Convert 3GPP to CAVS — Free Online Tool
Convert 3GPP mobile video files to CAVS format using H.264 video and AAC audio encoded directly in your browser. This tool re-encodes the 3GPP stream into the Chinese Audio Video Standard container, making content compatible with CAVS-based broadcast and media systems without any server uploads.
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FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
Drop your 3GPP 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
3GPP files typically contain H.264 or MJPEG video paired with AAC or MP3 audio, optimized for low-bitrate mobile transmission. During this conversion, the video is re-encoded using libx264 with a CRF of 23 — a constant rate factor that balances quality and file size — while the audio is transcoded to AAC at 128k bitrate. Neither stream is simply copied (remuxed); both undergo full re-encoding because the output targets the CAVS container format with specific codec and quality expectations distinct from the mobile-optimized 3GPP profile. The result is a .cavs file using H.264 video and AAC audio that conforms to the Chinese Audio Video Standard, with audio quality stepping up significantly from 3GPP's typical 64k default to the 128k CAVS default.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg program, the open-source multimedia processing engine that handles all decoding, re-encoding, and container muxing for this 3GPP-to-CAVS conversion. |
-i input.3gp
|
Specifies the input 3GPP file. FFmpeg reads the 3GPP container and demuxes the video and audio streams for re-encoding; the .3gp extension signals the mobile multimedia container standardized by the Third Generation Partnership Project. |
-c:v libx264
|
Sets the video encoder to libx264, which re-encodes the 3GPP video stream (originally H.264 Baseline or MJPEG) into H.264 video suitable for the CAVS output container. |
-c:a aac
|
Selects FFmpeg's native AAC encoder to transcode the audio stream from its 3GPP source format (AAC at 64k or MP3) into AAC audio for the CAVS file, which is the only audio codec supported in this output format. |
-crf 23
|
Applies Constant Rate Factor 23 to the libx264 video encode, a mid-range quality setting that balances file size and visual fidelity; this is appropriate for 3GPP source material which is already lossy and may have limited resolution. |
-b:a 128k
|
Sets the AAC audio bitrate to 128 kilobits per second, doubling the 3GPP default of 64k to meet the CAVS format's broadcast-oriented audio quality expectation. |
output.cavs
|
Defines the output filename with the .cavs extension, which tells FFmpeg to mux the re-encoded H.264 video and AAC audio into the Chinese Audio Video Standard container format. |
Common Use Cases
- Preparing mobile-captured 3GPP video footage for submission to Chinese broadcast or media distribution platforms that require CAVS-compliant files
- Upgrading the audio quality of 3GPP recordings from the low-bitrate 64k mobile default to the 128k AAC expected in broadcast-oriented CAVS workflows
- Converting archived 3G-era phone videos into a CAVS format for integration into Chinese national media library systems
- Re-encoding 3GPP clips recorded on older handsets into CAVS for use in Chinese streaming or digital television pipelines
- Producing a CAVS-format reference file from a 3GPP source to verify codec compatibility before a larger batch workflow
Frequently Asked Questions
Yes, some quality loss occurs because both the video and audio streams are fully re-encoded rather than copied. The 3GPP source is often already compressed at low mobile bitrates, so the libx264 encoder at CRF 23 will produce a reasonable output, but cannot recover detail lost in the original 3GPP encoding. If your source 3GPP file was recorded at very low resolution or high compression, the CAVS output will reflect those limitations.
3GPP files are designed for 3G mobile networks and default to 64k AAC audio to keep file sizes small. The CAVS conversion targets 128k AAC by default, which is the standard for broadcast-oriented use cases. This means the audio undergoes transcoding that increases the bitrate, but since 3GPP audio was already lossy-compressed, the perceived improvement depends on the quality of the original recording.
CAVS (Chinese Audio Video Standard) is a Chinese national standard developed as a domestically controlled alternative to H.264/AVC, primarily used in Chinese broadcast, government, and institutional media workflows. If you are submitting video content to a Chinese broadcaster, digital television system, or media archive that mandates CAVS-compliant files, you would need to convert source footage — including 3GPP clips from mobile devices — into this format.
No. Neither 3GPP nor CAVS supports subtitles or chapters in this tool's implementation, and the FFmpeg command does not include any subtitle or chapter mapping flags. If your 3GPP file contains embedded text or chapter data, that metadata will be dropped during conversion.
To change video quality, modify the -crf value: lower numbers (e.g., 18) produce higher quality at larger file sizes, while higher numbers (e.g., 28) reduce quality but shrink the file. To change audio bitrate, replace the -b:a 128k value with an alternative such as 64k, 96k, 192k, or 320k. For example: ffmpeg -i input.3gp -c:v libx264 -c:a aac -crf 18 -b:a 192k output.cavs would produce higher quality video and audio than the default command.
The command shown on this page processes a single file, but you can adapt it for batch processing in a shell script. On Linux or macOS, use: for f in *.3gp; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "${f%.3gp}.cavs"; done. On Windows, a similar loop can be written in PowerShell or a .bat file. Batch processing is especially useful for files over 1GB, which exceed this browser tool's limit.
Technical Notes
3GPP containers support a limited codec profile designed for constrained mobile bandwidth, often carrying H.264 Baseline Profile or MJPEG video alongside low-bitrate AAC or MP3 audio. The CAVS container as implemented here uses libx264 for video encoding and AAC for audio, meaning the conversion is codec-compatible at the encoder level but not a simple remux — full re-encoding is required. One notable limitation is that 3GPP's -movflags +faststart optimization for streaming has no equivalent in CAVS output, so the resulting file is structured for local playback or broadcast ingest rather than progressive web streaming. Neither format supports transparency, subtitles, chapters, or multiple audio tracks, so this conversion preserves only the primary video and audio streams. File size may increase relative to the original 3GPP file because the audio bitrate doubles (64k to 128k default) and the video encoder targets a broader quality envelope than a mobile-optimized 3GPP encode. Users processing files over 1GB should use the displayed FFmpeg command locally rather than the browser-based tool.