Codec & format support

Every decoder, encoder, demuxer, muxer, and image format compiled into the default wasmpeg build, grouped by family, with how compatibility is measured.

This is the complete list of components compiled into the default LGPL build of wasmpeg, grouped by family. The selection is data-driven — it lives in the lgpl preset in src/cli/configure.mjs — so a custom build may enable more or fewer. To check what a particular binary actually contains, see Configuration & presets.

Use this page the way you’d use FFmpeg’s own -decoders / -formats output: scan for the name you need, confirm which side of the decode/encode line it sits on, and follow through to the compatibility report if you care about bit-exact results. A component being listed here means it’s compiled in — coverage and correctness for a given sample are separate questions answered by the live report.

How to read this page

The build is decode-first, so the lists break down roughly like this:

Category	Coverage in this build
Video / audio / image decoders	Broad — modern web codecs through to a long tail of legacy and game formats
Demuxers (input containers)	Broad — matches the decoder spread
Encoders	Narrow — image codecs plus a handful of audio codecs; no inter-frame video encode
Muxers (output containers)	Narrow — sized to the encoder set

If you only want to know whether wasmpeg can open and read a file, look at the decoder and demuxer sections. If you want to write a file back out, look at the encoder and muxer sections — that’s the smaller side.

Decode-first

wasmpeg is built to get pixels, samples, and metadata out of media. The decoder and demuxer coverage is broad; the encoder and muxer coverage is intentionally narrow (image codecs for thumbnails, a handful of audio codecs). H.264/H.265 decode is in this build; H.264/H.265 encode is GPL-only (wasmpeg-full).

Video decoders

Modern web video

h264 · hevc (H.265) · vp8 · vp9 · av1

The codecs you will hit most often on the web. H.264 and HEVC decode are included here in the LGPL build.

Classic and broadcast

mpeg1video · mpeg2video · mpeg4 · h263 · h261

MPEG-1/2 for DVD and broadcast streams, MPEG-4 Part 2, and the H.26x video-conferencing codecs.

Microsoft

msmpeg4v1 · msmpeg4v2 · msmpeg4v3 · wmv1 · wmv2 · wmv3 · vc1 · mss2

Windows Media Video 7–9, VC-1, and the MS-MPEG4 variants found in older AVI/ASF files.

Apple and QuickTime

prores · qtrle · svq1 · svq3 · rpza · smc

Apple ProRes, QuickTime Animation (RLE), Sorenson Video, and the early QuickTime codecs.

Professional and broadcast

dnxhd (DNxHD/DNxHR) · mjpeg · mjpegb · cfhd (CineForm)

Editing and acquisition codecs used in professional workflows.

Lossless and archival

huffyuv · ffv1 · ffvhuff · utvideo · magicyuv · lagarith · hap

Lossless intermediate and archival codecs. FFV1 is the common choice for preservation.

Screen capture and lossless AVI/MOV

dxtory · fic · fmvc · frwu · mszh · zlib · lscr · rscc · tscc · tscc2 · vble · zerocodec · mwsc · screenpresso · g2meet · mss1 · lead · dxv · aic

TechSmith, Camtasia, and other screen-recording and lossless-ish codecs.

Legacy and game video

theora · vp3 · vp4 · vp5 · vp6 · vp6a · vp6f · vp7 · rv10 · rv20 · rv30 · rv40 · rv60 · flashsv · flashsv2 · cinepak · msvideo1 · fraps · cdxl · flic · zmbv · cllc · hq_hqa · hqx · speedhq · truemotion1 · truemotion2 · truemotion2rt · mimic · mdec · roqvideo · dirac · cavs · smacker · bmv_video · vmdvideo · paf_video · idcin · dsicinvideo · bethsoftvid · bfi · tmv · rl2 · c93 · dfa · fourxm · jv · vb · dxa · kmvc · motionpixels · mvc1 · mvc2 · escape124 · escape130

On2/Truemotion, RealVideo, Sorenson/Flash, id Software, Bink, Smacker, and a long tail of multimedia and game-engine codecs carried for FATE coverage.

Intel, vendor, and miscellaneous

indeo2 · indeo3 · indeo4 · indeo5 · loco · msrle · dvvideo · aura · aura2 · cljr · cyuv · ulti · vcr1 · xl · wnv1 · vqc · xan_wc3 · xan_wc4 · eamad · eatgq · sgirle · nuv · thp · txd · mts2 · avui · avrn · qpeg · sp5x · aasc · ansi · cscd · tdsc · qdraw · pixlet · cdgraphics · brender_pix

Raw packed-pixel

r210 · v210 · v410 · r10k

Uncompressed 10-bit packed formats found in .avi/.mov captures.

Image formats

png · apng · gif · bmp · tiff · webp · tga / targa · dpx · xbm · sunrast · xface · jpeg2000 · jpegls · exr · psd · mjpeg (JPEG)

Still-image decoders. PNG, JPEG, WebP, and GIF cover the common cases; the rest support EXR, Photoshop PSD, JPEG-2000, and legacy raster formats.

Tip

Single-frame images decode most reliably through a file path (createDecoderFile) or by forcing the image2 demuxer — the pipe demuxers can fail to resolve dimensions for a lone image. The high-level decode() handles this for you.

Audio decoders

Modern

aac · aac_latm · opus · mp3 · mp2 · mp1 · vorbis · flac

Surround and professional

ac3 · ac3_fixed · eac3 (E-AC-3) · dca (DTS) · truehd · mlp

Dolby and DTS family, including Dolby TrueHD and Meridian Lossless Packing.

Lossless

alac · wavpack · ape (Monkey’s Audio) · tta · shorten

Microsoft

wmav1 · wmav2 · wmapro · wmalossless · wmavoice

PCM

pcm_s8 · pcm_u8 · pcm_s16le · pcm_s16be · pcm_u16le · pcm_u16be · pcm_s24le · pcm_s24be · pcm_u24le · pcm_u24be · pcm_s32le · pcm_s32be · pcm_u32le · pcm_u32be · pcm_f32le · pcm_f32be · pcm_f64le · pcm_f64be · pcm_mulaw · pcm_alaw · pcm_dvd · pcm_bluray · pcm_vidc

All signed/unsigned/float PCM variants, plus µ-law/A-law and the DVD/Blu-ray packings.

ADPCM

Common: adpcm_ms · adpcm_ima_wav · adpcm_ima_qt · adpcm_swf · adpcm_yamaha · adpcm_thp · adpcm_g726 · adpcm_g726le · adpcm_g722

Game and vendor variants: adpcm_4xm · adpcm_afc · adpcm_dtk · adpcm_ea · adpcm_ea_maxis_xa · adpcm_ea_r1 · adpcm_ea_r2 · adpcm_ea_r3 · adpcm_ima_amv · adpcm_ima_apc · adpcm_ima_dk3 · adpcm_ima_dk4 · adpcm_ima_ea_eacs · adpcm_ima_ea_sead · adpcm_ima_iss · adpcm_ima_oki · adpcm_ima_rad · adpcm_ima_smjpeg · adpcm_ima_ws · adpcm_argo · adpcm_sanyo · adpcm_vima · adpcm_xa · adpcm_sbpro_2 · adpcm_sbpro_3 · adpcm_sbpro_4

DPCM

roq_dpcm · interplay_dpcm · sol_dpcm · xan_dpcm

Speech and telephony

speex · nellymoser · amrnb · amrwb · g722 · g723_1 · g726 · g728 · gsm · gsm_ms · qcelp · sipr · truespeech · dss_sp

Sony, Bink, and niche

atrac1 · atrac3 · atrac3p · imc · cook · ra_144 · ra_288 · twinvq · dolby_e · dst · mpc7 · mpc8 · mace3 · mace6 · binkaudio_dct · binkaudio_rdft · qdm2 · qoa · tak · smackaud · paf_audio · vmdaudio · bmv_audio · dsicinaudio · msnsiren · dsd_lsbf · dsd_msbf

Video encoders

mjpeg · png · gif · bmp · tiff · tga · dpx · huffyuv · ffv1

Image-oriented encoders for thumbnails and frame export, plus two intra-frame video codecs (huffyuv, ffv1) that write one independently-coded frame at a time. There is no inter-frame (P/B-frame) video encoder in the LGPL build; H.264/H.265 encode lives in wasmpeg-full. See the GPL build below.

Audio encoders

aac · opus · flac · mp2 · wavpack · wmav1 · wmav2 · eac3 · ac3_fixed · pcm_s16le · pcm_s24le · pcm_f32le · pcm_mulaw · pcm_alaw · adpcm_ms · adpcm_ima_wav

All of these are FFmpeg built-ins — no external library is linked — which is what keeps the default build LGPL-clean.

The GPL build (wasmpeg-full)

Everything above is the LGPL build. The gpl preset (wasmpeg-full) inherits the entire LGPL component set and extends it; it never drifts from this list because it’s defined as [...lgpl, ...extras] in configure.mjs. The intended extras are H.264 and H.265 encode via libx264 / libx265, which are GPL-licensed external libraries.

Caution

Linking the GPL binary into a closed-source product carries GPL obligations. The libx264 / libx265 encoders are scaffolded in the gpl preset and gated behind the external-lib flags; consult src/cli/configure.mjs and the build docs for the current state before relying on them. Decode coverage is identical between the two builds.

Containers (demuxers)

Major containers

mov (MP4/MOV) · matroska (MKV/WebM) · avi · ogg · asf (WMV/WMA) · flv · rm (RealMedia) · mxf · dv

Audio containers

mp3 · wav · flac · aac · ac3 · eac3 · dts · truehd · mlp · amr · g722 · g723_1 · g726 · gsm · wv (WavPack) · ape · oma (Sony OMA/AA3) · tta · mpc · qcp · vqf · xwma · dsf · shorten · aea · brstm · bfstm

Raw bitstreams

h264 · hevc · h263 · h261 · av1 · ivf · m4v · mpegps · mpegvideo · mpegts · rawvideo · vc1 · vc1t · dnxhd · cavsvideo · dirac · eac3

Image pipes

image2 · image2pipe · image_png_pipe · image_bmp_pipe · image_gif_pipe · image_tiff_pipe · image_webp_pipe · image_j2k_pipe · image_jpeg_pipe · image_jpegls_pipe · image_exr_pipe · image_psd_pipe · image_dpx_pipe · image_tga_pipe · image_xbm_pipe · image_sunrast_pipe · image_xface_pipe

Demuxer naming

The --enable-demuxer= name and the runtime av_find_input_format() name differ for image pipes (image_png_pipe vs png_pipe). See Configuration.

Game and multimedia

bink · binka · cdxl · nuv · thp · txd · mv · apng · dfa · paf · vmd · fits · qoa · bmv · dsicin · smacker · jv · siff · ipmovie · dss · tak · rl2 · c93 · cdg · bethsoftvid · bfi · tmv · mm · idcin · yop · ea · ea_cdata · flic · fourxm · ast · voc · amv · apc · wsvqa · iss · rsd · smjpeg · smush · roq · mve · sol · xa · str · dxa · kvag · apm · alp · pp_bnk · argo_asf · rpl · s337m · g728 · concat · wtv

PCM raw demuxers

Output containers (muxers)

mp4 · webm · ogg · matroska · avi · flv · asf · mpegts · wav · flac · ac3 · adts · opus · truehd · image2 · image2pipe · mjpeg · apng · gif · webp · null · pcm_s16le · pcm_f32le · pcm_mulaw · pcm_alaw

Note

Muxers are used by the encoder for image and audio output. image2pipe is the default for in-memory image encode — image2 expects numbered files on a real filesystem.

Measuring compatibility

wasmpeg is tracked against FFmpeg’s FATE sample suite on two axes:

Coverage — does a sample decode without erroring? Generated by tests/compat.mjs into COMPAT.md.
Correctness — does the decode match FFmpeg byte-for-byte? Each frame’s checksum is compared against FFmpeg’s own vendored reference output by tests/fate.mjs into CORRECTNESS.md.

Correctness is the number that matters: not “does it run,” but “does it produce the exact right pixels.” See the live Compatibility page for the current overall figures and a per-codec breakdown, charted from those reports.

Requesting a codec

If a format does not content-probe, force its demuxer with decode(input, { format }). If a codec is genuinely not in your build, decoding fails with AVERROR_DECODER_NOT_FOUND; add it to a preset and rebuild per Configuration.