voice tracking listens to your delivery on-device and advances the script when you say the words, so there's no thumb on the screen and no guessing at a scroll speed. it's controlled by two lines you can drag, and the gap between them decides whether the scroll feels snappy or smooth.
the fastest way to understand them is to grab them yourself.
you write the script on your mac.
save the file. the phone catches up.
hit play, or let voice tracking follow you.
the READ line is where the word you just said lands.
the FEATHER line is where the scroll eases into a glide.
drag them apart for smoother momentum.
drag them together for snappy, word-for-word tracking.
no thumb on the screen. no subscription. no cloud.
you write the script on your mac.
save the file. the phone catches up.
hit play, or let voice tracking follow you.
the READ line is where the word you just said lands.
the FEATHER line is where the scroll eases into a glide.
drag them apart for smoother momentum.
drag them together for snappy, word-for-word tracking.
no thumb on the screen. no subscription. no cloud.
READ at 18% · FEATHER at 42% · band 24% (snappy follow)
drag the two handles. the top one is the READ line. the lower one is the FEATHER line. move them around while the text scrolls and watch how the feel changes. the rest of this post is only naming what you're already seeing.
what the two lines do#
the READ line is where the word you just said lands. as voice tracking matches your speech, it keeps the current word parked at that line. by default it sits near the top of the screen, around 5% down, which is close to the lens on most rigs.
the FEATHER line sits lower, around 18% by default. it's where the scroll stops sprinting and starts gliding. above the feather, the controller is in catch-up mode: if you jumped ahead or read fast, it moves quickly to get your word back to the READ line. below the feather, it eases off into a smooth, continuous scroll.
so the READ line answers "where should my current word be," and the FEATHER line answers "where does the motion calm down."
the band between them is the real control#
the lines matter, but the space between them matters more. that band is the dial.
drag them close together and tracking gets tight. the scroll snaps to your words almost one-for-one, which is great for slow, deliberate reads where you want the prompter glued to your pace.
drag them apart and the scroll gets smoother. there's more room for the feather to ease the motion, so it feels less like the page chasing each word and more like a calm, continuous glide. this is the better feel for fast or conversational delivery, where snapping to every word would look twitchy on camera.
try it on the demo above. pinch the handles together, read a line in your head, then pull them apart and read the same line. the difference in feel is the whole point.
finding the handles in the app#
voice tracking is opt-in and off by default, so turn it on first. once it's running, the READ and FEATHER lines appear as draggable handles right on the prompter. press and drag either one to move it. your positions stick, so you set them once for the way you read and leave them.
a few things to know going in:
- it runs fully on-device. the audio never leaves your phone.
- it's labeled BETA, because the feel is still being tuned.
- if you stop talking for about a second and a half, scrolling pauses on its own. that's silence detection, and it lets you stop, breathe, or scroll back to re-read a line without the page running off without you.
tuning the feel#
most of the dialing-in is two adjustments, and they pull in opposite directions.
if the scroll feels jerky or it lurches between words, widen the band. pull the FEATHER line further from the READ line. more space means the feather has more room to smooth the catch-up, so the motion softens.
if the scroll feels laggy, like it's trailing behind where you are, tighten the band. bring the FEATHER line closer to the READ line. less space means the controller spends less time gliding and more time keeping your word pinned to the READ line.
one thing to watch for: the word you're saying should land on the READ line. if your current word keeps sitting above or below it, your lines are probably set for a faster or slower pace than you're really reading at. nudge them and read a few sentences until the matched word settles where the READ line is.
a note on mic source#
voice tracking listens on the recording audio path, not just the built-in mic. so if you route a lavalier into the phone over USB-C or a 3.5 mm TRRS input, voice tracking follows that source. on a beam-splitter rig that means it can keep your place even when you're standing well back from the device, past the range of the built-in mic. set your READ and FEATHER lines the same way regardless of which mic is feeding it.
next#
turn on voice tracking, set the band wide for your first conversational read, then tighten it for a slower take and feel the difference. once both feels are dialed for the way you talk, you'll rarely touch the lines again.
it's beta, and the feel is exactly the kind of thing that's hard to get right for everyone. if the tracking is fighting you, or if there's a band setting that finally clicked, email hello@openprompter.app. real notes from real reads are what move this forward.