Supported Video Formats

Which files this app can read, which engine handles each format, what it can write, and what the person you send it to can play. Everything runs in your browser; nothing is uploaded.

Two engines, and two different questions

The app has two engines. Mediabunny uses your browser's built-in decoders and encoders (WebCodecs) and is fast. FFmpeg.wasm reads many more formats but runs on the CPU, single-threaded, and is much slower. Mediabunny is always tried first.

"We can convert it" and "the recipient can play it" are separate answers. MP4 can hold Dolby Digital, Opus or HEVC, and the app can write them, but many phones, browsers and TVs will not play them. The output tables below rate both. For sharing, H.264 video with AAC audio in MP4 is the safe choice.

Containers (file types) the app reads

The answers are for a file with H.264 video and AAC audio inside; the codec tables below cover the rest.

Container	Extensions	Read by	What happens
MP4	.mp4 .m4v	Mediabunny	WebCodecsMediabunny (WebCodecs) does the whole job.
MOV	.mov	Mediabunny	WebCodecsMediabunny (WebCodecs) does the whole job.
MKV	.mkv	Mediabunny	WebCodecsMediabunny (WebCodecs) does the whole job.
WebM	.webm	Mediabunny	WebCodecsMediabunny (WebCodecs) does the whole job.
MPEG-TS	.ts .mts .m2ts	Mediabunny	WebCodecsMediabunny (WebCodecs) does the whole job.
Oggaudio file	.ogg .ogv	Mediabunny	WebCodecsMediabunny (WebCodecs) does the whole job.Needs the upload box to accept the file first.
WAVaudio file	.wav	Mediabunny	WebCodecsMediabunny (WebCodecs) does the whole job.Needs the upload box to accept the file first.
MP3audio file	.mp3	Mediabunny	WebCodecsMediabunny (WebCodecs) does the whole job.Needs the upload box to accept the file first.
FLACaudio file	.flac	Mediabunny	WebCodecsMediabunny (WebCodecs) does the whole job.Needs the upload box to accept the file first.
AAC (ADTS)audio file	.aac	Mediabunny	WebCodecsMediabunny (WebCodecs) does the whole job.Needs the upload box to accept the file first.
AVI	.avi	FFmpeg.wasm only	FFmpeg prepares, WebCodecs does the restFFmpeg repacks the container (seconds, no re-encode), then Mediabunny (WebCodecs) does the rest.
WMV / ASF	.wmv .asf	FFmpeg.wasm only	FFmpeg prepares, WebCodecs does the restFFmpeg repacks the container (seconds, no re-encode), then Mediabunny (WebCodecs) does the rest.
FLV	.flv	FFmpeg.wasm only	FFmpeg prepares, WebCodecs does the restFFmpeg repacks the container (seconds, no re-encode), then Mediabunny (WebCodecs) does the rest.
MPEG-PS (VOB)	.vob .mpg .mpeg	FFmpeg.wasm only	FFmpeg prepares, WebCodecs does the restFFmpeg repacks the container (seconds, no re-encode), then Mediabunny (WebCodecs) does the rest.

Video codecs the app reads

"Convert" is a plain conversion to H.264 MP4. "With effects" is a tool with a feature only the WebCodecs path has (soft-edged blur, face blur, background removal, burned-in captions).

Codec	Decoded by	What happens
H.264, H.265 (HEVC), VP9, VP8	The browser (WebCodecs), through Mediabunny	Convert: WebCodecs. With effects: WebCodecs. If the browser cannot decode it Convert: FFmpeg.wasm. FFmpeg.wasm does the whole job on the CPU. With effects: FFmpeg prepares, WebCodecs does the rest. FFmpeg decodes the video once into a near-lossless intermediate copy, then Mediabunny (WebCodecs) does the rest. The intermediate copy is a CPU encode: one to three times the length of the video at 1080p on a recent laptop, less for smaller videos; the app shows its estimate when the conversion starts.
AV1	The browser (WebCodecs), through Mediabunny	Convert: WebCodecs. With effects: WebCodecs. If the browser cannot decode it Convert: Not possible. This video is AV1, which this browser cannot decode, and the FFmpeg engine in this app has no AV1 decoder either. Open the file in a browser that decodes AV1 (recent Chrome, Edge or Firefox), or convert it with a desktop app. With effects: Not possible. This video is AV1, which this browser cannot decode, and the FFmpeg engine in this app has no AV1 decoder either. Open the file in a browser that decodes AV1 (recent Chrome, Edge or Firefox), or convert it with a desktop app.
ProRes	Mediabunny, with a WebAssembly decoder downloaded on first use	Convert: WebCodecs. With effects: WebCodecs.
MPEG-1, MPEG-2, MPEG-4 Part 2 (Xvid / DivX), MPEG-4 (Microsoft), MPEG-4 (DivX 3), WMV 7, WMV 8, WMV 9, VC-1, H.263, Sorenson Spark, Motion JPEG, Theora, DV, Cinepak, Uncompressed video, HuffYUV, FFV1, Sorenson Video, Sorenson Video 3, Indeo, VP6 (Flash)	FFmpeg.wasm only	Convert: FFmpeg.wasm. FFmpeg.wasm does the whole job on the CPU. With effects: FFmpeg prepares, WebCodecs does the rest. FFmpeg decodes the video once into a near-lossless intermediate copy, then Mediabunny (WebCodecs) does the rest. The intermediate copy is a CPU encode: one to three times the length of the video at 1080p on a recent laptop, less for smaller videos; the app shows its estimate when the conversion starts.

Audio codecs the app reads

"Convert" is a conversion to H.264 + AAC MP4 of a video with this audio; "Extract audio" is Extract Audio to M4A.

Codec	Decoded by	What happens
AAC	The browser (WebCodecs), through Mediabunny	Convert: WebCodecs. Extract audio: WebCodecs. If the browser cannot decode it Convert: WebCodecs. Extract audio: FFmpeg prepares, WebCodecs does the rest. FFmpeg decodes the audio to uncompressed PCM, then Mediabunny (WebCodecs) does the rest.
Opus, MP3, Vorbis, FLAC	The browser (WebCodecs), through Mediabunny	Convert: WebCodecs. Extract audio: WebCodecs. If the browser cannot decode it Convert: FFmpeg prepares, WebCodecs does the rest. FFmpeg decodes the audio to uncompressed PCM, then Mediabunny (WebCodecs) does the rest. Extract audio: FFmpeg prepares, WebCodecs does the rest. FFmpeg decodes the audio to uncompressed PCM, then Mediabunny (WebCodecs) does the rest.
Dolby Digital (AC-3), Dolby Digital Plus (E-AC-3), DTS	Mediabunny, with a WebAssembly decoder downloaded on first use	Convert: WebCodecs. Extract audio: WebCodecs.
PCM (uncompressed, incl. µ-law / A-law)	Mediabunny itself	Convert: WebCodecs. Extract audio: WebCodecs.
MP2, MP1, Dolby TrueHD, MLP, ALAC (Apple Lossless), WMA, WMA Pro, WMA Lossless, WMA Voice, AMR, AMR-WB, RealAudio, ATRAC3, Nellymoser, Speex, GSM, QDesign, Monkey's Audio, True Audio (TTA), WavPack	FFmpeg.wasm only	Convert: FFmpeg prepares, WebCodecs does the rest. FFmpeg decodes the audio to uncompressed PCM, then Mediabunny (WebCodecs) does the rest. Extract audio: FFmpeg prepares, WebCodecs does the rest. FFmpeg decodes the audio to uncompressed PCM, then Mediabunny (WebCodecs) does the rest.

What the app writes, and what plays where

Playability is a conservative summary of common support, not a guarantee for one device. H.265 (HEVC), VP9, AV1 output needs a browser that can encode it with WebCodecs: the FFmpeg engine in this app cannot encode them. The Video Info page lists the exact encoder configurations this browser accepts.

Container	Video codecs	Audio codecs
MP4written by Mediabunny	H.264 (WebCodecs, or FFmpeg.wasm where the browser cannot): plays almost everywhere. H.265 (HEVC) (WebCodecs only (depends on the browser)): plays in some places.HEVC (H.265) plays on Apple devices, but often not on Windows without the HEVC extension, on older Android phones or in some browsers. VP8 (WebCodecs, or FFmpeg.wasm where the browser cannot): plays in some places. VP9 (WebCodecs only (depends on the browser)): plays in some places.VP9 in MP4 plays in Chrome and Firefox but not in QuickTime or on many TVs. AV1 (WebCodecs only (depends on the browser)): plays in some places.AV1 needs a recent browser or device; older iPhones and many TVs do not play it.	AAC: plays almost everywhere. MP3: plays in most places.MP3 audio in MP4 plays in current browsers and common players, but some devices, editors and upload sites expect AAC. Opus: plays in some places.Opus audio in MP4 does not play on older iPhones, in QuickTime or in many editors; AAC is the safe choice. Vorbis: often does not play.Vorbis audio in MP4 commonly does not play; AAC is the safe choice.
WebMwritten by Mediabunny	VP8 (WebCodecs, or FFmpeg.wasm where the browser cannot): plays almost everywhere. VP9 (WebCodecs only (depends on the browser)): plays almost everywhere. AV1 (WebCodecs only (depends on the browser)): plays in some places.AV1 needs a recent browser or device; older iPhones and many TVs do not play it.	Opus: plays almost everywhere. Vorbis: plays in some places.Vorbis audio in WebM plays in Chrome and Firefox; Opus is the safer choice.
MOVwritten by Mediabunny	H.264 (WebCodecs, or FFmpeg.wasm where the browser cannot): plays almost everywhere. H.265 (HEVC) (WebCodecs only (depends on the browser)): plays in some places.HEVC (H.265) plays on Apple devices, but often not on Windows without the HEVC extension, on older Android phones or in some browsers. VP8 (WebCodecs, or FFmpeg.wasm where the browser cannot): plays in some places. VP9 (WebCodecs only (depends on the browser)): plays in some places.VP9 in MP4 plays in Chrome and Firefox but not in QuickTime or on many TVs. AV1 (WebCodecs only (depends on the browser)): plays in some places.AV1 needs a recent browser or device; older iPhones and many TVs do not play it.	AAC: plays almost everywhere. MP3: plays in most places.MP3 audio in MP4 plays in current browsers and common players, but some devices, editors and upload sites expect AAC. Opus: plays in some places.Opus audio in MP4 does not play on older iPhones, in QuickTime or in many editors; AAC is the safe choice. Vorbis: often does not play.Vorbis audio in MP4 commonly does not play; AAC is the safe choice.
MKVwritten by Mediabunny	H.264 (WebCodecs, or FFmpeg.wasm where the browser cannot): plays in some places.MKV files do not play on iPhones, iPads or in Safari, and many TVs and apps refuse them. H.265 (HEVC) (WebCodecs only (depends on the browser)): plays in some places.MKV files do not play on iPhones, iPads or in Safari, and many TVs and apps refuse them. VP8 (WebCodecs, or FFmpeg.wasm where the browser cannot): plays in some places.MKV files do not play on iPhones, iPads or in Safari, and many TVs and apps refuse them. VP9 (WebCodecs only (depends on the browser)): plays in some places.MKV files do not play on iPhones, iPads or in Safari, and many TVs and apps refuse them. AV1 (WebCodecs only (depends on the browser)): plays in some places.MKV files do not play on iPhones, iPads or in Safari, and many TVs and apps refuse them.	AAC: plays in some places.MKV files do not play on iPhones, iPads or in Safari, and many TVs and apps refuse them. MP3: plays in some places.MKV files do not play on iPhones, iPads or in Safari, and many TVs and apps refuse them. Opus: plays in some places.MKV files do not play on iPhones, iPads or in Safari, and many TVs and apps refuse them. Vorbis: plays in some places.MKV files do not play on iPhones, iPads or in Safari, and many TVs and apps refuse them.
AVIwritten by FFmpeg.wasm	H.264 (FFmpeg.wasm): plays in some places.AVI is a legacy container: many phones and browsers do not play it.	MP3: plays in some places. AAC: plays in some places.
Animated GIFwritten by FFmpeg.wasm	Animated GIF (no audio)	—

Audio-only files

M4A (AAC): plays almost everywhere.
MP3: plays almost everywhere.
WAV: plays almost everywhere.
FLAC: plays in most places. FLAC plays in current browsers, on Windows, macOS and Android, but some older iPhones, car stereos and players expect MP3 or AAC.

Limits

2.0 GB for anything FFmpeg touches. The app refuses files larger than 2.0 GB when FFmpeg has to open them: that is the largest size it has been checked with end to end (FFmpeg.wasm itself read a 2.4 GB AVI; its memory, not the file size, is the hard limit, see docs/memory-model-2026-10.md). Files over 2 GB in a format the browser cannot read need a desktop converter. The free HandBrake (Windows, macOS, Linux) handles them and is much faster for big files. Files the browser reads itself (MP4, MOV, MKV, WebM with WebCodecs codecs) have no such limit.
Large results. A result is normally kept in memory until you download it, up to 512.0 MB. Desktop Chrome and Edge can save larger results straight to a file on the tool pages; the app says before it starts when a result is too large.
AV1 without a browser decoder. This video is AV1, which this browser cannot decode, and the FFmpeg engine in this app has no AV1 decoder either. Open the file in a browser that decodes AV1 (recent Chrome, Edge or Firefox), or convert it with a desktop app.
H.265 (HEVC), VP9, AV1 output is WebCodecs-only. If this browser cannot encode one of them, the app says so and suggests a codec it can write (H.264 and VP8 always work).
HDR, 10-bit and transparent video are never squeezed through an 8-bit intermediate. This video is HDR and this browser cannot decode its codec. FFmpeg would have to decode it into an 8-bit SDR intermediate copy first, which changes the colours, so this job is not offered for it. A plain conversion without this tool's effects may still work. The same applies to 10-bit colour and to video with a transparent (alpha) channel. HDR is not tone-mapped: the HEVC to MP4 tool explains HDR files rather than converting them.
Subtitle tracks inside the source file are not carried by the WebCodecs path; keeping them needs FFmpeg. The Auto Caption tool can add a new WebVTT track.

How these answers were checked

The tables are generated from the same planner the app runs. On 19 October 2026 we loaded 23 test files (the containers and codecs above, including AVI, WMV, VOB, HDR, ProRes and transparent video) into the main converter, Trim, Blur Video, Auto Caption and Video to Image in Chromium, Chrome, Firefox and WebKit (the engine of Safari). 543 of 552 runs did exactly what these tables say for that browser; the 9 exceptions are known and listed for fixing. A browser without a decoder (HEVC in Chromium and Firefox, for example) gets the answer for that case, which the live check above shows for your browser.

More help

The FAQ explains why some conversions are fast and others slow, and Privacy and How It Works lists what the app downloads, including the FFmpeg engine and the decoder extensions.