film slides through a housing with a light on one side and a horizontal array of photodetectors on the opposite side. The film carries a mask that is divided into columns and rows, one column for each photodetector, one row for each damper/shaft position. At each shaft position, the mask blocks the light in some column positions and allows it to pass in the others The pattern sensed by the photodetector array represents the position of the film and thus of the damper. A DKV designer might be tempted to pattern the mask in the traditional binary pattern: 0000, 0001, 0010, 0011, 0100, etc. . . . opaque boxes for zeros, and transparent for ones. Note, however, that some transitions (like the last one above) involve changes in more than a single bit and would invite an unacceptable ambiguity should the mask be positioned halfway between two mask rows. To preclude such a gross ambiguity, a different pattern, called the Gray Code, is used on the mask. The relevant characteristic of the Gray Code is that only one mask column (thus bit) changes during any row transition; thus, ambiguities can be reduced to a single bit. Now, everybody, please join me in shutting down your computers, returning to your pianos, sitting down, and trying to learn to play something on it--with your hands and fingers on the keys. If you can't resist goofing off to pursue this wild Gray Code tangent further, you may first consult the following link before getting down to business at your piano. http://www.cs.bham.ac.uk/Mirrors/ftp.de.uu.net/EC/clife/www/Q21.htm Bob Danny wrote: > From: "Carol Beigel" <crbrpt@...> > >>To save some of you a lot of time, I thought I would mention what I perceive >>to be a misconception. Pedal, key and hammer sensors only affect the >>Recording and have nothing to do with playback. > > > D: Hi Carol, > > D: Thanks for your input and clarification here. > > >>All Yamaha PianoSoft music is RECORDED on DKV models with incremental >>pedaling. When you use the Record feature yourself, this data is also >>recorded. Using the gray scale, this data is encoded in the pedal >>information. If you have a DKV with incremental pedaling, as most do, then >>this data plays back on your DKV. If you don't have this feature, the pedal >>will be either ON or OFF. The gray scale sensors only observe and record >>data, not do anything to control the playback of the pedal solenoid. >>Disklaviers without incremental pedaling will ALWAYS be thumpier than those >>equipped with this feature. > > > D: Can you elaborate on the term 'gray scale'? > > D: I am currently working on only playing back existing MIDI files. What I am > currently working on is attempting to first find out which models have the > incrementing pedaling feature, i.e., which models began to implement it. The > .pdf file that you placed in the 'files' section here does not include that > information. Do you happen to know which models started implementing it? Also, > it seems that there are still differences in 'behavior' between models that do > have the incremental pedaling implemented; i.e., the differences between the > Mark II and MarkII XG models that Robert and I have. Obviously, this could get > quite detailed... > > D: Out of curiosity, does the incremental pedaling info also get recorded (when > a DKV supports it) to MIDI out when using the DKV MIDI output to a MIDI > sequencer using either the MIDI port <or> the 'To Host' connector? > > >>The same goes for Key and Hammer sensors. These things simply record what >>is happening and translate the information into data. They have no control >>over playback. Disklavier acoustic pianos are completely controlled by the >>geometry and mechanics of the mechanical piano action that causes the piano >>hammers to strike the strings. > > > D: Understood. The DKV has a totally separate recording and playback mechanism. > This 'geometry and mechanics of the mechanical piano action' between different > pianos is also a factor in addition to the firmware differences. > > >>All this means is that Disklaviers equipped with incremental pedaling and >>hammer sensors will RECORD a piano performance with more nuance than those >>DKVs without them. Your Disklavier, however, will respond to music recorded >>on other pianos even though the data on these files is not necessarily >>optimized for your model. Yamaha PianoSoft will always be optimized to play >>on your instruments. Most of the MIDI files on the internet, as most have >>you have noticed, are NOT optimized for playback on an acoustic piano and >>require adjustments to the volume and sometimes the pedal data. That does >>not mean there are deficiencies in your DKV design or condition!! > > > D: I realize that it would be impossible to playback accurately any downloadable > MIDI file. (Even a good quality one.) What I am trying to ascertain, is possibly > a good 'medium' that *may* help for various MIDI files on earlier DKVs. The > biggest problem in working on this this, is that I would need several DKVs > sitting in front of me to try different ideas on. This may turn out to be too > complex to be achievable, but I am investigating it. The main thing that I am > looking at is the pedaling issue, and maybe how to lessen the effects on those > models which do not support the playback incremental pedaling and are having > difficulty in having it adjusted. After personally 'hearing' this thumping on my > DKV, I am somewhat motivated in trying to find a 'fix' for those that cannot get > rid of it. I will need to find an owner locally in my area with such a model > willing to try some MIDI conttoller ideas on their piano. This would be > difficult to work on something as this 'long distance' by sending out MIDI files > for possible trial and error... > > D: Danny > > > To Post a message to the group, send it to: disklavier@... > > To Post a private message to Todd Muncy, the group's founder and moderator, send it to: > disklavier-owner@... > > To reach our group's web site go to: > http://Yahoogroups.com/group/disklavier > > Todd's family web site was completely updated 012/22/03. It contains some fun disklavier content and links to midi sites among many other things, The url is: > http://MuncyFamily.com > > THINKING OF LEAVING THE GROUP? > If you are thinking of unsubcribing because you are getting too much mail, go the the web site and change your email delivery option instead. That will fix the problem, while maintaining your access to the group. If you insist on leaving us completely send a blank email to: > disklavier-unsubscribe@... > > Know someone who wants to join? Have them send a blank email to: > disklavier-subscribe@... or give them this link: > http://Yahoogroups.com/group/disklavier/join > > > Yahoo! Groups Links > > To visit your group on the web, go to: > http://groups.yahoo.com/group/disklavier/ > > To unsubscribe from this group, send an email to: > disklavier-unsubscribe@yahoogroups.com > > Your use of Yahoo! Groups is subject to: > http://docs.yahoo.com/info/terms/ > > > -- Robert Welcyng Anchorage, Alaska