CAVS to HEVC Converter

CAVS to HEVC Converter

A .cavs file is a raw Chinese AVS (AVS1) video elementary stream — China's home-grown video-coding standard, used in domestic digital TV, IPTV, and set-top-box recordings, and almost nothing outside that ecosystem decodes it. HEVC (H.265) is the global modern codec that succeeded H.264, roughly twice as efficient. This converter decodes the orphaned AVS1 picture and re-encodes it to HEVC, moving niche broadcast footage onto a codec that recent phones, Apple devices, and 2017-or-newer TVs can play. Two honest points up front: a bare .cavs is video-only, so the HEVC output is silent, and this is a lossy-to-lossy re-encode — the file gets smaller and more portable, not sharper.

CAVS (AVS1) Format at a Glance

HEVC (H.265) Format at a Glance

How to Convert CAVS to HEVC

1. Upload Your CAVS File: Drag and drop your .cavs onto the page or click "+ Add Files" to browse from your device. You can queue several raw AVS1 streams and convert them with the same settings.
2. Pick a Quality Preset: Open Advanced Options and leave "Preset" on "Very High (Recommended)" to stay close to the source, or switch to "Specific file size" to target an exact size in MB. "Constant Quality" (CRF), "Constant Bitrate", and "Variable Bitrate" are there if you want tighter control over the H.265 output.
3. Set Resolution or Trim (Optional): Under "Video resolution" choose "Keep original", a "Preset Resolutions" entry, "Resolution Percentage", or an exact "Width x Height". Open "Trim" and switch to "Time Range" to export just one segment from a long broadcast capture.
4. Convert and Download: Click "Convert" and download your .hevc file. No sign-up, no watermark.

For footage you want to play everywhere with the least fuss, CAVS to MP4 (H.264) is the safer target, and CAVS to MKV wraps the stream in a container that more apps open directly.

Frequently Asked Questions

What exactly is a .cavs file, and what standard defines it?

It is a raw video elementary stream encoded with AVS1, China's national video-coding standard, defined by GB/T 20090.2-2006 and promulgated in February 2006 by the AVS Working Group (founded June 2002). The picture uses the AVS1-P2 JiZhun (base) profile, a block-based motion-compensated design with coding efficiency broadly comparable to H.264 of the same era. It appears mostly in Chinese digital-TV, IPTV, and set-top-box environments and is rarely seen elsewhere, which is why general-purpose players usually can't open it directly.

What kind of file does this output — a video container or a raw stream?

A raw H.265 elementary stream (Annex B bitstream) with the .hevc extension, not a container like MP4 or MKV. Players such as VLC, mpv, and IINA generally open it directly, but QuickTime, Windows Photos, and most smart-TV apps expect the HEVC stream wrapped in a container. If you need a file those play, use CAVS to MP4 for a universally playable H.264 file, or CAVS to MKV to wrap the video in a container.

Will converting CAVS to HEVC improve the picture quality?

No — it makes the file smaller and more portable, not better. The .cavs stream is already lossily coded with AVS1, and re-encoding it to HEVC is a lossy-to-lossy step: H.265 cannot add back detail the original AVS1 encode discarded. What you gain is reach (a codec modern devices decode) and size (HEVC is roughly 50% smaller than H.264 at similar quality). Keep "Preset" on "Very High" and leave the native resolution so the re-encode stays visually close to the source.

Why does the converted HEVC file have no sound?

Because a raw .cavs is an AVS1 video elementary stream — picture only, with no audio for the converter to carry. In Chinese AVS workflows the sound was encoded as a separate stream and muxed in only when the final container was built, so the bare .cavs on its own is mute, and the raw .hevc output (which is also video-only) is therefore silent. It is not a fault in the conversion — there was never any audio in the source. If you have the original container (an MPEG transport stream or MP4) that holds both streams, convert that file instead, because the audio lives there.

Why does my HEVC output play on fewer devices than I expected?

Because HEVC playback is fragmented despite the codec being a decade old. Per caniuse, Safari supports it from version 11, Chrome added partial support in v107 and Firefox in v137 — both relying on OS-level hardware decode — and Edge needs the HEVC Video Extensions package. So HEVC is the smaller but less universally compatible target compared with the H.264 your devices already play. If reach matters more than size, convert to CAVS to MP4 (H.264) instead. The codec's three patent pools and slow encoding are the historical reasons browser vendors were cautious about it.

Is the AVS1 standard behind CAVS still maintained, or is it obsolete?

AVS1 is dated — promulgated as GB/T 20090.2-2006 to match H.264's efficiency at lower complexity under a more transparent royalty policy — but the family is not abandoned. It continued through AVS+ (GY/T 257.1-2012) for HD broadcast and on to AVS2 and AVS3 for UHD. The original AVS1 .cavs streams persist in older Chinese broadcast and set-top-box archives, which is exactly why re-encoding them to a globally supported codec like HEVC (or the more compatible H.264 via CAVS to MP4) is the practical way to keep that footage playable.

Could my file actually be an AviSynth .avs script instead?

Worth checking, because the extensions look similar. An .avs AviSynth file is a small text script that tells a video frameserver how to process other clips — it is not video data and not Chinese AVS. A .cavs (Chinese AVS) file is genuine coded video. If your file opens as readable text in an editor, it is an AviSynth script and there is no coded picture inside it to re-encode. If it is binary coded data from Chinese digital TV or broadcast, it is a real AVS1 video stream — still video-only, so the silent-output explanation above applies.

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

In our testing, re-encoding a short raw .cavs stream to HEVC at the "Very High" preset produced a clean, VLC-playable .hevc file with no audio track — exactly what a silent, video-only source should yield. Your file is uploaded over an encrypted connection, decoded and re-encoded into HEVC on our servers, and deleted automatically a few hours after conversion — no sign-up, no watermark, never shared or made public. The realistic limit on very large broadcast captures is upload time, not anything on your device, and HEVC encoding (slower than H.264) runs on our servers rather than your machine.