Online Audio & Video Tools

Container, codec, and which one you are changing

MP4, MOV and WebM are containers: the wrapper that holds streams and timing. H.264, AV1, AAC and Opus are codecs: how the picture and sound inside are compressed. Most confusion about video conversion comes from treating the file extension as if it described both. Where the streams inside a file are already acceptable to the target container, changing the wrapper copies them across untouched, which is quick and lossless. Changing the codec is a re-encode, and re-encoding already-compressed material always throws away a little more than the previous pass did.

That is the rule to carry through the rest of these tools. Video converter and audio converter handle the general case; MP4 to MOV and MP3 to M4A are the two specific swaps people ask for most. Trimming video or audio, removing the audio track and pulling the audio out as MP3 change no picture data at all. The video compressor is the one that deliberately does, and it is worth compressing from your highest-quality source rather than from a file that has already been through an export.

Stills, GIFs and animation

Extract a single frame or every frame as images when you need stills. For a short looping clip, video to GIF is the format everything accepts, but GIF holds only 256 colours per frame and its transparency is a single on/off palette entry, so gradients band and the files get large fast. Video to animated WebP is usually much smaller at the same length and colour depth, where the destination supports it.

Subtitles and transcripts

SRT carries timings and plain text. WebVTT is the format a browser accepts in a <track> element. ASS and SSA add positioning, fonts and styling, so converting one of those down to SRT loses the styling permanently. The subtitle converter moves between them, the shifter fixes a file that runs early or late, the merger combines two language tracks, and the quality checker catches lines that are too long or held on screen too briefly to read. Subtitles to plain text and transcript to subtitles convert between the timed and untimed forms.

Everything else here uses FFmpeg compiled to WebAssembly, running on your CPU without the hardware encoder your operating system would normally reach for. Nothing is uploaded and there is no size limit, but a long, high-resolution encode takes the time it takes. Trim first, then convert.