Coding agents still need strong checks for real playback quality
FastPlay is a small native Windows video player built in Rust. Its goal is narrow: open quickly, show the first frame fast, scrub smoothly, resume from the last position, and stay out of the way. It is not meant to replace large, mature players like VLC or MPC-HC. The stack includes Rust, FFmpeg, , WASAPI, and native Windows UI.
helped with writing code, playback modules, writing timing tests, and noticing drift. They were much weaker at proving that media playback actually felt correct. One playback bug appeared after seeking backward: audio could run several seconds ahead of video. The cause was an old partial audio batch that survived the seek and gave new audio the wrong timing.
Resetting the audio batcher during seek fixed the issue. The better workflow became asking for , clear rules that must stay true, small pull-request-sized patches, validation steps, tests where possible, and manual playback checks when tests are not enough.
Key points
- FastPlay is a small Windows video player focused on local playback.
- helped with code, , timing tests, and structure checks.
- A backward seek bug made audio run several seconds ahead of video.
- The fix was to reset the audio batcher during seek.
- The workflow shifted toward small patches, clear checks, tests, and manual playback review.