Resync Clip

Make any video play properly on iPhone and iPad. Convert, resize, crop and compress images, right in your browser.

by Moamen Sherif

Video Images
Drop your videos here or click to browse · MP4, MOV, M4V Up to 50 MB per file
Drop your images here or click to browse · HEIC, JPEG, PNG, WebP, AVIF, GIF, BMP Never uploaded · converted on your device

Applies to every image. Use Crop & edit on a card to crop, rotate or give it its own scale.

Why videos don't play on iPhone

A video can be perfectly valid and still refuse to play on iOS. Here are the four usual culprits — Resync Clip repairs all of them.

  1. 01

    The moov atom is at the end

    An MP4 keeps its metadata — track layout, codecs, sample offsets — in a box called moov. Written after the media data, a player must download the entire file before it can start. Moving it to the front is faststart.

    Fixed in your browser
  2. 02

    HEVC tagged hev1, not hvc1

    Both tags describe identical HEVC video; only the label differs. Apple plays hvc1 inline and refuses hev1. The video itself is unchanged, so this is a tag rewrite — quality is untouched.

    Fixed in your browser
  3. 03

    A codec iOS won't decode

    MPEG-4 Part 2, ProRes and VP9 need converting to H.264 — as do the H.264 High 4:2:2 and 4:4:4 profiles, which are valid H.264 that iOS still refuses to play.

    Re-encoded on the server
  4. 04

    Audio that plays as silence

    AC-3, E-AC-3 and PCM tracks leave you with a video that plays with no sound at all on iOS. They are converted to AAC.

    Re-encoded on the server

Your videos stay on your device

Checking a video reads only its atom headers and moov box — a few kilobytes, whatever the file size. Faststart and HEVC-tag repairs are container rewrites, so they run entirely in your browser and the video is never uploaded. Only a file that genuinely needs re-encoding is sent to the server, and it is deleted once the result is returned.

Images are never uploaded at all: converting, resizing and cropping all happen on your device. The converted copy leaves out the original's metadata, such as camera details and location.

Anonymous usage data is recorded to see how the tool is doing: the file name, size and format details of each video or image, what was done to it and whether it worked. No account, no tracking across sites, and never the video or image itself.

Questions

Does it re-compress my video?

Only when it has no choice. Faststart and HEVC-tag repairs copy the encoded video across untouched, so quality is bit-for-bit identical to the original. A real re-encode happens only for a codec, profile or audio track that iOS genuinely cannot play.

Is there a file size limit?

50 MB for videos that need server-side conversion. Repairs that run in your browser have no practical limit, because nothing is uploaded.

Which formats can I use?

MP4, MOV and M4V. You get back an MP4 that plays inline on iPhone, iPad and Safari on macOS.

Does it work on Android or desktop?

The tool runs in any modern browser. The fixes target Apple's playback requirements, and the resulting files play just as well everywhere else — faststart in particular helps every platform start sooner.

What is left alone?

10-bit HEVC from iPhone HDR recording plays fine on iOS and is not touched. Rotation metadata is honoured correctly. Timecode, subtitle and metadata tracks are ignored rather than flagged, because iOS simply skips what it does not understand.

Is it free?

Yes, and there is no account or sign-up.

What you can do with your images

Convert iPhone photos, shrink files for email or the web, and crop to an exact size, one image or a whole batch at a time. Your images never leave your device.

  1. 01

    Convert HEIC photos to JPEG or PNG

    iPhones save photos as HEIC, which Windows, many websites and older apps can't open. Convert them to JPEG for sharing, or PNG when you need lossless quality. It works in Chrome, Edge and Firefox as well as Safari.

    In your browser
  2. 02

    Make images smaller

    Scale images down from 1% to 100% and set the quality for JPEG, WebP, AVIF and PDF. WebP and AVIF are usually far smaller than JPEG at the same quality. Each image shows its size before and after, like 4.2 MB → 380 KB.

    In your browser
  3. 03

    Compress PNGs without losing anything

    The PNG compression slider trades speed for size. The result is always pixel-for-pixel identical to the original: images with few colours are stored as a palette, and an alpha channel that isn't used is dropped.

    Lossless
  4. 04

    Crop, rotate and flip

    Drag a crop box or type exact pixel values, and lock it to 1:1, 4:3, 3:2, 16:9 or 9:16 for profile pictures, thumbnails and stories. Rotate in 90° steps, flip either way, and give any image its own scale.

    Per image
  5. 05

    Turn images into PDFs and icons

    Save any image as a one-page PDF to email or upload where only documents are accepted, or as an ICO favicon with every standard icon size inside (16 px up to 256 px).

    In your browser
  6. 06

    Work in batches

    Drop a whole folder of photos, set the format once, and convert them all. Save them one by one or all together as a single .zip.

    Save all as zip

Your images stay on your device

Every step, from reading the file to converting, cropping and saving it, happens inside your browser. Nothing is uploaded, so private photos stay private. The converted copy leaves out the original's metadata, such as camera details and GPS location.

Anonymous usage data is recorded to see how the tool is doing: the file name, size and format of each image, the settings used and whether it worked. Never the image itself.

Questions

How do I convert HEIC to JPG?

Drop your HEIC photos above, choose JPEG under Convert to, then press Convert all. Save each image, or use Save all to get them in one zip file. Nothing is uploaded.

Are my images uploaded anywhere?

No. Decoding, resizing, cropping and encoding all run in your browser. The only network request is the page itself (and, the first time you need them, the HEIC decoder or AVIF encoder, which are part of the site).

Which formats can I convert from and to?

In: HEIC/HEIF, JPEG, PNG, WebP, AVIF, GIF and BMP. Out: JPEG, PNG, WebP (where your browser supports it), AVIF, PDF and ICO. TIFF, RAW and SVG files are not supported yet.

Does it keep the photo's location and camera details?

No. The converted image contains only the picture, without EXIF metadata such as GPS location, camera model or date. The photo's orientation is applied first, so it still appears the right way up.

Why is my converted file bigger than the original?

A JPEG or HEIC photo is already heavily compressed. Converting it to PNG, which is lossless, stores every pixel exactly and is usually much larger. For smaller files choose WebP, AVIF or JPEG, lower the quality, or scale the image down. Each card shows the size before and after.

What does the PNG compression slider do?

It controls how hard the encoder works. Higher settings take longer and give smaller files. PNG is lossless, so the image itself is never changed: every setting gives the same pixels.

Can I crop to an exact size?

Yes. Open Crop & edit on an image and type the X, Y, width and height in pixels, or drag the box with an aspect ratio locked. The dialog shows the final output size before you convert.

What happens to animated GIFs?

Only the first frame is kept, and the image's card says so. Animated GIF, APNG and animated WebP are all handled this way.

Is there a size limit?

No fixed limit, since nothing is uploaded. Very large photos (around 50 megapixels and up) can exceed what a phone's browser can hold in memory; if that happens the image's card will say so, and a lower scale or a crop will fix it.

Is it free?

Yes, with no account, no watermark and no limit on the number of images.