ERF to HEVC Converter

.hevc or .mp4 — Which Should You Convert an Epson Raw Still To?

An ERF is a single Epson RAW photograph from the R-D1 rangefinder line, so either target has to invent time: the raw is developed into ordinary pixels and then held on screen as a short, silent clip. The real question is which wrapper that clip should live in. The .hevc file this page produces is a Matroska container carrying an H.265 video stream — excellent compression, awkward compatibility. An MP4 carrying H.264 is bigger by a hair on a single repeated frame and plays essentially everywhere. Convert to .hevc when a specific H.265 pipeline asks for it; otherwise take the MP4.

Side-by-side: This Page's .hevc Output vs an MP4

When to Pick .hevc

• Something downstream names H.265 explicitly. An encoder chain, a hardware decoder, a broadcast or camera-adjacent tool that wants an H.265 stream and will not take H.264.
• You are feeding a player that handles Matroska happily. VLC, mpv and ffmpeg open the file directly with no fuss and no renaming.
• You are stacking many frames into one long clip. Merge a large batch of R-D1 photos with a long per-frame duration and H.265's efficiency starts to matter; on a five-second single still it does not.
• You will rename the file anyway. Because the container is Matroska, changing the extension to .mkv makes most players and file managers treat it correctly.

When to Pick MP4 Instead

• Anyone else has to open it. Phones, browsers, messaging apps, presentation software and non-linear editors all take an H.264 MP4 without discussion.
• You want it to behave like a normal video file. A double-click on an .hevc file frequently opens nothing, because the extension is unfamiliar even though the container is not.
• Encoding time matters. H.265 is meaningfully slower to encode for a benefit that a static frame barely realises.
• You actually wanted a picture, not a clip. In that case neither is right — convert to ERF to JPG and keep full photographic resolution with no video wrapper at all.

Where H.265 Actually Plays

How to Convert ERF to HEVC

1. Upload Your ERF Files: Drag and drop your .erf files onto the page or click "+ Add Files". Raw files are large, so the upload is usually the longest step; several R-D1, R-D1s or R-D1x frames can be queued at once.
2. Set Merge strategy and Duration: "Merge strategy" is preselected to "Merge images", placing every uploaded photo back to back in one file; "Video per image" writes a separate file each. Under "Image Duration", the "Duration" dropdown is preselected to "5 seconds per frame".
3. Choose Background Color, Quality Preset and Video resolution (Optional): "Background Color" is preselected to White and fills the letterbox bars when the photo's shape does not match the output frame. "Quality Preset" sits on "Very High (Recommended)", with Constant Quality and Constraint Quality as the alternatives; "Video resolution" stays on "Keep original" unless you pick a Fixed or Preset resolution.
4. Convert and Download: Click "Convert" and download the file. Files upload over an encrypted connection, are processed on our servers, and are deleted automatically after a few hours. No sign-up, no watermark.

Frequently Asked Questions

What exactly is the .hevc file I get — a raw stream or a container?

A container. The output is a Matroska file carrying an H.265 video stream, written under the .hevc extension rather than .mkv. That matters in practice: it is not a bare elementary bitstream, so it carries proper timing and stream metadata, and VLC, mpv and ffmpeg open it directly. If a player or file manager refuses it, rename the file to .mkv — the bytes are already correct and only the extension is unfamiliar.

Does converting one ERF to HEVC produce any motion or sound?

No on both counts. An ERF is a single photograph with no motion and no audio, so the result is a freeze-frame: the rendered picture held for the Duration you set, with no pan, zoom or transition, and no audio track. The Audio Codec control does not even render for image-to-video conversions, because there is nothing to fill it. Uploading several ERFs with "Merge images" selected gives you each photo in turn with hard cuts between them.

Why does H.265's compression advantage barely show up here?

Because a static frame is the easiest thing a video codec ever encodes. H.265 was standardised in 2013 as a 25-50% bitrate improvement over H.264 at equal quality, but that figure comes from real moving footage where the codec's better prediction tools have something to predict. With one identical frame repeated for five seconds, both codecs reduce the repeats to almost nothing and the absolute saving is tiny — while H.265 still costs you the slower encode and the compatibility friction.

Do I lose quality going from a 12-bit raw to H.265?

Yes, at three separate stages. Demosaicing the Bayer sensor data bakes in one white balance, exposure and tone curve, which ends the raw editing latitude for good. The frame is then scaled to a video resolution, which for a 6.1-megapixel photograph normally means downscaling. Finally H.265 compresses lossily. Keep the original .erf as your master and treat the clip as a delivery file you can regenerate at any time.

Is ERF a compressed raw format?

No, and several converter sites get this backwards. darktable's RawSpeed decodes ERF using its uncompressed decompressor, reading 12-bit samples MSB-first with a control byte inserted roughly every ten pixels — there is no entropy-coding stage on the sensor data. That is why an ERF is bulky for a 6-megapixel camera: 6.1 million photosites at 12 bits each is about 9 MB of pixel data by simple arithmetic, before metadata and the embedded preview are added.

Why is there a Background Color option on a photo conversion?

Because the picture's aspect ratio rarely matches the video frame's. When the rendered 3:2 R-D1 image sits inside an output resolution with a different shape, the leftover area must be filled with something, and the alternatives — stretching or cropping — would damage the photograph. Background Color chooses that fill and is preselected to White; the dropdown offers a list of named colours including Black. It never touches the photo itself.

Why can't I choose a bitrate or a target file size here?

Because the source is an image. Image-to-video conversions offer Quality Preset (the default, on "Very High (Recommended)"), Constant Quality and Constraint Quality; the bitrate and target-size modes that appear on video-to-video pages are not shown. With one repeated frame there is nothing for a bitrate ladder to allocate, and quality-based encoding produces a more predictable result.

What is ERF, and why do so few tools handle it?

ERF is Epson RAW Format, written only by the Epson R-D1 — announced in March 2004 and described by Wikipedia as the first digital rangefinder ever commercially produced — and by its successors, the R-D1s (March 2006) and the Japan-only R-D1x / R-D1xG (April 2009). All three used a 6.1-megapixel Sony ICX413AQ APS-C CCD behind a Leica M mount, and Epson then left the camera business, so ERF is a closed set. It is a TIFF-based raw identified by a SEIKO EPSON CORP. maker tag; LibRaw lists all three bodies, and ExifTool reads and writes its EXIF, IPTC, XMP and ICC metadata. For every other output from the same file, see the ERF converter hub.