Supported formats

This chapter lists what the custom pipeline plays, and what it does not. A source plays when its container, its video track, and its selected audio track all appear below, and the running browser and GPU pass the route’s evidence. A codec whose decoder is a package plays only when the host loaded a decoder package for it. Anything else is ineligible, and the host falls back. HEVC and Dolby Vision support holds the full HEVC and Dolby Vision matrix, and Eligibility and routes the checks, routes, and evidence behind every row.

The pipeline plays a direct-play file over http(s), or a local File the host holds. It does not play live streams, HLS or DASH, or a server transcode.

Containers

PCM in Matroska is 8-bit unsigned, 16, 24, or 32-bit integer in either byte order, or little-endian 32 or 64-bit float. PCM in MP4, M4V, and MOV is 16, 24, or 32-bit integer or 32 or 64-bit float, in either byte order; MOV also carries 8-bit, mu-law, and A-law PCM. PCM in AVI is 8-bit unsigned, little-endian 16, 24, or 32-bit integer or 32 or 64-bit float, mu-law, or A-law, under its own format tag or as the SubFormat of WAVE_FORMAT_EXTENSIBLE, which FFmpeg writes for a layout other than mono or stereo, a rate above 48 kHz, or integer samples wider than 16 bits. FLAC and Vorbis in AVI play when their strf extradata holds the STREAMINFO block or the three Xiph-laced Vorbis headers, as FFmpeg’s muxer writes them. WMA plays from a Matroska A_MS/ACM track and from an AVI or ASF stream, whose WAVEFORMATEX names it by its format tag: 0x0160 WMA v1, 0x0161 WMA v2, 0x0162 WMA Pro, 0x0163 WMA Lossless, and 0x000A WMA Voice, as FFmpeg’s RIFF tags do, under its own tag or as the SubFormat of WAVE_FORMAT_EXTENSIBLE. Any other tag in these containers is refused by its tag. An AVI audio stream whose format tag the fork names no codec for opens codec-less with its tag, in decimal, as its codec ID, as a video stream of an unknown FourCC does, and keeps its packets timed as FFmpeg’s demuxer times them. The rows come from capability/CustomContainerCodecSupport.ts.

AVI plays every packet its indexes list, read as FFmpeg reads them: a stream’s OpenDML index when it has one (its indx super index and the ix## standard index that index locates in each RIFF list), else idx1, which covers only the first RIFF list. An OpenDML file past about 1 GiB, whose later AVIX RIFF lists only the OpenDML indexes cover, therefore plays to its end and seeks there. A video stream that still outruns its index, as in a truncated file or one whose OpenDML index cannot be read in full, is refused rather than stopped where the index ends. MPEG-4 Part 2 in the packed bitstream of DivX 5 and Xvid, which DivX user data ending in p marks, is unpacked to one VOP per packet as FFmpeg’s mpeg4_unpack_bframes filter does. AVI keeps no presentation times, only each chunk’s slot in decode order, so the fork’s AVI demuxer gives H.264 and HEVC packets their pictures’ presentation times from the picture order counts in their slice headers, as FFmpeg does, and B-frames play in order on every browser. The worker restamps MPEG-4 Part 2’s B-VOPs into presentation order itself, as it does for Matroska Video for Windows tracks (see Eligibility and routes). A video stream whose FourCC the fork names no codec for, such as DIV3, MP42, or H263, opens codec-less with its FourCC as its codec ID, so the MPEG-4 decoder package’s route takes it by that FourCC and any other route refuses it by its FourCC. HEVC in AVI plays under the HEVC, H265, hvc1, and hev1 tags, and under the zero tag FFmpeg’s AVI muxer writes unless told one, which the fork recognizes by the parameter sets of the first chunk; FFmpeg, and so Jellyfin, reads such a stream as uncompressed video. MPEG audio, AC-3, and E-AC-3 in AVI play one frame per packet however the muxer cut its chunks: the fork’s AVI demuxer reads a stream’s chunks as one byte stream and splits it into frames, as FFmpeg’s parser does, timing a byte-timed stream’s frames by their byte offsets and a chunk-timed stream’s by their chunk’s time, and drops zero-filled chunks, a leading ID3 tag, and a frame cut short. ASF is read by the fork’s ASF demuxer, as FFmpeg’s asfdec_f.c reads it: the Header Object’s streams, and each media object reassembled from its payloads (compressed payloads and audio spread included), timestamped by its presentation time less the preroll. Those timestamps are in decode order, as FFmpeg reads them and as its muxer writes them, so the worker restamps VC-1, WMV3, and MPEG-4 Part 2 B-frames into presentation order, as for Matroska Video for Windows tracks; H.264 and HEVC in ASF, which the fork would hand on in decode order, are refused. A stream opens by its FourCC or format tag as an AVI stream does: WVC1 and WMVA as VC-1, and WMV3, WMA, and the MPEG-4 Part 2 and MS-MPEG4 FourCCs codec-less, with the FourCC or the tag, in decimal, as its codec ID. A DRM-protected ASF file (a Content Encryption, Extended Content Encryption, or Advanced Content Encryption Object, or a stream flagged as encrypted) is refused, and so is a live broadcast, whose data packets vary in size; WMV1 and WMV2 have no route. MPEG program streams, MPEG-1 system streams and MPEG-2 program streams such as DVD-Video’s VOB files, are read by the fork’s program stream demuxer: MPEG-1 and MPEG-2 video and MPEG audio by their stream IDs, and the AC-3, DTS, and LPCM substreams of private stream 1 as FFmpeg’s mpeg.c numbers them. Its tracks come in the order of their first PES packets, as FFmpeg’s demuxer creates them, and their packets are FFmpeg’s, split as in MPEG-TS and stamped with the PTS of the PES packets they begin in. A picture whose PES packet carries no PTS, as on DVD-Video, which often stamps only the I pictures, is timed by MPEG video’s display order. MPEG audio Layer II (mp2) has no route, and neither does DVD-Video’s LPCM, which Jellyfin names pcm_dvd; subpictures and DVD-Video navigation packets are skipped. A .wma file is audio only, so it falls back to the host as every audio-only file does. An AIFF file opens, but the pipeline plays only sources with video, so AIFF, like every audio-only file, falls back to the host. A track whose edit list Mediabunny cannot honor, as getUnsupportedFeatures() reports, is refused rather than played out of sync.

Video

Every other video codec is not supported, among them WMV1, WMV2, Theora, VVC, ProRes, DNxHD, and Motion JPEG. Eligibility refuses Theora as a known codec with no route (video-codec-without-route), and the others as unsupported (codec-unsupported). WebCodecs is the browser’s own decoder. A GPU decoder package is WGSL a host loads, which decodes on the presenter’s device; it plays only what no native route plays, and the decoder projects in wgpud/ build one for HEVC, MPEG-1 with MPEG-2, VC-1 with WMV3, MPEG-4 Part 2 with H.263 and MS-MPEG4, and JPEG 2000. A package’s frames take the format that holds the stream’s pixel format, so 4:2:2 and 4:4:4 streams keep their chroma. The JPEG 2000 package converts X’Y’Z’ (xyz12le) to R’G’B’ as FFmpeg’s converter does, gamma 2.6, the XYZ to BT.709 matrix, then gamma 1/2.2, and writes it as limited-range BT.709 Y’CbCr at 12-bit 4:4:4, which presents as an untagged SDR stream’s BT.709.

HDR

Audio

Every other audio codec is not supported, among them MP2, ALAC, AMR, and Speex. A source whose selected audio track is not supported does not play through the pipeline. Every route resamples to 48 kHz. The host’s speaker layout setting picks the output layout: auto takes 7.1.4 on a device with 12 channels, 7.1.2 with 10, 7.1 with 8, 5.1 with 6, and stereo below; 5.1.2 and 5.1.4 play only when chosen. Dolby Atmos a package renders as objects plays to the whole layout, or to binaural stereo for headphones when the host asks for it on a stereo output. Every other source plays within the layout’s floor: a three-channel or 5.1 source outputs 5.1, a 7.1 source 7.1, or 5.1 on a 5.1 floor, and everything else downmixes to stereo.

Subtitles

The engine reads no subtitle track and renders no subtitles, and a source’s subtitle tracks never affect its eligibility. The host draws subtitles over the video: style.css keeps the host’s subtitle layers (.videoSubtitles, libass canvases, and other canvases) above the WebGPU canvas.