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MP4, M4V, MOV, WebM, or MKV. One primary video track and, optionally, one primary audio track.
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The generated short clip is safe for testing the complete local workflow.

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Compatible primary streams are copied; other streams are re-encoded only after browser capability checks.
Secondary audio tracks and subtitles are not included.
Conversion starts only after this action and runs locally.
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Off is neutral and preserves tags supported by the destination container.
Profile
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Conversion
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Dimensions
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Duration
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Audio
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File size
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CheckpointSourceOutputMeaningCopy
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A video file combines a container with encoded video and audio streams. MP4, MOV, WebM, and MKV name containers, while H.264, VP9, AAC, and Opus describe codecs inside them. Changing the filename extension alone cannot make an unsupported stream compatible.

Format conversion may copy an already compatible stream into a new container or decode and re-encode it for the destination profile. Copying is faster and avoids a new lossy encoding pass. Re-encoding enables a different codec, but it can change file size and introduce generation loss even when dimensions and timing are preserved.

PathWhen it appliesMain consequence
Stream copyThe source codec already matches the target profileNo new codec loss; the container and file size may still change
Re-encodeThe source codec does not match or its audio layout exceeds the targetBroader compatibility with possible quality and bitrate changes
Discard audioA muted output is requestedThe video timing remains, but no audio track is written

Compatibility is ultimately a playback question, not a promise attached to an extension. A useful conversion should confirm the destination codecs, dimensions, duration, and readability, then be watched and heard in the intended player before the source is replaced.

How to Use This Tool:

Choose the destination that matches the playback or publishing system. MP4 favors broad device support; WebM is suited to open-web delivery.

  1. Choose one Source video in MP4, M4V, MOV, WebM, or MKV format. The file must be no larger than 80 MiB, five minutes, or 1920 × 1080.
  2. Select Target format, then choose whether to keep the primary audio track or create a muted video.
  3. Enable Remove supported tags only when embedded title, author, date, location, or other supported metadata should be omitted.
  4. Start conversion and wait for verification. Review the converted preview, duration, dimensions, codecs, and sound before downloading the file.

Interpreting Results:

A verified result has the selected video codec, the requested audio policy, unchanged pixel dimensions, and a duration within the accepted tolerance. The conversion label tells you whether streams were copied, re-encoded, or handled by a mixture of both paths.

File size is evidence, not a quality score. A smaller output may reflect a more efficient codec, a lower bitrate, discarded audio, or a different container overhead. Watch representative motion and listen to the audio instead of judging fidelity from byte count alone.

Technical Details:

The destination profile fixes the container and primary codecs while retaining source dimensions and frame cadence. Codec capability is checked before conversion, so a browser that cannot decode the source or encode the required target will stop instead of exposing an unverified download.

Transformation Core

TargetVideoAudioCopy condition
MP4H.264AAC or noneCopy H.264 video; copy AAC audio only at up to 48 kHz and two channels
WebMVP9Opus or noneCopy VP9 video; copy Opus audio only at up to 48 kHz and two channels

When video must be re-encoded, the planned bitrate stays between 500 kbit/s and 20 Mbit/s, using the source bitrate when it falls inside that range. Re-encoded audio becomes mono at 128 kbit/s or stereo at 192 kbit/s. More than two source channels are downmixed, and sample rates above 48 kHz are reduced to 48 kHz.

Verification Rule Core

  1. Read one primary video track and, when present and requested, one primary audio track.
  2. Copy compatible streams; otherwise re-encode them to the selected profile after checking browser support.
  3. Write the destination container while preserving source dimensions and frame cadence. Secondary audio tracks and subtitle tracks are omitted.
  4. Reopen the output and compare its codec, dimensions, duration, and browser readability with the conversion plan.

Duration passes when the difference is no more than 150 milliseconds or 2% of the source duration, whichever is larger. The output is offered only after these checks succeed.

Privacy and Limits:

The selected video and converted output remain in browser memory for the current page and are not uploaded or retained by the service.

  • Only one primary video stream and one optional primary audio stream are included.
  • Conversion does not resize, trim, change speed, add captions, apply effects, or target an exact file size.
  • Metadata removal covers supported container tags, not a forensic guarantee that every identifying detail has been removed from visible frames or audio.
  • Large or complex files can exceed browser memory or codec capabilities even when they meet the stated size limits.

Worked Examples:

Compatible MP4 handoff

An MP4 containing H.264 video and two-channel AAC at 48 kHz can keep both primary streams. The result may differ slightly in file size because the container is rewritten, but no codec re-encoding is required.

MP4 source for WebM delivery

Choosing WebM for an H.264 and AAC source requires VP9 and Opus encoding. Dimensions and timing are preserved, while bitrate, file size, and fine visual or audio detail may change.

References: