Make room for music.

Each session has 2–9 parts. Audio sessions use sound from recordings or imported files. Video sessions use filmed parts to create a split-screen mosaic. A session uses one mode; it does not mix camera-free recordings and filmed parts into a single video session.

Use Add part or Session settings to grow the session. You can remove empty parts at the end only when they have no saved recording to undo.

Select a part and choose Files, or choose Photos for a video. Audio sessions can use an audio file or extract sound from an imported video. Video sessions require video for each part. Supported imports include MP4, MOV, M4V, M4A, MP3, WAV, AIFF, AAC and CAF, where the file contains a playable track appropriate for the session. Protected media cannot be imported.

Use Import guide audio to add a reference or backing track. Choose whether to hear it while recording and previewing, and separately whether to include it in the exported mix. The guide is excluded from the finished mix by default. Imports and recordings can be up to 10 minutes.

Use recordings you made or have permission to use. PartStack does not supply licensed songs or clear the rights to music you import or share.

Open Session settings. Choose Off, 4 beats or 8 beats, and turn the count-in sound on or off. It ends before recording begins. The tempo controls the count-in; it does not stretch your recordings or provide a continuous metronome.

Select a recorded part. Adjust its Volume, use Mute to silence it, or Solo to hear selected parts. More than one part can be soloed. A muted part remains silent even if soloed. These choices affect preview, playback while recording and the final mix.

Use Alignment for a broad timing adjustment, then the ±1 ms and ±10 ms buttons for small changes. Earlier moves the part forward in the arrangement; Later delays it. Reset returns its alignment to zero.

Trim removes unwanted material from the beginning or end of a single take. Replace phrase lets you record a chosen section again while preserving the surrounding material. Use Undo last edit to return to the previous recording edit. Undo is limited to the most recent saved edit for that part, not an unlimited history.

Recording or importing a whole new take replaces the selected part. Review the selection before recording. Save a session backup before making changes you may want to keep separately.

Tap the export icon in Studio. Audio makes an M4A mix. Video sessions also offer an MP4 split-screen video with square, portrait or landscape canvas options in Session settings.

Create the export, then use Share or Save to Files. Video can also be saved to Photos. A completed export is temporary until you save or share it; the editable source session stays in the library. Filenames begin with your session title, followed by a date and unique suffix.

1. Open Export, select Backup, and tap Create session backup.
2. Choose Save to Files and save the .partstack file somewhere you can find again. You may choose iCloud Drive or another Files destination.
3. To restore, return to the home screen and choose Restore a session backup, then select the file.

The backup includes parts, the guide, mix settings and the last undoable takes. Restoration creates a separate session rather than overwriting the original. A backup can be restored on another device with PartStack. This is a deliberate file transfer, not automatic cloud sync.

Deleting a session removes its locally stored recordings. Deleting the app removes its local data. PartStack has no server copy or account-based recovery. Save a .partstack backup before deleting anything you want to edit later. A finished M4A or MP4 keeps the mix, but does not replace an editable backup. Copies you save elsewhere have their own storage and deletion controls.

In iOS Settings, open Apps → PartStack and check the relevant permission. Audio sessions need the microphone; Video sessions also need the camera. Close another app that may be using the camera or microphone, return to PartStack, and try again. Confirm that the device has available storage. Denying Photos permission does not prevent saving an export to Files.

Use wired headphones to keep earlier parts out of the microphone and reduce playback delay. Bluetooth equipment can add latency. Check the selected input and output, lower playback volume if it leaks into the mic, and use Alignment after recording for fine adjustments. Solo and Mute also control the parts you hear while recording.

Keep PartStack in the foreground during a take. A call, an audio-route change or backgrounding can interrupt recording. If the app offers a captured take for review, listen and decide whether to keep it or retake it. Do not assume that every interruption or force-quit can recover a recording.

Download cloud files fully to the device before trying again. Use a supported, unprotected media format; an audio-only file cannot be used as a Video part. Check the 10-minute clip limit and available device storage. Session restore requires a compatible .partstack backup, not a finished M4A or MP4 export.

Leave PartStack open until export finishes. More video parts require more processing and storage. Free space on the device, close unneeded apps and retry. If saving to Photos is unavailable, use Save to Files. Verify your saved file before deleting the original session.

Apple handles App Store purchases and billing. Use the Apple Account that purchased the app to download it again. Visit Apple’s billing and subscriptions help for purchase or refund questions. PartStack has no subscription or in-app purchase.