HEIC to MKV Converter

Turning iPhone Photos into an MKV: What This Covers

HEIC is a still photograph and MKV is a video container, so the conversion has to invent a time axis: your photo is held on screen as a motionless clip for a duration you choose, and several photos become one slideshow. This walk-through covers the settings that actually change the result — duration, merge strategy, frame size and background colour — plus the errors people hit when a photo-shaped picture meets a video-shaped container.

How to Convert HEIC to MKV

1. Upload Your HEIC Photos: Drag the files onto the page or click "+ Add Files". Several photos are fine; they are used in the order they appear in the list.
2. Choose a Merge Strategy: "Merge images" is the default and concatenates everything into one MKV. "Video per image" produces a separate clip for each photo instead.
3. Set Image Duration and Background Color: "Image Duration" holds each photo for 5 seconds by default, adjustable from a single frame to 10 seconds. "Background Color" defaults to White and fills both the bars around an off-shape photo and any transparent area of the source.
4. Convert and Download: Click Convert and save the .mkv. No sign-up, no watermark. Files are uploaded over an encrypted connection, converted on our servers, and deleted automatically a few hours later.

Walk-through: Duration, Frame Size and Codec

The encoder writes one frame per second and disables B-frames, because every frame of a still-image clip is identical — that is why a ten-second hold is barely larger than a two-second one, and why these files stay small no matter how long you make them.

• If you want a slideshow, leave the merge strategy on "Merge images" and set Image Duration to 3-5 seconds per photo. Ten photos at 4 seconds gives a 40-second MKV.
• If you want a placeholder clip for an editing timeline, set Image Duration to one of the single-frame values (1/60s, 1/30s or 1/24s) and you get the shortest legal clip the container allows.
• If the photos have different shapes, pick a fixed frame under "Video resolution" so every image lands on the same canvas, and set Background Color to Black if you would rather have cinematic bars than white ones. Leaving resolution on "Keep original" uses the first photo's own dimensions.
• If a player rejects the file, check the codec before anything else. H.264 is the default and the safest choice; the MKV container will hold almost anything, but that does not mean the player at the other end will decode it.

Codec Choices That Make Sense Here

The legacy codecs in that last row size themselves against the source video's bitrate, and a photograph does not have one, so the quality preset has nothing to work from. On a still image they cost you file size without buying quality.

HEIC and MKV Side by Side

Common Errors and How to Fix Them

• "The clip is silent." Expected. A photo has no audio stream, so the output is video-only and no audio codec control is offered. Add music afterwards in a video editor.
• "Nothing moves." Also expected. The source is a single frame; the MKV holds it still for the duration you chose. Motion would have to come from multiple photos plus a merge.
• "QuickTime won't open it." QuickTime does not support Matroska at all. Use VLC or mpv on macOS, or convert to HEIC to MP4 if the file has to open in Apple's own player.
• "There are white bars down the sides." The photo's aspect ratio does not match the chosen frame size. Switch "Video resolution" back to "Keep original", or pick Black under Background Color.
• "My 48-megapixel photo looks softer than the original." Each image is normalised and capped at 4096 pixels on the long edge before encoding, so very large photos are scaled down to fit.
• "The MKV won't play on my TV." Many smart TVs and set-top boxes only demux MP4. Container support and codec support are separate problems — check both before blaming the file.

When This Doesn't Work

If your goal is a web page, an email attachment or a phone that has to play the clip without a third-party app, MKV is the wrong target — its strength is holding many tracks, not universal playback, and MP4 will do the same job with far fewer support questions. If you actually want a still image that opens everywhere, no video is needed at all: convert straight to HEIC to JPG. And if a HEIC refuses to convert, it is usually not a standard camera photo — depth-map, ProRAW and screenshot variants can carry unusual layouts, and re-exporting a normal copy from the Photos app resolves it.

Frequently Asked Questions

Why would I put an iPhone photo into an MKV at all?

Because some pipelines only accept video. Digital-signage players, media servers, editing timelines and playlist software want a clip, not a picture file. Wrapping a photo in MKV lets it sit in a video playlist, loop on a display, or be concatenated with real footage without the receiving tool having to understand HEIC.

Does merging several photos create real motion?

No — it creates a sequence of held stills. Each photo is displayed for the Image Duration you set and then replaced by the next, which is a slideshow. There is no cross-fade, pan or zoom, and no interpolation between images.

Does the MKV keep any of the photo's EXIF data?

Not in a form a photo tool will read. Video containers store their own metadata — title, duration, track information — not camera EXIF, so capture date, GPS position and exposure settings do not survive as photo metadata. Keep the original HEIC if any of that matters.

Which players open MKV without extra software?

VLC and mpv on Windows, macOS and Linux, plus Windows 10 and 11 out of the box. Apple's QuickTime does not support it, most browsers will not play it inline, and TV and set-top support varies by model. That is the trade you accept for Matroska's flexibility.

Can I put a soundtrack in the MKV?

Not in this conversion — the source images carry no audio, so nothing is written. MKV itself will happily hold AAC, MP3, Opus, FLAC, subtitles and chapters, so add the music in a video editor once the clip exists.

How long can the slideshow be?

Long enough that the limit is your patience with the upload, not the format. Each photo can be held for up to 10 seconds, and there is no cap on how many photos you merge; because every frame is identical, the encoded result stays small even for long runs.

Why is the video only 1 frame per second?

Because more frames would be identical copies. Encoding a static picture at 1 fps with B-frames disabled produces a smaller file and avoids the start-time offset that B-frames cause on very short clips. Players handle a 1 fps stream normally — the picture simply does not change.

What happens to my files after conversion?

They are uploaded over an encrypted connection, converted on our servers, and deleted automatically a few hours later — no sign-up, no watermark, never shared or made public.