Show HN: TromPhone, a Trombone for Your Phone

[depsypher]

A few months ago I had a silly idea of making a mobile app that used the accelerometer to track the slide motion for playing a virtual trombone. Just wanted to share the story of bringing it to fruition here on hn.

I started out spending a couple days trying to get something cross-platform going in Flutter, but it soon became clear that wasn't the best fit, seeing as I'd need native hooks for most of what the app needed to do, and it wasn't yet clear it'd be possible at all. So I switched to making it an iOS app in Swift. The accelerometer data turned out to be not nearly accurate enough to do the job, so I switched to using the camera/AR using ARKit... and it worked instantly. Like the very first time I hooked up a slider UI element to the distance function. It felt a bit like magic. And also just ridiculous.

Here's a video I recorded to send to some friends at the time: https://youtu.be/6BIogfGH3IQ

Here's a video of it in action in it's current state: https://youtube.com/shorts/8kS2TRzV4I4?feature=share

Apologies for the non-responsive website (using nextjs on cloudflare). It doesn't look great on mobile, which is kind of inexcusable, I'm working on it: https://www.tromphoneapp.com

Anyway, I'm not sure where I'll take it from here. I have some ideas for more AR content like hats, heart eyes, etc. Possibly a song editor so users can add songs that might have issues with copyright if I included them in the app? Any ideas you guys have would be fun to hear.

[dmje]

Super great, lovely idea!

Only comment is that you've got discrete notes in there by the sound of it? Could you make it entirely analogue per a real trombone? Sounds a bit jarring jumping from note to note...

But. Great.

[rjewell]

I held it up in front of my daughter without telling her what it was, and when i tapped the screen she fell over backwards in shock. Perfectly executed.

[depsypher]

This warms my heart. Thanks!

[dr_kiszonka]

If the app could be used as a Bluetooth controller, you could have a colab with these folks https://store.steampowered.com/app/1059990/Trombone_Champ/

[filoleg]

I love it, great job, OP!

One question, are there future plans to add either a song editor (so that people can encode their own sequences instead of being stuck with the default 4 songs) or a mode where instead of guiding you through a preset song, it simply shows which notes you are playing? The latter one, especially, is something that I find sorely missing :(

[depsypher]

Great idea! It may be a bit challenging to execute on that because currently it "snaps" to the note you're supposed to be playing, and given that even shifts of a centimeter or two will change the pitch to a different note, so it would require superhuman hand steadiness to play a real song.

A true trombone doesn't have the same issue because the entire range of playable notes isn't regulated by the slide, you change your lips to change the pitch. I'll think on this though. At very least it would be fun to have that mode to do a sad trombone womp womp sound.

[ralphw]

Cool!

Some kind of "arm exercise for musicians" fitness app might be interesting, kind of a Guitar Hero meets Dance Dance Revolution mashup.

People might need to be cautioned to use arm weights AND hold their iPhone at the same time.

[latchkey]

That's a really silly great idea. Nice work!

[tylerpachal]

This is the first new app I have downloaded in a long time, it is a lot of fun!

[anibalin]

haha very cool!

[l3uwin]

I'm more hyped about this than gpt3 tbh. I cannot wait to get a tromphone quartet going at the office holiday party