# audio media Published articles for audio media. This is one page of public article previews, not the complete archive. Follow Next page to continue. Summaries are not the original full articles. ## Smoother sailing: Studying audio imperfections in Steamboat Willie DevFeed: [Smoother sailing: Studying audio imperfections in Steamboat Willie]() Original publisher: [Read original article]() Author: Oona Räisänen (noreply@blogger.com) Published: 2024-01-23T19:47:00Z Content type: tutorial Language: en Sources: [Oona Räisänen]() Topics: [Playback](), [Compression](), [Tool](), [Code]() Tags: [audio](), [audio-media](), [code](), [compression](), [music](), [playback](), [tool]() ### AI overview The article examines flutter distortion in the soundtrack of the 1928 cartoon Steamboat Willie. It discusses prior attempts to reduce the unstable playback or recording speed, including Celemony Capstan, and considers a homemade approach using a high-quality digital source. ### Source excerpt Steamboat Willie (1928) was one of the earliest cartoons with synchronized sound. That is, it had post-production sound effects; this was something new and exciting. Now that the cartoon has recently entered the public domain[bbc24] we can safely delve into its famous soundtrack. See, there's something interesting about how it sounds... If you listen closely to the soundtrack on Youtube it sounds somehow distorted. You might be tempted to point out that it's 96 years old, yes. But you might also recognize that it is suffering from flutter, i.e. an unstable playback or recording speed. In the spirit of this blog let's geek out for a bit and study this flutter distortion further. Can we learn something interesting? Could we perhaps learn enough to be able to reduce it? Of course the flutter might be 100% authentic to how it sounded in theatres in the 1920s; we don't know when and why it appeared in the audio (more on that later!). It might have sounded even worse. But we can still hope to enjoy the sound effects in their original recorded form. Prior work I'm not the first one to notice this clip is 'fluttering' and to try and do something about it. I found videos of people's attempts to un-flutter it using Celemony Capstan, a professional tool made just for this purpose, with varying results. Capstan uses Melodyne's famous note detection engine to detect musical features and then controls a varispeed effect to cancel out any flutter. But Capstan is expensive, and it's more fun to come up with a home-made solution anyway. And what about non-musical sounds? Besides, I had some code laying around in a forgotten desk drawer that just might fit the purpose. Finding a high quality source Why would I need a high-quality digital file of a poor-quality soundtrack from the 1920s? I guess it's the archivist in me hoping that it has been preserved with high level of detail. But also, if you're going to try and dig up some hidden details in the sound, you'd want minimal interfere ## Plotting patterns in music with a fantasy record player DevFeed: [Plotting patterns in music with a fantasy record player]() Original publisher: [Read original article]() Author: Oona Räisänen (noreply@blogger.com) Published: 2020-12-08T21:42:00Z Content type: article Language: en Sources: [Oona Räisänen]() Topics: [Script](), [e-ink](), [3D]() Tags: [3d](), [art](), [audio-media](), [blender](), [computer](), [e-ink](), [experiment](), [music](), [patterns](), [physics](), [plotting](), [script](), [shower-thoughts](), [signal](), [video]() ### AI overview The article explores how a vinyl record's wavy surface pattern can reflect the tempo and beat structure of its music. It describes a script that plots FLAC amplitude into a tempo-based grid and discusses clearer patterns in quantized electronic, pop, and rock music, along with a 3D-rendered fantasy record-player experiment. ### Source excerpt Back in April I bought a vinyl record that had a weird wavy pattern near the outer edge. I though I may have broken it somehow but couldn't even test this because I don't own a record player. *) But when I took a closer look at the pattern it seemed to somehow follow changes in the music. That doesn't look like damage at all. When I played the CD version it became clear: this was an artifact of the tempo of the electronic track (100 bpm) being a multiple of the rotational speed (33 1/3 rpm), and these were probably drum hits! My tweet sparked some interesting discussion and I've been pondering this ever since. Could we plot any song as a loop or grid based on its own tempo and see interesting patterns? (*) I know, it's a little odd. But I have a few unplayed vinyl records waiting for the day that I finally have the proper equipment. By the way, the song was Black Pink by RinneRadio from their wonderful album staRRk. I wrote a little script to do just this: to plot the amplitude of the FLAC into a grid with an adjustable width. The result looks very similar to the pattern on the vinyl surface! Note that this image is a "straightened out" version of the disc surface and it's showing three of those wavy patterns. The top edge corresponds to the outer edge of the vinyl. Later I wrote a little more ambitious plotter that shall be explained soon. Computer-conducted music gives best patterns After plotting several different songs against their own tempo like this it seemed that in addition to electronic music a lot of pop and rock has this type of a pattern, too. The most striking and clear patterns can be seen in music that makes use of drum samples in a quantized time base (aka. a drum machine): the same kick drum sample, for example, repeats four times in each bar, perfectly timed by a computer so that they align in phase. Somewhat similar patterns can be seen in live music that is played to a "click track": each band member hears a common computer-generated time signal ## 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