🎬 3GP 转 MP4（无损转换）3GP to MP4 Converter
把老式手机、行车记录仪或彩信里的 3GP/3G2 视频转成 MP4：H.264 或 MPEG-4 视频 + AAC 音频的文件直接无损转封装，几秒完成且画质不变；H.263 视频和 AMR 语音等 MP4 不支持的编码会明确提示，文件不上传。Convert 3GP/3G2 videos from older phones, dashcams or MMS messages to MP4. Files with H.264 or MPEG-4 video and AAC audio are remuxed losslessly in seconds with identical quality; codecs MP4 can't hold, such as H.263 video or AMR speech, are clearly flagged. Nothing is uploaded.
使用说明与常见问题How-to & FAQ
「3GP 转 MP4（无损转换）」是什么？What is the 3GP to MP4 Converter tool?
把老式手机、行车记录仪或彩信里的 3GP/3G2 视频转成 MP4：H.264 或 MPEG-4 视频 + AAC 音频的文件直接无损转封装，几秒完成且画质不变；H.263 视频和 AMR 语音等 MP4 不支持的编码会明确提示，文件不上传。Convert 3GP/3G2 videos from older phones, dashcams or MMS messages to MP4. Files with H.264 or MPEG-4 video and AAC audio are remuxed losslessly in seconds with identical quality; codecs MP4 can't hold, such as H.263 video or AMR speech, are clearly flagged. Nothing is uploaded.
如何使用「3GP 转 MP4（无损转换）」？How do I use the 3GP to MP4 Converter tool?
在「3GP 转 MP4（无损转换）」中，选择或拖入文件，然后点击「无损转换为 MP4」、「重新编码（较慢）」、「停止」按钮即可。In the 3GP to MP4 Converter: Choose or drop your files, then click "Convert to MP4 (lossless)", "Re-encode (slow)", "Stop".
为什么转换只要几秒？画质会变差吗？Why does it take only seconds? Is quality lost?
3GP 是为手机制定的 MP4 简化版，文件结构（ISO 基础媒体格式）与 MP4 相同。只要视频是 H.264 或 MPEG-4 Part 2、音频是 AAC，就只需改写文件头和索引，音视频数据原样复制，所以几秒就能完成，画质和音质完全不变。分辨率不会被放大——老手机常见的 176×144 或 320×240 转换后仍是原尺寸。3GP is a phone-oriented subset of MP4 with the same ISO base media structure. If the video is H.264 or MPEG-4 Part 2 and the audio AAC, only the header and index are rewritten and the media data is copied as-is, so it takes seconds and picture and sound are unchanged. Resolution isn't upscaled — the 176×144 or 320×240 typical of old phones stays the same.
哪些 3GP 不能无损转换？Which 3GP files can't be converted losslessly?
很多老手机用 H.263 视频和 AMR 语音音频录制 3GP。这两种编码不在标准 MP4 的支持范围内（例如 ffmpeg 也拒绝把 H.263 直接封装进 MP4），工具会列出具体编码而不是生成一个可能放不出来的文件。浏览器同样无法解码 H.263 和 AMR，所以需要用 ffmpeg、HandBrake 或 VLC 等桌面软件重新编码。Many older phones record 3GP with H.263 video and AMR speech audio. Neither codec is supported in standard MP4 (ffmpeg, for example, refuses to put H.263 straight into MP4), so the tool names the codec instead of producing a file that may not play. Browsers can't decode H.263 or AMR either, so re-encode with desktop software such as ffmpeg, HandBrake or VLC.
MPEG-4 Part 2 视频转换后能播放吗？Will MPEG-4 Part 2 video play after conversion?
MPEG-4 Part 2（mp4v）是 MP4 标准支持的编码，可以无损转换，VLC、Windows 和 macOS 自带播放器以及大多数电视都能播放；但 Chrome、Edge 等浏览器和部分网站不支持它。需要在网页上播放时，可以在支持该编码的浏览器中使用“重新编码”输出 H.264。MPEG-4 Part 2 (mp4v) is a codec the MP4 standard supports, so it converts losslessly and plays in VLC, the built-in Windows and macOS players and most TVs — but Chrome, Edge and some websites don't support it. For web playback, use Re-encode in a browser that can decode it to get H.264.
“快速启动”是什么？3G2 文件可以吗？What is fast start, and do 3G2 files work?
勾选后索引（moov）会移到文件开头，网页和手机可以边下载边播放。3G2 是 CDMA 手机使用的同类格式，结构相同，H.264/MPEG-4 + AAC 的 3G2 也能无损转换；EVRC 或 QCELP 语音音频与 AMR 一样会被提示无法放入 MP4。With fast start the index (moov) moves to the front so web and phone players can stream it. 3G2 is the equivalent format from CDMA phones with the same structure: 3G2 files with H.264/MPEG-4 + AAC convert losslessly too, while EVRC or QCELP speech audio is flagged as unsupported in MP4, just like AMR.
视频会上传到服务器吗？Is my video uploaded?
不会。所有处理都在你的浏览器里完成，文件不会离开你的设备，所以也不受上传大小和网速限制（但受电脑内存和性能限制）。No. Everything runs in your browser and the file never leaves your device, so there are no upload limits or waits — only your computer's memory and speed.
「3GP 转 MP4（无损转换）」免费吗？需要注册吗？Is the 3GP to MP4 Converter free? Do I need an account?
「3GP 转 MP4（无损转换）」完全免费，无需注册或安装，打开网页即可使用，手机和电脑都能用；输入的内容只在你的浏览器本地处理。The 3GP to MP4 Converter is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.