> For the complete documentation index, see [llms.txt](https://docs.memorystring.app/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.memorystring.app/build-your-movie/auto-detection.md).

# Auto detection

Keep Best Shots, upright photos, and Auto Trim for a messy camera roll, on your Mac. MemoryString’s helpers stay on-device; Auto Trim is not on import, and original files are never rewritten.

These tools help with a messy camera roll. Everything runs on your Mac. Original files are never changed.

## The helpers

* [**Long story short**](/build-your-movie/long-story-short.md): Builds a movie of the length you pick from your best shots. Uses Keep Best and Auto Trim. The rest go to **Outtakes**.
* **Keep Best Shots**: From similar burst photos, keep the strongest shot (on a large import, sometimes a second, wider one). Extras move to **Outtakes** (still in the project, not in the show). Import may ask; **Library** Show menu anytime. Default: **Keep Best**. Undo **⌘Z**.
* **Auto Trim**: About four seconds from the middle of a video clip, with up to about one second nudge toward a face. Works about 70% of the time. Right-click or **Library** Show menu, not on import. After it runs, use **Reset Video Duration** to restore full length. Undo **⌘Z**.
* **Video mute**: On import, quiet clips with only room noise so music can lead.
* **Orientation**: Turns sideways and upside-down photos and videos upright while they import, before they land on the timeline. Original files stay as shot.
* **Center of interest**: Finds faces and subjects so motion frames the right area.
* **Auto Caption**: Fills captions only when you choose **Auto Caption**, never on import by itself.

![Paused photo with the center-of-interest ring](https://316881897-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F6lG8Zi4VdmddHJ8jUOT5%2Fuploads%2Fgit-blob-08607241949411314a078f72beab6a9cba08442f%2Fpreview-coi.png?alt=media)

## Keep Best Shots

When several photos are the same moment in the same framing, MemoryString can keep the one with open eyes, a smile, sharpness, and good exposure. A different pose stays in the show. On a large import it can also keep a second, wider shot from that moment.

**When:** during **import**, before the show is built, the fog (or the loading pill on an existing show) says **Comparing similar shots N of M...**, then asks. Anytime later from **Library** Show menu → **Keep Best Shots…**. Videos are not included.

**The dialog** shows how many groups and extra shots. **Keep the best shot only?** Default button: **Keep Best**. **Keep All** leaves every photo.

![Keep Best import prompt: Keep All or Keep Best](https://316881897-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F6lG8Zi4VdmddHJ8jUOT5%2Fuploads%2Fgit-blob-97b06deebcd404e5903fba2aa32253ef35a3167f%2Fkeep-best-import-prompt.png?alt=media)

{% hint style="info" %}
Other shots move to **Outtakes**. Undo with **⌘Z**.
{% endhint %}

One undo restores the whole pass. See [Library](/build-your-movie/library.md#import) and [Library Show menu](/build-your-movie/library.md#show-menu).

## Auto Trim

For a long phone clip, **Auto Trim** keeps about **four seconds** around the middle (two seconds before and after the midpoint, clamped to the clip). If a face is just outside that window, it may shift up to **\~1 second** toward it. Clips shorter than four seconds keep the whole file.

The cut works about **70%** of the time. Trim by hand when you need to.

Clips trimmed by **Auto Trim** show a small scissors mark below the mute icon on **Timeline**, **Library**, and **Outtakes** cards. Solid scissors = **Auto Trim**. Outline = you trimmed by hand. The mark shows on hover or selection and goes away after **Reset Video Duration**.

**When:** **not** on import. Right-click a video → **Auto Trim** (runs immediately). Or **Library** Show menu → **Auto Trim Videos…** (confirms when several videos are selected). Works on group videos too.

![Clip context menu with Auto Trim](https://316881897-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F6lG8Zi4VdmddHJ8jUOT5%2Fuploads%2Fgit-blob-f59ad3245c1fee595975d95d680ce4faf6bde8e6%2Fauto-trim-context-menu.png?alt=media)

It does not mute, caption, or delete clips.

**Undo:** **⌘Z**. **Reset Video Duration** restores the full source. **Library** Show menu → **Reset Video Durations** resets all videos.

See [Library → Videos](/build-your-movie/library.md#videos) and [Timeline](/build-your-movie/timeline.md#reorder-and-trim).

## Video sound (auto-mute)

Speech on camera stays audible. Wind, hiss, and quiet room tone may mute so the soundtrack can lead. Talking, music, and sharp hits (a bounce, a clap) stay on.

**When:** as each **video** is imported (**Essential** and **Studio**), and again when you open a show, for clips you have not already unmuted. Stills have no clip audio. Soundtrack tracks are not auto-muted. **Library** Show menu → **Mute Noisy Videos** runs the same pass on every show video while you keep working.

**First import with video:** MemoryString may ask **Allow On-Device Speech Detection?** The sheet waits until the show is on screen. It does not pop during the loading fog.

* **Continue**: then macOS’s Speech prompt. Detection is **on-device**. It does not save a transcript.
* **Use Loudness Only**: skip speech. Mute still uses loudness.

If you deny speech, later imports use loudness only until you reset that choice.

**Rules** (whole file):

1. **No audio track** → muted
2. **Very quiet** throughout → muted
3. If speech is allowed and **speech is found** → **audible**
4. Else if energy looks like **music, singing, or cries** → **audible**
5. Else steady noise, wind, hiss, or ambience → muted

Muted clips show a speaker-off badge in **Library** and **Timeline**.

**Override:** right-click **Mute Video Sound** / **Unmute Video Sound**, the speaker badge, or the Inspector clip footer. **Library** Show menu → **Videos** → **Mute All Videos** / **Unmute All Videos** flips every show video at once and remembers that choice. See [Library](/build-your-movie/library.md#videos) and [Music](/build-your-movie/music.md#video-sound-not-the-audioline).

## Orientation

Sideways and upside-down photos and videos are turned upright on their own. The turn lives in the show. Original files are never rewritten. Someone lying on a sofa or the floor is left as shot. That is not a sideways phone.

**When:** during import, while the loader is up: **+**, Finder drop, paste, folders, and **Import from Photos…**. The line under the title reads **Straightening N of M...**. The show lands already upright.

**Long story short** turns the shots it keeps, after **Reviewing**, before the movie is laid out. Extras added to reach the length are turned the same way.

**Opening a show:** turns this Mac already knows are applied before the timeline appears, so the length does not change a moment later. Photos this Mac has never checked are turned shortly after the show opens.

**Override:** right-click **Rotate & Flip**, or **⌘]** / **⌘\[**. Turning a photo back to as-shot sticks. MemoryString will not turn it again. The blurred backdrop follows the same turn as the card. See [Preview](/build-your-movie/preview.md#rotate-while-paused).

## Center of interest

Motion aims at the person or subject that matters. **When:** on **import**, every photo and video gets a focus point.

**How it picks** (on-device):

1. **Largest usable face**: near the **eyes**
2. Else **main subject**
3. Else **center** of the frame

**Videos:** several frames in the trim window. The strongest face or subject wins.

**Override:** pause and click the photo. **Reset Center of Interest** (right-click) removes override and runs detection again.

![Paused preview: Rotate, Flip, Reset Center of Interest](https://316881897-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F6lG8Zi4VdmddHJ8jUOT5%2Fuploads%2Fgit-blob-f378c531a75d3f0d5b226f03e7fe3be973d9e2d1%2Fpreview-context-menu.png?alt=media)

Ken Burns and punch-in use center of interest. Some whole-photo transitions ignore it. Details: [Preview](/build-your-movie/preview.md#center-of-interest).

## Auto Caption

**Auto Caption** can fill **place · date**, not camera codes like `IMG_4821`. You run it yourself from the **Library** captions bubble, **Edit → Auto Caption Untitled Slides**, Style → Captions, or Inspector **Generate**. Not on import.

Untitled-only commands **never overwrite** text you typed. **Auto Caption All Slides…** overwrites after confirmation.

**Fill order** for an empty caption:

1. **Place · date**: GPS (EXIF / QuickTime) or IPTC city/country. **Country** follows **Caption Details**. With **Only When the Show Visits Several Countries** on (Studio, and on by default), a one-country show leaves it out.
2. Else **capture date** from EXIF or video creation date.
3. Else a **readable filename** with real words.

**Never used:** UUID names, `IMG_1234`, `DSC…`, WhatsApp export titles. Those stay blank.

Geocoding uses coordinates **in the media**, not your Mac’s location. Offline still gets date / IPTC when available. One **⌘Z** undoes a full Auto Caption pass.

See [Titles and captions](/build-your-movie/intro-captions.md#auto-caption).


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