LLMs Will Replace 8-Track Duplication Engineers | Benchoff Design Portfolio
LLMs Will Replace 8-Track Duplication Engineers | Benchoff Design Portfolio
Brian Benchoff
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Human Performance on an NP-Hard Partitioning Problem at Industrial Scale
Or, LLMs Will Replace 8-Track Duplication Engineers
Columbia Records introduced the LP format in 1948, giving listeners twenty-five minutes of music per side of a vinyl record. For fifty years, every album, through vinyl and cassette, was built around this fifty-minute, two-sided limitation. In 1965, the 8-track cartridge changed this format. 8-track cartridges are a single, continuous loop of tape with four programs. To create the 8-track version of an LP, someone at the record company or tape duplication facility must take the track listing of the LP, and partition it in such a way so that the four programs are as close to equal length as possible. The longest program determines the length of tape in the cartridge. A cartridge with an 11-minute long Program 1 and only 8 minutes on programs 2, 3, and 4 will have nine total minutes of silence.
This is a classic NP-hard problem, the easiest hard problem, and a problem that was solved thousands of times by unknown audio engineers all without the aid of a computer. Deep in the bowels of the Discogs and MusicBrainz APIs are data indexing human performance on NP-hard problems done by experts in their field.
Frontier labs are still paying Mechanical Turk workers pennies per hour, when they could be nerding out on a music format that has been dead for forty years. I pity them.
In case you’re wondering, I’m putting an 8-track player in my car and I wanted a copy of Frank Ocean’s Blonde. Then I started thinking. Then I realized an 8-track of Girls’ Broken Dreams Club is impossible. And now we’re here.
The problem
An 8-track cartridge is one continuous loop of tape with four parallel “programs” recorded side by side. The player works through them in sequence, physically shifting the head at the end of each pass — and because all four programs share the same loop, all four are exactly the same length . The longest program sets the physical tape length; every shorter program plays out its remainder as dead air. Wasted tape costs the duplicator money. Splitting the songs across tracks interrupts the flow of the song. Check out the Harvest release of Dark Side of the Moon; “Money” is split across programs 2 and 3. “Us and Them” is split across programs 3 and 4. It retains the track order of the LP but pays for it by killing the vibe of the best songs on the album.
For every 8-track release, someone at a duplication plant had to divide the songs into four groups with the most balanced possible total durations. This is balanced 4-way number partitioning, an NP-hard optimization problem solved by hand with a stopwatch or a paper and pen. Here’s the job done well. Rumours — Fleetwood Mac, WEA, 1977 — eleven<br>songs, shipped like this:
Program 110:07
Second Hand News2:54
Oh Daddy3:58
I Don't Want To Know3:15
Program 210:06
Dreams4:18
Never Going Back Again2:15
You Make Loving Fun3:33
Program 310:17
Don't Stop3:14
Go Your Own Way3:40
Songbird3:23
Program 49:33
The Chain4:31
Gold Dust Woman5:02
This is not the LP’s running order. It’s nowhere near the LP’s running order. The engineer responsible for this 8-track got really close to the optimum, but because we now have computers that can search every permutation, I can tell you the optimum 8-track ordering of Rumours:
Program 110:13
Dreams4:18
Never Going Back Again2:15
Go Your Own Way3:40
Program 210:10
Don't Stop3:14
Songbird3:23
You Make Loving Fun3:33
Program 310:07
Second Hand News2:54
I Don't Want To Know3:15
Oh Daddy3:58
Program 49:33
The Chain4:31
Gold Dust Woman5:02
The only change with the ideal ordering versus the release ordering is that “Go Your Own Way” is swapped with “You Make Loving Fun”. This saves four seconds of tape. 8-tracks run at 3.75 ips, so assuming 100,000...