🎬 音视频工具Video & Audio
MP4 转 MP3（视频提取音频）MP4 to MP3 Converter
从 MP4、MOV、WebM、MKV 等视频中提取声音并保存为 MP3：可选 128–320 kbps 码率、立体声或单声道，可截取开始和结束时间，还能写入标题和歌手标签；解码和编码都在浏览器本地完成。Extract the soundtrack from MP4, MOV, WebM, MKV and other videos and save it as MP3 — 128–320 kbps, stereo or mono, optional start/end trim and title/artist tags. Decoding and encoding both run locally in your browser.
MOV 转 MP4（无损转换）MOV to MP4 Converter
把 iPhone、相机或 QuickTime 的 MOV 视频转成 MP4：H.264/HEVC + AAC 的文件直接无损转封装，几秒完成且画质不变，可选“快速启动”让网页和手机边下边播；ProRes 等不兼容编码会提示并可改为重新编码。Convert MOV videos from iPhones, cameras or QuickTime to MP4. H.264/HEVC + AAC files are remuxed losslessly in seconds with identical quality, with optional fast start for streaming on the web and phones; incompatible codecs such as ProRes are flagged, with a re-encode option.
视频转 GIF 动图Video to GIF Converter
把 MP4、MOV、WebM 视频片段做成 GIF 动图：在预览中定位开始时间，设置时长（最长 30 秒）、帧率、宽度和播放速度，可选全局调色板减少闪烁、是否循环；逐帧精确截取，在浏览器本地生成。Turn a clip of an MP4, MOV or WebM video into an animated GIF — pick the start in the preview, then set length (up to 30 s), frame rate, width and speed, with an optional global palette to reduce flicker and loop on/off. Frames are captured precisely and the GIF is built locally.
视频压缩（减小视频文件大小）Video Compressor
在浏览器里压缩 MP4、MOV、WebM 视频：可按目标文件大小（例如压到 25 MB 以内发邮件或聊天）或按画质档位压缩，降低分辨率到 1080p/720p/480p，调整音频码率或去掉声音，还能只截取一段，处理前预估大小。Compress MP4, MOV or WebM videos in your browser — aim for a target file size (e.g. under 25 MB for email or chat) or a quality level, downscale to 1080p/720p/480p, lower the audio bitrate or drop the sound, and optionally keep just one segment, with a size estimate before you start.
视频裁剪（画面裁切）Video Cropper
裁掉视频画面的黑边、水印区域或多余部分：在预览上拖动和缩放裁剪框，或直接输入像素坐标，一键套用 1:1、9:16（抖音/Reels）、16:9、4:5 等比例，同时可截取开始和结束时间，保留声音，本地导出。Crop black bars, a corner or unwanted areas out of a video frame — drag and resize the crop box on the preview or type pixel values, snap to 1:1, 9:16 (TikTok/Reels), 16:9, 4:5 and more, trim start and end, keep the audio, and export locally.
在线录屏（屏幕录制）Online Screen Recorder
直接在浏览器里录制整个屏幕、某个窗口或浏览器标签页，可同时录入系统/标签页声音和麦克风解说，支持暂停继续、画质和帧率选择，录完立即预览并下载 MP4/WebM；无需安装软件、没有水印、不上传。Record your whole screen, a single window or a browser tab right in the browser, with tab/system audio and microphone narration mixed in, pause/resume, and quality and frame-rate options; preview and download MP4/WebM as soon as you stop. No install, no watermark, no upload.
摄像头测试（在线检测）Webcam Test
在线检测电脑或手机摄像头和麦克风是否正常：一键打开实时画面，显示实际分辨率、实测帧率、设备支持的最大分辨率和宽高比，可切换多个摄像头、测试 4K、查看麦克风音量电平、镜像显示并拍照保存。Check that your webcam and microphone work: open a live preview in one click and see the actual resolution, measured frame rate, the maximum resolution the device reports and the aspect ratio. Switch between cameras, test 4K, watch the microphone level meter, mirror the view and save a snapshot.
MP4 转 GIF 动图MP4 to GIF Converter
把 MP4（及 MOV / WebM）视频片段做成 GIF：定位开始时间，设置时长（最长 30 秒）、帧率、宽度和速度，可选全局调色板，浏览器本地生成。Turn an MP4 (or MOV / WebM) clip into an animated GIF - set start, length (up to 30 s), frame rate, width and speed, optional global palette, built locally in your browser.
视频按时间截取（示意）Video Time Clip (demo)
记下开始/结束秒数，生成 ffmpeg 命令示意（不在浏览器内切割大视频）。可设置「开始秒」、「结束秒」、「文件名」。Note start/end seconds and show an ffmpeg command demo (does not cut large videos in-browser). Settings: Start s, End s, Filename.
音频按时间截取（示意）Audio Time Clip (demo)
生成 ffmpeg 音频截取命令示意。可设置「开始秒」、「结束秒」、「文件名」。Show an ffmpeg audio clip command demo. Settings: Start s, End s, Filename.
麦克风测试（在线检测）Mic Test (Online Microphone Test)
在线检测麦克风是否正常：显示实时音量电平（dBFS）和峰值，列出设备名称、采样率和声道数，可切换多个麦克风、开关回声消除和降噪。声音只在本页分析，不录音、不上传。Check that your microphone works: see a live level meter (dBFS) with peak, the device name, sample rate and channels; switch between microphones and toggle echo cancellation and noise suppression. Audio is analysed on this page only - never recorded or uploaded.
裁剪 GIF 动图Crop GIF
裁剪动画 GIF 的每一帧并重新打包（本地，需 Chrome / Edge）。可设置「X」、「Y」、「宽」、「高」。Crop every frame of an animated GIF and re-pack (local; Chrome / Edge). Settings: X, Y, Width, Height.
M4A 转 MP3M4A to MP3 Converter
把 M4A（AAC）音频转换成兼容性最好的 MP3：iPhone 录音、语音备忘录、iTunes 歌曲和播客下载都适用，可选 128–320 kbps（单声道最高 160 kbps）、单声道/立体声、截取片段并写入标题和歌手，全部在浏览器本地完成。Convert M4A (AAC) audio — iPhone recordings, Voice Memos, iTunes tracks and podcast downloads — into universally compatible MP3 at 128–320 kbps (mono up to 160 kbps), mono or stereo, with optional trimming and title/artist tags. Everything runs locally in your browser.
M2TS 转换助手M2TS Converter
生成把 .m2ts / .mts（及 .ts）转成 MP4 的 ffmpeg 命令：可选尝试 -c copy 无损封装，或重编码为 H.264+AAC。浏览器内不解码大视频；命令在你电脑上运行。Build an ffmpeg command to turn .m2ts / .mts (and .ts) into MP4: try -c copy remux, or re-encode to H.264+AAC. The browser does not decode large videos - run the command on your computer.
MP3 转 WAV（也支持 M4A、AAC、OGG、FLAC）MP3 to WAV Converter (also M4A, AAC, OGG, FLAC)
把 MP3、M4A（AAC）、OGG、FLAC 等音频解码为无压缩的 WAV（PCM）：保持原采样率或改为 48 / 44.1 / 22.05 / 16 / 8 kHz，可选 16 位、24 位或 32 位浮点，立体声或单声道，并可截取片段，适合剪辑软件、语音识别和需要 WAV 的设备，全部在浏览器本地完成。Decode MP3, M4A (AAC), OGG, FLAC and other audio into uncompressed WAV (PCM) — keep the original sample rate or pick 48 / 44.1 / 22.05 / 16 / 8 kHz, 16-bit, 24-bit or 32-bit float, stereo or mono, with optional trimming — for editors, speech recognition and devices that need WAV. Everything runs locally in your browser.
在线录音（麦克风录音，可导出 WAV）Online Voice Recorder
用电脑或手机的麦克风在浏览器里直接录音：可选择麦克风、开关降噪和回声消除，录音时显示时长和音量，支持暂停和继续，录完立即试听，下载原始录音（WebM/Opus 或 MP4/AAC）或转换为 WAV，可以连续录多段，录音不会上传。Record from your computer or phone microphone right in the browser — choose the microphone, toggle noise suppression and echo cancellation, watch the timer and level meter, pause and resume, play it back at once and download the original recording (WebM/Opus or MP4/AAC) or a WAV, with several takes in a row. Nothing is uploaded.
音符频率计算器Note Frequency Calculator
根据十二平均律计算任意音符的频率：f = 参考频率 × 2^((n − 69)/12)，n 为 MIDI 音高。选择音名和八度（科学音高记号，A4 = 440 Hz），得到频率、MIDI 编号和声波波长；参考音 A4 可调（如 432 Hz）。Find any note's frequency in equal temperament: f = reference × 2^((n − 69)/12), where n is the MIDI pitch. Pick a note name and octave (scientific pitch notation, A4 = 440 Hz) to get the frequency, MIDI number and sound wavelength; the A4 reference is adjustable (e.g. 432 Hz).
音频文件大小计算器Audio File Size Calculator
估算音频文件大小：压缩格式按 大小 = 比特率 × 时长 ÷ 8（如 MP3 128 kbps）；未压缩 PCM/WAV 按 采样率 × 位深 × 声道数 × 时长 ÷ 8。给出字节、KB/MB（十进制）和 KiB/MiB（二进制）及每分钟大小。Estimate an audio file's size: for compressed formats, size = bitrate × duration ÷ 8 (e.g. MP3 at 128 kbps); for uncompressed PCM/WAV, sample rate × bit depth × channels × duration ÷ 8. Shows bytes, KB/MB (decimal) and KiB/MiB (binary), plus size per minute.
景深计算器Depth of Field Calculator
根据焦距、光圈、对焦距离和画幅（弥散圆）计算景深：给出超焦距、近点、远点和景深范围，以及对焦点前后的景深分布。对焦距离达到或超过超焦距时远点为无穷远。Calculate depth of field from focal length, aperture, focus distance and sensor format (circle of confusion): the hyperfocal distance, near and far limits, total depth of field, and how it splits in front of and behind the focus point. Beyond the hyperfocal distance the far limit is infinity.
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.
MP3 转 OGGMP3 to OGG Converter
把 MP3 转换为 OGG（Ogg Vorbis）：可选音质（约 48–320 kbps）、采样率和单声道，并可截取片段，适合游戏引擎、网页和 Android；在浏览器本地解码和编码，文件不上传。Convert MP3 to OGG (Ogg Vorbis) with a choice of quality (about 48–320 kbps), sample rate and mono, plus optional trimming — handy for game engines, the web and Android. Decoding and encoding run locally in your browser and nothing is uploaded.
WAV 转 OGGWAV to OGG Converter
把无压缩的 WAV 转换为 OGG（Ogg Vorbis），体积通常只有原来的十分之一左右：可选音质、采样率和单声道，并可截取片段；在浏览器本地编码，文件不上传。Convert uncompressed WAV to OGG (Ogg Vorbis), usually around a tenth of the size, with a choice of quality, sample rate and mono plus optional trimming. Encoding runs locally in your browser and nothing is uploaded.
M4A 转 OGGM4A to OGG Converter
把 M4A（AAC，iPhone 录音、iTunes 音乐、语音备忘录等）转换为 OGG（Ogg Vorbis）：可选音质、采样率和单声道，并可截取片段；在浏览器本地解码和编码，文件不上传。受 DRM 保护的 iTunes 歌曲无法转换。Convert M4A (AAC — iPhone recordings, iTunes music, Voice Memos and so on) to OGG (Ogg Vorbis), with a choice of quality, sample rate and mono plus optional trimming. Decoding and encoding run locally in your browser and nothing is uploaded. DRM-protected iTunes songs can't be converted.
提取音频（视频转 MP3）Extract Audio
从视频或音频文件提取音轨并编码为 MP3。本地处理。可设置「码率」、「声道」、「开始（秒或 分:秒）」、「结束」、「标题」。Extract the audio track from video/audio and encode MP3. Processed locally. Settings: Bitrate, Channels, Start (s or m:ss), End, Title.
AAC 转 MP3AAC to MP3 Converter
把 AAC / M4A 音频转成 MP3。本地处理。可设置「码率」、「声道」、「开始（秒或 分:秒）」、「结束」、「标题」。Convert AAC / M4A audio to MP3. Processed locally. Settings: Bitrate, Channels, Start (s or m:ss), End, Title.
AVI 转 MP3AVI to MP3 Converter
从 AVI 视频提取音轨为 MP3。本地处理。可设置「码率」、「声道」、「开始（秒或 分:秒）」、「结束」、「标题」。Extract audio from AVI to MP3. Processed locally. Settings: Bitrate, Channels, Start (s or m:ss), End, Title.
AAC 转 WAVAAC to WAV Converter
把 AAC / M4A 解码为 WAV。本地处理。可设置「采样率」、「位深」、「声道」、「开始（秒或 分:秒）」、「结束」。Decode AAC / M4A to WAV. Processed locally. Settings: Sample rate, Bit depth, Channels, Start (s or m:ss), End.
MOV 转 WAVMOV to WAV Converter
从 MOV 视频提取音轨为 WAV。本地处理。可设置「采样率」、「位深」、「声道」、「开始（秒或 分:秒）」、「结束」。Extract audio from MOV to WAV. Processed locally. Settings: Sample rate, Bit depth, Channels, Start (s or m:ss), End.
MP4 转 OGGMP4 to OGG Converter
从 MP4 提取音轨并编码为 OGG。本地处理。可设置「音质」、「采样率」、「声道」、「开始（秒或 分:秒）」、「结束」。Extract audio from MP4 and encode OGG. Processed locally. Settings: Quality, Sample rate, Channels, Start (s or m:ss), End.
MP4 转 WAVMP4 to WAV Converter
从 MP4（或 M4A、MOV 等）中提取音轨并解码为无压缩 WAV，可选采样率、位深、声道并截取片段；更改设置后旧结果会自动清除。本地处理。Extract the audio track from an MP4 (or M4A, MOV, etc.) and decode it to uncompressed WAV, with sample rate, bit depth, channels and optional trimming; changing a setting clears the old result. Processed locally.