Path: utzoo!attcan!uunet!samsung!zaphod.mps.ohio-state.edu!mips!ultra!jimh From: jimh@ultra.com (Jim Hurley) Newsgroups: comp.music Subject: Re: Compact Disks with Musical Instruments on them Message-ID: <1990Apr11.170900.558@ultra.com> Date: 11 Apr 90 17:09:00 GMT References: <6184@accuvax.nwu.edu> Organization: Ultra Network Technologies Lines: 124 sandell@ferret.Berkeley.EDU (Greg Sandell) writes: >Recently I purchased four of the compact disks in the McGill University >Master Samples series. [ deleted ] >I have been doing spectral analyses of entire instruments in the >McGill series, and, having seen tremendous note-to-note differences, >am convinced that a strategy of recording only every fourth note >is a real error. [deleted] > I am not a Sampling Keyboard >user, but it strikes me that just because the current memory >capacities of these devices only allow the sampling of every fourth >note, it is extremely shortsighted to go through the trouble of >recording such tones at great expense and releasing them on CDs when >it's only a matter of time before memory is so cheap that the current >limitations of Sampling Keyboards will be a joke. [deleted] >**************************************************************** >* Greg Sandell (sandell@ils.nwu.edu) * >* Institute for the Learning Sciences, Northwestern University * >**************************************************************** You haven't gotten any responses to this yet so I'll take a stab. I had a fairly violent reaction to this posting because of my own synthesis bias and I'm by no means a sampler expert - never having used one. But that won't stop me from expressing some opinions. I'll relate my bias as I go. About every fourth note... I think most samplers allow you to place a sample over any range of keys, down to a single key, and it will pitch-shift within that range. There may be individual limitations due to design or memory but there's nothing intrinsic in a sampler to prevent this. I suppose that every fourth note was just a concession to space or time constraints on the CD or the performers. I could be wrong about this because as I said I have never used a sampler, but I understand the technical architecture. In the following discussion I'll use a violin instrument for the sake of a concrete example, other instruments share some of this and perhaps have other topics of import. Firstly: where do you stop? Are the notes tuned in equal-temperament? If so, won't your sampler's chamber music sound odd? I thought most good chamber players use just or Pythagorean tunings or tend in that direction. And what if you want microtonal intervals? In short, just what interval do you want? Second point: what instrument do you want sampled and how many? Do you want a Stradivarius and a Guarnerius violin sample? Third point: how was the sample made? Radiation patterns around the violin are difficult to simulate from a single microphone source or even a stereo pair. Depending on where the mic(s) are you may see spectral changes more radical on a single note from mic location-to-location than you see from note-to-note at a fixed location. Fourth point: this relates to the final sound from a sampler. The original sample will probably be neutral, void of as much artistic modulation as possible, since it is the basic source in the synth and you will want to impose performance modulations from the synth controls. In other words, the vibrato will come from, say, a mod wheel controlling an LFO which modulates various internal processors in the synth. I don't think you want the sample to have any vibrato at all or you're stuck with this at the source level and will get peculiar results if you want to change it (or if you want to play, say, a Bartok piece that requires no vibrato). Bowing effects will also have to be programmed somehow and you don't want to have any strong bowing in the original sample. By the time you reduce the sample to this simple basic source, it hardly seems to matter much how many notes were originally sampled, as long as you get the main registers correct. Your real problem will be to put some life into that sound within the limitations of the sampler. Fifth point: here's where my own bias comes in. Why do you want to sample a live instrument anyway? If it's to imitate it as much as possible get a mellotron;-). If it's just a starting point to an original sound then you're talking my language and the number of samples is not such a problem. I happen to feel that there's many wonderful and unique sounds out there that are the rightful domain of electronic instruments. We should spend our time looking for these and learning how to be skillful in their execution. Imitation can be an extremely valuable lesson in synthesis, but it is a tool and not an end result. Of course this is idealistic and there are practical concessions to make to those who want to play others' compositions and don't have the resources of a symphony at their disposal (this probably includes all of us:-). I'm addressing this note from the point of view of a composer, not a performer. Some other points. I don't think that memory limitations will ever be the main problem here. I think it will be the ability to to translate human gestures into meaningful modulation processes. Let's look at the memory requirements, however, and let's be a bit extravagant in our hypothetical design. Let's assume that we want better-than-CD quality stereo output over the 128 note MIDI range from our instrument and let's see how much memory that will consume per instrument. In practice there may be multiple samples cross-faded or otherwise mixed to get a real instrument, but that will just be a multiplier in the final number. Assumptions: 100KHz sampling, 32 bit samples (32-bits is a nice memory width with current micros), 128 notes, 2 channels, 10 second sample time (pick your time here); the memory requirements are then 100000 samples/sec/note/channel * 10 secs * 128 notes * 32 bits/sample * 2 channels = 8 192 000 000 bits or approximately 2**33 bits. Current memory chips are now 4Meg (is that right?, it's been a while since I looked at these) and the size is doubling or squaring every few years. So in a few years we can store about one of these instruments in a memory chip. Of course, storage of the whole repertoire of instruments will probably be an external devices, but we'll still need to store a few instruments in the main sound memory. And undoubtedly there will be storage technology breakthroughs that we can't imagine in the next decade. -- Jim Hurley --> jimh@ultra.com ...!ames!ultra!jimh (408) 922-0100 Ultra Network Technologies / 101 Daggett Drive / San Jose CA 95134