Video Converter

What Video Converter helps you do

Move a video between MP4, WebM, MOV and MKV without uploading it. When the existing video and audio codecs already fit the target container, the tool remuxes the streams, which is fast and does not change the picture. When they do not fit, it can re-encode so the file plays on the device or platform you have in mind.

The conversion pipeline is local. No part of the video is uploaded, and no temporary file is left on a Haivix server.

How it works

A container is a box that holds encoded video and audio tracks plus timing information. Remuxing rewrites that box while copying the tracks, so the quality is untouched and the operation finishes quickly. Re-encoding decodes each frame and compresses it again in a codec the target container accepts. The tool inspects the source first and recommends the cheaper path, but you stay in control of the final choice and can compare the two results.

How to use Video Converter

1. Load the video and read which container, codecs and tracks it contains.
2. Pick the output container you need.
3. Leave remux selected when the codecs are compatible, or enable re-encoding for compatibility.
4. Start the conversion and wait for the progress indicator.
5. Check that the audio survived and that the file plays in the target app.
6. Download the converted video.

When to use it

• Turn a WebM download into an MP4 that a phone or TV will play.
• Wrap an MKV recording in MP4 without losing quality.
• Prepare a file for an editor or platform that accepts only one container.
• Fix a video whose audio is missing after a container change.
• Standardise a folder of clips before merging them.

When not to use it

• Do not convert a file you have no right to copy or redistribute.
• Do not expect remuxing to fix a corrupted or unsupported codec inside the file.
• Avoid re-encoding when a remux already produces a playable file.

Example

A browser recording saved as WebM with VP9 video and Opus audio needs to go to a client who uses an older phone. Remuxing to MP4 fails because the phone does not recognise those codecs, so the tool re-encodes to H.264 and AAC. The result is larger but plays everywhere, and the original WebM stays untouched for the web version.

What you can do with Video Converter

• Read the container, codecs and track layout before converting.
• Remux when the source codecs are compatible with the target.
• Re-encode to H.264/AAC or another browser-supported combination when needed.
• Preserve multiple audio tracks where the target container allows them.
• Keep metadata such as rotation where the container supports it.
• Copy the source tracks without touching them in remux mode.
• Convert local files only, with no upload step.

Example workflow

Convert before merging. The merge tool can copy packets only when every clip shares a codec, profile and resolution, so converting all parts to MP4 with the same settings first avoids a normalization pass later.

Convert after trimming when you only need the short section. Re-encoding a five-minute clip is much faster than re-encoding an hour of footage that will be discarded.

Keep the original container until the destination is confirmed. If a client asks for a different format later, starting from the source avoids stacking two lossy conversions.

What to know before you start

• Remuxing cannot repair a stream the target device does not support.
• Re-encoding introduces a small generation loss, like saving a JPEG twice.
• Some container and codec combinations are not supported by browser encoders.
• Audio may be dropped when neither remux nor re-encode can carry the source codec.
• DRM-protected files are not supported.

Common mistakes

• Re-encoding when a remux would have worked, adding an unnecessary quality loss.
• Changing the container but not the codecs, then testing only in the same browser.
• Forgetting to check the audio track after conversion.
• Converting a file twice instead of keeping the first good output as the master.
• Assuming a file extension tells you which codec is inside.

Troubleshooting

If the audio disappears, the target container or the browser encoder did not accept the source audio codec. Try MP4 or MKV, which accept a wider range, or enable re-encoding.

If the converted file will not play on a TV or phone, check the video codec rather than the extension. Many devices accept the MP4 box but not every codec inside it.

If the conversion is very slow, the tool is probably re-encoding. Switch to remux when the source codecs already match the target.

If a remux fails immediately, the target container cannot hold one of the source tracks. Re-encode the file or choose a container that supports both the video and audio codecs.

Related standards and documentation

• ISO/IEC 14496-12 (MP4) and the Matroska specification describe the two most common containers here.
• RFC 6381 defines the codec strings used to describe tracks inside a container.