Convert 3GP to MTS — Free Online Tool
Convert 3GP mobile video files to MTS (AVCHD) format, re-encoding the low-bandwidth H.264 or MJPEG video from your mobile container into a full H.264 stream inside an MPEG-2 Transport Stream — the same container used by Sony and Panasonic camcorders. This is especially useful when you need to bring older mobile footage into a camcorder-based editing workflow that expects AVCHD-compliant files.
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FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
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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
3GP is a stripped-down multimedia container built for 3G mobile devices, typically carrying H.264 or MJPEG video and AAC or MP3 audio at low bitrates optimized for constrained bandwidth. MTS is the AVCHD container format — an MPEG-2 Transport Stream (.mts) carrying H.264 video and AAC or AC-3 audio — designed for broadcast-quality camcorder recordings. Because both formats use H.264 video, you might expect a simple remux, but 3GP's H.264 streams often use mobile-specific encoding profiles, level constraints, and scaling that are incompatible with AVCHD's stricter transport stream packetization. This tool therefore fully re-encodes the video using libx264 with CRF 23 and re-encodes the audio as AAC at 128k — a significant step up from the typical 64k audio bitrate found in 3GP files. The special scale filter from the 3GP input side (ensuring even pixel dimensions) is applied during encoding to prevent artifacts, and the output is wrapped in a proper MPEG-2 Transport Stream container that camcorder-aware editing software can ingest.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg binary — the open-source multimedia processing engine that powers this conversion. In the browser, this runs as a WebAssembly build (FFmpeg.wasm) with no server upload required. |
-i input.3gp
|
Specifies the input file in 3GP format — a mobile multimedia container that FFmpeg demuxes to extract the raw H.264 or MJPEG video stream and the AAC or MP3 audio stream for re-encoding. |
-c:v libx264
|
Re-encodes the video stream using the libx264 encoder, producing H.264 video suitable for the MPEG-2 Transport Stream container. This is necessary because the 3GP's mobile-profile H.264 stream is not directly compatible with AVCHD transport stream packetization. |
-c:a aac
|
Re-encodes the audio using FFmpeg's native AAC encoder, producing an AAC audio stream compatible with the MTS/AVCHD container. The 3GP source may carry AAC at very low bitrates, so this re-encodes it at the higher 128k default specified separately. |
-crf 23
|
Sets the Constant Rate Factor for the libx264 video encoder to 23 — a perceptually balanced quality level. Since 3GP source material is already low-bitrate, CRF 23 preserves available detail without wasteful over-encoding; lower values like 18 can be used if you want to minimize additional compression loss. |
-b:a 128k
|
Sets the output AAC audio bitrate to 128 kilobits per second — double the typical 64k audio found in 3GP files. This higher bitrate produces a more broadcast-suitable audio stream in the MTS output and avoids compounding quality loss from re-encoding the already-compressed mobile audio. |
output.mts
|
Defines the output filename with the .mts extension, which FFmpeg uses to select the MPEG-2 Transport Stream muxer — the container format used by Sony and Panasonic AVCHD camcorders that wraps the H.264 video and AAC audio streams. |
Common Use Cases
- Importing old 3G-era mobile phone footage into Sony Vegas, Premiere Pro, or Final Cut Pro projects that use an AVCHD-based media structure and expect MTS files
- Archiving 3GP clips from legacy Nokia, Samsung, or early Android phones into a format compatible with Sony or Panasonic camcorder backup software and disc authoring tools
- Combining mobile-shot 3GP clips with AVCHD footage from a camcorder so all files share the same container and codec profile for a seamless multi-source edit
- Upscaling audio quality from the low-bitrate AAC or MP3 tracks common in 3GP files to 128k AAC inside a proper transport stream for a more broadcast-suitable deliverable
- Converting 3GP footage captured on embedded or IoT cameras — which often default to 3GP output — into MTS for integration with professional video archival or surveillance review systems that parse AVCHD
- Preparing mobile video clips for playback on Sony camcorder LCD preview screens or through HDMI output, which may require AVCHD-formatted MTS files on a compatible card structure
Frequently Asked Questions
No — because 3GP files are encoded at low bitrates suited for mobile networks, the source quality is already limited. Re-encoding to MTS with CRF 23 preserves as much of that source detail as possible without inventing information that was never there. You may notice cleaner color grading and fewer container-related playback issues, but the underlying resolution and detail from the original 3GP recording cannot be recovered. For the best results, use a low CRF value (closer to 18) to avoid adding compression artifacts on top of the existing ones.
3GP files typically carry AAC or MP3 audio at 64k or lower, which was standard for 3G mobile transmission. The MTS output in this tool defaults to 128k AAC, doubling the audio bitrate. While this cannot restore audio detail lost during the original 3GP encoding, it prevents the additional quality loss that would occur if the already-compressed audio were re-encoded at the same or lower bitrate. The result is a more stable, broadcast-compatible audio stream in the output file.
Yes — MTS files produced with libx264 video and AAC audio inside an MPEG-2 Transport Stream are recognized by most professional NLEs including Sony Vegas Pro, Adobe Premiere Pro, and DaVinci Resolve. However, some AVCHD workflows expect the MTS file to be part of a specific AVCHD folder structure (BDMV/STREAM/) to be auto-detected by media browsers. If your NLE does not recognize the standalone MTS file, try importing it directly using 'File > Import' rather than relying on media browser auto-detection.
No — 3GP does not support subtitles or chapter markers at the container level, so there is nothing to carry forward. MTS (AVCHD) does support subtitles in the transport stream, but since the source 3GP file has no subtitle tracks, the output MTS file will not contain any. If you need to add subtitles, you would need to do so as a separate step after conversion using a tool like MKVToolNix or a subtitle burn-in pass with FFmpeg.
To change video quality, modify the -crf value: lower numbers (e.g., -crf 18) produce higher quality and larger files, while higher numbers (e.g., -crf 28) produce smaller files with more compression. To change audio bitrate, replace -b:a 128k with your preferred value such as 96k, 192k, or 256k. For example, a high-quality version of this command would be: ffmpeg -i input.3gp -c:v libx264 -c:a aac -crf 18 -b:a 192k output.mts. Note that increasing quality beyond what the 3GP source contains will increase file size without a visible improvement.
Yes — on Linux or macOS you can use a shell loop: for f in *.3gp; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "${f%.3gp}.mts"; done. On Windows Command Prompt use: for %f in (*.3gp) do ffmpeg -i "%f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "%~nf.mts". Each file is processed sequentially. The in-browser tool handles single files only, so the FFmpeg command is the recommended path for batch processing large collections of 3GP clips.
Technical Notes
3GP imposes constraints that are important to understand before converting to MTS. Its H.264 streams often use Baseline or Main profile at mobile-tier levels (e.g., Level 3.0 or lower), which limits resolution, frame rate, and reference frames. When re-encoding to MTS, libx264 defaults to a more capable High profile, so the output stream is structurally different even at the same resolution. The MPEG-2 Transport Stream container used by MTS packetizes the bitstream differently from the MP4-derived 3GP container — hence the need for full re-encoding rather than remuxing. The scale filter (trunc(iw/2)*2:trunc(ih/2)*2) inherited from the 3GP input side ensures pixel dimensions are always even numbers, which is a hard requirement for H.264 encoding and prevents green-line artifacts on odd-resolution 3GP sources. Metadata such as creation date, GPS location tags, and device information stored in the 3GP's moov atom will not be transferred to the MTS output, as the AVCHD transport stream uses a different metadata scheme. If metadata preservation is critical, extract it with a tool like ExifTool before conversion. The output MTS file will not be embedded in an AVCHD folder hierarchy, so camcorder firmware that strictly validates the BDMV structure will not auto-detect it, though NLEs will import it directly without issue.