# Podsync - I finally built my podcast track syncer

DevFeed: [Podsync - I finally built my podcast track syncer](<https://devfeed.tech/articles/podsync-i-finally-built-my-podcast-track-syncer-25308.md>)

Original publisher: [Read original article](<https://kau.sh/blog/podsync/>)

Author: Kaushik Gopal

Published: 2026-03-20T00:00:00Z

Content type: opinion

Language: en

Sources: [Kaushik Gopal's Site](<https://devfeed.tech/sources/kaushik-gopal-s-site.md>)

Topics: [Algorithm](<https://devfeed.tech/topics/algorithm.md>), [Rust](<https://devfeed.tech/topics/rust.md>), [Claude](<https://devfeed.tech/topics/claude.md>), [Java](<https://devfeed.tech/topics/java.md>)

Tags: [algorithm](<https://devfeed.tech/tags/algorithm.md>), [claude](<https://devfeed.tech/tags/claude.md>), [engineering](<https://devfeed.tech/tags/engineering.md>), [rust](<https://devfeed.tech/tags/rust.md>)

## AI overview

The author built PodSync to automate alignment of locally recorded podcast tracks. The tool uses voice activity detection, MFCC audio features, and cross-correlation to match tracks, and was developed with Claude in Rust after earlier difficulties finding suitable JVM audio-processing libraries.

## Source excerpt

I host and edit a podcast1. When recording remotely, we each record our own audio locally (I on my end, my co-host on his). The service we use (Adobe Podcast, Zoom, Skype-RIP) captures everyone together as a master track. But the quality doesn't match what each person records locally with their own microphone. So we use that master as a reference point and stitch the individual local tracks together. This is what the industry calls a "double-ender". Add a guest and it becomes a "triple-ender". But this gets hairy during editing. Each person starts their recording at a slightly different moment -- everyone hits record at a different time. Before I can edit, I need to line everything up. Drop all the tracks into a DAW, play the master alongside each individual track, nudge by ear until the speech aligns. Add a guest and it gets tedious fast. 10-15 minutes of fiddly, ear-straining alignment before I've even started editing. There's also drift. Each machine's audio clock runs at a slightly different rate, so two tracks that are perfectly aligned at minute one might be 200ms apart by minute sixty. So I built PodSync2. I've wanted this since 2019 ## I first heard of a similar technique from Marco Arment -- back in ATP episode 25. He had a new app for aligning double-ender tracks and was already thinking about whether something so niche was even worth releasing publicly. I don't think he ever released it. Being a Kotlin developer at the time, I figured I'd build my own. Java was mature. Surely there were audio processing libraries that could handle this. There weren't 😅. At least not in any clean, usable form. Getting the right signal processing pieces together in JVM-land was awkward enough that my interest fizzled, so I kept doing it by hand. tis the age of AI ## When I revamped Fragmented, I finally came back to this. I used Claude to help me build it -- in Rust, no less.3 But before you chalk this up to another vibecoded project, hear me out. The interesting part here was