# gnireenigne Published articles for gnireenigne. This is one page of public article previews, not the complete archive. Follow Next page to continue. Summaries are not the original full articles. ## Analyzing and Synthesizing the Otamatone's Tone DevFeed: [Analyzing and Synthesizing the Otamatone's Tone]() Original publisher: [Read original article]() Author: Oona Räisänen (noreply@blogger.com) Published: 2017-11-25T14:03:00Z Content type: article Language: en Sources: [Oona Räisänen]() Topics: [Software](), [MIDI](), [coding]() Tags: [art](), [audio](), [gnireenigne](), [music](), [software](), [toys]() ### AI overview The article investigates how to recreate the Otamatone's sound as a programmable virtual instrument. It compares microphone recordings with simpler waveform models, then describes capturing the speaker input directly through a soldered Line Out connection. The recorded signal appears to combine a low-duty-cycle square wave with a quieter 584 Hz sinusoidal ring that fades over 30 milliseconds. ### Source excerpt It would be fun to use the Otamatone in a musical piece. But for someone used to keyboard instruments it's not so easy to play cleanly. It has a touch-sensitive (resistive) slider that spans roughly two octaves in just 14 centimeters, which makes it very sensitive to finger placement. And in any case, I'd just like to have a programmable virtual instrument that sounds like the Otamatone. What options do we have, as hackers? Of course the slider could be replaced with a MIDI interface, so that we could use a piano keyboard to hit the correct frequencies. But what if we could synthesize a similar sound all in software? Sampling via microphone We'll have to take a look at the waveform first. The Otamatone has a piercing electronic-sounding tone to it. One is inclined to think the waveform is something quite simple, perhaps a sawtooth wave with some harmonic coloring. Such a primitive signal would be easy to synthesize. A friend lended me her Otamatone for recording purposes. Turns out the wave is nothing that simple. It's not a sawtooth wave, nor a square wave, no matter how the microphone is placed. But it sounds like one! Why could that be? I suspect this is because the combination of speaker and air interface filters out the lowest harmonics (and parts of the others as well) of square waves. But the human ear still recognizes the residual features of a more primitive kind of waveform. We have to get to the source! Sampling the input voltage to the Otamatone's speaker could reveal the original signal. Also, by recording both the speaker input and the audio recorded via microphone, we could perhaps devise a software filter to simulate the speaker and head resonance. Then our synthesizer would simplify into a simple generator and filter. But this would require opening up the instrument and soldering a couple of leads in, to make a Line Out connector. I'm not doing this to my friend's Otamatone, so I bought one of my own. I named it TÄMÄ. I soldered the left channel and ## Headerless train announcements DevFeed: [Headerless train announcements]() Original publisher: [Read original article]() Author: Oona Räisänen (noreply@blogger.com) Published: 2014-06-16T18:55:00Z Content type: article Language: en Sources: [Oona Räisänen]() Topics: [data](), [Filesystems]() Tags: [audio](), [audio-media](), [data](), [encoding](), [files](), [format](), [gnireenigne](), [iso]() ### AI overview The article examines a 67-megabyte ISO 9660 image from an older Finnish train announcement device. It documents the file and directory structure, language separation, and 1,950 stored sound files, then investigates their unidentified headerless audio encoding. Analysis suggests 4-bit adaptive differential PCM, and partial decoding produces garbled speech after frequency and spectral processing. ### Source excerpt The Finnish state railway company just changed their automatic announcement voice, discarding old recordings from trains. It's a good time for some data dumpster diving for the old ones, don't you think? A 67-megabyte ISO 9660 image is produced that once belonged to an older-type onboard announcement device. It contains a file system of 58 directories with five-digit names, and one called "yleis" (Finnish for "general"). Each directory contains files with three-digit file names. For each number, there's 001.inf, 001.txt and 001.snd. The .inf and .txt files seem to contain parts of announcements as ISO 8859 encoded strings, such as "InterCity train" and "to Helsinki". The .snd files obviously contain the corresponding audio announcements. There's a total of 1950 sound files. Directory structure The file system seems to be structurally pointless; there's nothing apparent that differentiates all files in /00104 from files in /00105. Announcements in different languages are numerically separated, though (/001xx = Finnish, /002xx = Swedish, /003xx = English). Track numbers and time readouts are stored sequentially, but there are out-of-place announcements and test files in between. The logic connecting numbers to their meanings is probably programmed into the device for every train route. Everything can be spliced together from almost single words. But many common announcements are also recorded as whole sentences, probably to make them sound more natural. Audio format The audio files are headerless; there is no explicit information about the format, sample rate or sample size anywhere. The byte histogram and Poincaré plot of the raw data suggest a 4-bit sample size; this, along with the fact that all files start with 0x80, is indicative of an adaptive differential PCM encoding scheme. Unfortunately there are as many variations to ADPCM as there are manufacturers of encoder chips. None of the decoders known by SoX produce clean results. But with the right settings for th