Comparison

Audio Unit Player vs Billie Tracker

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Audio Unit Player

This music player offers real-time audio processing, including time stretching, pitch shifting, and a 31-band equalizer. It supports AUv3 effects and allows for A-B loop playback, making it ideal for practice, transcription, and performance adjustments.

Highlights
  • Real-time time stretch (50-200%)
  • Real-time pitch shift (-12 to +12 semitones)
  • 31-band equalizer with presets
  • AUv3 effects support
  • A-B loop playback
  • Background playback
  • Audio file export
Read full description

This app is a music player that can process the following effects in real time. - Time stretch (0.5-2.0 double speed) - Pitch shift (-1 ~ +1 octave) - 31 band equalizer - Reverb - AUv3 (Audio Unit v3) host [Use cases] - Karaoke's training. (Can be changed speed units of 10%, pitch shift in semitones easily) - Can playback at reduced tempo to copy phrase for guitar or bass, the keyboard instrument. - Can playback by changing the pitch to play by changing the key in the band performance (Developer himself has experience). [Function] - Perform time stretch (50 - 200%) / pitch shift (-12 - +12) in real time. - 31 bands EQ (Hz: 20, 25, 31.5, 40, 50, 63, 80, 100, 125, 160, 200, 250, 315, 400, 500, 630, 800, 1k, 1.25k, 1.6k, 2k, 2.5k, 3.15k, 4k, 5k, 6.3k, 8k, 10k, 12.5k, 16k, 20k). - EQ preset (Abundant Built-in Presets / Custom Presets). - Reverb: Adjustable decay time (Low freq, High freq) / 13 presets - Reverb preset (Built-in Presets / Custom Presets) - Can be used as an AUv3 host. - A-B loop playback. - Center Cancel / Center Emphasis. - Lch, Rch each mute. - Quick fast forward, rewind (specify the number of seconds). - Check and set current position graphically in wave view. - Supports Auto-Lock ON/OFF. - Supports background playback. - Supports export (file writing) function (Each effect (speed/pitch/EQ) value set for each song is also reflected. The range specified in the loop section is output.) In addition to loading "music" data included in the standard music app, it also supports the function to import audio files from other apps ("Voice Memos" etc.). [How to import from "Voice Memos"] 1. Start the app "Voice Memos" and tap the mark "..." of the file to be imported from the list. 2. Tap "Share" on the sheet displayed from the bottom. 3. Tap "More" found by scrolling the displayed list of sharing destination apps to the right. 4. Select "AU Player" if available. The file is copied to this app. ================================================ [Note 1] This application will not be able to read songs of the following formats. - Songs from Apple Music, iCloud, iTunes Match - Songs that are protected by digital copyright (DRM) [Note 2] Depending on the state of your device, your custom AUv3 effects may not appear in the list. As a solution, you can solve the problem by starting "GarageBand" once and restarting this app. ================================================

About

Billie Tracker

Create music with a powerful groovebox featuring a step sequencer, synthesizers, and a sampler. Arrange patterns into songs, shape unique sounds, and export your finished tracks. Designed for intuitive music production on mobile devices.

Highlights
  • Step sequencer for notes and instruments
  • Shapeable synth instruments
  • In-app sampler for recording sounds
  • Mixer with per-track controls
  • Song arrangement and export options
  • Hardware controller support
Features
Read full description

Billie Tracker is a groovebox: a step sequencer, synth instruments, a sampler and a mixer, built as one instrument for your phone or tablet. You write music in a grid. Notes go into patterns, patterns chain into sections, and sections line up into a song, so a full track grows out of small pieces you can reuse and rearrange. Trackers have worked this way for decades. If you have used one, this will feel like home. If you haven't, a built-in tutorial walks you through your first pattern, and every screen has help one key away. It is not tied to one sound. Shape the synths from clean tones to heavy drive, sample anything and play it back as an instrument, and make whatever you want to make: techno, ambient, hip hop, pop, or the 8-bit styles trackers are known for. Rows hold up to four notes, not just one. Every instrument is polyphonic, so a chord goes into the grid the same way a single note does. Hold one on a MIDI keyboard and it lands across the row's note lanes, quantized and in key. What you get: - A step sequencer for notes, instruments, volume and effects, with chains and a song view for arrangement - Up to four note lanes on every row, so chords are typed in like single notes, on any instrument - Synth instruments you can shape: timbre, color, filter, drive, envelopes and LFOs - A sampler that records straight into the app, so your own sounds sit next to the synths - A mixer with per-track levels and sends - BOUNCE and STEMS, so a finished song leaves the app as audio - Bundles: a song and every sample it uses travel as one file - A control surface built for tracker speed. Hold one key, press another, fast. Rearrange the layout to fit your hands, or plug in a hardware keyboard or game controller - Themes, KEY and SCALE settings, and a HELP key that explains whatever you are looking at Your songs are ordinary files. There is no account and nothing to sign into. Send a song to a friend, email one to yourself, or move it around in your file manager. Nothing is uploaded to us and nothing is locked to us. Billie Tracker is made by Billie Workers' Co-op. The people using it steer what gets built, and the Discord is the fastest way to reach us.

Screenshots

Audio Unit Player3 screens
Billie Tracker4 screens

Verdict

The call

The clearest difference is rating: Billie Tracker at 5.0 against Audio Unit Player's 3.9. Billie Tracker also leads on in-app purchases (none vs 1) and ads (none vs shown). Audio Unit Player's advantage is ratings volume (30 vs 5). On price and device support there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Audio Unit Player sells 1 one-off in-app purchase. Billie Tracker asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Billie Tracker holds the better App Store score, 5.0 against 3.9. That said, the two scores are not equally well evidenced: Audio Unit Player has 30 ratings behind it against 5, so its average is the more settled of the two. Written reviews point the same way: 67% of Audio Unit Player's written reviews are positive against 100% of Billie Tracker's.

UpkeepUpdate frequency

Audio Unit Player ships an update every 2 weeks, Billie Tracker every 2 days. The most recent releases landed on October 9, 2026 and October 1, 2026 respectively.

Scorecard8 real differences · 2 level
Audio Unit Player versus Billie Tracker: the parameters behind the verdict, then further details
ParameterAudio Unit PlayerBillie Tracker
PriceFreeFree
Rating3.9 (30 ratings)5.0 (5 ratings) — better
Positive reviews66.7% of reviews100.0% of reviews — better
Number of ratings30 — better5
Update frequencyEvery 2 weeksEvery 2 days — better
AdsYesNo — better
In-app purchasesYesNo — better
MonetizationPaidFree — better
DevicesiPhone, iPadiPhone, iPad, iPod — better
Requires iOS17.015.1 — better
Further details — not scored
Size5 MB56 MB
Age rating4+4+
DeveloperLoop-Sessions.LLC.Billie Cooperative

Customer experience

Audio Unit Player

All ratings30 ratings
Positive70.0%
Neutral6.7%
Negative23.3%
Written reviews48 reviews
Positive66.7%
Neutral4.2%
Negative29.2%

Billie Tracker

All ratings5 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews3 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

1 purchases

Audio Unit Player

One-time1
  • Always remove banner ads.$3.99
None

Billie Tracker

No in-app purchases

Questions

Is Audio Unit Player free?
Audio Unit Player is free to download, with in-app purchases available.
Is Billie Tracker free?
Billie Tracker is free to download, with no in-app purchases.
Which has better reviews, Audio Unit Player or Billie Tracker?
Billie Tracker is rated higher. Audio Unit Player averages 3.9 out of 5 from 30 ratings, while Billie Tracker averages 5.0 from 5 ratings.
Do Audio Unit Player or Billie Tracker have ads?
Audio Unit Player shows ads; Billie Tracker does not.
Which is updated more often, Audio Unit Player or Billie Tracker?
Audio Unit Player ships an update every 2 weeks, and Billie Tracker every 2 days. Most recently, Audio Unit Player was updated on October 9, 2026 and Billie Tracker on October 1, 2026.

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