We build FoxTake , an iPhone app for recording talking-head videos with a teleprompter. After you record, it cuts retakes and burns captions into the video. Version 2.0 targets iOS 26, so captions use Apple's new SpeechAnalyzer / SpeechTranscriber APIs and are transcribed on the phone.

This post covers what we learned getting from a recorded .mov to captions that look right on TikTok, Reels and Shorts. Some of it is in the docs. Most of it we found by testing.

Why on-device

Our users mostly record short clips: one take of 30 seconds to 3 minutes. For that size, on-device transcription is quick, works without a network connection, and costs nothing per minute. We tested the iOS 26 transcriber against Whisper small on a 46.8-second outdoor Mandarin clip.

Speed. On an iPhone with an A14 chip, SpeechTranscriber finished in 0.86 s , about 54× real time.

Accuracy. Whisper small made one word error and dropped two filler particles.…