CAVS to MKV Converter

CAVS to MKV Converter

A bare .cavs file is a raw Chinese AVS (AVS1) video bitstream — coded picture data with no container around it and no audio track inside, which is why most players and editors refuse to open it directly. MKV (Matroska) is a royalty-free open container that can hold an unlimited number of video, audio, subtitle, and chapter tracks in one seekable file. This converter wraps the orphaned AVS1 stream into MKV so ordinary players can index and play it — and is honest about the two catches: MKV does not carry AVS1 natively here, so the video is re-encoded to H.264, and the MKV comes out silent because the raw stream never had any sound.

CAVS (AVS1) Format at a Glance

MKV (Matroska) Format at a Glance

How to Convert CAVS to MKV

1. Upload Your CAVS File: Drag and drop your .cavs onto the page or click "+ Add Files" to browse from your computer. You can queue several raw streams and process them with the same settings.
2. Set the Preset: Open Advanced Options. Under "File Compression" leave "Preset" on "Very High (Recommended)" for a near-source result, or switch to "Specific file size" to target an exact size in MB.
3. Set Resolution and Trim (Optional): Use the "Video resolution" presets or "Width x Height" to rescale; under "Show All Options" the "Video Codec" defaults to H.264. Use the "Trim" section's "Time Range" to keep only the segment you need.
4. Convert and Download: Click "Convert" and download your MKV. No sign-up, no watermark.

Frequently Asked Questions

Is converting CAVS to MKV a lossless rewrap or a re-encode?

A re-encode. A .cavs stream is coded with AVS1, and this converter writes H.264 into the MKV by default — so it decodes the AVS1 frames and re-encodes them to H.264, which is one lossy generation. Matroska itself can technically carry an AVS1 stream, but here the pipeline does not drop the original frames in byte-for-byte; it re-encodes. Keep "Preset" on "Very High" so the second compression pass stays as invisible as possible. There is no setting that recovers detail the original AVS encoder already discarded.

Why doesn't the converted MKV have any audio?

Because a raw .cavs file is an AVS1 video elementary stream — it carries no audio for the converter to copy or transcode. In Chinese AVS broadcast workflows the picture was encoded as the AVS stream and the sound was carried as a separate stream, the two muxed together only when the final container (an MP4, transport stream, or MKV) was built. The bare .cavs on its own is mute, so the MKV comes out silent. If you have the original combined container that holds both the video and its audio, convert that file instead.

What is a .cavs file, and why won't it open in my player?

It is a raw Chinese AVS video bitstream — the picture half of AVS1, China's first-generation Audio Video Standard, standardized as GB/T 20090.2 and promulgated as a national standard in February 2006 by the AVS Workgroup (founded June 2002). A plain .cavs is an elementary stream handled by FFmpeg's cavsvideo raw demuxer: coded video frames with no container, no audio, and no timing index. Most players expect a container rather than a loose stream, so they refuse to open a .cavs directly. Wrapping it into MKV gives them the seekable container they need.

Why pick MKV over MP4 for this conversion?

MKV (Matroska) is a royalty-free open container built on EBML that can hold an unlimited number of video, audio, subtitle, and chapter tracks, which makes it a strong target for archival and for adding tracks later. The tradeoff is reach: MP4 plays natively almost everywhere — phones, smart TVs, and every browser — while MKV relies on the player's own decoder (VLC, MPV, and MPC-HC handle it reliably; Chrome and Firefox play it through their built-in ffmpeg paths). If your goal is a clip that just plays anywhere, CAVS to MP4 is the more universal wrap; choose MKV when you value the open container and multi-track flexibility.

Does MKV carry the AVS1 stream natively, or is it always H.264 inside?

The Matroska container is codec-agnostic and could in principle store an AVS1 stream, with the codec details kept in its CodecPrivate element. In practice this converter writes H.264 into the MKV by default, because almost no player can decode an AVS1 track even when it is inside a Matroska file — so a remux to raw-AVS-in-MKV would still not play. Re-encoding to H.264 produces an MKV that actually opens in mainstream players. Under "Show All Options" you can switch "Video Codec" to other formats MKV accepts.

Is .cavs the same as a .avs AviSynth script?

No, and they are easy to confuse. A .cavs file is a raw AVS1 video bitstream — actual coded picture data from the Chinese AVS standard. A .avs file is an AviSynth script: a small text file of frameserving instructions, not video itself. This converter expects the video bitstream. If you uploaded an AviSynth script by mistake, there is no AVS1 picture inside it to wrap into MKV.

Is the AVS1 standard still maintained, and should I migrate off it?

AVS1 (GB/T 20090.2) remains a published national standard, but for new work it has been superseded — AVS2 targets 4K/ultra-HD and AVS3 is the current generation. A .cavs file you are converting today is almost always legacy Chinese-broadcast-era material. Wrapping it into MKV (or CAVS to MP4) gets that older footage into a modern, seekable container that current players and editors recognize, without needing AVS decoding support at playback time.

How are my files handled, and how long are they kept?

In our testing, wrapping a short raw .cavs stream into MKV at the "Very High" preset produced a clean H.264 file with no audio track, exactly as expected from a silent source. Your file is uploaded over an encrypted connection, decoded and re-encoded into MKV on our servers, and deleted automatically a few hours after conversion — no sign-up, no watermark, never shared or made public.