Convert CAVS to OGA — Free Online Tool
Extract and convert the audio track from a CAVS video file into an OGA container using the Vorbis codec — a fully open, royalty-free audio format ideal for archiving or streaming audio from Chinese broadcast content. This tool strips the video entirely and re-encodes the AAC audio stream to Vorbis, delivering a compact, widely supported OGA file directly in your browser.
to
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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Free — no uploads, no signups. Your files never leave your browser.
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 typically carry AAC audio alongside a CAVS/AVS video stream. Since OGA is a pure audio container (based on Ogg) with no support for video, the video stream is completely discarded during this conversion — not remuxed, simply dropped. The AAC audio is decoded and then re-encoded from scratch using the libvorbis encoder into a Vorbis stream, which is then wrapped in an Ogg container and saved with the .oga extension. This is a full transcode of the audio: AAC and Vorbis use fundamentally different compression algorithms, so the re-encoding introduces a second generation of lossy compression. The default quality setting (-q:a 4) targets a variable bitrate of roughly 128–160 kbps, which preserves most perceptible audio fidelity from the original AAC track.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool — in this case running as FFmpeg.wasm compiled to WebAssembly and executing entirely inside your browser, with no server involvement. |
-i input.cavs
|
Specifies the input file in CAVS format. FFmpeg will detect the AVS video stream and the AAC audio stream contained within it; both are read, but only the audio will be used in the output. |
-c:a libvorbis
|
Selects the libvorbis encoder for the audio output stream. This re-encodes the decoded AAC audio from the CAVS file into Vorbis, the open and royalty-free audio codec used natively in Ogg containers like OGA. |
-q:a 4
|
Sets the Vorbis variable bitrate quality level to 4 on a 0–10 scale, which targets approximately 128–160 kbps. This is a balanced default for broadcast speech and music content extracted from CAVS files, preserving good perceptible fidelity without excessive file size. |
output.oga
|
Defines the output filename with the .oga extension, which signals to both FFmpeg and downstream media players that this is an audio-only Ogg container. FFmpeg automatically wraps the Vorbis stream in the Ogg container format based on this extension. |
Common Use Cases
- Extracting dialogue or commentary audio from CAVS broadcast recordings for transcription or translation work
- Pulling background music or sound effects out of CAVS video clips for use in open-source or Creative Commons media projects where Vorbis is preferred over AAC due to its patent-free status
- Converting CAVS-encoded Chinese television or streaming content into OGA files for playback in Ogg-native audio players on Linux desktops
- Archiving the audio portion of Chinese broadcast media in an open format that does not require proprietary codecs or licensing to decode
- Preparing audio content from CAVS source files for upload to platforms or CMS systems that accept Ogg Vorbis but not AAC or CAVS
- Reducing storage size for a collection of CAVS recordings where only the audio is needed long-term, discarding the large video stream entirely
Frequently Asked Questions
Yes, there is a small additional quality loss because this conversion involves two generations of lossy compression: the original CAVS file already has AAC audio encoded with lossy compression, and re-encoding that decoded audio into Vorbis introduces further artifacts. However, at the default quality setting of -q:a 4, the Vorbis output targets roughly 128–160 kbps variable bitrate, which is sufficient to preserve most perceptible fidelity for speech and typical broadcast audio. The difference is usually imperceptible unless the source AAC was encoded at a very low bitrate to begin with.
OGA and OGG use the same underlying Ogg container format — the difference is purely in the file extension convention. The .oga extension was formally defined to specifically indicate an audio-only Ogg file, distinguishing it from .ogv (Ogg video) and .ogg (which historically was used for everything). Using .oga makes it immediately clear to media players and file managers that the file contains only audio, which can improve playback compatibility on players that inspect extensions.
OGA (Ogg) technically supports chapter metadata via Vorbis Comment tags, so the container is capable of storing chapter information. However, CAVS files rarely carry structured chapter data in the first place, and the FFmpeg command used here does not explicitly map or write chapter metadata. In practice, the output OGA file will not contain chapters unless they were explicitly present and mapped in a customized command.
The -q:a flag controls Vorbis quality on a scale from 0 (lowest, ~64 kbps) to 10 (highest, ~500 kbps), with 4 as the default (roughly 128–160 kbps). To increase quality, replace 4 with a higher number, for example: ffmpeg -i input.cavs -c:a libvorbis -q:a 7 output.oga. For archival purposes where maximum fidelity matters, -q:a 8 or -q:a 9 is a common choice. Keep in mind that going above the bitrate of the original AAC source will not recover lost detail.
Yes — OGA supports FLAC as an audio codec, which would avoid the second generation of lossy compression. You can modify the FFmpeg command to: ffmpeg -i input.cavs -c:a flac output.oga. Be aware that since the source AAC audio is already lossy, the FLAC output will be a lossless copy of an already-compressed signal — not a restoration of the original uncompressed audio. The file will be significantly larger than the Vorbis version but will introduce no additional quality degradation.
Yes. On Linux or macOS, you can use a shell loop: for f in *.cavs; do ffmpeg -i "$f" -c:a libvorbis -q:a 4 "${f%.cavs}.oga"; done. On Windows Command Prompt, use: for %f in (*.cavs) do ffmpeg -i "%f" -c:a libvorbis -q:a 4 "%~nf.oga". The browser-based tool on this page processes one file at a time, so the FFmpeg command is particularly valuable for batch workflows involving many CAVS files or files larger than 1GB.
Technical Notes
CAVS (Chinese Audio Video Standard) is a niche format primarily used in Chinese broadcast and media contexts, and it is not as universally supported as H.264/MP4. The audio track in CAVS files is typically AAC, which is a lossy codec using psychoacoustic modeling quite different from Vorbis. When converting to OGA, the AAC stream must be fully decoded to PCM and then re-encoded with libvorbis — there is no way to copy the stream directly because the two codecs are incompatible. OGA's Ogg container supports Vorbis Comment metadata tags, so any title, artist, or album metadata present in the CAVS file may be partially preserved depending on how the source file was authored, but CAVS files from broadcast sources often carry minimal metadata. OGA does not support video, multiple audio tracks, or subtitle streams, so all of those are dropped silently. One notable feature of Vorbis is its fully open, patent-unencumbered status, making OGA/Vorbis a preferred output format in environments that avoid proprietary codecs like AAC. The libvorbis encoder's variable bitrate mode (used by -q:a) generally produces better quality-per-bit than constant bitrate encoding for this type of content.