Which Video Formats Can Compress Video Online Handle?

Updated

Compress Video Online accepts MP4, WEBM, MOV, FLV, 3GP, M4V, MPG, MPEG, MKV, AVI, WMV, MV, DV, ASF, and 3G2 files. Most of these can be loaded and compressed directly in the browser; a few less common formats may need a conversion step first, which adds processing time. The tool also lets you choose the output format, so you are not locked into the format you started with.

Supported input formats

According to the tool's own documentation, the following video formats can be processed:

Format Notes
MP4 Common, typically processed directly
WEBM Common, typically processed directly
MOV Common, typically processed directly
FLV Supported
3GP Supported
M4V Supported
MPG / MPEG Supported
MKV Supported
AVI Supported
WMV Supported
MV Supported
DV Supported
ASF Supported
3G2 Supported

If your file is in one of these formats, you can try loading it straight into the tool.

What "some formats need conversion" actually means

The tool states that most formats can be processed directly, but some require post-conversion processing, and that conversion takes some time. In practice this means:

  • Direct processing — the file loads and compresses without an extra step.
  • Conversion first — the tool has to convert the file before compressing, so expect a longer wait and possibly a larger temporary load on your browser.

The documentation does not list exactly which formats fall into the "needs conversion" group, so the practical approach is to load your file and watch whether the tool reports a conversion step or simply proceeds to compression.

Output format choices

You are not limited to the input format. The tool includes a video output format setting, so after loading and trimming your clip you can pick the format you want the compressed file to be saved in. This is useful when, for example, you have an AVI file but need an MP4 for sharing or uploading elsewhere.

How to check your format works

  1. Open the tool in a current browser (it runs on HTML5 and FFMPEG JS, so a newer browser version is required).
  2. Click the file button or drag your video into the page.
  3. Watch what happens after loading:
    • If the preview appears and the compression controls become usable, your format is being handled directly.
    • If the tool indicates a conversion step, wait for it to finish before setting your trim points and target size.
  4. Set start and end times (default is the whole video).
  5. Set the output file size by dragging or entering a precise value.
  6. Choose your output format.
  7. Start compression, then save the finished file to your device.

Practical notes

  • Processing happens in your browser. The tool states that files are not uploaded to a server, which is why format handling depends on your browser's capabilities rather than a remote converter.
  • Uncommon formats are the slow cases. If you are working with DV, MV, or ASF, budget extra time for the conversion stage.
  • No login or email is required according to the tool, and the output carries no watermark.
  • If a format fails to load, converting it to MP4 with another tool first is the simplest fallback, since MP4 is the most broadly handled format here.

The short answer: if your video is MP4, WEBM, MOV, or another mainstream format, expect it to work directly. If it is an older or less common format from the supported list, it should still work but may take longer because of the conversion step.