Convert CAVS to M2TS — Free Online Tool
Convert CAVS (Chinese Audio Video Standard) files to M2TS (Blu-ray BDAV Transport Stream) using H.264 video encoding and AAC audio, entirely in your browser. This conversion bridges a niche Chinese broadcast format with the internationally recognized Blu-ray container, making CAVS content compatible with Blu-ray players, AVCHD workflows, and high-definition editing pipelines.
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FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
Drop your CAVS file here
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Settings
Note: Browser-based encoding uses approximate quality targets. For precise CRF compression, copy the FFmpeg command above and run it on your desktop.
Estimated output:
Conversion Complete!
DownloadHow It Works
CAVS files use a proprietary Chinese video codec (AVS/AVS+) that is not natively supported by most international playback or editing software. During this conversion, FFmpeg decodes the CAVS video stream and re-encodes it as H.264 (libx264) using a CRF of 23 — a visually transparent quality level for most content. The audio is simultaneously decoded and re-encoded as AAC at 128k bitrate. The resulting streams are then muxed into an M2TS container, which uses the MPEG-2 Transport Stream structure expected by Blu-ray Disc Audio-Video (BDAV) systems. Because both the video and audio require full transcoding (not just remuxing), this process is compute-intensive and processing time scales with file length and resolution.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg binary — the open-source multimedia processing engine that handles decoding the CAVS input, transcoding both streams, and muxing the M2TS output entirely through a single pipeline. |
-i input.cavs
|
Specifies the input file in CAVS format. FFmpeg will use its built-in AVS decoder to demux and decode the Chinese Audio Video Standard video stream and its accompanying audio from this container. |
-c:v libx264
|
Re-encodes the decoded CAVS video frames as H.264 using the libx264 encoder — the codec required to produce an M2TS file compatible with Blu-ray players, AVCHD software, and international video workflows that cannot read the native AVS codec. |
-c:a aac
|
Re-encodes the audio as AAC using FFmpeg's native AAC encoder, producing a compressed audio stream compatible with the M2TS container and most Blu-ray software players. |
-crf 23
|
Sets the H.264 Constant Rate Factor to 23 — FFmpeg's default, which balances file size and visual quality well for most CAVS source material. Lower values (e.g., 18) increase quality and file size; higher values (e.g., 28) reduce both. |
-b:a 128k
|
Sets the AAC audio bitrate to 128 kilobits per second, which provides good stereo audio quality suitable for the majority of CAVS broadcast recordings without producing unnecessarily large output files. |
output.m2ts
|
Defines the output filename with the .m2ts extension, which signals FFmpeg to use the MPEG-2 Transport Stream muxer in BDAV mode — the correct container structure for Blu-ray Disc Audio-Video compatible files. |
Common Use Cases
- Making CAVS broadcast recordings from Chinese television or set-top boxes playable on Blu-ray players and home theater systems that support AVCHD or M2TS
- Importing CAVS footage into professional NLEs like Adobe Premiere or DaVinci Resolve, which natively handle M2TS from AVCHD camcorders but cannot read CAVS
- Archiving Chinese digital broadcast recordings in a standardized, internationally recognized container format for long-term preservation
- Preparing CAVS-encoded video content for inclusion in Blu-ray authoring workflows where M2TS is the required input format
- Converting CAVS files captured from Chinese streaming or broadcast equipment so they can be played on Sony or Panasonic AVCHD-compatible camcorder playback software
- Standardizing a library of mixed Chinese broadcast recordings into a single consistent container format for media server ingestion (e.g., Plex, Jellyfin)
Frequently Asked Questions
Yes, some quality loss is inevitable because the CAVS video codec must be fully decoded and then re-encoded as H.264 — this is a transcode, not a lossless remux. At the default CRF 23 setting, the quality loss is generally imperceptible for standard-definition and most high-definition CAVS content, but the H.264 output will not be a perfect bitwise copy of the original AVS-encoded frames. If your source CAVS file is already compressed, each generation of transcoding accumulates some quality degradation.
The M2TS container (MPEG-2 Transport Stream / BDAV) is designed to carry specific codec streams — primarily MPEG-2, H.264, H.265, and VC-1 for video. The native AVS/AVS+ codec used in CAVS files is not a recognized stream type in the M2TS/BDAV specification, so copying the raw stream would produce an unplayable or non-compliant file. Re-encoding to H.264 is therefore necessary to produce a valid, widely compatible M2TS output.
M2TS does support subtitles (PGS bitmap subtitles for Blu-ray, or DVB subtitles in broadcast contexts), but CAVS files rarely carry subtitle streams in a format FFmpeg can extract and transcode cleanly into M2TS. This conversion tool does not transfer subtitle data. If your CAVS file has embedded subtitles, they will be dropped during conversion, so you should extract and handle subtitle tracks separately if needed.
Adjust the -crf value to control H.264 quality. CRF (Constant Rate Factor) ranges from 0 (lossless) to 51 (worst quality), with lower numbers producing larger files at higher quality. For archiving CAVS content with minimal quality loss, try CRF 18. For smaller file sizes where some quality degradation is acceptable, CRF 28 is reasonable. For example: ffmpeg -i input.cavs -c:v libx264 -c:a aac -crf 18 -b:a 128k output.m2ts
Yes, on the command line you can use a shell loop to process multiple files. On Linux or macOS: for f in *.cavs; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "${f%.cavs}.m2ts"; done. On Windows Command Prompt: for %f in (*.cavs) do ffmpeg -i "%f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "%~nf.m2ts". The browser-based tool processes one file at a time, so use the local FFmpeg command for bulk conversions.
M2TS files with H.264 video and AAC audio are broadly compatible with Blu-ray players and PlayStation 3/4/5 when the video is within Blu-ray profile constraints (e.g., High Profile, appropriate resolution and bitrate). However, standalone Blu-ray players reading from USB or disc expect specific BDMV folder structures, not loose M2TS files. For direct disc playback, you would need to author a proper BDMV structure around the M2TS. For PC software players like VLC, PowerDVD, or media servers, a standalone M2TS file will play without any additional structure.
Technical Notes
CAVS (Chinese Audio Video Standard, also known as AVS1 or GB/T 20090) is a Chinese national codec standard that achieves compression efficiency comparable to H.264 but remains largely unsupported outside of Chinese hardware and software ecosystems. FFmpeg can decode most CAVS streams via its built-in AVS decoder, but the codec cannot be stream-copied into M2TS due to container incompatibility, making a full transcode mandatory. The output uses libx264 in M2TS via the mpegts muxer, which FFmpeg handles correctly — however, be aware that the BDAV specification mandates specific constraints on H.264 streams (e.g., Level 4.1 for 1080p) that FFmpeg does not enforce by default; for strict Blu-ray compliance you may need to add flags like -level 4.1 -profile:v high. AAC audio in M2TS is technically permitted by BDAV but some hardware players prefer AC-3 (Dolby Digital); if you encounter audio compatibility issues on standalone players, substitute -c:a ac3 -b:a 192k. CAVS files sourced from Chinese broadcast or set-top box recordings sometimes contain non-standard timestamps or bitstream errors that can cause FFmpeg to misreport duration or produce A/V sync issues — adding -fflags +genpts to the command before the output can help correct timestamp irregularities.